polyadvent

stb_image.c (227313B)

---

 
 #include "stb_image.h"
 
 #if defined(STBI_ONLY_JPEG) || defined(STBI_ONLY_PNG) || defined(STBI_ONLY_BMP) \
   || defined(STBI_ONLY_TGA) || defined(STBI_ONLY_GIF) || defined(STBI_ONLY_PSD) \
   || defined(STBI_ONLY_HDR) || defined(STBI_ONLY_PIC) || defined(STBI_ONLY_PNM) \
   || defined(STBI_ONLY_ZLIB)
    #ifndef STBI_ONLY_JPEG
    #define STBI_NO_JPEG
    #endif
    #ifndef STBI_ONLY_PNG
    #define STBI_NO_PNG
    #endif
    #ifndef STBI_ONLY_BMP
    #define STBI_NO_BMP
    #endif
    #ifndef STBI_ONLY_PSD
    #define STBI_NO_PSD
    #endif
    #ifndef STBI_ONLY_TGA
    #define STBI_NO_TGA
    #endif
    #ifndef STBI_ONLY_GIF
    #define STBI_NO_GIF
    #endif
    #ifndef STBI_ONLY_HDR
    #define STBI_NO_HDR
    #endif
    #ifndef STBI_ONLY_PIC
    #define STBI_NO_PIC
    #endif
    #ifndef STBI_ONLY_PNM
    #define STBI_NO_PNM
    #endif
 #endif
 
 #if defined(STBI_NO_PNG) && !defined(STBI_SUPPORT_ZLIB) && !defined(STBI_NO_ZLIB)
 #define STBI_NO_ZLIB
 #endif
 
 
 #include <stdarg.h>
 #include <stddef.h> // ptrdiff_t on osx
 #include <stdlib.h>
 #include <string.h>
 #include <limits.h>
 
 #if !defined(STBI_NO_LINEAR) || !defined(STBI_NO_HDR)
 #include <math.h>  // ldexp, pow
 #endif
 
 #ifndef STBI_NO_STDIO
 #include <stdio.h>
 #endif
 
 #ifndef STBI_ASSERT
 #include <assert.h>
 #define STBI_ASSERT(x) assert(x)
 #endif
 
 
 #ifndef _MSC_VER
    #ifdef __cplusplus
    #define stbi_inline inline
    #else
    #define stbi_inline
    #endif
 #else
    #define stbi_inline __forceinline
 #endif
 
 
 #ifdef _MSC_VER
 typedef unsigned short stbi__uint16;
 typedef   signed short stbi__int16;
 typedef unsigned int   stbi__uint32;
 typedef   signed int   stbi__int32;
 #else
 #include <stdint.h>
 typedef uint16_t stbi__uint16;
 typedef int16_t  stbi__int16;
 typedef uint32_t stbi__uint32;
 typedef int32_t  stbi__int32;
 #endif
 
 // should produce compiler error if size is wrong
 typedef unsigned char validate_uint32[sizeof(stbi__uint32)==4 ? 1 : -1];
 
 #ifdef _MSC_VER
 #define STBI_NOTUSED(v)  (void)(v)
 #else
 #define STBI_NOTUSED(v)  (void)sizeof(v)
 #endif
 
 #ifdef _MSC_VER
 #define STBI_HAS_LROTL
 #endif
 
 #ifdef STBI_HAS_LROTL
    #define stbi_lrot(x,y)  _lrotl(x,y)
 #else
    #define stbi_lrot(x,y)  (((x) << (y)) | ((x) >> (32 - (y))))
 #endif
 
 #if defined(STBI_MALLOC) && defined(STBI_FREE) && (defined(STBI_REALLOC) || defined(STBI_REALLOC_SIZED))
 // ok
 #elif !defined(STBI_MALLOC) && !defined(STBI_FREE) && !defined(STBI_REALLOC) && !defined(STBI_REALLOC_SIZED)
 // ok
 #else
 #error "Must define all or none of STBI_MALLOC, STBI_FREE, and STBI_REALLOC (or STBI_REALLOC_SIZED)."
 #endif
 
 #ifndef STBI_MALLOC
 #define STBI_MALLOC(sz)           malloc(sz)
 #define STBI_REALLOC(p,newsz)     realloc(p,newsz)
 #define STBI_FREE(p)              free(p)
 #endif
 
 #ifndef STBI_REALLOC_SIZED
 #define STBI_REALLOC_SIZED(p,oldsz,newsz) STBI_REALLOC(p,newsz)
 #endif
 
 // x86/x64 detection
 #if defined(__x86_64__) || defined(_M_X64)
 #define STBI__X64_TARGET
 #elif defined(__i386) || defined(_M_IX86)
 #define STBI__X86_TARGET
 #endif
 
 #if defined(__GNUC__) && defined(STBI__X86_TARGET) && !defined(__SSE2__) && !defined(STBI_NO_SIMD)
 // gcc doesn't support sse2 intrinsics unless you compile with -msse2,
 // which in turn means it gets to use SSE2 everywhere. This is unfortunate,
 // but previous attempts to provide the SSE2 functions with runtime
 // detection caused numerous issues. The way architecture extensions are
 // exposed in GCC/Clang is, sadly, not really suited for one-file libs.
 // New behavior: if compiled with -msse2, we use SSE2 without any
 // detection; if not, we don't use it at all.
 #define STBI_NO_SIMD
 #endif
 
 #if defined(__MINGW32__) && defined(STBI__X86_TARGET) && !defined(STBI_MINGW_ENABLE_SSE2) && !defined(STBI_NO_SIMD)
 // Note that __MINGW32__ doesn't actually mean 32-bit, so we have to avoid STBI__X64_TARGET
 //
 // 32-bit MinGW wants ESP to be 16-byte aligned, but this is not in the
 // Windows ABI and VC++ as well as Windows DLLs don't maintain that invariant.
 // As a result, enabling SSE2 on 32-bit MinGW is dangerous when not
 // simultaneously enabling "-mstackrealign".
 //
 // See https://github.com/nothings/stb/issues/81 for more information.
 //
 // So default to no SSE2 on 32-bit MinGW. If you've read this far and added
 // -mstackrealign to your build settings, feel free to #define STBI_MINGW_ENABLE_SSE2.
 #define STBI_NO_SIMD
 #endif
 
 #if !defined(STBI_NO_SIMD) && (defined(STBI__X86_TARGET) || defined(STBI__X64_TARGET))
 #define STBI_SSE2
 #include <emmintrin.h>
 
 #ifdef _MSC_VER
 
 #if _MSC_VER >= 1400  // not VC6
 #include <intrin.h> // __cpuid
 static int stbi__cpuid3(void)
 {
    int info[4];
    __cpuid(info,1);
    return info[3];
 }
 #else
 static int stbi__cpuid3(void)
 {
    int res;
    __asm {
       mov  eax,1
       cpuid
       mov  res,edx
    }
    return res;
 }
 #endif
 
 #define STBI_SIMD_ALIGN(type, name) __declspec(align(16)) type name
 
 static int stbi__sse2_available(void)
 {
    int info3 = stbi__cpuid3();
    return ((info3 >> 26) & 1) != 0;
 }
 #else // assume GCC-style if not VC++
 #define STBI_SIMD_ALIGN(type, name) type name __attribute__((aligned(16)))
 
 static int stbi__sse2_available(void)
 {
    // If we're even attempting to compile this on GCC/Clang, that means
    // -msse2 is on, which means the compiler is allowed to use SSE2
    // instructions at will, and so are we.
    return 1;
 }
 #endif
 #endif
 
 // ARM NEON
 #if defined(STBI_NO_SIMD) && defined(STBI_NEON)
 #undef STBI_NEON
 #endif
 
 #ifdef STBI_NEON
 #include <arm_neon.h>
 // assume GCC or Clang on ARM targets
 #define STBI_SIMD_ALIGN(type, name) type name __attribute__((aligned(16)))
 #endif
 
 #ifndef STBI_SIMD_ALIGN
 #define STBI_SIMD_ALIGN(type, name) type name
 #endif
 
 ///////////////////////////////////////////////
 //
 //  stbi__context struct and start_xxx functions
 
 // stbi__context structure is our basic context used by all images, so it
 // contains all the IO context, plus some basic image information
 typedef struct
 {
    stbi__uint32 img_x, img_y;
    int img_n, img_out_n;
 
    stbi_io_callbacks io;
    void *io_user_data;
 
    int read_from_callbacks;
    int buflen;
    stbi_uc buffer_start[128];
 
    stbi_uc *img_buffer, *img_buffer_end;
    stbi_uc *img_buffer_original, *img_buffer_original_end;
 } stbi__context;
 
 
 static void stbi__refill_buffer(stbi__context *s);
 
 // initialize a memory-decode context
 static void stbi__start_mem(stbi__context *s, stbi_uc const *buffer, int len)
 {
    s->io.read = NULL;
    s->read_from_callbacks = 0;
    s->img_buffer = s->img_buffer_original = (stbi_uc *) buffer;
    s->img_buffer_end = s->img_buffer_original_end = (stbi_uc *) buffer+len;
 }
 
 // initialize a callback-based context
 static void stbi__start_callbacks(stbi__context *s, stbi_io_callbacks *c, void *user)
 {
    s->io = *c;
    s->io_user_data = user;
    s->buflen = sizeof(s->buffer_start);
    s->read_from_callbacks = 1;
    s->img_buffer_original = s->buffer_start;
    stbi__refill_buffer(s);
    s->img_buffer_original_end = s->img_buffer_end;
 }
 
 #ifndef STBI_NO_STDIO
 
 static int stbi__stdio_read(void *user, char *data, int size)
 {
    return (int) fread(data,1,size,(FILE*) user);
 }
 
 static void stbi__stdio_skip(void *user, int n)
 {
    fseek((FILE*) user, n, SEEK_CUR);
 }
 
 static int stbi__stdio_eof(void *user)
 {
    return feof((FILE*) user);
 }
 
 static stbi_io_callbacks stbi__stdio_callbacks =
 {
    stbi__stdio_read,
    stbi__stdio_skip,
    stbi__stdio_eof,
 };
 
 static void stbi__start_file(stbi__context *s, FILE *f)
 {
    stbi__start_callbacks(s, &stbi__stdio_callbacks, (void *) f);
 }
 
 //static void stop_file(stbi__context *s) { }
 
 #endif // !STBI_NO_STDIO
 
 static void stbi__rewind(stbi__context *s)
 {
    // conceptually rewind SHOULD rewind to the beginning of the stream,
    // but we just rewind to the beginning of the initial buffer, because
    // we only use it after doing 'test', which only ever looks at at most 92 bytes
    s->img_buffer = s->img_buffer_original;
    s->img_buffer_end = s->img_buffer_original_end;
 }
 
 enum
 {
    STBI_ORDER_RGB,
    STBI_ORDER_BGR
 };
 
 typedef struct
 {
    int bits_per_channel;
    int num_channels;
    int channel_order;
 } stbi__result_info;
 
 #ifndef STBI_NO_JPEG
 static int      stbi__jpeg_test(stbi__context *s);
 static void    *stbi__jpeg_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri);
 static int      stbi__jpeg_info(stbi__context *s, int *x, int *y, int *comp);
 #endif
 
 #ifndef STBI_NO_PNG
 static int      stbi__png_test(stbi__context *s);
 static void    *stbi__png_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri);
 static int      stbi__png_info(stbi__context *s, int *x, int *y, int *comp);
 static int      stbi__png_is16(stbi__context *s);
 #endif
 
 #ifndef STBI_NO_BMP
 static int      stbi__bmp_test(stbi__context *s);
 static void    *stbi__bmp_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri);
 static int      stbi__bmp_info(stbi__context *s, int *x, int *y, int *comp);
 #endif
 
 #ifndef STBI_NO_TGA
 static int      stbi__tga_test(stbi__context *s);
 static void    *stbi__tga_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri);
 static int      stbi__tga_info(stbi__context *s, int *x, int *y, int *comp);
 #endif
 
 #ifndef STBI_NO_PSD
 static int      stbi__psd_test(stbi__context *s);
 static void    *stbi__psd_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri, int bpc);
 static int      stbi__psd_info(stbi__context *s, int *x, int *y, int *comp);
 static int      stbi__psd_is16(stbi__context *s);
 #endif
 
 #ifndef STBI_NO_HDR
 static int      stbi__hdr_test(stbi__context *s);
 static float   *stbi__hdr_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri);
 static int      stbi__hdr_info(stbi__context *s, int *x, int *y, int *comp);
 #endif
 
 #ifndef STBI_NO_PIC
 static int      stbi__pic_test(stbi__context *s);
 static void    *stbi__pic_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri);
 static int      stbi__pic_info(stbi__context *s, int *x, int *y, int *comp);
 #endif
 
 #ifndef STBI_NO_GIF
 static int      stbi__gif_test(stbi__context *s);
 static void    *stbi__gif_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri);
 static void    *stbi__load_gif_main(stbi__context *s, int **delays, int *x, int *y, int *z, int *comp, int req_comp);
 static int      stbi__gif_info(stbi__context *s, int *x, int *y, int *comp);
 #endif
 
 #ifndef STBI_NO_PNM
 static int      stbi__pnm_test(stbi__context *s);
 static void    *stbi__pnm_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri);
 static int      stbi__pnm_info(stbi__context *s, int *x, int *y, int *comp);
 #endif
 
 // this is not threadsafe
 static const char *stbi__g_failure_reason;
 
 STBIDEF const char *stbi_failure_reason(void)
 {
    return stbi__g_failure_reason;
 }
 
 static int stbi__err(const char *str)
 {
    stbi__g_failure_reason = str;
    return 0;
 }
 
 static void *stbi__malloc(size_t size)
 {
     return STBI_MALLOC(size);
 }
 
 // stb_image uses ints pervasively, including for offset calculations.
 // therefore the largest decoded image size we can support with the
 // current code, even on 64-bit targets, is INT_MAX. this is not a
 // significant limitation for the intended use case.
 //
 // we do, however, need to make sure our size calculations don't
 // overflow. hence a few helper functions for size calculations that
 // multiply integers together, making sure that they're non-negative
 // and no overflow occurs.
 
 // return 1 if the sum is valid, 0 on overflow.
 // negative terms are considered invalid.
 static int stbi__addsizes_valid(int a, int b)
 {
    if (b < 0) return 0;
    // now 0 <= b <= INT_MAX, hence also
    // 0 <= INT_MAX - b <= INTMAX.
    // And "a + b <= INT_MAX" (which might overflow) is the
    // same as a <= INT_MAX - b (no overflow)
    return a <= INT_MAX - b;
 }
 
 // returns 1 if the product is valid, 0 on overflow.
 // negative factors are considered invalid.
 static int stbi__mul2sizes_valid(int a, int b)
 {
    if (a < 0 || b < 0) return 0;
    if (b == 0) return 1; // mul-by-0 is always safe
    // portable way to check for no overflows in a*b
    return a <= INT_MAX/b;
 }
 
 // returns 1 if "a*b + add" has no negative terms/factors and doesn't overflow
 static int stbi__mad2sizes_valid(int a, int b, int add)
 {
    return stbi__mul2sizes_valid(a, b) && stbi__addsizes_valid(a*b, add);
 }
 
 // returns 1 if "a*b*c + add" has no negative terms/factors and doesn't overflow
 static int stbi__mad3sizes_valid(int a, int b, int c, int add)
 {
    return stbi__mul2sizes_valid(a, b) && stbi__mul2sizes_valid(a*b, c) &&
       stbi__addsizes_valid(a*b*c, add);
 }
 
 // returns 1 if "a*b*c*d + add" has no negative terms/factors and doesn't overflow
 #if !defined(STBI_NO_LINEAR) || !defined(STBI_NO_HDR)
 static int stbi__mad4sizes_valid(int a, int b, int c, int d, int add)
 {
    return stbi__mul2sizes_valid(a, b) && stbi__mul2sizes_valid(a*b, c) &&
       stbi__mul2sizes_valid(a*b*c, d) && stbi__addsizes_valid(a*b*c*d, add);
 }
 #endif
 
 // mallocs with size overflow checking
 static void *stbi__malloc_mad2(int a, int b, int add)
 {
    if (!stbi__mad2sizes_valid(a, b, add)) return NULL;
    return stbi__malloc(a*b + add);
 }
 
 static void *stbi__malloc_mad3(int a, int b, int c, int add)
 {
    if (!stbi__mad3sizes_valid(a, b, c, add)) return NULL;
    return stbi__malloc(a*b*c + add);
 }
 
 #if !defined(STBI_NO_LINEAR) || !defined(STBI_NO_HDR)
 static void *stbi__malloc_mad4(int a, int b, int c, int d, int add)
 {
    if (!stbi__mad4sizes_valid(a, b, c, d, add)) return NULL;
    return stbi__malloc(a*b*c*d + add);
 }
 #endif
 
 // stbi__err - error
 // stbi__errpf - error returning pointer to float
 // stbi__errpuc - error returning pointer to unsigned char
 
 #ifdef STBI_NO_FAILURE_STRINGS
    #define stbi__err(x,y)  0
 #elif defined(STBI_FAILURE_USERMSG)
    #define stbi__err(x,y)  stbi__err(y)
 #else
    #define stbi__err(x,y)  stbi__err(x)
 #endif
 
 #define stbi__errpf(x,y)   ((float *)(size_t) (stbi__err(x,y)?NULL:NULL))
 #define stbi__errpuc(x,y)  ((unsigned char *)(size_t) (stbi__err(x,y)?NULL:NULL))
 
 STBIDEF void stbi_image_free(void *retval_from_stbi_load)
 {
    STBI_FREE(retval_from_stbi_load);
 }
 
 #ifndef STBI_NO_LINEAR
 static float   *stbi__ldr_to_hdr(stbi_uc *data, int x, int y, int comp);
 #endif
 
 #ifndef STBI_NO_HDR
 static stbi_uc *stbi__hdr_to_ldr(float   *data, int x, int y, int comp);
 #endif
 
 static int stbi__vertically_flip_on_load = 0;
 
 STBIDEF void stbi_set_flip_vertically_on_load(int flag_true_if_should_flip)
 {
     stbi__vertically_flip_on_load = flag_true_if_should_flip;
 }
 
 static void *stbi__load_main(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri, int bpc)
 {
    memset(ri, 0, sizeof(*ri)); // make sure it's initialized if we add new fields
    ri->bits_per_channel = 8; // default is 8 so most paths don't have to be changed
    ri->channel_order = STBI_ORDER_RGB; // all current input & output are this, but this is here so we can add BGR order
    ri->num_channels = 0;
 
    #ifndef STBI_NO_JPEG
    if (stbi__jpeg_test(s)) return stbi__jpeg_load(s,x,y,comp,req_comp, ri);
    #endif
    #ifndef STBI_NO_PNG
    if (stbi__png_test(s))  return stbi__png_load(s,x,y,comp,req_comp, ri);
    #endif
    #ifndef STBI_NO_BMP
    if (stbi__bmp_test(s))  return stbi__bmp_load(s,x,y,comp,req_comp, ri);
    #endif
    #ifndef STBI_NO_GIF
    if (stbi__gif_test(s))  return stbi__gif_load(s,x,y,comp,req_comp, ri);
    #endif
    #ifndef STBI_NO_PSD
    if (stbi__psd_test(s))  return stbi__psd_load(s,x,y,comp,req_comp, ri, bpc);
    #endif
    #ifndef STBI_NO_PIC
    if (stbi__pic_test(s))  return stbi__pic_load(s,x,y,comp,req_comp, ri);
    #endif
    #ifndef STBI_NO_PNM
    if (stbi__pnm_test(s))  return stbi__pnm_load(s,x,y,comp,req_comp, ri);
    #endif
 
    #ifndef STBI_NO_HDR
    if (stbi__hdr_test(s)) {
       float *hdr = stbi__hdr_load(s, x,y,comp,req_comp, ri);
       return stbi__hdr_to_ldr(hdr, *x, *y, req_comp ? req_comp : *comp);
    }
    #endif
 
    #ifndef STBI_NO_TGA
    // test tga last because it's a crappy test!
    if (stbi__tga_test(s))
       return stbi__tga_load(s,x,y,comp,req_comp, ri);
    #endif
 
    return stbi__errpuc("unknown image type", "Image not of any known type, or corrupt");
 }
 
 static stbi_uc *stbi__convert_16_to_8(stbi__uint16 *orig, int w, int h, int channels)
 {
    int i;
    int img_len = w * h * channels;
    stbi_uc *reduced;
 
    reduced = (stbi_uc *) stbi__malloc(img_len);
    if (reduced == NULL) return stbi__errpuc("outofmem", "Out of memory");
 
    for (i = 0; i < img_len; ++i)
       reduced[i] = (stbi_uc)((orig[i] >> 8) & 0xFF); // top half of each byte is sufficient approx of 16->8 bit scaling
 
    STBI_FREE(orig);
    return reduced;
 }
 
 static stbi__uint16 *stbi__convert_8_to_16(stbi_uc *orig, int w, int h, int channels)
 {
    int i;
    int img_len = w * h * channels;
    stbi__uint16 *enlarged;
 
    enlarged = (stbi__uint16 *) stbi__malloc(img_len*2);
    if (enlarged == NULL) return (stbi__uint16 *) stbi__errpuc("outofmem", "Out of memory");
 
    for (i = 0; i < img_len; ++i)
       enlarged[i] = (stbi__uint16)((orig[i] << 8) + orig[i]); // replicate to high and low byte, maps 0->0, 255->0xffff
 
    STBI_FREE(orig);
    return enlarged;
 }
 
 static void stbi__vertical_flip(void *image, int w, int h, int bytes_per_pixel)
 {
    int row;
    size_t bytes_per_row = (size_t)w * bytes_per_pixel;
    stbi_uc temp[2048];
    stbi_uc *bytes = (stbi_uc *)image;
 
    for (row = 0; row < (h>>1); row++) {
       stbi_uc *row0 = bytes + row*bytes_per_row;
       stbi_uc *row1 = bytes + (h - row - 1)*bytes_per_row;
       // swap row0 with row1
       size_t bytes_left = bytes_per_row;
       while (bytes_left) {
          size_t bytes_copy = (bytes_left < sizeof(temp)) ? bytes_left : sizeof(temp);
          memcpy(temp, row0, bytes_copy);
          memcpy(row0, row1, bytes_copy);
          memcpy(row1, temp, bytes_copy);
          row0 += bytes_copy;
          row1 += bytes_copy;
          bytes_left -= bytes_copy;
       }
    }
 }
 
 static void stbi__vertical_flip_slices(void *image, int w, int h, int z, int bytes_per_pixel)
 {
    int slice;
    int slice_size = w * h * bytes_per_pixel;
 
    stbi_uc *bytes = (stbi_uc *)image;
    for (slice = 0; slice < z; ++slice) {
       stbi__vertical_flip(bytes, w, h, bytes_per_pixel); 
       bytes += slice_size; 
    }
 }
 
 static unsigned char *stbi__load_and_postprocess_8bit(stbi__context *s, int *x, int *y, int *comp, int req_comp)
 {
    stbi__result_info ri;
    void *result = stbi__load_main(s, x, y, comp, req_comp, &ri, 8);
 
    if (result == NULL)
       return NULL;
 
    if (ri.bits_per_channel != 8) {
       STBI_ASSERT(ri.bits_per_channel == 16);
       result = stbi__convert_16_to_8((stbi__uint16 *) result, *x, *y, req_comp == 0 ? *comp : req_comp);
       ri.bits_per_channel = 8;
    }
 
    // @TODO: move stbi__convert_format to here
 
    if (stbi__vertically_flip_on_load) {
       int channels = req_comp ? req_comp : *comp;
       stbi__vertical_flip(result, *x, *y, channels * sizeof(stbi_uc));
    }
 
    return (unsigned char *) result;
 }
 
 static stbi__uint16 *stbi__load_and_postprocess_16bit(stbi__context *s, int *x, int *y, int *comp, int req_comp)
 {
    stbi__result_info ri;
    void *result = stbi__load_main(s, x, y, comp, req_comp, &ri, 16);
 
    if (result == NULL)
       return NULL;
 
    if (ri.bits_per_channel != 16) {
       STBI_ASSERT(ri.bits_per_channel == 8);
       result = stbi__convert_8_to_16((stbi_uc *) result, *x, *y, req_comp == 0 ? *comp : req_comp);
       ri.bits_per_channel = 16;
    }
 
    // @TODO: move stbi__convert_format16 to here
    // @TODO: special case RGB-to-Y (and RGBA-to-YA) for 8-bit-to-16-bit case to keep more precision
 
    if (stbi__vertically_flip_on_load) {
       int channels = req_comp ? req_comp : *comp;
       stbi__vertical_flip(result, *x, *y, channels * sizeof(stbi__uint16));
    }
 
    return (stbi__uint16 *) result;
 }
 
 #if !defined(STBI_NO_HDR) || !defined(STBI_NO_LINEAR)
 static void stbi__float_postprocess(float *result, int *x, int *y, int *comp, int req_comp)
 {
    if (stbi__vertically_flip_on_load && result != NULL) {
       int channels = req_comp ? req_comp : *comp;
       stbi__vertical_flip(result, *x, *y, channels * sizeof(float));
    }
 }
 #endif
 
 #ifndef STBI_NO_STDIO
 
 static FILE *stbi__fopen(char const *filename, char const *mode)
 {
    FILE *f;
 #if defined(_MSC_VER) && _MSC_VER >= 1400
    if (0 != fopen_s(&f, filename, mode))
       f=0;
 #else
    f = fopen(filename, mode);
 #endif
    return f;
 }
 
 
 STBIDEF stbi_uc *stbi_load(char const *filename, int *x, int *y, int *comp, int req_comp)
 {
    FILE *f = stbi__fopen(filename, "rb");
    unsigned char *result;
    if (!f) return stbi__errpuc("can't fopen", "Unable to open file");
    result = stbi_load_from_file(f,x,y,comp,req_comp);
    fclose(f);
    return result;
 }
 
 STBIDEF stbi_uc *stbi_load_from_file(FILE *f, int *x, int *y, int *comp, int req_comp)
 {
    unsigned char *result;
    stbi__context s;
    stbi__start_file(&s,f);
    result = stbi__load_and_postprocess_8bit(&s,x,y,comp,req_comp);
    if (result) {
       // need to 'unget' all the characters in the IO buffer
       fseek(f, - (int) (s.img_buffer_end - s.img_buffer), SEEK_CUR);
    }
    return result;
 }
 
 STBIDEF stbi__uint16 *stbi_load_from_file_16(FILE *f, int *x, int *y, int *comp, int req_comp)
 {
    stbi__uint16 *result;
    stbi__context s;
    stbi__start_file(&s,f);
    result = stbi__load_and_postprocess_16bit(&s,x,y,comp,req_comp);
    if (result) {
       // need to 'unget' all the characters in the IO buffer
       fseek(f, - (int) (s.img_buffer_end - s.img_buffer), SEEK_CUR);
    }
    return result;
 }
 
 STBIDEF stbi_us *stbi_load_16(char const *filename, int *x, int *y, int *comp, int req_comp)
 {
    FILE *f = stbi__fopen(filename, "rb");
    stbi__uint16 *result;
    if (!f) return (stbi_us *) stbi__errpuc("can't fopen", "Unable to open file");
    result = stbi_load_from_file_16(f,x,y,comp,req_comp);
    fclose(f);
    return result;
 }
 
 
 #endif //!STBI_NO_STDIO
 
 STBIDEF stbi_us *stbi_load_16_from_memory(stbi_uc const *buffer, int len, int *x, int *y, int *channels_in_file, int desired_channels)
 {
    stbi__context s;
    stbi__start_mem(&s,buffer,len);
    return stbi__load_and_postprocess_16bit(&s,x,y,channels_in_file,desired_channels);
 }
 
 STBIDEF stbi_us *stbi_load_16_from_callbacks(stbi_io_callbacks const *clbk, void *user, int *x, int *y, int *channels_in_file, int desired_channels)
 {
    stbi__context s;
    stbi__start_callbacks(&s, (stbi_io_callbacks *)clbk, user);
    return stbi__load_and_postprocess_16bit(&s,x,y,channels_in_file,desired_channels);
 }
 
 STBIDEF stbi_uc *stbi_load_from_memory(stbi_uc const *buffer, int len, int *x, int *y, int *comp, int req_comp)
 {
    stbi__context s;
    stbi__start_mem(&s,buffer,len);
    return stbi__load_and_postprocess_8bit(&s,x,y,comp,req_comp);
 }
 
 STBIDEF stbi_uc *stbi_load_from_callbacks(stbi_io_callbacks const *clbk, void *user, int *x, int *y, int *comp, int req_comp)
 {
    stbi__context s;
    stbi__start_callbacks(&s, (stbi_io_callbacks *) clbk, user);
    return stbi__load_and_postprocess_8bit(&s,x,y,comp,req_comp);
 }
 
 #ifndef STBI_NO_GIF
 STBIDEF stbi_uc *stbi_load_gif_from_memory(stbi_uc const *buffer, int len, int **delays, int *x, int *y, int *z, int *comp, int req_comp)
 {
    unsigned char *result;
    stbi__context s; 
    stbi__start_mem(&s,buffer,len); 
    
    result = (unsigned char*) stbi__load_gif_main(&s, delays, x, y, z, comp, req_comp);
    if (stbi__vertically_flip_on_load) {
       stbi__vertical_flip_slices( result, *x, *y, *z, *comp ); 
    }
 
    return result; 
 }
 #endif
 
 #ifndef STBI_NO_LINEAR
 static float *stbi__loadf_main(stbi__context *s, int *x, int *y, int *comp, int req_comp)
 {
    unsigned char *data;
    #ifndef STBI_NO_HDR
    if (stbi__hdr_test(s)) {
       stbi__result_info ri;
       float *hdr_data = stbi__hdr_load(s,x,y,comp,req_comp, &ri);
       if (hdr_data)
          stbi__float_postprocess(hdr_data,x,y,comp,req_comp);
       return hdr_data;
    }
    #endif
    data = stbi__load_and_postprocess_8bit(s, x, y, comp, req_comp);
    if (data)
       return stbi__ldr_to_hdr(data, *x, *y, req_comp ? req_comp : *comp);
    return stbi__errpf("unknown image type", "Image not of any known type, or corrupt");
 }
 
 STBIDEF float *stbi_loadf_from_memory(stbi_uc const *buffer, int len, int *x, int *y, int *comp, int req_comp)
 {
    stbi__context s;
    stbi__start_mem(&s,buffer,len);
    return stbi__loadf_main(&s,x,y,comp,req_comp);
 }
 
 STBIDEF float *stbi_loadf_from_callbacks(stbi_io_callbacks const *clbk, void *user, int *x, int *y, int *comp, int req_comp)
 {
    stbi__context s;
    stbi__start_callbacks(&s, (stbi_io_callbacks *) clbk, user);
    return stbi__loadf_main(&s,x,y,comp,req_comp);
 }
 
 #ifndef STBI_NO_STDIO
 STBIDEF float *stbi_loadf(char const *filename, int *x, int *y, int *comp, int req_comp)
 {
    float *result;
    FILE *f = stbi__fopen(filename, "rb");
    if (!f) return stbi__errpf("can't fopen", "Unable to open file");
    result = stbi_loadf_from_file(f,x,y,comp,req_comp);
    fclose(f);
    return result;
 }
 
 STBIDEF float *stbi_loadf_from_file(FILE *f, int *x, int *y, int *comp, int req_comp)
 {
    stbi__context s;
    stbi__start_file(&s,f);
    return stbi__loadf_main(&s,x,y,comp,req_comp);
 }
 #endif // !STBI_NO_STDIO
 
 #endif // !STBI_NO_LINEAR
 
 // these is-hdr-or-not is defined independent of whether STBI_NO_LINEAR is
 // defined, for API simplicity; if STBI_NO_LINEAR is defined, it always
 // reports false!
 
 STBIDEF int stbi_is_hdr_from_memory(stbi_uc const *buffer, int len)
 {
    #ifndef STBI_NO_HDR
    stbi__context s;
    stbi__start_mem(&s,buffer,len);
    return stbi__hdr_test(&s);
    #else
    STBI_NOTUSED(buffer);
    STBI_NOTUSED(len);
    return 0;
    #endif
 }
 
 #ifndef STBI_NO_STDIO
 STBIDEF int      stbi_is_hdr          (char const *filename)
 {
    FILE *f = stbi__fopen(filename, "rb");
    int result=0;
    if (f) {
       result = stbi_is_hdr_from_file(f);
       fclose(f);
    }
    return result;
 }
 
 STBIDEF int stbi_is_hdr_from_file(FILE *f)
 {
    #ifndef STBI_NO_HDR
    long pos = ftell(f);
    int res;
    stbi__context s;
    stbi__start_file(&s,f);
    res = stbi__hdr_test(&s);
    fseek(f, pos, SEEK_SET);
    return res;
    #else
    STBI_NOTUSED(f);
    return 0;
    #endif
 }
 #endif // !STBI_NO_STDIO
 
 STBIDEF int      stbi_is_hdr_from_callbacks(stbi_io_callbacks const *clbk, void *user)
 {
    #ifndef STBI_NO_HDR
    stbi__context s;
    stbi__start_callbacks(&s, (stbi_io_callbacks *) clbk, user);
    return stbi__hdr_test(&s);
    #else
    STBI_NOTUSED(clbk);
    STBI_NOTUSED(user);
    return 0;
    #endif
 }
 
 #ifndef STBI_NO_LINEAR
 static float stbi__l2h_gamma=2.2f, stbi__l2h_scale=1.0f;
 
 STBIDEF void   stbi_ldr_to_hdr_gamma(float gamma) { stbi__l2h_gamma = gamma; }
 STBIDEF void   stbi_ldr_to_hdr_scale(float scale) { stbi__l2h_scale = scale; }
 #endif
 
 static float stbi__h2l_gamma_i=1.0f/2.2f, stbi__h2l_scale_i=1.0f;
 
 STBIDEF void   stbi_hdr_to_ldr_gamma(float gamma) { stbi__h2l_gamma_i = 1/gamma; }
 STBIDEF void   stbi_hdr_to_ldr_scale(float scale) { stbi__h2l_scale_i = 1/scale; }
 
 
 //////////////////////////////////////////////////////////////////////////////
 //
 // Common code used by all image loaders
 //
 
 enum
 {
    STBI__SCAN_load=0,
    STBI__SCAN_type,
    STBI__SCAN_header
 };
 
 static void stbi__refill_buffer(stbi__context *s)
 {
    int n = (s->io.read)(s->io_user_data,(char*)s->buffer_start,s->buflen);
    if (n == 0) {
       // at end of file, treat same as if from memory, but need to handle case
       // where s->img_buffer isn't pointing to safe memory, e.g. 0-byte file
       s->read_from_callbacks = 0;
       s->img_buffer = s->buffer_start;
       s->img_buffer_end = s->buffer_start+1;
       *s->img_buffer = 0;
    } else {
       s->img_buffer = s->buffer_start;
       s->img_buffer_end = s->buffer_start + n;
    }
 }
 
 stbi_inline static stbi_uc stbi__get8(stbi__context *s)
 {
    if (s->img_buffer < s->img_buffer_end)
       return *s->img_buffer++;
    if (s->read_from_callbacks) {
       stbi__refill_buffer(s);
       return *s->img_buffer++;
    }
    return 0;
 }
 
 stbi_inline static int stbi__at_eof(stbi__context *s)
 {
    if (s->io.read) {
       if (!(s->io.eof)(s->io_user_data)) return 0;
       // if feof() is true, check if buffer = end
       // special case: we've only got the special 0 character at the end
       if (s->read_from_callbacks == 0) return 1;
    }
 
    return s->img_buffer >= s->img_buffer_end;
 }
 
 static void stbi__skip(stbi__context *s, int n)
 {
    if (n < 0) {
       s->img_buffer = s->img_buffer_end;
       return;
    }
    if (s->io.read) {
       int blen = (int) (s->img_buffer_end - s->img_buffer);
       if (blen < n) {
          s->img_buffer = s->img_buffer_end;
          (s->io.skip)(s->io_user_data, n - blen);
          return;
       }
    }
    s->img_buffer += n;
 }
 
 static int stbi__getn(stbi__context *s, stbi_uc *buffer, int n)
 {
    if (s->io.read) {
       int blen = (int) (s->img_buffer_end - s->img_buffer);
       if (blen < n) {
          int res, count;
 
          memcpy(buffer, s->img_buffer, blen);
 
          count = (s->io.read)(s->io_user_data, (char*) buffer + blen, n - blen);
          res = (count == (n-blen));
          s->img_buffer = s->img_buffer_end;
          return res;
       }
    }
 
    if (s->img_buffer+n <= s->img_buffer_end) {
       memcpy(buffer, s->img_buffer, n);
       s->img_buffer += n;
       return 1;
    } else
       return 0;
 }
 
 static int stbi__get16be(stbi__context *s)
 {
    int z = stbi__get8(s);
    return (z << 8) + stbi__get8(s);
 }
 
 static stbi__uint32 stbi__get32be(stbi__context *s)
 {
    stbi__uint32 z = stbi__get16be(s);
    return (z << 16) + stbi__get16be(s);
 }
 
 #if defined(STBI_NO_BMP) && defined(STBI_NO_TGA) && defined(STBI_NO_GIF)
 // nothing
 #else
 static int stbi__get16le(stbi__context *s)
 {
    int z = stbi__get8(s);
    return z + (stbi__get8(s) << 8);
 }
 #endif
 
 #ifndef STBI_NO_BMP
 static stbi__uint32 stbi__get32le(stbi__context *s)
 {
    stbi__uint32 z = stbi__get16le(s);
    return z + (stbi__get16le(s) << 16);
 }
 #endif
 
 #define STBI__BYTECAST(x)  ((stbi_uc) ((x) & 255))  // truncate int to byte without warnings
 
 
 //////////////////////////////////////////////////////////////////////////////
 //
 //  generic converter from built-in img_n to req_comp
 //    individual types do this automatically as much as possible (e.g. jpeg
 //    does all cases internally since it needs to colorspace convert anyway,
 //    and it never has alpha, so very few cases ). png can automatically
 //    interleave an alpha=255 channel, but falls back to this for other cases
 //
 //  assume data buffer is malloced, so malloc a new one and free that one
 //  only failure mode is malloc failing
 
 static stbi_uc stbi__compute_y(int r, int g, int b)
 {
    return (stbi_uc) (((r*77) + (g*150) +  (29*b)) >> 8);
 }
 
 static unsigned char *stbi__convert_format(unsigned char *data, int img_n, int req_comp, unsigned int x, unsigned int y)
 {
    int i,j;
    unsigned char *good;
 
    if (req_comp == img_n) return data;
    STBI_ASSERT(req_comp >= 1 && req_comp <= 4);
 
    good = (unsigned char *) stbi__malloc_mad3(req_comp, x, y, 0);
    if (good == NULL) {
       STBI_FREE(data);
       return stbi__errpuc("outofmem", "Out of memory");
    }
 
    for (j=0; j < (int) y; ++j) {
       unsigned char *src  = data + j * x * img_n   ;
       unsigned char *dest = good + j * x * req_comp;
 
       #define STBI__COMBO(a,b)  ((a)*8+(b))
       #define STBI__CASE(a,b)   case STBI__COMBO(a,b): for(i=x-1; i >= 0; --i, src += a, dest += b)
       // convert source image with img_n components to one with req_comp components;
       // avoid switch per pixel, so use switch per scanline and massive macros
       switch (STBI__COMBO(img_n, req_comp)) {
          STBI__CASE(1,2) { dest[0]=src[0], dest[1]=255;                                     } break;
          STBI__CASE(1,3) { dest[0]=dest[1]=dest[2]=src[0];                                  } break;
          STBI__CASE(1,4) { dest[0]=dest[1]=dest[2]=src[0], dest[3]=255;                     } break;
          STBI__CASE(2,1) { dest[0]=src[0];                                                  } break;
          STBI__CASE(2,3) { dest[0]=dest[1]=dest[2]=src[0];                                  } break;
          STBI__CASE(2,4) { dest[0]=dest[1]=dest[2]=src[0], dest[3]=src[1];                  } break;
          STBI__CASE(3,4) { dest[0]=src[0],dest[1]=src[1],dest[2]=src[2],dest[3]=255;        } break;
          STBI__CASE(3,1) { dest[0]=stbi__compute_y(src[0],src[1],src[2]);                   } break;
          STBI__CASE(3,2) { dest[0]=stbi__compute_y(src[0],src[1],src[2]), dest[1] = 255;    } break;
          STBI__CASE(4,1) { dest[0]=stbi__compute_y(src[0],src[1],src[2]);                   } break;
          STBI__CASE(4,2) { dest[0]=stbi__compute_y(src[0],src[1],src[2]), dest[1] = src[3]; } break;
          STBI__CASE(4,3) { dest[0]=src[0],dest[1]=src[1],dest[2]=src[2];                    } break;
          default: STBI_ASSERT(0);
       }
       #undef STBI__CASE
    }
 
    STBI_FREE(data);
    return good;
 }
 
 static stbi__uint16 stbi__compute_y_16(int r, int g, int b)
 {
    return (stbi__uint16) (((r*77) + (g*150) +  (29*b)) >> 8);
 }
 
 static stbi__uint16 *stbi__convert_format16(stbi__uint16 *data, int img_n, int req_comp, unsigned int x, unsigned int y)
 {
    int i,j;
    stbi__uint16 *good;
 
    if (req_comp == img_n) return data;
    STBI_ASSERT(req_comp >= 1 && req_comp <= 4);
 
    good = (stbi__uint16 *) stbi__malloc(req_comp * x * y * 2);
    if (good == NULL) {
       STBI_FREE(data);
       return (stbi__uint16 *) stbi__errpuc("outofmem", "Out of memory");
    }
 
    for (j=0; j < (int) y; ++j) {
       stbi__uint16 *src  = data + j * x * img_n   ;
       stbi__uint16 *dest = good + j * x * req_comp;
 
       #define STBI__COMBO(a,b)  ((a)*8+(b))
       #define STBI__CASE(a,b)   case STBI__COMBO(a,b): for(i=x-1; i >= 0; --i, src += a, dest += b)
       // convert source image with img_n components to one with req_comp components;
       // avoid switch per pixel, so use switch per scanline and massive macros
       switch (STBI__COMBO(img_n, req_comp)) {
          STBI__CASE(1,2) { dest[0]=src[0], dest[1]=0xffff;                                     } break;
          STBI__CASE(1,3) { dest[0]=dest[1]=dest[2]=src[0];                                     } break;
          STBI__CASE(1,4) { dest[0]=dest[1]=dest[2]=src[0], dest[3]=0xffff;                     } break;
          STBI__CASE(2,1) { dest[0]=src[0];                                                     } break;
          STBI__CASE(2,3) { dest[0]=dest[1]=dest[2]=src[0];                                     } break;
          STBI__CASE(2,4) { dest[0]=dest[1]=dest[2]=src[0], dest[3]=src[1];                     } break;
          STBI__CASE(3,4) { dest[0]=src[0],dest[1]=src[1],dest[2]=src[2],dest[3]=0xffff;        } break;
          STBI__CASE(3,1) { dest[0]=stbi__compute_y_16(src[0],src[1],src[2]);                   } break;
          STBI__CASE(3,2) { dest[0]=stbi__compute_y_16(src[0],src[1],src[2]), dest[1] = 0xffff; } break;
          STBI__CASE(4,1) { dest[0]=stbi__compute_y_16(src[0],src[1],src[2]);                   } break;
          STBI__CASE(4,2) { dest[0]=stbi__compute_y_16(src[0],src[1],src[2]), dest[1] = src[3]; } break;
          STBI__CASE(4,3) { dest[0]=src[0],dest[1]=src[1],dest[2]=src[2];                       } break;
          default: STBI_ASSERT(0);
       }
       #undef STBI__CASE
    }
 
    STBI_FREE(data);
    return good;
 }
 
 #ifndef STBI_NO_LINEAR
 static float   *stbi__ldr_to_hdr(stbi_uc *data, int x, int y, int comp)
 {
    int i,k,n;
    float *output;
    if (!data) return NULL;
    output = (float *) stbi__malloc_mad4(x, y, comp, sizeof(float), 0);
    if (output == NULL) { STBI_FREE(data); return stbi__errpf("outofmem", "Out of memory"); }
    // compute number of non-alpha components
    if (comp & 1) n = comp; else n = comp-1;
    for (i=0; i < x*y; ++i) {
       for (k=0; k < n; ++k) {
          output[i*comp + k] = (float) (pow(data[i*comp+k]/255.0f, stbi__l2h_gamma) * stbi__l2h_scale);
       }
       if (k < comp) output[i*comp + k] = data[i*comp+k]/255.0f;
    }
    STBI_FREE(data);
    return output;
 }
 #endif
 
 #ifndef STBI_NO_HDR
 #define stbi__float2int(x)   ((int) (x))
 static stbi_uc *stbi__hdr_to_ldr(float   *data, int x, int y, int comp)
 {
    int i,k,n;
    stbi_uc *output;
    if (!data) return NULL;
    output = (stbi_uc *) stbi__malloc_mad3(x, y, comp, 0);
    if (output == NULL) { STBI_FREE(data); return stbi__errpuc("outofmem", "Out of memory"); }
    // compute number of non-alpha components
    if (comp & 1) n = comp; else n = comp-1;
    for (i=0; i < x*y; ++i) {
       for (k=0; k < n; ++k) {
          float z = (float) pow(data[i*comp+k]*stbi__h2l_scale_i, stbi__h2l_gamma_i) * 255 + 0.5f;
          if (z < 0) z = 0;
          if (z > 255) z = 255;
          output[i*comp + k] = (stbi_uc) stbi__float2int(z);
       }
       if (k < comp) {
          float z = data[i*comp+k] * 255 + 0.5f;
          if (z < 0) z = 0;
          if (z > 255) z = 255;
          output[i*comp + k] = (stbi_uc) stbi__float2int(z);
       }
    }
    STBI_FREE(data);
    return output;
 }
 #endif
 
 //////////////////////////////////////////////////////////////////////////////
 //
 //  "baseline" JPEG/JFIF decoder
 //
 //    simple implementation
 //      - doesn't support delayed output of y-dimension
 //      - simple interface (only one output format: 8-bit interleaved RGB)
 //      - doesn't try to recover corrupt jpegs
 //      - doesn't allow partial loading, loading multiple at once
 //      - still fast on x86 (copying globals into locals doesn't help x86)
 //      - allocates lots of intermediate memory (full size of all components)
 //        - non-interleaved case requires this anyway
 //        - allows good upsampling (see next)
 //    high-quality
 //      - upsampled channels are bilinearly interpolated, even across blocks
 //      - quality integer IDCT derived from IJG's 'slow'
 //    performance
 //      - fast huffman; reasonable integer IDCT
 //      - some SIMD kernels for common paths on targets with SSE2/NEON
 //      - uses a lot of intermediate memory, could cache poorly
 
 #ifndef STBI_NO_JPEG
 
 // huffman decoding acceleration
 #define FAST_BITS   9  // larger handles more cases; smaller stomps less cache
 
 typedef struct
 {
    stbi_uc  fast[1 << FAST_BITS];
    // weirdly, repacking this into AoS is a 10% speed loss, instead of a win
    stbi__uint16 code[256];
    stbi_uc  values[256];
    stbi_uc  size[257];
    unsigned int maxcode[18];
    int    delta[17];   // old 'firstsymbol' - old 'firstcode'
 } stbi__huffman;
 
 typedef struct
 {
    stbi__context *s;
    stbi__huffman huff_dc[4];
    stbi__huffman huff_ac[4];
    stbi__uint16 dequant[4][64];
    stbi__int16 fast_ac[4][1 << FAST_BITS];
 
 // sizes for components, interleaved MCUs
    int img_h_max, img_v_max;
    int img_mcu_x, img_mcu_y;
    int img_mcu_w, img_mcu_h;
 
 // definition of jpeg image component
    struct
    {
       int id;
       int h,v;
       int tq;
       int hd,ha;
       int dc_pred;
 
       int x,y,w2,h2;
       stbi_uc *data;
       void *raw_data, *raw_coeff;
       stbi_uc *linebuf;
       short   *coeff;   // progressive only
       int      coeff_w, coeff_h; // number of 8x8 coefficient blocks
    } img_comp[4];
 
    stbi__uint32   code_buffer; // jpeg entropy-coded buffer
    int            code_bits;   // number of valid bits
    unsigned char  marker;      // marker seen while filling entropy buffer
    int            nomore;      // flag if we saw a marker so must stop
 
    int            progressive;
    int            spec_start;
    int            spec_end;
    int            succ_high;
    int            succ_low;
    int            eob_run;
    int            jfif;
    int            app14_color_transform; // Adobe APP14 tag
    int            rgb;
 
    int scan_n, order[4];
    int restart_interval, todo;
 
 // kernels
    void (*idct_block_kernel)(stbi_uc *out, int out_stride, short data[64]);
    void (*YCbCr_to_RGB_kernel)(stbi_uc *out, const stbi_uc *y, const stbi_uc *pcb, const stbi_uc *pcr, int count, int step);
    stbi_uc *(*resample_row_hv_2_kernel)(stbi_uc *out, stbi_uc *in_near, stbi_uc *in_far, int w, int hs);
 } stbi__jpeg;
 
 static int stbi__build_huffman(stbi__huffman *h, int *count)
 {
    int i,j,k=0;
    unsigned int code;
    // build size list for each symbol (from JPEG spec)
    for (i=0; i < 16; ++i)
       for (j=0; j < count[i]; ++j)
          h->size[k++] = (stbi_uc) (i+1);
    h->size[k] = 0;
 
    // compute actual symbols (from jpeg spec)
    code = 0;
    k = 0;
    for(j=1; j <= 16; ++j) {
       // compute delta to add to code to compute symbol id
       h->delta[j] = k - code;
       if (h->size[k] == j) {
          while (h->size[k] == j)
             h->code[k++] = (stbi__uint16) (code++);
          if (code-1 >= (1u << j)) return stbi__err("bad code lengths","Corrupt JPEG");
       }
       // compute largest code + 1 for this size, preshifted as needed later
       h->maxcode[j] = code << (16-j);
       code <<= 1;
    }
    h->maxcode[j] = 0xffffffff;
 
    // build non-spec acceleration table; 255 is flag for not-accelerated
    memset(h->fast, 255, 1 << FAST_BITS);
    for (i=0; i < k; ++i) {
       int s = h->size[i];
       if (s <= FAST_BITS) {
          int c = h->code[i] << (FAST_BITS-s);
          int m = 1 << (FAST_BITS-s);
          for (j=0; j < m; ++j) {
             h->fast[c+j] = (stbi_uc) i;
          }
       }
    }
    return 1;
 }
 
 // build a table that decodes both magnitude and value of small ACs in
 // one go.
 static void stbi__build_fast_ac(stbi__int16 *fast_ac, stbi__huffman *h)
 {
    int i;
    for (i=0; i < (1 << FAST_BITS); ++i) {
       stbi_uc fast = h->fast[i];
       fast_ac[i] = 0;
       if (fast < 255) {
          int rs = h->values[fast];
          int run = (rs >> 4) & 15;
          int magbits = rs & 15;
          int len = h->size[fast];
 
          if (magbits && len + magbits <= FAST_BITS) {
             // magnitude code followed by receive_extend code
             int k = ((i << len) & ((1 << FAST_BITS) - 1)) >> (FAST_BITS - magbits);
             int m = 1 << (magbits - 1);
             if (k < m) k += (~0U << magbits) + 1;
             // if the result is small enough, we can fit it in fast_ac table
             if (k >= -128 && k <= 127)
                fast_ac[i] = (stbi__int16) ((k * 256) + (run * 16) + (len + magbits));
          }
       }
    }
 }
 
 static void stbi__grow_buffer_unsafe(stbi__jpeg *j)
 {
    do {
       unsigned int b = j->nomore ? 0 : stbi__get8(j->s);
       if (b == 0xff) {
          int c = stbi__get8(j->s);
          while (c == 0xff) c = stbi__get8(j->s); // consume fill bytes
          if (c != 0) {
             j->marker = (unsigned char) c;
             j->nomore = 1;
             return;
          }
       }
       j->code_buffer |= b << (24 - j->code_bits);
       j->code_bits += 8;
    } while (j->code_bits <= 24);
 }
 
 // (1 << n) - 1
 static const stbi__uint32 stbi__bmask[17]={0,1,3,7,15,31,63,127,255,511,1023,2047,4095,8191,16383,32767,65535};
 
 // decode a jpeg huffman value from the bitstream
 stbi_inline static int stbi__jpeg_huff_decode(stbi__jpeg *j, stbi__huffman *h)
 {
    unsigned int temp;
    int c,k;
 
    if (j->code_bits < 16) stbi__grow_buffer_unsafe(j);
 
    // look at the top FAST_BITS and determine what symbol ID it is,
    // if the code is <= FAST_BITS
    c = (j->code_buffer >> (32 - FAST_BITS)) & ((1 << FAST_BITS)-1);
    k = h->fast[c];
    if (k < 255) {
       int s = h->size[k];
       if (s > j->code_bits)
          return -1;
       j->code_buffer <<= s;
       j->code_bits -= s;
       return h->values[k];
    }
 
    // naive test is to shift the code_buffer down so k bits are
    // valid, then test against maxcode. To speed this up, we've
    // preshifted maxcode left so that it has (16-k) 0s at the
    // end; in other words, regardless of the number of bits, it
    // wants to be compared against something shifted to have 16;
    // that way we don't need to shift inside the loop.
    temp = j->code_buffer >> 16;
    for (k=FAST_BITS+1 ; ; ++k)
       if (temp < h->maxcode[k])
          break;
    if (k == 17) {
       // error! code not found
       j->code_bits -= 16;
       return -1;
    }
 
    if (k > j->code_bits)
       return -1;
 
    // convert the huffman code to the symbol id
    c = ((j->code_buffer >> (32 - k)) & stbi__bmask[k]) + h->delta[k];
    STBI_ASSERT((((j->code_buffer) >> (32 - h->size[c])) & stbi__bmask[h->size[c]]) == h->code[c]);
 
    // convert the id to a symbol
    j->code_bits -= k;
    j->code_buffer <<= k;
    return h->values[c];
 }
 
 // bias[n] = (-1<<n) + 1
 static const int stbi__jbias[16] = {0,-1,-3,-7,-15,-31,-63,-127,-255,-511,-1023,-2047,-4095,-8191,-16383,-32767};
 
 // combined JPEG 'receive' and JPEG 'extend', since baseline
 // always extends everything it receives.
 stbi_inline static int stbi__extend_receive(stbi__jpeg *j, int n)
 {
    unsigned int k;
    int sgn;
    if (j->code_bits < n) stbi__grow_buffer_unsafe(j);
 
    sgn = (stbi__int32)j->code_buffer >> 31; // sign bit is always in MSB
    k = stbi_lrot(j->code_buffer, n);
    STBI_ASSERT(n >= 0 && n < (int) (sizeof(stbi__bmask)/sizeof(*stbi__bmask)));
    j->code_buffer = k & ~stbi__bmask[n];
    k &= stbi__bmask[n];
    j->code_bits -= n;
    return k + (stbi__jbias[n] & ~sgn);
 }
 
 // get some unsigned bits
 stbi_inline static int stbi__jpeg_get_bits(stbi__jpeg *j, int n)
 {
    unsigned int k;
    if (j->code_bits < n) stbi__grow_buffer_unsafe(j);
    k = stbi_lrot(j->code_buffer, n);
    j->code_buffer = k & ~stbi__bmask[n];
    k &= stbi__bmask[n];
    j->code_bits -= n;
    return k;
 }
 
 stbi_inline static int stbi__jpeg_get_bit(stbi__jpeg *j)
 {
    unsigned int k;
    if (j->code_bits < 1) stbi__grow_buffer_unsafe(j);
    k = j->code_buffer;
    j->code_buffer <<= 1;
    --j->code_bits;
    return k & 0x80000000;
 }
 
 // given a value that's at position X in the zigzag stream,
 // where does it appear in the 8x8 matrix coded as row-major?
 static const stbi_uc stbi__jpeg_dezigzag[64+15] =
 {
     0,  1,  8, 16,  9,  2,  3, 10,
    17, 24, 32, 25, 18, 11,  4,  5,
    12, 19, 26, 33, 40, 48, 41, 34,
    27, 20, 13,  6,  7, 14, 21, 28,
    35, 42, 49, 56, 57, 50, 43, 36,
    29, 22, 15, 23, 30, 37, 44, 51,
    58, 59, 52, 45, 38, 31, 39, 46,
    53, 60, 61, 54, 47, 55, 62, 63,
    // let corrupt input sample past end
    63, 63, 63, 63, 63, 63, 63, 63,
    63, 63, 63, 63, 63, 63, 63
 };
 
 // decode one 64-entry block--
 static int stbi__jpeg_decode_block(stbi__jpeg *j, short data[64], stbi__huffman *hdc, stbi__huffman *hac, stbi__int16 *fac, int b, stbi__uint16 *dequant)
 {
    int diff,dc,k;
    int t;
 
    if (j->code_bits < 16) stbi__grow_buffer_unsafe(j);
    t = stbi__jpeg_huff_decode(j, hdc);
    if (t < 0) return stbi__err("bad huffman code","Corrupt JPEG");
 
    // 0 all the ac values now so we can do it 32-bits at a time
    memset(data,0,64*sizeof(data[0]));
 
    diff = t ? stbi__extend_receive(j, t) : 0;
    dc = j->img_comp[b].dc_pred + diff;
    j->img_comp[b].dc_pred = dc;
    data[0] = (short) (dc * dequant[0]);
 
    // decode AC components, see JPEG spec
    k = 1;
    do {
       unsigned int zig;
       int c,r,s;
       if (j->code_bits < 16) stbi__grow_buffer_unsafe(j);
       c = (j->code_buffer >> (32 - FAST_BITS)) & ((1 << FAST_BITS)-1);
       r = fac[c];
       if (r) { // fast-AC path
          k += (r >> 4) & 15; // run
          s = r & 15; // combined length
          j->code_buffer <<= s;
          j->code_bits -= s;
          // decode into unzigzag'd location
          zig = stbi__jpeg_dezigzag[k++];
          data[zig] = (short) ((r >> 8) * dequant[zig]);
       } else {
          int rs = stbi__jpeg_huff_decode(j, hac);
          if (rs < 0) return stbi__err("bad huffman code","Corrupt JPEG");
          s = rs & 15;
          r = rs >> 4;
          if (s == 0) {
             if (rs != 0xf0) break; // end block
             k += 16;
          } else {
             k += r;
             // decode into unzigzag'd location
             zig = stbi__jpeg_dezigzag[k++];
             data[zig] = (short) (stbi__extend_receive(j,s) * dequant[zig]);
          }
       }
    } while (k < 64);
    return 1;
 }
 
 static int stbi__jpeg_decode_block_prog_dc(stbi__jpeg *j, short data[64], stbi__huffman *hdc, int b)
 {
    int diff,dc;
    int t;
    if (j->spec_end != 0) return stbi__err("can't merge dc and ac", "Corrupt JPEG");
 
    if (j->code_bits < 16) stbi__grow_buffer_unsafe(j);
 
    if (j->succ_high == 0) {
       // first scan for DC coefficient, must be first
       memset(data,0,64*sizeof(data[0])); // 0 all the ac values now
       t = stbi__jpeg_huff_decode(j, hdc);
       diff = t ? stbi__extend_receive(j, t) : 0;
 
       dc = j->img_comp[b].dc_pred + diff;
       j->img_comp[b].dc_pred = dc;
       data[0] = (short) (dc << j->succ_low);
    } else {
       // refinement scan for DC coefficient
       if (stbi__jpeg_get_bit(j))
          data[0] += (short) (1 << j->succ_low);
    }
    return 1;
 }
 
 // @OPTIMIZE: store non-zigzagged during the decode passes,
 // and only de-zigzag when dequantizing
 static int stbi__jpeg_decode_block_prog_ac(stbi__jpeg *j, short data[64], stbi__huffman *hac, stbi__int16 *fac)
 {
    int k;
    if (j->spec_start == 0) return stbi__err("can't merge dc and ac", "Corrupt JPEG");
 
    if (j->succ_high == 0) {
       int shift = j->succ_low;
 
       if (j->eob_run) {
          --j->eob_run;
          return 1;
       }
 
       k = j->spec_start;
       do {
          unsigned int zig;
          int c,r,s;
          if (j->code_bits < 16) stbi__grow_buffer_unsafe(j);
          c = (j->code_buffer >> (32 - FAST_BITS)) & ((1 << FAST_BITS)-1);
          r = fac[c];
          if (r) { // fast-AC path
             k += (r >> 4) & 15; // run
             s = r & 15; // combined length
             j->code_buffer <<= s;
             j->code_bits -= s;
             zig = stbi__jpeg_dezigzag[k++];
             data[zig] = (short) ((r >> 8) << shift);
          } else {
             int rs = stbi__jpeg_huff_decode(j, hac);
             if (rs < 0) return stbi__err("bad huffman code","Corrupt JPEG");
             s = rs & 15;
             r = rs >> 4;
             if (s == 0) {
                if (r < 15) {
                   j->eob_run = (1 << r);
                   if (r)
                      j->eob_run += stbi__jpeg_get_bits(j, r);
                   --j->eob_run;
                   break;
                }
                k += 16;
             } else {
                k += r;
                zig = stbi__jpeg_dezigzag[k++];
                data[zig] = (short) (stbi__extend_receive(j,s) << shift);
             }
          }
       } while (k <= j->spec_end);
    } else {
       // refinement scan for these AC coefficients
 
       short bit = (short) (1 << j->succ_low);
 
       if (j->eob_run) {
          --j->eob_run;
          for (k = j->spec_start; k <= j->spec_end; ++k) {
             short *p = &data[stbi__jpeg_dezigzag[k]];
             if (*p != 0)
                if (stbi__jpeg_get_bit(j))
                   if ((*p & bit)==0) {
                      if (*p > 0)
                         *p += bit;
                      else
                         *p -= bit;
                   }
          }
       } else {
          k = j->spec_start;
          do {
             int r,s;
             int rs = stbi__jpeg_huff_decode(j, hac); // @OPTIMIZE see if we can use the fast path here, advance-by-r is so slow, eh
             if (rs < 0) return stbi__err("bad huffman code","Corrupt JPEG");
             s = rs & 15;
             r = rs >> 4;
             if (s == 0) {
                if (r < 15) {
                   j->eob_run = (1 << r) - 1;
                   if (r)
                      j->eob_run += stbi__jpeg_get_bits(j, r);
                   r = 64; // force end of block
                } else {
                   // r=15 s=0 should write 16 0s, so we just do
                   // a run of 15 0s and then write s (which is 0),
                   // so we don't have to do anything special here
                }
             } else {
                if (s != 1) return stbi__err("bad huffman code", "Corrupt JPEG");
                // sign bit
                if (stbi__jpeg_get_bit(j))
                   s = bit;
                else
                   s = -bit;
             }
 
             // advance by r
             while (k <= j->spec_end) {
                short *p = &data[stbi__jpeg_dezigzag[k++]];
                if (*p != 0) {
                   if (stbi__jpeg_get_bit(j))
                      if ((*p & bit)==0) {
                         if (*p > 0)
                            *p += bit;
                         else
                            *p -= bit;
                      }
                } else {
                   if (r == 0) {
                      *p = (short) s;
                      break;
                   }
                   --r;
                }
             }
          } while (k <= j->spec_end);
       }
    }
    return 1;
 }
 
 // take a -128..127 value and stbi__clamp it and convert to 0..255
 stbi_inline static stbi_uc stbi__clamp(int x)
 {
    // trick to use a single test to catch both cases
    if ((unsigned int) x > 255) {
       if (x < 0) return 0;
       if (x > 255) return 255;
    }
    return (stbi_uc) x;
 }
 
 #define stbi__f2f(x)  ((int) (((x) * 4096 + 0.5)))
 #define stbi__fsh(x)  ((x) * 4096)
 
 // derived from jidctint -- DCT_ISLOW
 #define STBI__IDCT_1D(s0,s1,s2,s3,s4,s5,s6,s7) \
    int t0,t1,t2,t3,p1,p2,p3,p4,p5,x0,x1,x2,x3; \
    p2 = s2;                                    \
    p3 = s6;                                    \
    p1 = (p2+p3) * stbi__f2f(0.5411961f);       \
    t2 = p1 + p3*stbi__f2f(-1.847759065f);      \
    t3 = p1 + p2*stbi__f2f( 0.765366865f);      \
    p2 = s0;                                    \
    p3 = s4;                                    \
    t0 = stbi__fsh(p2+p3);                      \
    t1 = stbi__fsh(p2-p3);                      \
    x0 = t0+t3;                                 \
    x3 = t0-t3;                                 \
    x1 = t1+t2;                                 \
    x2 = t1-t2;                                 \
    t0 = s7;                                    \
    t1 = s5;                                    \
    t2 = s3;                                    \
    t3 = s1;                                    \
    p3 = t0+t2;                                 \
    p4 = t1+t3;                                 \
    p1 = t0+t3;                                 \
    p2 = t1+t2;                                 \
    p5 = (p3+p4)*stbi__f2f( 1.175875602f);      \
    t0 = t0*stbi__f2f( 0.298631336f);           \
    t1 = t1*stbi__f2f( 2.053119869f);           \
    t2 = t2*stbi__f2f( 3.072711026f);           \
    t3 = t3*stbi__f2f( 1.501321110f);           \
    p1 = p5 + p1*stbi__f2f(-0.899976223f);      \
    p2 = p5 + p2*stbi__f2f(-2.562915447f);      \
    p3 = p3*stbi__f2f(-1.961570560f);           \
    p4 = p4*stbi__f2f(-0.390180644f);           \
    t3 += p1+p4;                                \
    t2 += p2+p3;                                \
    t1 += p2+p4;                                \
    t0 += p1+p3;
 
 static void stbi__idct_block(stbi_uc *out, int out_stride, short data[64])
 {
    int i,val[64],*v=val;
    stbi_uc *o;
    short *d = data;
 
    // columns
    for (i=0; i < 8; ++i,++d, ++v) {
       // if all zeroes, shortcut -- this avoids dequantizing 0s and IDCTing
       if (d[ 8]==0 && d[16]==0 && d[24]==0 && d[32]==0
            && d[40]==0 && d[48]==0 && d[56]==0) {
          //    no shortcut                 0     seconds
          //    (1|2|3|4|5|6|7)==0          0     seconds
          //    all separate               -0.047 seconds
          //    1 && 2|3 && 4|5 && 6|7:    -0.047 seconds
          int dcterm = d[0]*4;
          v[0] = v[8] = v[16] = v[24] = v[32] = v[40] = v[48] = v[56] = dcterm;
       } else {
          STBI__IDCT_1D(d[ 0],d[ 8],d[16],d[24],d[32],d[40],d[48],d[56])
          // constants scaled things up by 1<<12; let's bring them back
          // down, but keep 2 extra bits of precision
          x0 += 512; x1 += 512; x2 += 512; x3 += 512;
          v[ 0] = (x0+t3) >> 10;
          v[56] = (x0-t3) >> 10;
          v[ 8] = (x1+t2) >> 10;
          v[48] = (x1-t2) >> 10;
          v[16] = (x2+t1) >> 10;
          v[40] = (x2-t1) >> 10;
          v[24] = (x3+t0) >> 10;
          v[32] = (x3-t0) >> 10;
       }
    }
 
    for (i=0, v=val, o=out; i < 8; ++i,v+=8,o+=out_stride) {
       // no fast case since the first 1D IDCT spread components out
       STBI__IDCT_1D(v[0],v[1],v[2],v[3],v[4],v[5],v[6],v[7])
       // constants scaled things up by 1<<12, plus we had 1<<2 from first
       // loop, plus horizontal and vertical each scale by sqrt(8) so together
       // we've got an extra 1<<3, so 1<<17 total we need to remove.
       // so we want to round that, which means adding 0.5 * 1<<17,
       // aka 65536. Also, we'll end up with -128 to 127 that we want
       // to encode as 0..255 by adding 128, so we'll add that before the shift
       x0 += 65536 + (128<<17);
       x1 += 65536 + (128<<17);
       x2 += 65536 + (128<<17);
       x3 += 65536 + (128<<17);
       // tried computing the shifts into temps, or'ing the temps to see
       // if any were out of range, but that was slower
       o[0] = stbi__clamp((x0+t3) >> 17);
       o[7] = stbi__clamp((x0-t3) >> 17);
       o[1] = stbi__clamp((x1+t2) >> 17);
       o[6] = stbi__clamp((x1-t2) >> 17);
       o[2] = stbi__clamp((x2+t1) >> 17);
       o[5] = stbi__clamp((x2-t1) >> 17);
       o[3] = stbi__clamp((x3+t0) >> 17);
       o[4] = stbi__clamp((x3-t0) >> 17);
    }
 }
 
 #ifdef STBI_SSE2
 // sse2 integer IDCT. not the fastest possible implementation but it
 // produces bit-identical results to the generic C version so it's
 // fully "transparent".
 static void stbi__idct_simd(stbi_uc *out, int out_stride, short data[64])
 {
    // This is constructed to match our regular (generic) integer IDCT exactly.
    __m128i row0, row1, row2, row3, row4, row5, row6, row7;
    __m128i tmp;
 
    // dot product constant: even elems=x, odd elems=y
    #define dct_const(x,y)  _mm_setr_epi16((x),(y),(x),(y),(x),(y),(x),(y))
 
    // out(0) = c0[even]*x + c0[odd]*y   (c0, x, y 16-bit, out 32-bit)
    // out(1) = c1[even]*x + c1[odd]*y
    #define dct_rot(out0,out1, x,y,c0,c1) \
       __m128i c0##lo = _mm_unpacklo_epi16((x),(y)); \
       __m128i c0##hi = _mm_unpackhi_epi16((x),(y)); \
       __m128i out0##_l = _mm_madd_epi16(c0##lo, c0); \
       __m128i out0##_h = _mm_madd_epi16(c0##hi, c0); \
       __m128i out1##_l = _mm_madd_epi16(c0##lo, c1); \
       __m128i out1##_h = _mm_madd_epi16(c0##hi, c1)
 
    // out = in << 12  (in 16-bit, out 32-bit)
    #define dct_widen(out, in) \
       __m128i out##_l = _mm_srai_epi32(_mm_unpacklo_epi16(_mm_setzero_si128(), (in)), 4); \
       __m128i out##_h = _mm_srai_epi32(_mm_unpackhi_epi16(_mm_setzero_si128(), (in)), 4)
 
    // wide add
    #define dct_wadd(out, a, b) \
       __m128i out##_l = _mm_add_epi32(a##_l, b##_l); \
       __m128i out##_h = _mm_add_epi32(a##_h, b##_h)
 
    // wide sub
    #define dct_wsub(out, a, b) \
       __m128i out##_l = _mm_sub_epi32(a##_l, b##_l); \
       __m128i out##_h = _mm_sub_epi32(a##_h, b##_h)
 
    // butterfly a/b, add bias, then shift by "s" and pack
    #define dct_bfly32o(out0, out1, a,b,bias,s) \
       { \
          __m128i abiased_l = _mm_add_epi32(a##_l, bias); \
          __m128i abiased_h = _mm_add_epi32(a##_h, bias); \
          dct_wadd(sum, abiased, b); \
          dct_wsub(dif, abiased, b); \
          out0 = _mm_packs_epi32(_mm_srai_epi32(sum_l, s), _mm_srai_epi32(sum_h, s)); \
          out1 = _mm_packs_epi32(_mm_srai_epi32(dif_l, s), _mm_srai_epi32(dif_h, s)); \
       }
 
    // 8-bit interleave step (for transposes)
    #define dct_interleave8(a, b) \
       tmp = a; \
       a = _mm_unpacklo_epi8(a, b); \
       b = _mm_unpackhi_epi8(tmp, b)
 
    // 16-bit interleave step (for transposes)
    #define dct_interleave16(a, b) \
       tmp = a; \
       a = _mm_unpacklo_epi16(a, b); \
       b = _mm_unpackhi_epi16(tmp, b)
 
    #define dct_pass(bias,shift) \
       { \
          /* even part */ \
          dct_rot(t2e,t3e, row2,row6, rot0_0,rot0_1); \
          __m128i sum04 = _mm_add_epi16(row0, row4); \
          __m128i dif04 = _mm_sub_epi16(row0, row4); \
          dct_widen(t0e, sum04); \
          dct_widen(t1e, dif04); \
          dct_wadd(x0, t0e, t3e); \
          dct_wsub(x3, t0e, t3e); \
          dct_wadd(x1, t1e, t2e); \
          dct_wsub(x2, t1e, t2e); \
          /* odd part */ \
          dct_rot(y0o,y2o, row7,row3, rot2_0,rot2_1); \
          dct_rot(y1o,y3o, row5,row1, rot3_0,rot3_1); \
          __m128i sum17 = _mm_add_epi16(row1, row7); \
          __m128i sum35 = _mm_add_epi16(row3, row5); \
          dct_rot(y4o,y5o, sum17,sum35, rot1_0,rot1_1); \
          dct_wadd(x4, y0o, y4o); \
          dct_wadd(x5, y1o, y5o); \
          dct_wadd(x6, y2o, y5o); \
          dct_wadd(x7, y3o, y4o); \
          dct_bfly32o(row0,row7, x0,x7,bias,shift); \
          dct_bfly32o(row1,row6, x1,x6,bias,shift); \
          dct_bfly32o(row2,row5, x2,x5,bias,shift); \
          dct_bfly32o(row3,row4, x3,x4,bias,shift); \
       }
 
    __m128i rot0_0 = dct_const(stbi__f2f(0.5411961f), stbi__f2f(0.5411961f) + stbi__f2f(-1.847759065f));
    __m128i rot0_1 = dct_const(stbi__f2f(0.5411961f) + stbi__f2f( 0.765366865f), stbi__f2f(0.5411961f));
    __m128i rot1_0 = dct_const(stbi__f2f(1.175875602f) + stbi__f2f(-0.899976223f), stbi__f2f(1.175875602f));
    __m128i rot1_1 = dct_const(stbi__f2f(1.175875602f), stbi__f2f(1.175875602f) + stbi__f2f(-2.562915447f));
    __m128i rot2_0 = dct_const(stbi__f2f(-1.961570560f) + stbi__f2f( 0.298631336f), stbi__f2f(-1.961570560f));
    __m128i rot2_1 = dct_const(stbi__f2f(-1.961570560f), stbi__f2f(-1.961570560f) + stbi__f2f( 3.072711026f));
    __m128i rot3_0 = dct_const(stbi__f2f(-0.390180644f) + stbi__f2f( 2.053119869f), stbi__f2f(-0.390180644f));
    __m128i rot3_1 = dct_const(stbi__f2f(-0.390180644f), stbi__f2f(-0.390180644f) + stbi__f2f( 1.501321110f));
 
    // rounding biases in column/row passes, see stbi__idct_block for explanation.
    __m128i bias_0 = _mm_set1_epi32(512);
    __m128i bias_1 = _mm_set1_epi32(65536 + (128<<17));
 
    // load
    row0 = _mm_load_si128((const __m128i *) (data + 0*8));
    row1 = _mm_load_si128((const __m128i *) (data + 1*8));
    row2 = _mm_load_si128((const __m128i *) (data + 2*8));
    row3 = _mm_load_si128((const __m128i *) (data + 3*8));
    row4 = _mm_load_si128((const __m128i *) (data + 4*8));
    row5 = _mm_load_si128((const __m128i *) (data + 5*8));
    row6 = _mm_load_si128((const __m128i *) (data + 6*8));
    row7 = _mm_load_si128((const __m128i *) (data + 7*8));
 
    // column pass
    dct_pass(bias_0, 10);
 
    {
       // 16bit 8x8 transpose pass 1
       dct_interleave16(row0, row4);
       dct_interleave16(row1, row5);
       dct_interleave16(row2, row6);
       dct_interleave16(row3, row7);
 
       // transpose pass 2
       dct_interleave16(row0, row2);
       dct_interleave16(row1, row3);
       dct_interleave16(row4, row6);
       dct_interleave16(row5, row7);
 
       // transpose pass 3
       dct_interleave16(row0, row1);
       dct_interleave16(row2, row3);
       dct_interleave16(row4, row5);
       dct_interleave16(row6, row7);
    }
 
    // row pass
    dct_pass(bias_1, 17);
 
    {
       // pack
       __m128i p0 = _mm_packus_epi16(row0, row1); // a0a1a2a3...a7b0b1b2b3...b7
       __m128i p1 = _mm_packus_epi16(row2, row3);
       __m128i p2 = _mm_packus_epi16(row4, row5);
       __m128i p3 = _mm_packus_epi16(row6, row7);
 
       // 8bit 8x8 transpose pass 1
       dct_interleave8(p0, p2); // a0e0a1e1...
       dct_interleave8(p1, p3); // c0g0c1g1...
 
       // transpose pass 2
       dct_interleave8(p0, p1); // a0c0e0g0...
       dct_interleave8(p2, p3); // b0d0f0h0...
 
       // transpose pass 3
       dct_interleave8(p0, p2); // a0b0c0d0...
       dct_interleave8(p1, p3); // a4b4c4d4...
 
       // store
       _mm_storel_epi64((__m128i *) out, p0); out += out_stride;
       _mm_storel_epi64((__m128i *) out, _mm_shuffle_epi32(p0, 0x4e)); out += out_stride;
       _mm_storel_epi64((__m128i *) out, p2); out += out_stride;
       _mm_storel_epi64((__m128i *) out, _mm_shuffle_epi32(p2, 0x4e)); out += out_stride;
       _mm_storel_epi64((__m128i *) out, p1); out += out_stride;
       _mm_storel_epi64((__m128i *) out, _mm_shuffle_epi32(p1, 0x4e)); out += out_stride;
       _mm_storel_epi64((__m128i *) out, p3); out += out_stride;
       _mm_storel_epi64((__m128i *) out, _mm_shuffle_epi32(p3, 0x4e));
    }
 
 #undef dct_const
 #undef dct_rot
 #undef dct_widen
 #undef dct_wadd
 #undef dct_wsub
 #undef dct_bfly32o
 #undef dct_interleave8
 #undef dct_interleave16
 #undef dct_pass
 }
 
 #endif // STBI_SSE2
 
 #ifdef STBI_NEON
 
 // NEON integer IDCT. should produce bit-identical
 // results to the generic C version.
 static void stbi__idct_simd(stbi_uc *out, int out_stride, short data[64])
 {
    int16x8_t row0, row1, row2, row3, row4, row5, row6, row7;
 
    int16x4_t rot0_0 = vdup_n_s16(stbi__f2f(0.5411961f));
    int16x4_t rot0_1 = vdup_n_s16(stbi__f2f(-1.847759065f));
    int16x4_t rot0_2 = vdup_n_s16(stbi__f2f( 0.765366865f));
    int16x4_t rot1_0 = vdup_n_s16(stbi__f2f( 1.175875602f));
    int16x4_t rot1_1 = vdup_n_s16(stbi__f2f(-0.899976223f));
    int16x4_t rot1_2 = vdup_n_s16(stbi__f2f(-2.562915447f));
    int16x4_t rot2_0 = vdup_n_s16(stbi__f2f(-1.961570560f));
    int16x4_t rot2_1 = vdup_n_s16(stbi__f2f(-0.390180644f));
    int16x4_t rot3_0 = vdup_n_s16(stbi__f2f( 0.298631336f));
    int16x4_t rot3_1 = vdup_n_s16(stbi__f2f( 2.053119869f));
    int16x4_t rot3_2 = vdup_n_s16(stbi__f2f( 3.072711026f));
    int16x4_t rot3_3 = vdup_n_s16(stbi__f2f( 1.501321110f));
 
 #define dct_long_mul(out, inq, coeff) \
    int32x4_t out##_l = vmull_s16(vget_low_s16(inq), coeff); \
    int32x4_t out##_h = vmull_s16(vget_high_s16(inq), coeff)
 
 #define dct_long_mac(out, acc, inq, coeff) \
    int32x4_t out##_l = vmlal_s16(acc##_l, vget_low_s16(inq), coeff); \
    int32x4_t out##_h = vmlal_s16(acc##_h, vget_high_s16(inq), coeff)
 
 #define dct_widen(out, inq) \
    int32x4_t out##_l = vshll_n_s16(vget_low_s16(inq), 12); \
    int32x4_t out##_h = vshll_n_s16(vget_high_s16(inq), 12)
 
 // wide add
 #define dct_wadd(out, a, b) \
    int32x4_t out##_l = vaddq_s32(a##_l, b##_l); \
    int32x4_t out##_h = vaddq_s32(a##_h, b##_h)
 
 // wide sub
 #define dct_wsub(out, a, b) \
    int32x4_t out##_l = vsubq_s32(a##_l, b##_l); \
    int32x4_t out##_h = vsubq_s32(a##_h, b##_h)
 
 // butterfly a/b, then shift using "shiftop" by "s" and pack
 #define dct_bfly32o(out0,out1, a,b,shiftop,s) \
    { \
       dct_wadd(sum, a, b); \
       dct_wsub(dif, a, b); \
       out0 = vcombine_s16(shiftop(sum_l, s), shiftop(sum_h, s)); \
       out1 = vcombine_s16(shiftop(dif_l, s), shiftop(dif_h, s)); \
    }
 
 #define dct_pass(shiftop, shift) \
    { \
       /* even part */ \
       int16x8_t sum26 = vaddq_s16(row2, row6); \
       dct_long_mul(p1e, sum26, rot0_0); \
       dct_long_mac(t2e, p1e, row6, rot0_1); \
       dct_long_mac(t3e, p1e, row2, rot0_2); \
       int16x8_t sum04 = vaddq_s16(row0, row4); \
       int16x8_t dif04 = vsubq_s16(row0, row4); \
       dct_widen(t0e, sum04); \
       dct_widen(t1e, dif04); \
       dct_wadd(x0, t0e, t3e); \
       dct_wsub(x3, t0e, t3e); \
       dct_wadd(x1, t1e, t2e); \
       dct_wsub(x2, t1e, t2e); \
       /* odd part */ \
       int16x8_t sum15 = vaddq_s16(row1, row5); \
       int16x8_t sum17 = vaddq_s16(row1, row7); \
       int16x8_t sum35 = vaddq_s16(row3, row5); \
       int16x8_t sum37 = vaddq_s16(row3, row7); \
       int16x8_t sumodd = vaddq_s16(sum17, sum35); \
       dct_long_mul(p5o, sumodd, rot1_0); \
       dct_long_mac(p1o, p5o, sum17, rot1_1); \
       dct_long_mac(p2o, p5o, sum35, rot1_2); \
       dct_long_mul(p3o, sum37, rot2_0); \
       dct_long_mul(p4o, sum15, rot2_1); \
       dct_wadd(sump13o, p1o, p3o); \
       dct_wadd(sump24o, p2o, p4o); \
       dct_wadd(sump23o, p2o, p3o); \
       dct_wadd(sump14o, p1o, p4o); \
       dct_long_mac(x4, sump13o, row7, rot3_0); \
       dct_long_mac(x5, sump24o, row5, rot3_1); \
       dct_long_mac(x6, sump23o, row3, rot3_2); \
       dct_long_mac(x7, sump14o, row1, rot3_3); \
       dct_bfly32o(row0,row7, x0,x7,shiftop,shift); \
       dct_bfly32o(row1,row6, x1,x6,shiftop,shift); \
       dct_bfly32o(row2,row5, x2,x5,shiftop,shift); \
       dct_bfly32o(row3,row4, x3,x4,shiftop,shift); \
    }
 
    // load
    row0 = vld1q_s16(data + 0*8);
    row1 = vld1q_s16(data + 1*8);
    row2 = vld1q_s16(data + 2*8);
    row3 = vld1q_s16(data + 3*8);
    row4 = vld1q_s16(data + 4*8);
    row5 = vld1q_s16(data + 5*8);
    row6 = vld1q_s16(data + 6*8);
    row7 = vld1q_s16(data + 7*8);
 
    // add DC bias
    row0 = vaddq_s16(row0, vsetq_lane_s16(1024, vdupq_n_s16(0), 0));
 
    // column pass
    dct_pass(vrshrn_n_s32, 10);
 
    // 16bit 8x8 transpose
    {
 // these three map to a single VTRN.16, VTRN.32, and VSWP, respectively.
 // whether compilers actually get this is another story, sadly.
 #define dct_trn16(x, y) { int16x8x2_t t = vtrnq_s16(x, y); x = t.val[0]; y = t.val[1]; }
 #define dct_trn32(x, y) { int32x4x2_t t = vtrnq_s32(vreinterpretq_s32_s16(x), vreinterpretq_s32_s16(y)); x = vreinterpretq_s16_s32(t.val[0]); y = vreinterpretq_s16_s32(t.val[1]); }
 #define dct_trn64(x, y) { int16x8_t x0 = x; int16x8_t y0 = y; x = vcombine_s16(vget_low_s16(x0), vget_low_s16(y0)); y = vcombine_s16(vget_high_s16(x0), vget_high_s16(y0)); }
 
       // pass 1
       dct_trn16(row0, row1); // a0b0a2b2a4b4a6b6
       dct_trn16(row2, row3);
       dct_trn16(row4, row5);
       dct_trn16(row6, row7);
 
       // pass 2
       dct_trn32(row0, row2); // a0b0c0d0a4b4c4d4
       dct_trn32(row1, row3);
       dct_trn32(row4, row6);
       dct_trn32(row5, row7);
 
       // pass 3
       dct_trn64(row0, row4); // a0b0c0d0e0f0g0h0
       dct_trn64(row1, row5);
       dct_trn64(row2, row6);
       dct_trn64(row3, row7);
 
 #undef dct_trn16
 #undef dct_trn32
 #undef dct_trn64
    }
 
    // row pass
    // vrshrn_n_s32 only supports shifts up to 16, we need
    // 17. so do a non-rounding shift of 16 first then follow
    // up with a rounding shift by 1.
    dct_pass(vshrn_n_s32, 16);
 
    {
       // pack and round
       uint8x8_t p0 = vqrshrun_n_s16(row0, 1);
       uint8x8_t p1 = vqrshrun_n_s16(row1, 1);
       uint8x8_t p2 = vqrshrun_n_s16(row2, 1);
       uint8x8_t p3 = vqrshrun_n_s16(row3, 1);
       uint8x8_t p4 = vqrshrun_n_s16(row4, 1);
       uint8x8_t p5 = vqrshrun_n_s16(row5, 1);
       uint8x8_t p6 = vqrshrun_n_s16(row6, 1);
       uint8x8_t p7 = vqrshrun_n_s16(row7, 1);
 
       // again, these can translate into one instruction, but often don't.
 #define dct_trn8_8(x, y) { uint8x8x2_t t = vtrn_u8(x, y); x = t.val[0]; y = t.val[1]; }
 #define dct_trn8_16(x, y) { uint16x4x2_t t = vtrn_u16(vreinterpret_u16_u8(x), vreinterpret_u16_u8(y)); x = vreinterpret_u8_u16(t.val[0]); y = vreinterpret_u8_u16(t.val[1]); }
 #define dct_trn8_32(x, y) { uint32x2x2_t t = vtrn_u32(vreinterpret_u32_u8(x), vreinterpret_u32_u8(y)); x = vreinterpret_u8_u32(t.val[0]); y = vreinterpret_u8_u32(t.val[1]); }
 
       // sadly can't use interleaved stores here since we only write
       // 8 bytes to each scan line!
 
       // 8x8 8-bit transpose pass 1
       dct_trn8_8(p0, p1);
       dct_trn8_8(p2, p3);
       dct_trn8_8(p4, p5);
       dct_trn8_8(p6, p7);
 
       // pass 2
       dct_trn8_16(p0, p2);
       dct_trn8_16(p1, p3);
       dct_trn8_16(p4, p6);
       dct_trn8_16(p5, p7);
 
       // pass 3
       dct_trn8_32(p0, p4);
       dct_trn8_32(p1, p5);
       dct_trn8_32(p2, p6);
       dct_trn8_32(p3, p7);
 
       // store
       vst1_u8(out, p0); out += out_stride;
       vst1_u8(out, p1); out += out_stride;
       vst1_u8(out, p2); out += out_stride;
       vst1_u8(out, p3); out += out_stride;
       vst1_u8(out, p4); out += out_stride;
       vst1_u8(out, p5); out += out_stride;
       vst1_u8(out, p6); out += out_stride;
       vst1_u8(out, p7);
 
 #undef dct_trn8_8
 #undef dct_trn8_16
 #undef dct_trn8_32
    }
 
 #undef dct_long_mul
 #undef dct_long_mac
 #undef dct_widen
 #undef dct_wadd
 #undef dct_wsub
 #undef dct_bfly32o
 #undef dct_pass
 }
 
 #endif // STBI_NEON
 
 #define STBI__MARKER_none  0xff
 // if there's a pending marker from the entropy stream, return that
 // otherwise, fetch from the stream and get a marker. if there's no
 // marker, return 0xff, which is never a valid marker value
 static stbi_uc stbi__get_marker(stbi__jpeg *j)
 {
    stbi_uc x;
    if (j->marker != STBI__MARKER_none) { x = j->marker; j->marker = STBI__MARKER_none; return x; }
    x = stbi__get8(j->s);
    if (x != 0xff) return STBI__MARKER_none;
    while (x == 0xff)
       x = stbi__get8(j->s); // consume repeated 0xff fill bytes
    return x;
 }
 
 // in each scan, we'll have scan_n components, and the order
 // of the components is specified by order[]
 #define STBI__RESTART(x)     ((x) >= 0xd0 && (x) <= 0xd7)
 
 // after a restart interval, stbi__jpeg_reset the entropy decoder and
 // the dc prediction
 static void stbi__jpeg_reset(stbi__jpeg *j)
 {
    j->code_bits = 0;
    j->code_buffer = 0;
    j->nomore = 0;
    j->img_comp[0].dc_pred = j->img_comp[1].dc_pred = j->img_comp[2].dc_pred = j->img_comp[3].dc_pred = 0;
    j->marker = STBI__MARKER_none;
    j->todo = j->restart_interval ? j->restart_interval : 0x7fffffff;
    j->eob_run = 0;
    // no more than 1<<31 MCUs if no restart_interal? that's plenty safe,
    // since we don't even allow 1<<30 pixels
 }
 
 static int stbi__parse_entropy_coded_data(stbi__jpeg *z)
 {
    stbi__jpeg_reset(z);
    if (!z->progressive) {
       if (z->scan_n == 1) {
          int i,j;
          STBI_SIMD_ALIGN(short, data[64]);
          int n = z->order[0];
          // non-interleaved data, we just need to process one block at a time,
          // in trivial scanline order
          // number of blocks to do just depends on how many actual "pixels" this
          // component has, independent of interleaved MCU blocking and such
          int w = (z->img_comp[n].x+7) >> 3;
          int h = (z->img_comp[n].y+7) >> 3;
          for (j=0; j < h; ++j) {
             for (i=0; i < w; ++i) {
                int ha = z->img_comp[n].ha;
                if (!stbi__jpeg_decode_block(z, data, z->huff_dc+z->img_comp[n].hd, z->huff_ac+ha, z->fast_ac[ha], n, z->dequant[z->img_comp[n].tq])) return 0;
                z->idct_block_kernel(z->img_comp[n].data+z->img_comp[n].w2*j*8+i*8, z->img_comp[n].w2, data);
                // every data block is an MCU, so countdown the restart interval
                if (--z->todo <= 0) {
                   if (z->code_bits < 24) stbi__grow_buffer_unsafe(z);
                   // if it's NOT a restart, then just bail, so we get corrupt data
                   // rather than no data
                   if (!STBI__RESTART(z->marker)) return 1;
                   stbi__jpeg_reset(z);
                }
             }
          }
          return 1;
       } else { // interleaved
          int i,j,k,x,y;
          STBI_SIMD_ALIGN(short, data[64]);
          for (j=0; j < z->img_mcu_y; ++j) {
             for (i=0; i < z->img_mcu_x; ++i) {
                // scan an interleaved mcu... process scan_n components in order
                for (k=0; k < z->scan_n; ++k) {
                   int n = z->order[k];
                   // scan out an mcu's worth of this component; that's just determined
                   // by the basic H and V specified for the component
                   for (y=0; y < z->img_comp[n].v; ++y) {
                      for (x=0; x < z->img_comp[n].h; ++x) {
                         int x2 = (i*z->img_comp[n].h + x)*8;
                         int y2 = (j*z->img_comp[n].v + y)*8;
                         int ha = z->img_comp[n].ha;
                         if (!stbi__jpeg_decode_block(z, data, z->huff_dc+z->img_comp[n].hd, z->huff_ac+ha, z->fast_ac[ha], n, z->dequant[z->img_comp[n].tq])) return 0;
                         z->idct_block_kernel(z->img_comp[n].data+z->img_comp[n].w2*y2+x2, z->img_comp[n].w2, data);
                      }
                   }
                }
                // after all interleaved components, that's an interleaved MCU,
                // so now count down the restart interval
                if (--z->todo <= 0) {
                   if (z->code_bits < 24) stbi__grow_buffer_unsafe(z);
                   if (!STBI__RESTART(z->marker)) return 1;
                   stbi__jpeg_reset(z);
                }
             }
          }
          return 1;
       }
    } else {
       if (z->scan_n == 1) {
          int i,j;
          int n = z->order[0];
          // non-interleaved data, we just need to process one block at a time,
          // in trivial scanline order
          // number of blocks to do just depends on how many actual "pixels" this
          // component has, independent of interleaved MCU blocking and such
          int w = (z->img_comp[n].x+7) >> 3;
          int h = (z->img_comp[n].y+7) >> 3;
          for (j=0; j < h; ++j) {
             for (i=0; i < w; ++i) {
                short *data = z->img_comp[n].coeff + 64 * (i + j * z->img_comp[n].coeff_w);
                if (z->spec_start == 0) {
                   if (!stbi__jpeg_decode_block_prog_dc(z, data, &z->huff_dc[z->img_comp[n].hd], n))
                      return 0;
                } else {
                   int ha = z->img_comp[n].ha;
                   if (!stbi__jpeg_decode_block_prog_ac(z, data, &z->huff_ac[ha], z->fast_ac[ha]))
                      return 0;
                }
                // every data block is an MCU, so countdown the restart interval
                if (--z->todo <= 0) {
                   if (z->code_bits < 24) stbi__grow_buffer_unsafe(z);
                   if (!STBI__RESTART(z->marker)) return 1;
                   stbi__jpeg_reset(z);
                }
             }
          }
          return 1;
       } else { // interleaved
          int i,j,k,x,y;
          for (j=0; j < z->img_mcu_y; ++j) {
             for (i=0; i < z->img_mcu_x; ++i) {
                // scan an interleaved mcu... process scan_n components in order
                for (k=0; k < z->scan_n; ++k) {
                   int n = z->order[k];
                   // scan out an mcu's worth of this component; that's just determined
                   // by the basic H and V specified for the component
                   for (y=0; y < z->img_comp[n].v; ++y) {
                      for (x=0; x < z->img_comp[n].h; ++x) {
                         int x2 = (i*z->img_comp[n].h + x);
                         int y2 = (j*z->img_comp[n].v + y);
                         short *data = z->img_comp[n].coeff + 64 * (x2 + y2 * z->img_comp[n].coeff_w);
                         if (!stbi__jpeg_decode_block_prog_dc(z, data, &z->huff_dc[z->img_comp[n].hd], n))
                            return 0;
                      }
                   }
                }
                // after all interleaved components, that's an interleaved MCU,
                // so now count down the restart interval
                if (--z->todo <= 0) {
                   if (z->code_bits < 24) stbi__grow_buffer_unsafe(z);
                   if (!STBI__RESTART(z->marker)) return 1;
                   stbi__jpeg_reset(z);
                }
             }
          }
          return 1;
       }
    }
 }
 
 static void stbi__jpeg_dequantize(short *data, stbi__uint16 *dequant)
 {
    int i;
    for (i=0; i < 64; ++i)
       data[i] *= dequant[i];
 }
 
 static void stbi__jpeg_finish(stbi__jpeg *z)
 {
    if (z->progressive) {
       // dequantize and idct the data
       int i,j,n;
       for (n=0; n < z->s->img_n; ++n) {
          int w = (z->img_comp[n].x+7) >> 3;
          int h = (z->img_comp[n].y+7) >> 3;
          for (j=0; j < h; ++j) {
             for (i=0; i < w; ++i) {
                short *data = z->img_comp[n].coeff + 64 * (i + j * z->img_comp[n].coeff_w);
                stbi__jpeg_dequantize(data, z->dequant[z->img_comp[n].tq]);
                z->idct_block_kernel(z->img_comp[n].data+z->img_comp[n].w2*j*8+i*8, z->img_comp[n].w2, data);
             }
          }
       }
    }
 }
 
 static int stbi__process_marker(stbi__jpeg *z, int m)
 {
    int L;
    switch (m) {
       case STBI__MARKER_none: // no marker found
          return stbi__err("expected marker","Corrupt JPEG");
 
       case 0xDD: // DRI - specify restart interval
          if (stbi__get16be(z->s) != 4) return stbi__err("bad DRI len","Corrupt JPEG");
          z->restart_interval = stbi__get16be(z->s);
          return 1;
 
       case 0xDB: // DQT - define quantization table
          L = stbi__get16be(z->s)-2;
          while (L > 0) {
             int q = stbi__get8(z->s);
             int p = q >> 4, sixteen = (p != 0);
             int t = q & 15,i;
             if (p != 0 && p != 1) return stbi__err("bad DQT type","Corrupt JPEG");
             if (t > 3) return stbi__err("bad DQT table","Corrupt JPEG");
 
             for (i=0; i < 64; ++i)
                z->dequant[t][stbi__jpeg_dezigzag[i]] = (stbi__uint16)(sixteen ? stbi__get16be(z->s) : stbi__get8(z->s));
             L -= (sixteen ? 129 : 65);
          }
          return L==0;
 
       case 0xC4: // DHT - define huffman table
          L = stbi__get16be(z->s)-2;
          while (L > 0) {
             stbi_uc *v;
             int sizes[16],i,n=0;
             int q = stbi__get8(z->s);
             int tc = q >> 4;
             int th = q & 15;
             if (tc > 1 || th > 3) return stbi__err("bad DHT header","Corrupt JPEG");
             for (i=0; i < 16; ++i) {
                sizes[i] = stbi__get8(z->s);
                n += sizes[i];
             }
             L -= 17;
             if (tc == 0) {
                if (!stbi__build_huffman(z->huff_dc+th, sizes)) return 0;
                v = z->huff_dc[th].values;
             } else {
                if (!stbi__build_huffman(z->huff_ac+th, sizes)) return 0;
                v = z->huff_ac[th].values;
             }
             for (i=0; i < n; ++i)
                v[i] = stbi__get8(z->s);
             if (tc != 0)
                stbi__build_fast_ac(z->fast_ac[th], z->huff_ac + th);
             L -= n;
          }
          return L==0;
    }
 
    // check for comment block or APP blocks
    if ((m >= 0xE0 && m <= 0xEF) || m == 0xFE) {
       L = stbi__get16be(z->s);
       if (L < 2) {
          if (m == 0xFE)
             return stbi__err("bad COM len","Corrupt JPEG");
          else
             return stbi__err("bad APP len","Corrupt JPEG");
       }
       L -= 2;
 
       if (m == 0xE0 && L >= 5) { // JFIF APP0 segment
          static const unsigned char tag[5] = {'J','F','I','F','\0'};
          int ok = 1;
          int i;
          for (i=0; i < 5; ++i)
             if (stbi__get8(z->s) != tag[i])
                ok = 0;
          L -= 5;
          if (ok)
             z->jfif = 1;
       } else if (m == 0xEE && L >= 12) { // Adobe APP14 segment
          static const unsigned char tag[6] = {'A','d','o','b','e','\0'};
          int ok = 1;
          int i;
          for (i=0; i < 6; ++i)
             if (stbi__get8(z->s) != tag[i])
                ok = 0;
          L -= 6;
          if (ok) {
             stbi__get8(z->s); // version
             stbi__get16be(z->s); // flags0
             stbi__get16be(z->s); // flags1
             z->app14_color_transform = stbi__get8(z->s); // color transform
             L -= 6;
          }
       }
 
       stbi__skip(z->s, L);
       return 1;
    }
 
    return stbi__err("unknown marker","Corrupt JPEG");
 }
 
 // after we see SOS
 static int stbi__process_scan_header(stbi__jpeg *z)
 {
    int i;
    int Ls = stbi__get16be(z->s);
    z->scan_n = stbi__get8(z->s);
    if (z->scan_n < 1 || z->scan_n > 4 || z->scan_n > (int) z->s->img_n) return stbi__err("bad SOS component count","Corrupt JPEG");
    if (Ls != 6+2*z->scan_n) return stbi__err("bad SOS len","Corrupt JPEG");
    for (i=0; i < z->scan_n; ++i) {
       int id = stbi__get8(z->s), which;
       int q = stbi__get8(z->s);
       for (which = 0; which < z->s->img_n; ++which)
          if (z->img_comp[which].id == id)
             break;
       if (which == z->s->img_n) return 0; // no match
       z->img_comp[which].hd = q >> 4;   if (z->img_comp[which].hd > 3) return stbi__err("bad DC huff","Corrupt JPEG");
       z->img_comp[which].ha = q & 15;   if (z->img_comp[which].ha > 3) return stbi__err("bad AC huff","Corrupt JPEG");
       z->order[i] = which;
    }
 
    {
       int aa;
       z->spec_start = stbi__get8(z->s);
       z->spec_end   = stbi__get8(z->s); // should be 63, but might be 0
       aa = stbi__get8(z->s);
       z->succ_high = (aa >> 4);
       z->succ_low  = (aa & 15);
       if (z->progressive) {
          if (z->spec_start > 63 || z->spec_end > 63  || z->spec_start > z->spec_end || z->succ_high > 13 || z->succ_low > 13)
             return stbi__err("bad SOS", "Corrupt JPEG");
       } else {
          if (z->spec_start != 0) return stbi__err("bad SOS","Corrupt JPEG");
          if (z->succ_high != 0 || z->succ_low != 0) return stbi__err("bad SOS","Corrupt JPEG");
          z->spec_end = 63;
       }
    }
 
    return 1;
 }
 
 static int stbi__free_jpeg_components(stbi__jpeg *z, int ncomp, int why)
 {
    int i;
    for (i=0; i < ncomp; ++i) {
       if (z->img_comp[i].raw_data) {
          STBI_FREE(z->img_comp[i].raw_data);
          z->img_comp[i].raw_data = NULL;
          z->img_comp[i].data = NULL;
       }
       if (z->img_comp[i].raw_coeff) {
          STBI_FREE(z->img_comp[i].raw_coeff);
          z->img_comp[i].raw_coeff = 0;
          z->img_comp[i].coeff = 0;
       }
       if (z->img_comp[i].linebuf) {
          STBI_FREE(z->img_comp[i].linebuf);
          z->img_comp[i].linebuf = NULL;
       }
    }
    return why;
 }
 
 static int stbi__process_frame_header(stbi__jpeg *z, int scan)
 {
    stbi__context *s = z->s;
    int Lf,p,i,q, h_max=1,v_max=1,c;
    Lf = stbi__get16be(s);         if (Lf < 11) return stbi__err("bad SOF len","Corrupt JPEG"); // JPEG
    p  = stbi__get8(s);            if (p != 8) return stbi__err("only 8-bit","JPEG format not supported: 8-bit only"); // JPEG baseline
    s->img_y = stbi__get16be(s);   if (s->img_y == 0) return stbi__err("no header height", "JPEG format not supported: delayed height"); // Legal, but we don't handle it--but neither does IJG
    s->img_x = stbi__get16be(s);   if (s->img_x == 0) return stbi__err("0 width","Corrupt JPEG"); // JPEG requires
    c = stbi__get8(s);
    if (c != 3 && c != 1 && c != 4) return stbi__err("bad component count","Corrupt JPEG");
    s->img_n = c;
    for (i=0; i < c; ++i) {
       z->img_comp[i].data = NULL;
       z->img_comp[i].linebuf = NULL;
    }
 
    if (Lf != 8+3*s->img_n) return stbi__err("bad SOF len","Corrupt JPEG");
 
    z->rgb = 0;
    for (i=0; i < s->img_n; ++i) {
       static const unsigned char rgb[3] = { 'R', 'G', 'B' };
       z->img_comp[i].id = stbi__get8(s);
       if (s->img_n == 3 && z->img_comp[i].id == rgb[i])
          ++z->rgb;
       q = stbi__get8(s);
       z->img_comp[i].h = (q >> 4);  if (!z->img_comp[i].h || z->img_comp[i].h > 4) return stbi__err("bad H","Corrupt JPEG");
       z->img_comp[i].v = q & 15;    if (!z->img_comp[i].v || z->img_comp[i].v > 4) return stbi__err("bad V","Corrupt JPEG");
       z->img_comp[i].tq = stbi__get8(s);  if (z->img_comp[i].tq > 3) return stbi__err("bad TQ","Corrupt JPEG");
    }
 
    if (scan != STBI__SCAN_load) return 1;
 
    if (!stbi__mad3sizes_valid(s->img_x, s->img_y, s->img_n, 0)) return stbi__err("too large", "Image too large to decode");
 
    for (i=0; i < s->img_n; ++i) {
       if (z->img_comp[i].h > h_max) h_max = z->img_comp[i].h;
       if (z->img_comp[i].v > v_max) v_max = z->img_comp[i].v;
    }
 
    // compute interleaved mcu info
    z->img_h_max = h_max;
    z->img_v_max = v_max;
    z->img_mcu_w = h_max * 8;
    z->img_mcu_h = v_max * 8;
    // these sizes can't be more than 17 bits
    z->img_mcu_x = (s->img_x + z->img_mcu_w-1) / z->img_mcu_w;
    z->img_mcu_y = (s->img_y + z->img_mcu_h-1) / z->img_mcu_h;
 
    for (i=0; i < s->img_n; ++i) {
       // number of effective pixels (e.g. for non-interleaved MCU)
       z->img_comp[i].x = (s->img_x * z->img_comp[i].h + h_max-1) / h_max;
       z->img_comp[i].y = (s->img_y * z->img_comp[i].v + v_max-1) / v_max;
       // to simplify generation, we'll allocate enough memory to decode
       // the bogus oversized data from using interleaved MCUs and their
       // big blocks (e.g. a 16x16 iMCU on an image of width 33); we won't
       // discard the extra data until colorspace conversion
       //
       // img_mcu_x, img_mcu_y: <=17 bits; comp[i].h and .v are <=4 (checked earlier)
       // so these muls can't overflow with 32-bit ints (which we require)
       z->img_comp[i].w2 = z->img_mcu_x * z->img_comp[i].h * 8;
       z->img_comp[i].h2 = z->img_mcu_y * z->img_comp[i].v * 8;
       z->img_comp[i].coeff = 0;
       z->img_comp[i].raw_coeff = 0;
       z->img_comp[i].linebuf = NULL;
       z->img_comp[i].raw_data = stbi__malloc_mad2(z->img_comp[i].w2, z->img_comp[i].h2, 15);
       if (z->img_comp[i].raw_data == NULL)
          return stbi__free_jpeg_components(z, i+1, stbi__err("outofmem", "Out of memory"));
       // align blocks for idct using mmx/sse
       z->img_comp[i].data = (stbi_uc*) (((size_t) z->img_comp[i].raw_data + 15) & ~15);
       if (z->progressive) {
          // w2, h2 are multiples of 8 (see above)
          z->img_comp[i].coeff_w = z->img_comp[i].w2 / 8;
          z->img_comp[i].coeff_h = z->img_comp[i].h2 / 8;
          z->img_comp[i].raw_coeff = stbi__malloc_mad3(z->img_comp[i].w2, z->img_comp[i].h2, sizeof(short), 15);
          if (z->img_comp[i].raw_coeff == NULL)
             return stbi__free_jpeg_components(z, i+1, stbi__err("outofmem", "Out of memory"));
          z->img_comp[i].coeff = (short*) (((size_t) z->img_comp[i].raw_coeff + 15) & ~15);
       }
    }
 
    return 1;
 }
 
 // use comparisons since in some cases we handle more than one case (e.g. SOF)
 #define stbi__DNL(x)         ((x) == 0xdc)
 #define stbi__SOI(x)         ((x) == 0xd8)
 #define stbi__EOI(x)         ((x) == 0xd9)
 #define stbi__SOF(x)         ((x) == 0xc0 || (x) == 0xc1 || (x) == 0xc2)
 #define stbi__SOS(x)         ((x) == 0xda)
 
 #define stbi__SOF_progressive(x)   ((x) == 0xc2)
 
 static int stbi__decode_jpeg_header(stbi__jpeg *z, int scan)
 {
    int m;
    z->jfif = 0;
    z->app14_color_transform = -1; // valid values are 0,1,2
    z->marker = STBI__MARKER_none; // initialize cached marker to empty
    m = stbi__get_marker(z);
    if (!stbi__SOI(m)) return stbi__err("no SOI","Corrupt JPEG");
    if (scan == STBI__SCAN_type) return 1;
    m = stbi__get_marker(z);
    while (!stbi__SOF(m)) {
       if (!stbi__process_marker(z,m)) return 0;
       m = stbi__get_marker(z);
       while (m == STBI__MARKER_none) {
          // some files have extra padding after their blocks, so ok, we'll scan
          if (stbi__at_eof(z->s)) return stbi__err("no SOF", "Corrupt JPEG");
          m = stbi__get_marker(z);
       }
    }
    z->progressive = stbi__SOF_progressive(m);
    if (!stbi__process_frame_header(z, scan)) return 0;
    return 1;
 }
 
 // decode image to YCbCr format
 static int stbi__decode_jpeg_image(stbi__jpeg *j)
 {
    int m;
    for (m = 0; m < 4; m++) {
       j->img_comp[m].raw_data = NULL;
       j->img_comp[m].raw_coeff = NULL;
    }
    j->restart_interval = 0;
    if (!stbi__decode_jpeg_header(j, STBI__SCAN_load)) return 0;
    m = stbi__get_marker(j);
    while (!stbi__EOI(m)) {
       if (stbi__SOS(m)) {
          if (!stbi__process_scan_header(j)) return 0;
          if (!stbi__parse_entropy_coded_data(j)) return 0;
          if (j->marker == STBI__MARKER_none ) {
             // handle 0s at the end of image data from IP Kamera 9060
             while (!stbi__at_eof(j->s)) {
                int x = stbi__get8(j->s);
                if (x == 255) {
                   j->marker = stbi__get8(j->s);
                   break;
                }
             }
             // if we reach eof without hitting a marker, stbi__get_marker() below will fail and we'll eventually return 0
          }
       } else if (stbi__DNL(m)) {
          int Ld = stbi__get16be(j->s);
          stbi__uint32 NL = stbi__get16be(j->s);
          if (Ld != 4) return stbi__err("bad DNL len", "Corrupt JPEG");
          if (NL != j->s->img_y) return stbi__err("bad DNL height", "Corrupt JPEG");
       } else {
          if (!stbi__process_marker(j, m)) return 0;
       }
       m = stbi__get_marker(j);
    }
    if (j->progressive)
       stbi__jpeg_finish(j);
    return 1;
 }
 
 // static jfif-centered resampling (across block boundaries)
 
 typedef stbi_uc *(*resample_row_func)(stbi_uc *out, stbi_uc *in0, stbi_uc *in1,
                                     int w, int hs);
 
 #define stbi__div4(x) ((stbi_uc) ((x) >> 2))
 
 static stbi_uc *resample_row_1(stbi_uc *out, stbi_uc *in_near, stbi_uc *in_far, int w, int hs)
 {
    STBI_NOTUSED(out);
    STBI_NOTUSED(in_far);
    STBI_NOTUSED(w);
    STBI_NOTUSED(hs);
    return in_near;
 }
 
 static stbi_uc* stbi__resample_row_v_2(stbi_uc *out, stbi_uc *in_near, stbi_uc *in_far, int w, int hs)
 {
    // need to generate two samples vertically for every one in input
    int i;
    STBI_NOTUSED(hs);
    for (i=0; i < w; ++i)
       out[i] = stbi__div4(3*in_near[i] + in_far[i] + 2);
    return out;
 }
 
 static stbi_uc*  stbi__resample_row_h_2(stbi_uc *out, stbi_uc *in_near, stbi_uc *in_far, int w, int hs)
 {
    // need to generate two samples horizontally for every one in input
    int i;
    stbi_uc *input = in_near;
 
    if (w == 1) {
       // if only one sample, can't do any interpolation
       out[0] = out[1] = input[0];
       return out;
    }
 
    out[0] = input[0];
    out[1] = stbi__div4(input[0]*3 + input[1] + 2);
    for (i=1; i < w-1; ++i) {
       int n = 3*input[i]+2;
       out[i*2+0] = stbi__div4(n+input[i-1]);
       out[i*2+1] = stbi__div4(n+input[i+1]);
    }
    out[i*2+0] = stbi__div4(input[w-2]*3 + input[w-1] + 2);
    out[i*2+1] = input[w-1];
 
    STBI_NOTUSED(in_far);
    STBI_NOTUSED(hs);
 
    return out;
 }
 
 #define stbi__div16(x) ((stbi_uc) ((x) >> 4))
 
 static stbi_uc *stbi__resample_row_hv_2(stbi_uc *out, stbi_uc *in_near, stbi_uc *in_far, int w, int hs)
 {
    // need to generate 2x2 samples for every one in input
    int i,t0,t1;
    if (w == 1) {
       out[0] = out[1] = stbi__div4(3*in_near[0] + in_far[0] + 2);
       return out;
    }
 
    t1 = 3*in_near[0] + in_far[0];
    out[0] = stbi__div4(t1+2);
    for (i=1; i < w; ++i) {
       t0 = t1;
       t1 = 3*in_near[i]+in_far[i];
       out[i*2-1] = stbi__div16(3*t0 + t1 + 8);
       out[i*2  ] = stbi__div16(3*t1 + t0 + 8);
    }
    out[w*2-1] = stbi__div4(t1+2);
 
    STBI_NOTUSED(hs);
 
    return out;
 }
 
 #if defined(STBI_SSE2) || defined(STBI_NEON)
 static stbi_uc *stbi__resample_row_hv_2_simd(stbi_uc *out, stbi_uc *in_near, stbi_uc *in_far, int w, int hs)
 {
    // need to generate 2x2 samples for every one in input
    int i=0,t0,t1;
 
    if (w == 1) {
       out[0] = out[1] = stbi__div4(3*in_near[0] + in_far[0] + 2);
       return out;
    }
 
    t1 = 3*in_near[0] + in_far[0];
    // process groups of 8 pixels for as long as we can.
    // note we can't handle the last pixel in a row in this loop
    // because we need to handle the filter boundary conditions.
    for (; i < ((w-1) & ~7); i += 8) {
 #if defined(STBI_SSE2)
       // load and perform the vertical filtering pass
       // this uses 3*x + y = 4*x + (y - x)
       __m128i zero  = _mm_setzero_si128();
       __m128i farb  = _mm_loadl_epi64((__m128i *) (in_far + i));
       __m128i nearb = _mm_loadl_epi64((__m128i *) (in_near + i));
       __m128i farw  = _mm_unpacklo_epi8(farb, zero);
       __m128i nearw = _mm_unpacklo_epi8(nearb, zero);
       __m128i diff  = _mm_sub_epi16(farw, nearw);
       __m128i nears = _mm_slli_epi16(nearw, 2);
       __m128i curr  = _mm_add_epi16(nears, diff); // current row
 
       // horizontal filter works the same based on shifted vers of current
       // row. "prev" is current row shifted right by 1 pixel; we need to
       // insert the previous pixel value (from t1).
       // "next" is current row shifted left by 1 pixel, with first pixel
       // of next block of 8 pixels added in.
       __m128i prv0 = _mm_slli_si128(curr, 2);
       __m128i nxt0 = _mm_srli_si128(curr, 2);
       __m128i prev = _mm_insert_epi16(prv0, t1, 0);
       __m128i next = _mm_insert_epi16(nxt0, 3*in_near[i+8] + in_far[i+8], 7);
 
       // horizontal filter, polyphase implementation since it's convenient:
       // even pixels = 3*cur + prev = cur*4 + (prev - cur)
       // odd  pixels = 3*cur + next = cur*4 + (next - cur)
       // note the shared term.
       __m128i bias  = _mm_set1_epi16(8);
       __m128i curs = _mm_slli_epi16(curr, 2);
       __m128i prvd = _mm_sub_epi16(prev, curr);
       __m128i nxtd = _mm_sub_epi16(next, curr);
       __m128i curb = _mm_add_epi16(curs, bias);
       __m128i even = _mm_add_epi16(prvd, curb);
       __m128i odd  = _mm_add_epi16(nxtd, curb);
 
       // interleave even and odd pixels, then undo scaling.
       __m128i int0 = _mm_unpacklo_epi16(even, odd);
       __m128i int1 = _mm_unpackhi_epi16(even, odd);
       __m128i de0  = _mm_srli_epi16(int0, 4);
       __m128i de1  = _mm_srli_epi16(int1, 4);
 
       // pack and write output
       __m128i outv = _mm_packus_epi16(de0, de1);
       _mm_storeu_si128((__m128i *) (out + i*2), outv);
 #elif defined(STBI_NEON)
       // load and perform the vertical filtering pass
       // this uses 3*x + y = 4*x + (y - x)
       uint8x8_t farb  = vld1_u8(in_far + i);
       uint8x8_t nearb = vld1_u8(in_near + i);
       int16x8_t diff  = vreinterpretq_s16_u16(vsubl_u8(farb, nearb));
       int16x8_t nears = vreinterpretq_s16_u16(vshll_n_u8(nearb, 2));
       int16x8_t curr  = vaddq_s16(nears, diff); // current row
 
       // horizontal filter works the same based on shifted vers of current
       // row. "prev" is current row shifted right by 1 pixel; we need to
       // insert the previous pixel value (from t1).
       // "next" is current row shifted left by 1 pixel, with first pixel
       // of next block of 8 pixels added in.
       int16x8_t prv0 = vextq_s16(curr, curr, 7);
       int16x8_t nxt0 = vextq_s16(curr, curr, 1);
       int16x8_t prev = vsetq_lane_s16(t1, prv0, 0);
       int16x8_t next = vsetq_lane_s16(3*in_near[i+8] + in_far[i+8], nxt0, 7);
 
       // horizontal filter, polyphase implementation since it's convenient:
       // even pixels = 3*cur + prev = cur*4 + (prev - cur)
       // odd  pixels = 3*cur + next = cur*4 + (next - cur)
       // note the shared term.
       int16x8_t curs = vshlq_n_s16(curr, 2);
       int16x8_t prvd = vsubq_s16(prev, curr);
       int16x8_t nxtd = vsubq_s16(next, curr);
       int16x8_t even = vaddq_s16(curs, prvd);
       int16x8_t odd  = vaddq_s16(curs, nxtd);
 
       // undo scaling and round, then store with even/odd phases interleaved
       uint8x8x2_t o;
       o.val[0] = vqrshrun_n_s16(even, 4);
       o.val[1] = vqrshrun_n_s16(odd,  4);
       vst2_u8(out + i*2, o);
 #endif
 
       // "previous" value for next iter
       t1 = 3*in_near[i+7] + in_far[i+7];
    }
 
    t0 = t1;
    t1 = 3*in_near[i] + in_far[i];
    out[i*2] = stbi__div16(3*t1 + t0 + 8);
 
    for (++i; i < w; ++i) {
       t0 = t1;
       t1 = 3*in_near[i]+in_far[i];
       out[i*2-1] = stbi__div16(3*t0 + t1 + 8);
       out[i*2  ] = stbi__div16(3*t1 + t0 + 8);
    }
    out[w*2-1] = stbi__div4(t1+2);
 
    STBI_NOTUSED(hs);
 
    return out;
 }
 #endif
 
 static stbi_uc *stbi__resample_row_generic(stbi_uc *out, stbi_uc *in_near, stbi_uc *in_far, int w, int hs)
 {
    // resample with nearest-neighbor
    int i,j;
    STBI_NOTUSED(in_far);
    for (i=0; i < w; ++i)
       for (j=0; j < hs; ++j)
          out[i*hs+j] = in_near[i];
    return out;
 }
 
 // this is a reduced-precision calculation of YCbCr-to-RGB introduced
 // to make sure the code produces the same results in both SIMD and scalar
 #define stbi__float2fixed(x)  (((int) ((x) * 4096.0f + 0.5f)) << 8)
 static void stbi__YCbCr_to_RGB_row(stbi_uc *out, const stbi_uc *y, const stbi_uc *pcb, const stbi_uc *pcr, int count, int step)
 {
    int i;
    for (i=0; i < count; ++i) {
       int y_fixed = (y[i] << 20) + (1<<19); // rounding
       int r,g,b;
       int cr = pcr[i] - 128;
       int cb = pcb[i] - 128;
       r = y_fixed +  cr* stbi__float2fixed(1.40200f);
       g = y_fixed + (cr*-stbi__float2fixed(0.71414f)) + ((cb*-stbi__float2fixed(0.34414f)) & 0xffff0000);
       b = y_fixed                                     +   cb* stbi__float2fixed(1.77200f);
       r >>= 20;
       g >>= 20;
       b >>= 20;
       if ((unsigned) r > 255) { if (r < 0) r = 0; else r = 255; }
       if ((unsigned) g > 255) { if (g < 0) g = 0; else g = 255; }
       if ((unsigned) b > 255) { if (b < 0) b = 0; else b = 255; }
       out[0] = (stbi_uc)r;
       out[1] = (stbi_uc)g;
       out[2] = (stbi_uc)b;
       out[3] = 255;
       out += step;
    }
 }
 
 #if defined(STBI_SSE2) || defined(STBI_NEON)
 static void stbi__YCbCr_to_RGB_simd(stbi_uc *out, stbi_uc const *y, stbi_uc const *pcb, stbi_uc const *pcr, int count, int step)
 {
    int i = 0;
 
 #ifdef STBI_SSE2
    // step == 3 is pretty ugly on the final interleave, and i'm not convinced
    // it's useful in practice (you wouldn't use it for textures, for example).
    // so just accelerate step == 4 case.
    if (step == 4) {
       // this is a fairly straightforward implementation and not super-optimized.
       __m128i signflip  = _mm_set1_epi8(-0x80);
       __m128i cr_const0 = _mm_set1_epi16(   (short) ( 1.40200f*4096.0f+0.5f));
       __m128i cr_const1 = _mm_set1_epi16( - (short) ( 0.71414f*4096.0f+0.5f));
       __m128i cb_const0 = _mm_set1_epi16( - (short) ( 0.34414f*4096.0f+0.5f));
       __m128i cb_const1 = _mm_set1_epi16(   (short) ( 1.77200f*4096.0f+0.5f));
       __m128i y_bias = _mm_set1_epi8((char) (unsigned char) 128);
       __m128i xw = _mm_set1_epi16(255); // alpha channel
 
       for (; i+7 < count; i += 8) {
          // load
          __m128i y_bytes = _mm_loadl_epi64((__m128i *) (y+i));
          __m128i cr_bytes = _mm_loadl_epi64((__m128i *) (pcr+i));
          __m128i cb_bytes = _mm_loadl_epi64((__m128i *) (pcb+i));
          __m128i cr_biased = _mm_xor_si128(cr_bytes, signflip); // -128
          __m128i cb_biased = _mm_xor_si128(cb_bytes, signflip); // -128
 
          // unpack to short (and left-shift cr, cb by 8)
          __m128i yw  = _mm_unpacklo_epi8(y_bias, y_bytes);
          __m128i crw = _mm_unpacklo_epi8(_mm_setzero_si128(), cr_biased);
          __m128i cbw = _mm_unpacklo_epi8(_mm_setzero_si128(), cb_biased);
 
          // color transform
          __m128i yws = _mm_srli_epi16(yw, 4);
          __m128i cr0 = _mm_mulhi_epi16(cr_const0, crw);
          __m128i cb0 = _mm_mulhi_epi16(cb_const0, cbw);
          __m128i cb1 = _mm_mulhi_epi16(cbw, cb_const1);
          __m128i cr1 = _mm_mulhi_epi16(crw, cr_const1);
          __m128i rws = _mm_add_epi16(cr0, yws);
          __m128i gwt = _mm_add_epi16(cb0, yws);
          __m128i bws = _mm_add_epi16(yws, cb1);
          __m128i gws = _mm_add_epi16(gwt, cr1);
 
          // descale
          __m128i rw = _mm_srai_epi16(rws, 4);
          __m128i bw = _mm_srai_epi16(bws, 4);
          __m128i gw = _mm_srai_epi16(gws, 4);
 
          // back to byte, set up for transpose
          __m128i brb = _mm_packus_epi16(rw, bw);
          __m128i gxb = _mm_packus_epi16(gw, xw);
 
          // transpose to interleave channels
          __m128i t0 = _mm_unpacklo_epi8(brb, gxb);
          __m128i t1 = _mm_unpackhi_epi8(brb, gxb);
          __m128i o0 = _mm_unpacklo_epi16(t0, t1);
          __m128i o1 = _mm_unpackhi_epi16(t0, t1);
 
          // store
          _mm_storeu_si128((__m128i *) (out + 0), o0);
          _mm_storeu_si128((__m128i *) (out + 16), o1);
          out += 32;
       }
    }
 #endif
 
 #ifdef STBI_NEON
    // in this version, step=3 support would be easy to add. but is there demand?
    if (step == 4) {
       // this is a fairly straightforward implementation and not super-optimized.
       uint8x8_t signflip = vdup_n_u8(0x80);
       int16x8_t cr_const0 = vdupq_n_s16(   (short) ( 1.40200f*4096.0f+0.5f));
       int16x8_t cr_const1 = vdupq_n_s16( - (short) ( 0.71414f*4096.0f+0.5f));
       int16x8_t cb_const0 = vdupq_n_s16( - (short) ( 0.34414f*4096.0f+0.5f));
       int16x8_t cb_const1 = vdupq_n_s16(   (short) ( 1.77200f*4096.0f+0.5f));
 
       for (; i+7 < count; i += 8) {
          // load
          uint8x8_t y_bytes  = vld1_u8(y + i);
          uint8x8_t cr_bytes = vld1_u8(pcr + i);
          uint8x8_t cb_bytes = vld1_u8(pcb + i);
          int8x8_t cr_biased = vreinterpret_s8_u8(vsub_u8(cr_bytes, signflip));
          int8x8_t cb_biased = vreinterpret_s8_u8(vsub_u8(cb_bytes, signflip));
 
          // expand to s16
          int16x8_t yws = vreinterpretq_s16_u16(vshll_n_u8(y_bytes, 4));
          int16x8_t crw = vshll_n_s8(cr_biased, 7);
          int16x8_t cbw = vshll_n_s8(cb_biased, 7);
 
          // color transform
          int16x8_t cr0 = vqdmulhq_s16(crw, cr_const0);
          int16x8_t cb0 = vqdmulhq_s16(cbw, cb_const0);
          int16x8_t cr1 = vqdmulhq_s16(crw, cr_const1);
          int16x8_t cb1 = vqdmulhq_s16(cbw, cb_const1);
          int16x8_t rws = vaddq_s16(yws, cr0);
          int16x8_t gws = vaddq_s16(vaddq_s16(yws, cb0), cr1);
          int16x8_t bws = vaddq_s16(yws, cb1);
 
          // undo scaling, round, convert to byte
          uint8x8x4_t o;
          o.val[0] = vqrshrun_n_s16(rws, 4);
          o.val[1] = vqrshrun_n_s16(gws, 4);
          o.val[2] = vqrshrun_n_s16(bws, 4);
          o.val[3] = vdup_n_u8(255);
 
          // store, interleaving r/g/b/a
          vst4_u8(out, o);
          out += 8*4;
       }
    }
 #endif
 
    for (; i < count; ++i) {
       int y_fixed = (y[i] << 20) + (1<<19); // rounding
       int r,g,b;
       int cr = pcr[i] - 128;
       int cb = pcb[i] - 128;
       r = y_fixed + cr* stbi__float2fixed(1.40200f);
       g = y_fixed + cr*-stbi__float2fixed(0.71414f) + ((cb*-stbi__float2fixed(0.34414f)) & 0xffff0000);
       b = y_fixed                                   +   cb* stbi__float2fixed(1.77200f);
       r >>= 20;
       g >>= 20;
       b >>= 20;
       if ((unsigned) r > 255) { if (r < 0) r = 0; else r = 255; }
       if ((unsigned) g > 255) { if (g < 0) g = 0; else g = 255; }
       if ((unsigned) b > 255) { if (b < 0) b = 0; else b = 255; }
       out[0] = (stbi_uc)r;
       out[1] = (stbi_uc)g;
       out[2] = (stbi_uc)b;
       out[3] = 255;
       out += step;
    }
 }
 #endif
 
 // set up the kernels
 static void stbi__setup_jpeg(stbi__jpeg *j)
 {
    j->idct_block_kernel = stbi__idct_block;
    j->YCbCr_to_RGB_kernel = stbi__YCbCr_to_RGB_row;
    j->resample_row_hv_2_kernel = stbi__resample_row_hv_2;
 
 #ifdef STBI_SSE2
    if (stbi__sse2_available()) {
       j->idct_block_kernel = stbi__idct_simd;
       j->YCbCr_to_RGB_kernel = stbi__YCbCr_to_RGB_simd;
       j->resample_row_hv_2_kernel = stbi__resample_row_hv_2_simd;
    }
 #endif
 
 #ifdef STBI_NEON
    j->idct_block_kernel = stbi__idct_simd;
    j->YCbCr_to_RGB_kernel = stbi__YCbCr_to_RGB_simd;
    j->resample_row_hv_2_kernel = stbi__resample_row_hv_2_simd;
 #endif
 }
 
 // clean up the temporary component buffers
 static void stbi__cleanup_jpeg(stbi__jpeg *j)
 {
    stbi__free_jpeg_components(j, j->s->img_n, 0);
 }
 
 typedef struct
 {
    resample_row_func resample;
    stbi_uc *line0,*line1;
    int hs,vs;   // expansion factor in each axis
    int w_lores; // horizontal pixels pre-expansion
    int ystep;   // how far through vertical expansion we are
    int ypos;    // which pre-expansion row we're on
 } stbi__resample;
 
 // fast 0..255 * 0..255 => 0..255 rounded multiplication
 static stbi_uc stbi__blinn_8x8(stbi_uc x, stbi_uc y)
 {
    unsigned int t = x*y + 128;
    return (stbi_uc) ((t + (t >>8)) >> 8);
 }
 
 static stbi_uc *load_jpeg_image(stbi__jpeg *z, int *out_x, int *out_y, int *comp, int req_comp)
 {
    int n, decode_n, is_rgb;
    z->s->img_n = 0; // make stbi__cleanup_jpeg safe
 
    // validate req_comp
    if (req_comp < 0 || req_comp > 4) return stbi__errpuc("bad req_comp", "Internal error");
 
    // load a jpeg image from whichever source, but leave in YCbCr format
    if (!stbi__decode_jpeg_image(z)) { stbi__cleanup_jpeg(z); return NULL; }
 
    // determine actual number of components to generate
    n = req_comp ? req_comp : z->s->img_n >= 3 ? 3 : 1;
 
    is_rgb = z->s->img_n == 3 && (z->rgb == 3 || (z->app14_color_transform == 0 && !z->jfif));
 
    if (z->s->img_n == 3 && n < 3 && !is_rgb)
       decode_n = 1;
    else
       decode_n = z->s->img_n;
 
    // resample and color-convert
    {
       int k;
       unsigned int i,j;
       stbi_uc *output;
       stbi_uc *coutput[4];
 
       stbi__resample res_comp[4];
 
       for (k=0; k < decode_n; ++k) {
          stbi__resample *r = &res_comp[k];
 
          // allocate line buffer big enough for upsampling off the edges
          // with upsample factor of 4
          z->img_comp[k].linebuf = (stbi_uc *) stbi__malloc(z->s->img_x + 3);
          if (!z->img_comp[k].linebuf) { stbi__cleanup_jpeg(z); return stbi__errpuc("outofmem", "Out of memory"); }
 
          r->hs      = z->img_h_max / z->img_comp[k].h;
          r->vs      = z->img_v_max / z->img_comp[k].v;
          r->ystep   = r->vs >> 1;
          r->w_lores = (z->s->img_x + r->hs-1) / r->hs;
          r->ypos    = 0;
          r->line0   = r->line1 = z->img_comp[k].data;
 
          if      (r->hs == 1 && r->vs == 1) r->resample = resample_row_1;
          else if (r->hs == 1 && r->vs == 2) r->resample = stbi__resample_row_v_2;
          else if (r->hs == 2 && r->vs == 1) r->resample = stbi__resample_row_h_2;
          else if (r->hs == 2 && r->vs == 2) r->resample = z->resample_row_hv_2_kernel;
          else                               r->resample = stbi__resample_row_generic;
       }
 
       // can't error after this so, this is safe
       output = (stbi_uc *) stbi__malloc_mad3(n, z->s->img_x, z->s->img_y, 1);
       if (!output) { stbi__cleanup_jpeg(z); return stbi__errpuc("outofmem", "Out of memory"); }
 
       // now go ahead and resample
       for (j=0; j < z->s->img_y; ++j) {
          stbi_uc *out = output + n * z->s->img_x * j;
          for (k=0; k < decode_n; ++k) {
             stbi__resample *r = &res_comp[k];
             int y_bot = r->ystep >= (r->vs >> 1);
             coutput[k] = r->resample(z->img_comp[k].linebuf,
                                      y_bot ? r->line1 : r->line0,
                                      y_bot ? r->line0 : r->line1,
                                      r->w_lores, r->hs);
             if (++r->ystep >= r->vs) {
                r->ystep = 0;
                r->line0 = r->line1;
                if (++r->ypos < z->img_comp[k].y)
                   r->line1 += z->img_comp[k].w2;
             }
          }
          if (n >= 3) {
             stbi_uc *y = coutput[0];
             if (z->s->img_n == 3) {
                if (is_rgb) {
                   for (i=0; i < z->s->img_x; ++i) {
                      out[0] = y[i];
                      out[1] = coutput[1][i];
                      out[2] = coutput[2][i];
                      out[3] = 255;
                      out += n;
                   }
                } else {
                   z->YCbCr_to_RGB_kernel(out, y, coutput[1], coutput[2], z->s->img_x, n);
                }
             } else if (z->s->img_n == 4) {
                if (z->app14_color_transform == 0) { // CMYK
                   for (i=0; i < z->s->img_x; ++i) {
                      stbi_uc m = coutput[3][i];
                      out[0] = stbi__blinn_8x8(coutput[0][i], m);
                      out[1] = stbi__blinn_8x8(coutput[1][i], m);
                      out[2] = stbi__blinn_8x8(coutput[2][i], m);
                      out[3] = 255;
                      out += n;
                   }
                } else if (z->app14_color_transform == 2) { // YCCK
                   z->YCbCr_to_RGB_kernel(out, y, coutput[1], coutput[2], z->s->img_x, n);
                   for (i=0; i < z->s->img_x; ++i) {
                      stbi_uc m = coutput[3][i];
                      out[0] = stbi__blinn_8x8(255 - out[0], m);
                      out[1] = stbi__blinn_8x8(255 - out[1], m);
                      out[2] = stbi__blinn_8x8(255 - out[2], m);
                      out += n;
                   }
                } else { // YCbCr + alpha?  Ignore the fourth channel for now
                   z->YCbCr_to_RGB_kernel(out, y, coutput[1], coutput[2], z->s->img_x, n);
                }
             } else
                for (i=0; i < z->s->img_x; ++i) {
                   out[0] = out[1] = out[2] = y[i];
                   out[3] = 255; // not used if n==3
                   out += n;
                }
          } else {
             if (is_rgb) {
                if (n == 1)
                   for (i=0; i < z->s->img_x; ++i)
                      *out++ = stbi__compute_y(coutput[0][i], coutput[1][i], coutput[2][i]);
                else {
                   for (i=0; i < z->s->img_x; ++i, out += 2) {
                      out[0] = stbi__compute_y(coutput[0][i], coutput[1][i], coutput[2][i]);
                      out[1] = 255;
                   }
                }
             } else if (z->s->img_n == 4 && z->app14_color_transform == 0) {
                for (i=0; i < z->s->img_x; ++i) {
                   stbi_uc m = coutput[3][i];
                   stbi_uc r = stbi__blinn_8x8(coutput[0][i], m);
                   stbi_uc g = stbi__blinn_8x8(coutput[1][i], m);
                   stbi_uc b = stbi__blinn_8x8(coutput[2][i], m);
                   out[0] = stbi__compute_y(r, g, b);
                   out[1] = 255;
                   out += n;
                }
             } else if (z->s->img_n == 4 && z->app14_color_transform == 2) {
                for (i=0; i < z->s->img_x; ++i) {
                   out[0] = stbi__blinn_8x8(255 - coutput[0][i], coutput[3][i]);
                   out[1] = 255;
                   out += n;
                }
             } else {
                stbi_uc *y = coutput[0];
                if (n == 1)
                   for (i=0; i < z->s->img_x; ++i) out[i] = y[i];
                else
                   for (i=0; i < z->s->img_x; ++i) *out++ = y[i], *out++ = 255;
             }
          }
       }
       stbi__cleanup_jpeg(z);
       *out_x = z->s->img_x;
       *out_y = z->s->img_y;
       if (comp) *comp = z->s->img_n >= 3 ? 3 : 1; // report original components, not output
       return output;
    }
 }
 
 static void *stbi__jpeg_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri)
 {
    unsigned char* result;
    stbi__jpeg* j = (stbi__jpeg*) stbi__malloc(sizeof(stbi__jpeg));
    STBI_NOTUSED(ri);
    j->s = s;
    stbi__setup_jpeg(j);
    result = load_jpeg_image(j, x,y,comp,req_comp);
    STBI_FREE(j);
    return result;
 }
 
 static int stbi__jpeg_test(stbi__context *s)
 {
    int r;
    stbi__jpeg* j = (stbi__jpeg*)stbi__malloc(sizeof(stbi__jpeg));
    j->s = s;
    stbi__setup_jpeg(j);
    r = stbi__decode_jpeg_header(j, STBI__SCAN_type);
    stbi__rewind(s);
    STBI_FREE(j);
    return r;
 }
 
 static int stbi__jpeg_info_raw(stbi__jpeg *j, int *x, int *y, int *comp)
 {
    if (!stbi__decode_jpeg_header(j, STBI__SCAN_header)) {
       stbi__rewind( j->s );
       return 0;
    }
    if (x) *x = j->s->img_x;
    if (y) *y = j->s->img_y;
    if (comp) *comp = j->s->img_n >= 3 ? 3 : 1;
    return 1;
 }
 
 static int stbi__jpeg_info(stbi__context *s, int *x, int *y, int *comp)
 {
    int result;
    stbi__jpeg* j = (stbi__jpeg*) (stbi__malloc(sizeof(stbi__jpeg)));
    j->s = s;
    result = stbi__jpeg_info_raw(j, x, y, comp);
    STBI_FREE(j);
    return result;
 }
 #endif
 
 // public domain zlib decode    v0.2  Sean Barrett 2006-11-18
 //    simple implementation
 //      - all input must be provided in an upfront buffer
 //      - all output is written to a single output buffer (can malloc/realloc)
 //    performance
 //      - fast huffman
 
 #ifndef STBI_NO_ZLIB
 
 // fast-way is faster to check than jpeg huffman, but slow way is slower
 #define STBI__ZFAST_BITS  9 // accelerate all cases in default tables
 #define STBI__ZFAST_MASK  ((1 << STBI__ZFAST_BITS) - 1)
 
 // zlib-style huffman encoding
 // (jpegs packs from left, zlib from right, so can't share code)
 typedef struct
 {
    stbi__uint16 fast[1 << STBI__ZFAST_BITS];
    stbi__uint16 firstcode[16];
    int maxcode[17];
    stbi__uint16 firstsymbol[16];
    stbi_uc  size[288];
    stbi__uint16 value[288];
 } stbi__zhuffman;
 
 stbi_inline static int stbi__bitreverse16(int n)
 {
   n = ((n & 0xAAAA) >>  1) | ((n & 0x5555) << 1);
   n = ((n & 0xCCCC) >>  2) | ((n & 0x3333) << 2);
   n = ((n & 0xF0F0) >>  4) | ((n & 0x0F0F) << 4);
   n = ((n & 0xFF00) >>  8) | ((n & 0x00FF) << 8);
   return n;
 }
 
 stbi_inline static int stbi__bit_reverse(int v, int bits)
 {
    STBI_ASSERT(bits <= 16);
    // to bit reverse n bits, reverse 16 and shift
    // e.g. 11 bits, bit reverse and shift away 5
    return stbi__bitreverse16(v) >> (16-bits);
 }
 
 static int stbi__zbuild_huffman(stbi__zhuffman *z, const stbi_uc *sizelist, int num)
 {
    int i,k=0;
    int code, next_code[16], sizes[17];
 
    // DEFLATE spec for generating codes
    memset(sizes, 0, sizeof(sizes));
    memset(z->fast, 0, sizeof(z->fast));
    for (i=0; i < num; ++i)
       ++sizes[sizelist[i]];
    sizes[0] = 0;
    for (i=1; i < 16; ++i)
       if (sizes[i] > (1 << i))
          return stbi__err("bad sizes", "Corrupt PNG");
    code = 0;
    for (i=1; i < 16; ++i) {
       next_code[i] = code;
       z->firstcode[i] = (stbi__uint16) code;
       z->firstsymbol[i] = (stbi__uint16) k;
       code = (code + sizes[i]);
       if (sizes[i])
          if (code-1 >= (1 << i)) return stbi__err("bad codelengths","Corrupt PNG");
       z->maxcode[i] = code << (16-i); // preshift for inner loop
       code <<= 1;
       k += sizes[i];
    }
    z->maxcode[16] = 0x10000; // sentinel
    for (i=0; i < num; ++i) {
       int s = sizelist[i];
       if (s) {
          int c = next_code[s] - z->firstcode[s] + z->firstsymbol[s];
          stbi__uint16 fastv = (stbi__uint16) ((s << 9) | i);
          z->size [c] = (stbi_uc     ) s;
          z->value[c] = (stbi__uint16) i;
          if (s <= STBI__ZFAST_BITS) {
             int j = stbi__bit_reverse(next_code[s],s);
             while (j < (1 << STBI__ZFAST_BITS)) {
                z->fast[j] = fastv;
                j += (1 << s);
             }
          }
          ++next_code[s];
       }
    }
    return 1;
 }
 
 // zlib-from-memory implementation for PNG reading
 //    because PNG allows splitting the zlib stream arbitrarily,
 //    and it's annoying structurally to have PNG call ZLIB call PNG,
 //    we require PNG read all the IDATs and combine them into a single
 //    memory buffer
 
 typedef struct
 {
    stbi_uc *zbuffer, *zbuffer_end;
    int num_bits;
    stbi__uint32 code_buffer;
 
    char *zout;
    char *zout_start;
    char *zout_end;
    int   z_expandable;
 
    stbi__zhuffman z_length, z_distance;
 } stbi__zbuf;
 
 stbi_inline static stbi_uc stbi__zget8(stbi__zbuf *z)
 {
    if (z->zbuffer >= z->zbuffer_end) return 0;
    return *z->zbuffer++;
 }
 
 static void stbi__fill_bits(stbi__zbuf *z)
 {
    do {
       STBI_ASSERT(z->code_buffer < (1U << z->num_bits));
       z->code_buffer |= (unsigned int) stbi__zget8(z) << z->num_bits;
       z->num_bits += 8;
    } while (z->num_bits <= 24);
 }
 
 stbi_inline static unsigned int stbi__zreceive(stbi__zbuf *z, int n)
 {
    unsigned int k;
    if (z->num_bits < n) stbi__fill_bits(z);
    k = z->code_buffer & ((1 << n) - 1);
    z->code_buffer >>= n;
    z->num_bits -= n;
    return k;
 }
 
 static int stbi__zhuffman_decode_slowpath(stbi__zbuf *a, stbi__zhuffman *z)
 {
    int b,s,k;
    // not resolved by fast table, so compute it the slow way
    // use jpeg approach, which requires MSbits at top
    k = stbi__bit_reverse(a->code_buffer, 16);
    for (s=STBI__ZFAST_BITS+1; ; ++s)
       if (k < z->maxcode[s])
          break;
    if (s == 16) return -1; // invalid code!
    // code size is s, so:
    b = (k >> (16-s)) - z->firstcode[s] + z->firstsymbol[s];
    STBI_ASSERT(z->size[b] == s);
    a->code_buffer >>= s;
    a->num_bits -= s;
    return z->value[b];
 }
 
 stbi_inline static int stbi__zhuffman_decode(stbi__zbuf *a, stbi__zhuffman *z)
 {
    int b,s;
    if (a->num_bits < 16) stbi__fill_bits(a);
    b = z->fast[a->code_buffer & STBI__ZFAST_MASK];
    if (b) {
       s = b >> 9;
       a->code_buffer >>= s;
       a->num_bits -= s;
       return b & 511;
    }
    return stbi__zhuffman_decode_slowpath(a, z);
 }
 
 static int stbi__zexpand(stbi__zbuf *z, char *zout, int n)  // need to make room for n bytes
 {
    char *q;
    int cur, limit, old_limit;
    z->zout = zout;
    if (!z->z_expandable) return stbi__err("output buffer limit","Corrupt PNG");
    cur   = (int) (z->zout     - z->zout_start);
    limit = old_limit = (int) (z->zout_end - z->zout_start);
    while (cur + n > limit)
       limit *= 2;
    q = (char *) STBI_REALLOC_SIZED(z->zout_start, old_limit, limit);
    STBI_NOTUSED(old_limit);
    if (q == NULL) return stbi__err("outofmem", "Out of memory");
    z->zout_start = q;
    z->zout       = q + cur;
    z->zout_end   = q + limit;
    return 1;
 }
 
 static const int stbi__zlength_base[31] = {
    3,4,5,6,7,8,9,10,11,13,
    15,17,19,23,27,31,35,43,51,59,
    67,83,99,115,131,163,195,227,258,0,0 };
 
 static const int stbi__zlength_extra[31]=
 { 0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0,0,0 };
 
 static const int stbi__zdist_base[32] = { 1,2,3,4,5,7,9,13,17,25,33,49,65,97,129,193,
 257,385,513,769,1025,1537,2049,3073,4097,6145,8193,12289,16385,24577,0,0};
 
 static const int stbi__zdist_extra[32] =
 { 0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13};
 
 static int stbi__parse_huffman_block(stbi__zbuf *a)
 {
    char *zout = a->zout;
    for(;;) {
       int z = stbi__zhuffman_decode(a, &a->z_length);
       if (z < 256) {
          if (z < 0) return stbi__err("bad huffman code","Corrupt PNG"); // error in huffman codes
          if (zout >= a->zout_end) {
             if (!stbi__zexpand(a, zout, 1)) return 0;
             zout = a->zout;
          }
          *zout++ = (char) z;
       } else {
          stbi_uc *p;
          int len,dist;
          if (z == 256) {
             a->zout = zout;
             return 1;
          }
          z -= 257;
          len = stbi__zlength_base[z];
          if (stbi__zlength_extra[z]) len += stbi__zreceive(a, stbi__zlength_extra[z]);
          z = stbi__zhuffman_decode(a, &a->z_distance);
          if (z < 0) return stbi__err("bad huffman code","Corrupt PNG");
          dist = stbi__zdist_base[z];
          if (stbi__zdist_extra[z]) dist += stbi__zreceive(a, stbi__zdist_extra[z]);
          if (zout - a->zout_start < dist) return stbi__err("bad dist","Corrupt PNG");
          if (zout + len > a->zout_end) {
             if (!stbi__zexpand(a, zout, len)) return 0;
             zout = a->zout;
          }
          p = (stbi_uc *) (zout - dist);
          if (dist == 1) { // run of one byte; common in images.
             stbi_uc v = *p;
             if (len) { do *zout++ = v; while (--len); }
          } else {
             if (len) { do *zout++ = *p++; while (--len); }
          }
       }
    }
 }
 
 static int stbi__compute_huffman_codes(stbi__zbuf *a)
 {
    static const stbi_uc length_dezigzag[19] = { 16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15 };
    stbi__zhuffman z_codelength;
    stbi_uc lencodes[286+32+137];//padding for maximum single op
    stbi_uc codelength_sizes[19];
    int i,n;
 
    int hlit  = stbi__zreceive(a,5) + 257;
    int hdist = stbi__zreceive(a,5) + 1;
    int hclen = stbi__zreceive(a,4) + 4;
    int ntot  = hlit + hdist;
 
    memset(codelength_sizes, 0, sizeof(codelength_sizes));
    for (i=0; i < hclen; ++i) {
       int s = stbi__zreceive(a,3);
       codelength_sizes[length_dezigzag[i]] = (stbi_uc) s;
    }
    if (!stbi__zbuild_huffman(&z_codelength, codelength_sizes, 19)) return 0;
 
    n = 0;
    while (n < ntot) {
       int c = stbi__zhuffman_decode(a, &z_codelength);
       if (c < 0 || c >= 19) return stbi__err("bad codelengths", "Corrupt PNG");
       if (c < 16)
          lencodes[n++] = (stbi_uc) c;
       else {
          stbi_uc fill = 0;
          if (c == 16) {
             c = stbi__zreceive(a,2)+3;
             if (n == 0) return stbi__err("bad codelengths", "Corrupt PNG");
             fill = lencodes[n-1];
          } else if (c == 17)
             c = stbi__zreceive(a,3)+3;
          else {
             STBI_ASSERT(c == 18);
             c = stbi__zreceive(a,7)+11;
          }
          if (ntot - n < c) return stbi__err("bad codelengths", "Corrupt PNG");
          memset(lencodes+n, fill, c);
          n += c;
       }
    }
    if (n != ntot) return stbi__err("bad codelengths","Corrupt PNG");
    if (!stbi__zbuild_huffman(&a->z_length, lencodes, hlit)) return 0;
    if (!stbi__zbuild_huffman(&a->z_distance, lencodes+hlit, hdist)) return 0;
    return 1;
 }
 
 static int stbi__parse_uncompressed_block(stbi__zbuf *a)
 {
    stbi_uc header[4];
    int len,nlen,k;
    if (a->num_bits & 7)
       stbi__zreceive(a, a->num_bits & 7); // discard
    // drain the bit-packed data into header
    k = 0;
    while (a->num_bits > 0) {
       header[k++] = (stbi_uc) (a->code_buffer & 255); // suppress MSVC run-time check
       a->code_buffer >>= 8;
       a->num_bits -= 8;
    }
    STBI_ASSERT(a->num_bits == 0);
    // now fill header the normal way
    while (k < 4)
       header[k++] = stbi__zget8(a);
    len  = header[1] * 256 + header[0];
    nlen = header[3] * 256 + header[2];
    if (nlen != (len ^ 0xffff)) return stbi__err("zlib corrupt","Corrupt PNG");
    if (a->zbuffer + len > a->zbuffer_end) return stbi__err("read past buffer","Corrupt PNG");
    if (a->zout + len > a->zout_end)
       if (!stbi__zexpand(a, a->zout, len)) return 0;
    memcpy(a->zout, a->zbuffer, len);
    a->zbuffer += len;
    a->zout += len;
    return 1;
 }
 
 static int stbi__parse_zlib_header(stbi__zbuf *a)
 {
    int cmf   = stbi__zget8(a);
    int cm    = cmf & 15;
    /* int cinfo = cmf >> 4; */
    int flg   = stbi__zget8(a);
    if ((cmf*256+flg) % 31 != 0) return stbi__err("bad zlib header","Corrupt PNG"); // zlib spec
    if (flg & 32) return stbi__err("no preset dict","Corrupt PNG"); // preset dictionary not allowed in png
    if (cm != 8) return stbi__err("bad compression","Corrupt PNG"); // DEFLATE required for png
    // window = 1 << (8 + cinfo)... but who cares, we fully buffer output
    return 1;
 }
 
 static const stbi_uc stbi__zdefault_length[288] =
 {
    8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
    8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
    8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
    8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
    8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
    9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
    9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
    9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
    7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, 7,7,7,7,7,7,7,7,8,8,8,8,8,8,8,8
 };
 static const stbi_uc stbi__zdefault_distance[32] =
 {
    5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5
 };
 /*
 Init algorithm:
 {
    int i;   // use <= to match clearly with spec
    for (i=0; i <= 143; ++i)     stbi__zdefault_length[i]   = 8;
    for (   ; i <= 255; ++i)     stbi__zdefault_length[i]   = 9;
    for (   ; i <= 279; ++i)     stbi__zdefault_length[i]   = 7;
    for (   ; i <= 287; ++i)     stbi__zdefault_length[i]   = 8;
 
    for (i=0; i <=  31; ++i)     stbi__zdefault_distance[i] = 5;
 }
 */
 
 static int stbi__parse_zlib(stbi__zbuf *a, int parse_header)
 {
    int final, type;
    if (parse_header)
       if (!stbi__parse_zlib_header(a)) return 0;
    a->num_bits = 0;
    a->code_buffer = 0;
    do {
       final = stbi__zreceive(a,1);
       type = stbi__zreceive(a,2);
       if (type == 0) {
          if (!stbi__parse_uncompressed_block(a)) return 0;
       } else if (type == 3) {
          return 0;
       } else {
          if (type == 1) {
             // use fixed code lengths
             if (!stbi__zbuild_huffman(&a->z_length  , stbi__zdefault_length  , 288)) return 0;
             if (!stbi__zbuild_huffman(&a->z_distance, stbi__zdefault_distance,  32)) return 0;
          } else {
             if (!stbi__compute_huffman_codes(a)) return 0;
          }
          if (!stbi__parse_huffman_block(a)) return 0;
       }
    } while (!final);
    return 1;
 }
 
 static int stbi__do_zlib(stbi__zbuf *a, char *obuf, int olen, int exp, int parse_header)
 {
    a->zout_start = obuf;
    a->zout       = obuf;
    a->zout_end   = obuf + olen;
    a->z_expandable = exp;
 
    return stbi__parse_zlib(a, parse_header);
 }
 
 STBIDEF char *stbi_zlib_decode_malloc_guesssize(const char *buffer, int len, int initial_size, int *outlen)
 {
    stbi__zbuf a;
    char *p = (char *) stbi__malloc(initial_size);
    if (p == NULL) return NULL;
    a.zbuffer = (stbi_uc *) buffer;
    a.zbuffer_end = (stbi_uc *) buffer + len;
    if (stbi__do_zlib(&a, p, initial_size, 1, 1)) {
       if (outlen) *outlen = (int) (a.zout - a.zout_start);
       return a.zout_start;
    } else {
       STBI_FREE(a.zout_start);
       return NULL;
    }
 }
 
 STBIDEF char *stbi_zlib_decode_malloc(char const *buffer, int len, int *outlen)
 {
    return stbi_zlib_decode_malloc_guesssize(buffer, len, 16384, outlen);
 }
 
 STBIDEF char *stbi_zlib_decode_malloc_guesssize_headerflag(const char *buffer, int len, int initial_size, int *outlen, int parse_header)
 {
    stbi__zbuf a;
    char *p = (char *) stbi__malloc(initial_size);
    if (p == NULL) return NULL;
    a.zbuffer = (stbi_uc *) buffer;
    a.zbuffer_end = (stbi_uc *) buffer + len;
    if (stbi__do_zlib(&a, p, initial_size, 1, parse_header)) {
       if (outlen) *outlen = (int) (a.zout - a.zout_start);
       return a.zout_start;
    } else {
       STBI_FREE(a.zout_start);
       return NULL;
    }
 }
 
 STBIDEF int stbi_zlib_decode_buffer(char *obuffer, int olen, char const *ibuffer, int ilen)
 {
    stbi__zbuf a;
    a.zbuffer = (stbi_uc *) ibuffer;
    a.zbuffer_end = (stbi_uc *) ibuffer + ilen;
    if (stbi__do_zlib(&a, obuffer, olen, 0, 1))
       return (int) (a.zout - a.zout_start);
    else
       return -1;
 }
 
 STBIDEF char *stbi_zlib_decode_noheader_malloc(char const *buffer, int len, int *outlen)
 {
    stbi__zbuf a;
    char *p = (char *) stbi__malloc(16384);
    if (p == NULL) return NULL;
    a.zbuffer = (stbi_uc *) buffer;
    a.zbuffer_end = (stbi_uc *) buffer+len;
    if (stbi__do_zlib(&a, p, 16384, 1, 0)) {
       if (outlen) *outlen = (int) (a.zout - a.zout_start);
       return a.zout_start;
    } else {
       STBI_FREE(a.zout_start);
       return NULL;
    }
 }
 
 STBIDEF int stbi_zlib_decode_noheader_buffer(char *obuffer, int olen, const char *ibuffer, int ilen)
 {
    stbi__zbuf a;
    a.zbuffer = (stbi_uc *) ibuffer;
    a.zbuffer_end = (stbi_uc *) ibuffer + ilen;
    if (stbi__do_zlib(&a, obuffer, olen, 0, 0))
       return (int) (a.zout - a.zout_start);
    else
       return -1;
 }
 #endif
 
 // public domain "baseline" PNG decoder   v0.10  Sean Barrett 2006-11-18
 //    simple implementation
 //      - only 8-bit samples
 //      - no CRC checking
 //      - allocates lots of intermediate memory
 //        - avoids problem of streaming data between subsystems
 //        - avoids explicit window management
 //    performance
 //      - uses stb_zlib, a PD zlib implementation with fast huffman decoding
 
 #ifndef STBI_NO_PNG
 typedef struct
 {
    stbi__uint32 length;
    stbi__uint32 type;
 } stbi__pngchunk;
 
 static stbi__pngchunk stbi__get_chunk_header(stbi__context *s)
 {
    stbi__pngchunk c;
    c.length = stbi__get32be(s);
    c.type   = stbi__get32be(s);
    return c;
 }
 
 static int stbi__check_png_header(stbi__context *s)
 {
    static const stbi_uc png_sig[8] = { 137,80,78,71,13,10,26,10 };
    int i;
    for (i=0; i < 8; ++i)
       if (stbi__get8(s) != png_sig[i]) return stbi__err("bad png sig","Not a PNG");
    return 1;
 }
 
 typedef struct
 {
    stbi__context *s;
    stbi_uc *idata, *expanded, *out;
    int depth;
 } stbi__png;
 
 
 enum {
    STBI__F_none=0,
    STBI__F_sub=1,
    STBI__F_up=2,
    STBI__F_avg=3,
    STBI__F_paeth=4,
    // synthetic filters used for first scanline to avoid needing a dummy row of 0s
    STBI__F_avg_first,
    STBI__F_paeth_first
 };
 
 static stbi_uc first_row_filter[5] =
 {
    STBI__F_none,
    STBI__F_sub,
    STBI__F_none,
    STBI__F_avg_first,
    STBI__F_paeth_first
 };
 
 static int stbi__paeth(int a, int b, int c)
 {
    int p = a + b - c;
    int pa = abs(p-a);
    int pb = abs(p-b);
    int pc = abs(p-c);
    if (pa <= pb && pa <= pc) return a;
    if (pb <= pc) return b;
    return c;
 }
 
 static const stbi_uc stbi__depth_scale_table[9] = { 0, 0xff, 0x55, 0, 0x11, 0,0,0, 0x01 };
 
 // create the png data from post-deflated data
 static int stbi__create_png_image_raw(stbi__png *a, stbi_uc *raw, stbi__uint32 raw_len, int out_n, stbi__uint32 x, stbi__uint32 y, int depth, int color)
 {
    int bytes = (depth == 16? 2 : 1);
    stbi__context *s = a->s;
    stbi__uint32 i,j,stride = x*out_n*bytes;
    stbi__uint32 img_len, img_width_bytes;
    int k;
    int img_n = s->img_n; // copy it into a local for later
 
    int output_bytes = out_n*bytes;
    int filter_bytes = img_n*bytes;
    int width = x;
 
    STBI_ASSERT(out_n == s->img_n || out_n == s->img_n+1);
    a->out = (stbi_uc *) stbi__malloc_mad3(x, y, output_bytes, 0); // extra bytes to write off the end into
    if (!a->out) return stbi__err("outofmem", "Out of memory");
 
    if (!stbi__mad3sizes_valid(img_n, x, depth, 7)) return stbi__err("too large", "Corrupt PNG");
    img_width_bytes = (((img_n * x * depth) + 7) >> 3);
    img_len = (img_width_bytes + 1) * y;
 
    // we used to check for exact match between raw_len and img_len on non-interlaced PNGs,
    // but issue #276 reported a PNG in the wild that had extra data at the end (all zeros),
    // so just check for raw_len < img_len always.
    if (raw_len < img_len) return stbi__err("not enough pixels","Corrupt PNG");
 
    for (j=0; j < y; ++j) {
       stbi_uc *cur = a->out + stride*j;
       stbi_uc *prior;
       int filter = *raw++;
 
       if (filter > 4)
          return stbi__err("invalid filter","Corrupt PNG");
 
       if (depth < 8) {
          STBI_ASSERT(img_width_bytes <= x);
          cur += x*out_n - img_width_bytes; // store output to the rightmost img_len bytes, so we can decode in place
          filter_bytes = 1;
          width = img_width_bytes;
       }
       prior = cur - stride; // bugfix: need to compute this after 'cur +=' computation above
 
       // if first row, use special filter that doesn't sample previous row
       if (j == 0) filter = first_row_filter[filter];
 
       // handle first byte explicitly
       for (k=0; k < filter_bytes; ++k) {
          switch (filter) {
             case STBI__F_none       : cur[k] = raw[k]; break;
             case STBI__F_sub        : cur[k] = raw[k]; break;
             case STBI__F_up         : cur[k] = STBI__BYTECAST(raw[k] + prior[k]); break;
             case STBI__F_avg        : cur[k] = STBI__BYTECAST(raw[k] + (prior[k]>>1)); break;
             case STBI__F_paeth      : cur[k] = STBI__BYTECAST(raw[k] + stbi__paeth(0,prior[k],0)); break;
             case STBI__F_avg_first  : cur[k] = raw[k]; break;
             case STBI__F_paeth_first: cur[k] = raw[k]; break;
          }
       }
 
       if (depth == 8) {
          if (img_n != out_n)
             cur[img_n] = 255; // first pixel
          raw += img_n;
          cur += out_n;
          prior += out_n;
       } else if (depth == 16) {
          if (img_n != out_n) {
             cur[filter_bytes]   = 255; // first pixel top byte
             cur[filter_bytes+1] = 255; // first pixel bottom byte
          }
          raw += filter_bytes;
          cur += output_bytes;
          prior += output_bytes;
       } else {
          raw += 1;
          cur += 1;
          prior += 1;
       }
 
       // this is a little gross, so that we don't switch per-pixel or per-component
       if (depth < 8 || img_n == out_n) {
          int nk = (width - 1)*filter_bytes;
          #define STBI__CASE(f) \
              case f:     \
                 for (k=0; k < nk; ++k)
          switch (filter) {
             // "none" filter turns into a memcpy here; make that explicit.
             case STBI__F_none:         memcpy(cur, raw, nk); break;
             STBI__CASE(STBI__F_sub)          { cur[k] = STBI__BYTECAST(raw[k] + cur[k-filter_bytes]); } break;
             STBI__CASE(STBI__F_up)           { cur[k] = STBI__BYTECAST(raw[k] + prior[k]); } break;
             STBI__CASE(STBI__F_avg)          { cur[k] = STBI__BYTECAST(raw[k] + ((prior[k] + cur[k-filter_bytes])>>1)); } break;
             STBI__CASE(STBI__F_paeth)        { cur[k] = STBI__BYTECAST(raw[k] + stbi__paeth(cur[k-filter_bytes],prior[k],prior[k-filter_bytes])); } break;
             STBI__CASE(STBI__F_avg_first)    { cur[k] = STBI__BYTECAST(raw[k] + (cur[k-filter_bytes] >> 1)); } break;
             STBI__CASE(STBI__F_paeth_first)  { cur[k] = STBI__BYTECAST(raw[k] + stbi__paeth(cur[k-filter_bytes],0,0)); } break;
          }
          #undef STBI__CASE
          raw += nk;
       } else {
          STBI_ASSERT(img_n+1 == out_n);
          #define STBI__CASE(f) \
              case f:     \
                 for (i=x-1; i >= 1; --i, cur[filter_bytes]=255,raw+=filter_bytes,cur+=output_bytes,prior+=output_bytes) \
                    for (k=0; k < filter_bytes; ++k)
          switch (filter) {
             STBI__CASE(STBI__F_none)         { cur[k] = raw[k]; } break;
             STBI__CASE(STBI__F_sub)          { cur[k] = STBI__BYTECAST(raw[k] + cur[k- output_bytes]); } break;
             STBI__CASE(STBI__F_up)           { cur[k] = STBI__BYTECAST(raw[k] + prior[k]); } break;
             STBI__CASE(STBI__F_avg)          { cur[k] = STBI__BYTECAST(raw[k] + ((prior[k] + cur[k- output_bytes])>>1)); } break;
             STBI__CASE(STBI__F_paeth)        { cur[k] = STBI__BYTECAST(raw[k] + stbi__paeth(cur[k- output_bytes],prior[k],prior[k- output_bytes])); } break;
             STBI__CASE(STBI__F_avg_first)    { cur[k] = STBI__BYTECAST(raw[k] + (cur[k- output_bytes] >> 1)); } break;
             STBI__CASE(STBI__F_paeth_first)  { cur[k] = STBI__BYTECAST(raw[k] + stbi__paeth(cur[k- output_bytes],0,0)); } break;
          }
          #undef STBI__CASE
 
          // the loop above sets the high byte of the pixels' alpha, but for
          // 16 bit png files we also need the low byte set. we'll do that here.
          if (depth == 16) {
             cur = a->out + stride*j; // start at the beginning of the row again
             for (i=0; i < x; ++i,cur+=output_bytes) {
                cur[filter_bytes+1] = 255;
             }
          }
       }
    }
 
    // we make a separate pass to expand bits to pixels; for performance,
    // this could run two scanlines behind the above code, so it won't
    // intefere with filtering but will still be in the cache.
    if (depth < 8) {
       for (j=0; j < y; ++j) {
          stbi_uc *cur = a->out + stride*j;
          stbi_uc *in  = a->out + stride*j + x*out_n - img_width_bytes;
          // unpack 1/2/4-bit into a 8-bit buffer. allows us to keep the common 8-bit path optimal at minimal cost for 1/2/4-bit
          // png guarante byte alignment, if width is not multiple of 8/4/2 we'll decode dummy trailing data that will be skipped in the later loop
          stbi_uc scale = (color == 0) ? stbi__depth_scale_table[depth] : 1; // scale grayscale values to 0..255 range
 
          // note that the final byte might overshoot and write more data than desired.
          // we can allocate enough data that this never writes out of memory, but it
          // could also overwrite the next scanline. can it overwrite non-empty data
          // on the next scanline? yes, consider 1-pixel-wide scanlines with 1-bit-per-pixel.
          // so we need to explicitly clamp the final ones
 
          if (depth == 4) {
             for (k=x*img_n; k >= 2; k-=2, ++in) {
                *cur++ = scale * ((*in >> 4)       );
                *cur++ = scale * ((*in     ) & 0x0f);
             }
             if (k > 0) *cur++ = scale * ((*in >> 4)       );
          } else if (depth == 2) {
             for (k=x*img_n; k >= 4; k-=4, ++in) {
                *cur++ = scale * ((*in >> 6)       );
                *cur++ = scale * ((*in >> 4) & 0x03);
                *cur++ = scale * ((*in >> 2) & 0x03);
                *cur++ = scale * ((*in     ) & 0x03);
             }
             if (k > 0) *cur++ = scale * ((*in >> 6)       );
             if (k > 1) *cur++ = scale * ((*in >> 4) & 0x03);
             if (k > 2) *cur++ = scale * ((*in >> 2) & 0x03);
          } else if (depth == 1) {
             for (k=x*img_n; k >= 8; k-=8, ++in) {
                *cur++ = scale * ((*in >> 7)       );
                *cur++ = scale * ((*in >> 6) & 0x01);
                *cur++ = scale * ((*in >> 5) & 0x01);
                *cur++ = scale * ((*in >> 4) & 0x01);
                *cur++ = scale * ((*in >> 3) & 0x01);
                *cur++ = scale * ((*in >> 2) & 0x01);
                *cur++ = scale * ((*in >> 1) & 0x01);
                *cur++ = scale * ((*in     ) & 0x01);
             }
             if (k > 0) *cur++ = scale * ((*in >> 7)       );
             if (k > 1) *cur++ = scale * ((*in >> 6) & 0x01);
             if (k > 2) *cur++ = scale * ((*in >> 5) & 0x01);
             if (k > 3) *cur++ = scale * ((*in >> 4) & 0x01);
             if (k > 4) *cur++ = scale * ((*in >> 3) & 0x01);
             if (k > 5) *cur++ = scale * ((*in >> 2) & 0x01);
             if (k > 6) *cur++ = scale * ((*in >> 1) & 0x01);
          }
          if (img_n != out_n) {
             int q;
             // insert alpha = 255
             cur = a->out + stride*j;
             if (img_n == 1) {
                for (q=x-1; q >= 0; --q) {
                   cur[q*2+1] = 255;
                   cur[q*2+0] = cur[q];
                }
             } else {
                STBI_ASSERT(img_n == 3);
                for (q=x-1; q >= 0; --q) {
                   cur[q*4+3] = 255;
                   cur[q*4+2] = cur[q*3+2];
                   cur[q*4+1] = cur[q*3+1];
                   cur[q*4+0] = cur[q*3+0];
                }
             }
          }
       }
    } else if (depth == 16) {
       // force the image data from big-endian to platform-native.
       // this is done in a separate pass due to the decoding relying
       // on the data being untouched, but could probably be done
       // per-line during decode if care is taken.
       stbi_uc *cur = a->out;
       stbi__uint16 *cur16 = (stbi__uint16*)cur;
 
       for(i=0; i < x*y*out_n; ++i,cur16++,cur+=2) {
          *cur16 = (cur[0] << 8) | cur[1];
       }
    }
 
    return 1;
 }
 
 static int stbi__create_png_image(stbi__png *a, stbi_uc *image_data, stbi__uint32 image_data_len, int out_n, int depth, int color, int interlaced)
 {
    int bytes = (depth == 16 ? 2 : 1);
    int out_bytes = out_n * bytes;
    stbi_uc *final;
    int p;
    if (!interlaced)
       return stbi__create_png_image_raw(a, image_data, image_data_len, out_n, a->s->img_x, a->s->img_y, depth, color);
 
    // de-interlacing
    final = (stbi_uc *) stbi__malloc_mad3(a->s->img_x, a->s->img_y, out_bytes, 0);
    for (p=0; p < 7; ++p) {
       int xorig[] = { 0,4,0,2,0,1,0 };
       int yorig[] = { 0,0,4,0,2,0,1 };
       int xspc[]  = { 8,8,4,4,2,2,1 };
       int yspc[]  = { 8,8,8,4,4,2,2 };
       int i,j,x,y;
       // pass1_x[4] = 0, pass1_x[5] = 1, pass1_x[12] = 1
       x = (a->s->img_x - xorig[p] + xspc[p]-1) / xspc[p];
       y = (a->s->img_y - yorig[p] + yspc[p]-1) / yspc[p];
       if (x && y) {
          stbi__uint32 img_len = ((((a->s->img_n * x * depth) + 7) >> 3) + 1) * y;
          if (!stbi__create_png_image_raw(a, image_data, image_data_len, out_n, x, y, depth, color)) {
             STBI_FREE(final);
             return 0;
          }
          for (j=0; j < y; ++j) {
             for (i=0; i < x; ++i) {
                int out_y = j*yspc[p]+yorig[p];
                int out_x = i*xspc[p]+xorig[p];
                memcpy(final + out_y*a->s->img_x*out_bytes + out_x*out_bytes,
                       a->out + (j*x+i)*out_bytes, out_bytes);
             }
          }
          STBI_FREE(a->out);
          image_data += img_len;
          image_data_len -= img_len;
       }
    }
    a->out = final;
 
    return 1;
 }
 
 static int stbi__compute_transparency(stbi__png *z, stbi_uc tc[3], int out_n)
 {
    stbi__context *s = z->s;
    stbi__uint32 i, pixel_count = s->img_x * s->img_y;
    stbi_uc *p = z->out;
 
    // compute color-based transparency, assuming we've
    // already got 255 as the alpha value in the output
    STBI_ASSERT(out_n == 2 || out_n == 4);
 
    if (out_n == 2) {
       for (i=0; i < pixel_count; ++i) {
          p[1] = (p[0] == tc[0] ? 0 : 255);
          p += 2;
       }
    } else {
       for (i=0; i < pixel_count; ++i) {
          if (p[0] == tc[0] && p[1] == tc[1] && p[2] == tc[2])
             p[3] = 0;
          p += 4;
       }
    }
    return 1;
 }
 
 static int stbi__compute_transparency16(stbi__png *z, stbi__uint16 tc[3], int out_n)
 {
    stbi__context *s = z->s;
    stbi__uint32 i, pixel_count = s->img_x * s->img_y;
    stbi__uint16 *p = (stbi__uint16*) z->out;
 
    // compute color-based transparency, assuming we've
    // already got 65535 as the alpha value in the output
    STBI_ASSERT(out_n == 2 || out_n == 4);
 
    if (out_n == 2) {
       for (i = 0; i < pixel_count; ++i) {
          p[1] = (p[0] == tc[0] ? 0 : 65535);
          p += 2;
       }
    } else {
       for (i = 0; i < pixel_count; ++i) {
          if (p[0] == tc[0] && p[1] == tc[1] && p[2] == tc[2])
             p[3] = 0;
          p += 4;
       }
    }
    return 1;
 }
 
 static int stbi__expand_png_palette(stbi__png *a, stbi_uc *palette, int len, int pal_img_n)
 {
    stbi__uint32 i, pixel_count = a->s->img_x * a->s->img_y;
    stbi_uc *p, *temp_out, *orig = a->out;
 
    p = (stbi_uc *) stbi__malloc_mad2(pixel_count, pal_img_n, 0);
    if (p == NULL) return stbi__err("outofmem", "Out of memory");
 
    // between here and free(out) below, exitting would leak
    temp_out = p;
 
    if (pal_img_n == 3) {
       for (i=0; i < pixel_count; ++i) {
          int n = orig[i]*4;
          p[0] = palette[n  ];
          p[1] = palette[n+1];
          p[2] = palette[n+2];
          p += 3;
       }
    } else {
       for (i=0; i < pixel_count; ++i) {
          int n = orig[i]*4;
          p[0] = palette[n  ];
          p[1] = palette[n+1];
          p[2] = palette[n+2];
          p[3] = palette[n+3];
          p += 4;
       }
    }
    STBI_FREE(a->out);
    a->out = temp_out;
 
    STBI_NOTUSED(len);
 
    return 1;
 }
 
 static int stbi__unpremultiply_on_load = 0;
 static int stbi__de_iphone_flag = 0;
 
 STBIDEF void stbi_set_unpremultiply_on_load(int flag_true_if_should_unpremultiply)
 {
    stbi__unpremultiply_on_load = flag_true_if_should_unpremultiply;
 }
 
 STBIDEF void stbi_convert_iphone_png_to_rgb(int flag_true_if_should_convert)
 {
    stbi__de_iphone_flag = flag_true_if_should_convert;
 }
 
 static void stbi__de_iphone(stbi__png *z)
 {
    stbi__context *s = z->s;
    stbi__uint32 i, pixel_count = s->img_x * s->img_y;
    stbi_uc *p = z->out;
 
    if (s->img_out_n == 3) {  // convert bgr to rgb
       for (i=0; i < pixel_count; ++i) {
          stbi_uc t = p[0];
          p[0] = p[2];
          p[2] = t;
          p += 3;
       }
    } else {
       STBI_ASSERT(s->img_out_n == 4);
       if (stbi__unpremultiply_on_load) {
          // convert bgr to rgb and unpremultiply
          for (i=0; i < pixel_count; ++i) {
             stbi_uc a = p[3];
             stbi_uc t = p[0];
             if (a) {
                stbi_uc half = a / 2;
                p[0] = (p[2] * 255 + half) / a;
                p[1] = (p[1] * 255 + half) / a;
                p[2] = ( t   * 255 + half) / a;
             } else {
                p[0] = p[2];
                p[2] = t;
             }
             p += 4;
          }
       } else {
          // convert bgr to rgb
          for (i=0; i < pixel_count; ++i) {
             stbi_uc t = p[0];
             p[0] = p[2];
             p[2] = t;
             p += 4;
          }
       }
    }
 }
 
 #define STBI__PNG_TYPE(a,b,c,d)  (((unsigned) (a) << 24) + ((unsigned) (b) << 16) + ((unsigned) (c) << 8) + (unsigned) (d))
 
 static int stbi__parse_png_file(stbi__png *z, int scan, int req_comp)
 {
    stbi_uc palette[1024], pal_img_n=0;
    stbi_uc has_trans=0, tc[3];
    stbi__uint16 tc16[3];
    stbi__uint32 ioff=0, idata_limit=0, i, pal_len=0;
    int first=1,k,interlace=0, color=0, is_iphone=0;
    stbi__context *s = z->s;
 
    z->expanded = NULL;
    z->idata = NULL;
    z->out = NULL;
 
    if (!stbi__check_png_header(s)) return 0;
 
    if (scan == STBI__SCAN_type) return 1;
 
    for (;;) {
       stbi__pngchunk c = stbi__get_chunk_header(s);
       switch (c.type) {
          case STBI__PNG_TYPE('C','g','B','I'):
             is_iphone = 1;
             stbi__skip(s, c.length);
             break;
          case STBI__PNG_TYPE('I','H','D','R'): {
             int comp,filter;
             if (!first) return stbi__err("multiple IHDR","Corrupt PNG");
             first = 0;
             if (c.length != 13) return stbi__err("bad IHDR len","Corrupt PNG");
             s->img_x = stbi__get32be(s); if (s->img_x > (1 << 24)) return stbi__err("too large","Very large image (corrupt?)");
             s->img_y = stbi__get32be(s); if (s->img_y > (1 << 24)) return stbi__err("too large","Very large image (corrupt?)");
             z->depth = stbi__get8(s);  if (z->depth != 1 && z->depth != 2 && z->depth != 4 && z->depth != 8 && z->depth != 16)  return stbi__err("1/2/4/8/16-bit only","PNG not supported: 1/2/4/8/16-bit only");
             color = stbi__get8(s);  if (color > 6)         return stbi__err("bad ctype","Corrupt PNG");
             if (color == 3 && z->depth == 16)                  return stbi__err("bad ctype","Corrupt PNG");
             if (color == 3) pal_img_n = 3; else if (color & 1) return stbi__err("bad ctype","Corrupt PNG");
             comp  = stbi__get8(s);  if (comp) return stbi__err("bad comp method","Corrupt PNG");
             filter= stbi__get8(s);  if (filter) return stbi__err("bad filter method","Corrupt PNG");
             interlace = stbi__get8(s); if (interlace>1) return stbi__err("bad interlace method","Corrupt PNG");
             if (!s->img_x || !s->img_y) return stbi__err("0-pixel image","Corrupt PNG");
             if (!pal_img_n) {
                s->img_n = (color & 2 ? 3 : 1) + (color & 4 ? 1 : 0);
                if ((1 << 30) / s->img_x / s->img_n < s->img_y) return stbi__err("too large", "Image too large to decode");
                if (scan == STBI__SCAN_header) return 1;
             } else {
                // if paletted, then pal_n is our final components, and
                // img_n is # components to decompress/filter.
                s->img_n = 1;
                if ((1 << 30) / s->img_x / 4 < s->img_y) return stbi__err("too large","Corrupt PNG");
                // if SCAN_header, have to scan to see if we have a tRNS
             }
             break;
          }
 
          case STBI__PNG_TYPE('P','L','T','E'):  {
             if (first) return stbi__err("first not IHDR", "Corrupt PNG");
             if (c.length > 256*3) return stbi__err("invalid PLTE","Corrupt PNG");
             pal_len = c.length / 3;
             if (pal_len * 3 != c.length) return stbi__err("invalid PLTE","Corrupt PNG");
             for (i=0; i < pal_len; ++i) {
                palette[i*4+0] = stbi__get8(s);
                palette[i*4+1] = stbi__get8(s);
                palette[i*4+2] = stbi__get8(s);
                palette[i*4+3] = 255;
             }
             break;
          }
 
          case STBI__PNG_TYPE('t','R','N','S'): {
             if (first) return stbi__err("first not IHDR", "Corrupt PNG");
             if (z->idata) return stbi__err("tRNS after IDAT","Corrupt PNG");
             if (pal_img_n) {
                if (scan == STBI__SCAN_header) { s->img_n = 4; return 1; }
                if (pal_len == 0) return stbi__err("tRNS before PLTE","Corrupt PNG");
                if (c.length > pal_len) return stbi__err("bad tRNS len","Corrupt PNG");
                pal_img_n = 4;
                for (i=0; i < c.length; ++i)
                   palette[i*4+3] = stbi__get8(s);
             } else {
                if (!(s->img_n & 1)) return stbi__err("tRNS with alpha","Corrupt PNG");
                if (c.length != (stbi__uint32) s->img_n*2) return stbi__err("bad tRNS len","Corrupt PNG");
                has_trans = 1;
                if (z->depth == 16) {
                   for (k = 0; k < s->img_n; ++k) tc16[k] = (stbi__uint16)stbi__get16be(s); // copy the values as-is
                } else {
                   for (k = 0; k < s->img_n; ++k) tc[k] = (stbi_uc)(stbi__get16be(s) & 255) * stbi__depth_scale_table[z->depth]; // non 8-bit images will be larger
                }
             }
             break;
          }
 
          case STBI__PNG_TYPE('I','D','A','T'): {
             if (first) return stbi__err("first not IHDR", "Corrupt PNG");
             if (pal_img_n && !pal_len) return stbi__err("no PLTE","Corrupt PNG");
             if (scan == STBI__SCAN_header) { s->img_n = pal_img_n; return 1; }
             if ((int)(ioff + c.length) < (int)ioff) return 0;
             if (ioff + c.length > idata_limit) {
                stbi__uint32 idata_limit_old = idata_limit;
                stbi_uc *p;
                if (idata_limit == 0) idata_limit = c.length > 4096 ? c.length : 4096;
                while (ioff + c.length > idata_limit)
                   idata_limit *= 2;
                STBI_NOTUSED(idata_limit_old);
                p = (stbi_uc *) STBI_REALLOC_SIZED(z->idata, idata_limit_old, idata_limit); if (p == NULL) return stbi__err("outofmem", "Out of memory");
                z->idata = p;
             }
             if (!stbi__getn(s, z->idata+ioff,c.length)) return stbi__err("outofdata","Corrupt PNG");
             ioff += c.length;
             break;
          }
 
          case STBI__PNG_TYPE('I','E','N','D'): {
             stbi__uint32 raw_len, bpl;
             if (first) return stbi__err("first not IHDR", "Corrupt PNG");
             if (scan != STBI__SCAN_load) return 1;
             if (z->idata == NULL) return stbi__err("no IDAT","Corrupt PNG");
             // initial guess for decoded data size to avoid unnecessary reallocs
             bpl = (s->img_x * z->depth + 7) / 8; // bytes per line, per component
             raw_len = bpl * s->img_y * s->img_n /* pixels */ + s->img_y /* filter mode per row */;
             z->expanded = (stbi_uc *) stbi_zlib_decode_malloc_guesssize_headerflag((char *) z->idata, ioff, raw_len, (int *) &raw_len, !is_iphone);
             if (z->expanded == NULL) return 0; // zlib should set error
             STBI_FREE(z->idata); z->idata = NULL;
             if ((req_comp == s->img_n+1 && req_comp != 3 && !pal_img_n) || has_trans)
                s->img_out_n = s->img_n+1;
             else
                s->img_out_n = s->img_n;
             if (!stbi__create_png_image(z, z->expanded, raw_len, s->img_out_n, z->depth, color, interlace)) return 0;
             if (has_trans) {
                if (z->depth == 16) {
                   if (!stbi__compute_transparency16(z, tc16, s->img_out_n)) return 0;
                } else {
                   if (!stbi__compute_transparency(z, tc, s->img_out_n)) return 0;
                }
             }
             if (is_iphone && stbi__de_iphone_flag && s->img_out_n > 2)
                stbi__de_iphone(z);
             if (pal_img_n) {
                // pal_img_n == 3 or 4
                s->img_n = pal_img_n; // record the actual colors we had
                s->img_out_n = pal_img_n;
                if (req_comp >= 3) s->img_out_n = req_comp;
                if (!stbi__expand_png_palette(z, palette, pal_len, s->img_out_n))
                   return 0;
             } else if (has_trans) {
                // non-paletted image with tRNS -> source image has (constant) alpha
                ++s->img_n;
             }
             STBI_FREE(z->expanded); z->expanded = NULL;
             return 1;
          }
 
          default:
             // if critical, fail
             if (first) return stbi__err("first not IHDR", "Corrupt PNG");
             if ((c.type & (1 << 29)) == 0) {
                #ifndef STBI_NO_FAILURE_STRINGS
                // not threadsafe
                static char invalid_chunk[] = "XXXX PNG chunk not known";
                invalid_chunk[0] = STBI__BYTECAST(c.type >> 24);
                invalid_chunk[1] = STBI__BYTECAST(c.type >> 16);
                invalid_chunk[2] = STBI__BYTECAST(c.type >>  8);
                invalid_chunk[3] = STBI__BYTECAST(c.type >>  0);
                #endif
                return stbi__err(invalid_chunk, "PNG not supported: unknown PNG chunk type");
             }
             stbi__skip(s, c.length);
             break;
       }
       // end of PNG chunk, read and skip CRC
       stbi__get32be(s);
    }
 }
 
 static void *stbi__do_png(stbi__png *p, int *x, int *y, int *n, int req_comp, stbi__result_info *ri)
 {
    void *result=NULL;
    if (req_comp < 0 || req_comp > 4) return stbi__errpuc("bad req_comp", "Internal error");
    if (stbi__parse_png_file(p, STBI__SCAN_load, req_comp)) {
       if (p->depth < 8)
          ri->bits_per_channel = 8;
       else
          ri->bits_per_channel = p->depth;
       result = p->out;
       p->out = NULL;
       if (req_comp && req_comp != p->s->img_out_n) {
          if (ri->bits_per_channel == 8)
             result = stbi__convert_format((unsigned char *) result, p->s->img_out_n, req_comp, p->s->img_x, p->s->img_y);
          else
             result = stbi__convert_format16((stbi__uint16 *) result, p->s->img_out_n, req_comp, p->s->img_x, p->s->img_y);
          p->s->img_out_n = req_comp;
          if (result == NULL) return result;
       }
       *x = p->s->img_x;
       *y = p->s->img_y;
       if (n) *n = p->s->img_n;
    }
    STBI_FREE(p->out);      p->out      = NULL;
    STBI_FREE(p->expanded); p->expanded = NULL;
    STBI_FREE(p->idata);    p->idata    = NULL;
 
    return result;
 }
 
 static void *stbi__png_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri)
 {
    stbi__png p;
    p.s = s;
    return stbi__do_png(&p, x,y,comp,req_comp, ri);
 }
 
 static int stbi__png_test(stbi__context *s)
 {
    int r;
    r = stbi__check_png_header(s);
    stbi__rewind(s);
    return r;
 }
 
 static int stbi__png_info_raw(stbi__png *p, int *x, int *y, int *comp)
 {
    if (!stbi__parse_png_file(p, STBI__SCAN_header, 0)) {
       stbi__rewind( p->s );
       return 0;
    }
    if (x) *x = p->s->img_x;
    if (y) *y = p->s->img_y;
    if (comp) *comp = p->s->img_n;
    return 1;
 }
 
 static int stbi__png_info(stbi__context *s, int *x, int *y, int *comp)
 {
    stbi__png p;
    p.s = s;
    return stbi__png_info_raw(&p, x, y, comp);
 }
 
 static int stbi__png_is16(stbi__context *s)
 {
    stbi__png p;
    p.s = s;
    if (!stbi__png_info_raw(&p, NULL, NULL, NULL))
 	   return 0;
    if (p.depth != 16) {
       stbi__rewind(p.s);
       return 0;
    }
    return 1;
 }
 #endif
 
 // Microsoft/Windows BMP image
 
 #ifndef STBI_NO_BMP
 static int stbi__bmp_test_raw(stbi__context *s)
 {
    int r;
    int sz;
    if (stbi__get8(s) != 'B') return 0;
    if (stbi__get8(s) != 'M') return 0;
    stbi__get32le(s); // discard filesize
    stbi__get16le(s); // discard reserved
    stbi__get16le(s); // discard reserved
    stbi__get32le(s); // discard data offset
    sz = stbi__get32le(s);
    r = (sz == 12 || sz == 40 || sz == 56 || sz == 108 || sz == 124);
    return r;
 }
 
 static int stbi__bmp_test(stbi__context *s)
 {
    int r = stbi__bmp_test_raw(s);
    stbi__rewind(s);
    return r;
 }
 
 
 // returns 0..31 for the highest set bit
 static int stbi__high_bit(unsigned int z)
 {
    int n=0;
    if (z == 0) return -1;
    if (z >= 0x10000) n += 16, z >>= 16;
    if (z >= 0x00100) n +=  8, z >>=  8;
    if (z >= 0x00010) n +=  4, z >>=  4;
    if (z >= 0x00004) n +=  2, z >>=  2;
    if (z >= 0x00002) n +=  1, z >>=  1;
    return n;
 }
 
 static int stbi__bitcount(unsigned int a)
 {
    a = (a & 0x55555555) + ((a >>  1) & 0x55555555); // max 2
    a = (a & 0x33333333) + ((a >>  2) & 0x33333333); // max 4
    a = (a + (a >> 4)) & 0x0f0f0f0f; // max 8 per 4, now 8 bits
    a = (a + (a >> 8)); // max 16 per 8 bits
    a = (a + (a >> 16)); // max 32 per 8 bits
    return a & 0xff;
 }
 
 // extract an arbitrarily-aligned N-bit value (N=bits)
 // from v, and then make it 8-bits long and fractionally
 // extend it to full full range.
 static int stbi__shiftsigned(int v, int shift, int bits)
 {
    static unsigned int mul_table[9] = {
       0,
       0xff/*0b11111111*/, 0x55/*0b01010101*/, 0x49/*0b01001001*/, 0x11/*0b00010001*/,
       0x21/*0b00100001*/, 0x41/*0b01000001*/, 0x81/*0b10000001*/, 0x01/*0b00000001*/,
    };
    static unsigned int shift_table[9] = {
       0, 0,0,1,0,2,4,6,0,
    };
    if (shift < 0)
       v <<= -shift;
    else
       v >>= shift;
    STBI_ASSERT(v >= 0 && v < 256);
    v >>= (8-bits);
    STBI_ASSERT(bits >= 0 && bits <= 8);
    return (int) ((unsigned) v * mul_table[bits]) >> shift_table[bits];
 }
 
 typedef struct
 {
    int bpp, offset, hsz;
    unsigned int mr,mg,mb,ma, all_a;
 } stbi__bmp_data;
 
 static void *stbi__bmp_parse_header(stbi__context *s, stbi__bmp_data *info)
 {
    int hsz;
    if (stbi__get8(s) != 'B' || stbi__get8(s) != 'M') return stbi__errpuc("not BMP", "Corrupt BMP");
    stbi__get32le(s); // discard filesize
    stbi__get16le(s); // discard reserved
    stbi__get16le(s); // discard reserved
    info->offset = stbi__get32le(s);
    info->hsz = hsz = stbi__get32le(s);
    info->mr = info->mg = info->mb = info->ma = 0;
 
    if (hsz != 12 && hsz != 40 && hsz != 56 && hsz != 108 && hsz != 124) return stbi__errpuc("unknown BMP", "BMP type not supported: unknown");
    if (hsz == 12) {
       s->img_x = stbi__get16le(s);
       s->img_y = stbi__get16le(s);
    } else {
       s->img_x = stbi__get32le(s);
       s->img_y = stbi__get32le(s);
    }
    if (stbi__get16le(s) != 1) return stbi__errpuc("bad BMP", "bad BMP");
    info->bpp = stbi__get16le(s);
    if (hsz != 12) {
       int compress = stbi__get32le(s);
       if (compress == 1 || compress == 2) return stbi__errpuc("BMP RLE", "BMP type not supported: RLE");
       stbi__get32le(s); // discard sizeof
       stbi__get32le(s); // discard hres
       stbi__get32le(s); // discard vres
       stbi__get32le(s); // discard colorsused
       stbi__get32le(s); // discard max important
       if (hsz == 40 || hsz == 56) {
          if (hsz == 56) {
             stbi__get32le(s);
             stbi__get32le(s);
             stbi__get32le(s);
             stbi__get32le(s);
          }
          if (info->bpp == 16 || info->bpp == 32) {
             if (compress == 0) {
                if (info->bpp == 32) {
                   info->mr = 0xffu << 16;
                   info->mg = 0xffu <<  8;
                   info->mb = 0xffu <<  0;
                   info->ma = 0xffu << 24;
                   info->all_a = 0; // if all_a is 0 at end, then we loaded alpha channel but it was all 0
                } else {
                   info->mr = 31u << 10;
                   info->mg = 31u <<  5;
                   info->mb = 31u <<  0;
                }
             } else if (compress == 3) {
                info->mr = stbi__get32le(s);
                info->mg = stbi__get32le(s);
                info->mb = stbi__get32le(s);
                // not documented, but generated by photoshop and handled by mspaint
                if (info->mr == info->mg && info->mg == info->mb) {
                   // ?!?!?
                   return stbi__errpuc("bad BMP", "bad BMP");
                }
             } else
                return stbi__errpuc("bad BMP", "bad BMP");
          }
       } else {
          int i;
          if (hsz != 108 && hsz != 124)
             return stbi__errpuc("bad BMP", "bad BMP");
          info->mr = stbi__get32le(s);
          info->mg = stbi__get32le(s);
          info->mb = stbi__get32le(s);
          info->ma = stbi__get32le(s);
          stbi__get32le(s); // discard color space
          for (i=0; i < 12; ++i)
             stbi__get32le(s); // discard color space parameters
          if (hsz == 124) {
             stbi__get32le(s); // discard rendering intent
             stbi__get32le(s); // discard offset of profile data
             stbi__get32le(s); // discard size of profile data
             stbi__get32le(s); // discard reserved
          }
       }
    }
    return (void *) 1;
 }
 
 
 static void *stbi__bmp_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri)
 {
    stbi_uc *out;
    unsigned int mr=0,mg=0,mb=0,ma=0, all_a;
    stbi_uc pal[256][4];
    int psize=0,i,j,width;
    int flip_vertically, pad, target;
    stbi__bmp_data info;
    STBI_NOTUSED(ri);
 
    info.all_a = 255;
    if (stbi__bmp_parse_header(s, &info) == NULL)
       return NULL; // error code already set
 
    flip_vertically = ((int) s->img_y) > 0;
    s->img_y = abs((int) s->img_y);
 
    mr = info.mr;
    mg = info.mg;
    mb = info.mb;
    ma = info.ma;
    all_a = info.all_a;
 
    if (info.hsz == 12) {
       if (info.bpp < 24)
          psize = (info.offset - 14 - 24) / 3;
    } else {
       if (info.bpp < 16)
          psize = (info.offset - 14 - info.hsz) >> 2;
    }
 
    s->img_n = ma ? 4 : 3;
    if (req_comp && req_comp >= 3) // we can directly decode 3 or 4
       target = req_comp;
    else
       target = s->img_n; // if they want monochrome, we'll post-convert
 
    // sanity-check size
    if (!stbi__mad3sizes_valid(target, s->img_x, s->img_y, 0))
       return stbi__errpuc("too large", "Corrupt BMP");
 
    out = (stbi_uc *) stbi__malloc_mad3(target, s->img_x, s->img_y, 0);
    if (!out) return stbi__errpuc("outofmem", "Out of memory");
    if (info.bpp < 16) {
       int z=0;
       if (psize == 0 || psize > 256) { STBI_FREE(out); return stbi__errpuc("invalid", "Corrupt BMP"); }
       for (i=0; i < psize; ++i) {
          pal[i][2] = stbi__get8(s);
          pal[i][1] = stbi__get8(s);
          pal[i][0] = stbi__get8(s);
          if (info.hsz != 12) stbi__get8(s);
          pal[i][3] = 255;
       }
       stbi__skip(s, info.offset - 14 - info.hsz - psize * (info.hsz == 12 ? 3 : 4));
       if (info.bpp == 1) width = (s->img_x + 7) >> 3;
       else if (info.bpp == 4) width = (s->img_x + 1) >> 1;
       else if (info.bpp == 8) width = s->img_x;
       else { STBI_FREE(out); return stbi__errpuc("bad bpp", "Corrupt BMP"); }
       pad = (-width)&3;
       if (info.bpp == 1) {
          for (j=0; j < (int) s->img_y; ++j) {
             int bit_offset = 7, v = stbi__get8(s);
             for (i=0; i < (int) s->img_x; ++i) {
                int color = (v>>bit_offset)&0x1;
                out[z++] = pal[color][0];
                out[z++] = pal[color][1];
                out[z++] = pal[color][2];
                if((--bit_offset) < 0) {
                   bit_offset = 7;
                   v = stbi__get8(s);
                }
             }
             stbi__skip(s, pad);
          }
       } else {
          for (j=0; j < (int) s->img_y; ++j) {
             for (i=0; i < (int) s->img_x; i += 2) {
                int v=stbi__get8(s),v2=0;
                if (info.bpp == 4) {
                   v2 = v & 15;
                   v >>= 4;
                }
                out[z++] = pal[v][0];
                out[z++] = pal[v][1];
                out[z++] = pal[v][2];
                if (target == 4) out[z++] = 255;
                if (i+1 == (int) s->img_x) break;
                v = (info.bpp == 8) ? stbi__get8(s) : v2;
                out[z++] = pal[v][0];
                out[z++] = pal[v][1];
                out[z++] = pal[v][2];
                if (target == 4) out[z++] = 255;
             }
             stbi__skip(s, pad);
          }
       }
    } else {
       int rshift=0,gshift=0,bshift=0,ashift=0,rcount=0,gcount=0,bcount=0,acount=0;
       int z = 0;
       int easy=0;
       stbi__skip(s, info.offset - 14 - info.hsz);
       if (info.bpp == 24) width = 3 * s->img_x;
       else if (info.bpp == 16) width = 2*s->img_x;
       else /* bpp = 32 and pad = 0 */ width=0;
       pad = (-width) & 3;
       if (info.bpp == 24) {
          easy = 1;
       } else if (info.bpp == 32) {
          if (mb == 0xff && mg == 0xff00 && mr == 0x00ff0000 && ma == 0xff000000)
             easy = 2;
       }
       if (!easy) {
          if (!mr || !mg || !mb) { STBI_FREE(out); return stbi__errpuc("bad masks", "Corrupt BMP"); }
          // right shift amt to put high bit in position #7
          rshift = stbi__high_bit(mr)-7; rcount = stbi__bitcount(mr);
          gshift = stbi__high_bit(mg)-7; gcount = stbi__bitcount(mg);
          bshift = stbi__high_bit(mb)-7; bcount = stbi__bitcount(mb);
          ashift = stbi__high_bit(ma)-7; acount = stbi__bitcount(ma);
       }
       for (j=0; j < (int) s->img_y; ++j) {
          if (easy) {
             for (i=0; i < (int) s->img_x; ++i) {
                unsigned char a;
                out[z+2] = stbi__get8(s);
                out[z+1] = stbi__get8(s);
                out[z+0] = stbi__get8(s);
                z += 3;
                a = (easy == 2 ? stbi__get8(s) : 255);
                all_a |= a;
                if (target == 4) out[z++] = a;
             }
          } else {
             int bpp = info.bpp;
             for (i=0; i < (int) s->img_x; ++i) {
                stbi__uint32 v = (bpp == 16 ? (stbi__uint32) stbi__get16le(s) : stbi__get32le(s));
                unsigned int a;
                out[z++] = STBI__BYTECAST(stbi__shiftsigned(v & mr, rshift, rcount));
                out[z++] = STBI__BYTECAST(stbi__shiftsigned(v & mg, gshift, gcount));
                out[z++] = STBI__BYTECAST(stbi__shiftsigned(v & mb, bshift, bcount));
                a = (ma ? stbi__shiftsigned(v & ma, ashift, acount) : 255);
                all_a |= a;
                if (target == 4) out[z++] = STBI__BYTECAST(a);
             }
          }
          stbi__skip(s, pad);
       }
    }
 
    // if alpha channel is all 0s, replace with all 255s
    if (target == 4 && all_a == 0)
       for (i=4*s->img_x*s->img_y-1; i >= 0; i -= 4)
          out[i] = 255;
 
    if (flip_vertically) {
       stbi_uc t;
       for (j=0; j < (int) s->img_y>>1; ++j) {
          stbi_uc *p1 = out +      j     *s->img_x*target;
          stbi_uc *p2 = out + (s->img_y-1-j)*s->img_x*target;
          for (i=0; i < (int) s->img_x*target; ++i) {
             t = p1[i], p1[i] = p2[i], p2[i] = t;
          }
       }
    }
 
    if (req_comp && req_comp != target) {
       out = stbi__convert_format(out, target, req_comp, s->img_x, s->img_y);
       if (out == NULL) return out; // stbi__convert_format frees input on failure
    }
 
    *x = s->img_x;
    *y = s->img_y;
    if (comp) *comp = s->img_n;
    return out;
 }
 #endif
 
 // Targa Truevision - TGA
 // by Jonathan Dummer
 #ifndef STBI_NO_TGA
 // returns STBI_rgb or whatever, 0 on error
 static int stbi__tga_get_comp(int bits_per_pixel, int is_grey, int* is_rgb16)
 {
    // only RGB or RGBA (incl. 16bit) or grey allowed
    if (is_rgb16) *is_rgb16 = 0;
    switch(bits_per_pixel) {
       case 8:  return STBI_grey;
       case 16: if(is_grey) return STBI_grey_alpha;
                // fallthrough
       case 15: if(is_rgb16) *is_rgb16 = 1;
                return STBI_rgb;
       case 24: // fallthrough
       case 32: return bits_per_pixel/8;
       default: return 0;
    }
 }
 
 static int stbi__tga_info(stbi__context *s, int *x, int *y, int *comp)
 {
     int tga_w, tga_h, tga_comp, tga_image_type, tga_bits_per_pixel, tga_colormap_bpp;
     int sz, tga_colormap_type;
     stbi__get8(s);                   // discard Offset
     tga_colormap_type = stbi__get8(s); // colormap type
     if( tga_colormap_type > 1 ) {
         stbi__rewind(s);
         return 0;      // only RGB or indexed allowed
     }
     tga_image_type = stbi__get8(s); // image type
     if ( tga_colormap_type == 1 ) { // colormapped (paletted) image
         if (tga_image_type != 1 && tga_image_type != 9) {
             stbi__rewind(s);
             return 0;
         }
         stbi__skip(s,4);       // skip index of first colormap entry and number of entries
         sz = stbi__get8(s);    //   check bits per palette color entry
         if ( (sz != 8) && (sz != 15) && (sz != 16) && (sz != 24) && (sz != 32) ) {
             stbi__rewind(s);
             return 0;
         }
         stbi__skip(s,4);       // skip image x and y origin
         tga_colormap_bpp = sz;
     } else { // "normal" image w/o colormap - only RGB or grey allowed, +/- RLE
         if ( (tga_image_type != 2) && (tga_image_type != 3) && (tga_image_type != 10) && (tga_image_type != 11) ) {
             stbi__rewind(s);
             return 0; // only RGB or grey allowed, +/- RLE
         }
         stbi__skip(s,9); // skip colormap specification and image x/y origin
         tga_colormap_bpp = 0;
     }
     tga_w = stbi__get16le(s);
     if( tga_w < 1 ) {
         stbi__rewind(s);
         return 0;   // test width
     }
     tga_h = stbi__get16le(s);
     if( tga_h < 1 ) {
         stbi__rewind(s);
         return 0;   // test height
     }
     tga_bits_per_pixel = stbi__get8(s); // bits per pixel
     stbi__get8(s); // ignore alpha bits
     if (tga_colormap_bpp != 0) {
         if((tga_bits_per_pixel != 8) && (tga_bits_per_pixel != 16)) {
             // when using a colormap, tga_bits_per_pixel is the size of the indexes
             // I don't think anything but 8 or 16bit indexes makes sense
             stbi__rewind(s);
             return 0;
         }
         tga_comp = stbi__tga_get_comp(tga_colormap_bpp, 0, NULL);
     } else {
         tga_comp = stbi__tga_get_comp(tga_bits_per_pixel, (tga_image_type == 3) || (tga_image_type == 11), NULL);
     }
     if(!tga_comp) {
       stbi__rewind(s);
       return 0;
     }
     if (x) *x = tga_w;
     if (y) *y = tga_h;
     if (comp) *comp = tga_comp;
     return 1;                   // seems to have passed everything
 }
 
 static int stbi__tga_test(stbi__context *s)
 {
    int res = 0;
    int sz, tga_color_type;
    stbi__get8(s);      //   discard Offset
    tga_color_type = stbi__get8(s);   //   color type
    if ( tga_color_type > 1 ) goto errorEnd;   //   only RGB or indexed allowed
    sz = stbi__get8(s);   //   image type
    if ( tga_color_type == 1 ) { // colormapped (paletted) image
       if (sz != 1 && sz != 9) goto errorEnd; // colortype 1 demands image type 1 or 9
       stbi__skip(s,4);       // skip index of first colormap entry and number of entries
       sz = stbi__get8(s);    //   check bits per palette color entry
       if ( (sz != 8) && (sz != 15) && (sz != 16) && (sz != 24) && (sz != 32) ) goto errorEnd;
       stbi__skip(s,4);       // skip image x and y origin
    } else { // "normal" image w/o colormap
       if ( (sz != 2) && (sz != 3) && (sz != 10) && (sz != 11) ) goto errorEnd; // only RGB or grey allowed, +/- RLE
       stbi__skip(s,9); // skip colormap specification and image x/y origin
    }
    if ( stbi__get16le(s) < 1 ) goto errorEnd;      //   test width
    if ( stbi__get16le(s) < 1 ) goto errorEnd;      //   test height
    sz = stbi__get8(s);   //   bits per pixel
    if ( (tga_color_type == 1) && (sz != 8) && (sz != 16) ) goto errorEnd; // for colormapped images, bpp is size of an index
    if ( (sz != 8) && (sz != 15) && (sz != 16) && (sz != 24) && (sz != 32) ) goto errorEnd;
 
    res = 1; // if we got this far, everything's good and we can return 1 instead of 0
 
 errorEnd:
    stbi__rewind(s);
    return res;
 }
 
 // read 16bit value and convert to 24bit RGB
 static void stbi__tga_read_rgb16(stbi__context *s, stbi_uc* out)
 {
    stbi__uint16 px = (stbi__uint16)stbi__get16le(s);
    stbi__uint16 fiveBitMask = 31;
    // we have 3 channels with 5bits each
    int r = (px >> 10) & fiveBitMask;
    int g = (px >> 5) & fiveBitMask;
    int b = px & fiveBitMask;
    // Note that this saves the data in RGB(A) order, so it doesn't need to be swapped later
    out[0] = (stbi_uc)((r * 255)/31);
    out[1] = (stbi_uc)((g * 255)/31);
    out[2] = (stbi_uc)((b * 255)/31);
 
    // some people claim that the most significant bit might be used for alpha
    // (possibly if an alpha-bit is set in the "image descriptor byte")
    // but that only made 16bit test images completely translucent..
    // so let's treat all 15 and 16bit TGAs as RGB with no alpha.
 }
 
 static void *stbi__tga_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri)
 {
    //   read in the TGA header stuff
    int tga_offset = stbi__get8(s);
    int tga_indexed = stbi__get8(s);
    int tga_image_type = stbi__get8(s);
    int tga_is_RLE = 0;
    int tga_palette_start = stbi__get16le(s);
    int tga_palette_len = stbi__get16le(s);
    int tga_palette_bits = stbi__get8(s);
    int tga_x_origin = stbi__get16le(s);
    int tga_y_origin = stbi__get16le(s);
    int tga_width = stbi__get16le(s);
    int tga_height = stbi__get16le(s);
    int tga_bits_per_pixel = stbi__get8(s);
    int tga_comp, tga_rgb16=0;
    int tga_inverted = stbi__get8(s);
    // int tga_alpha_bits = tga_inverted & 15; // the 4 lowest bits - unused (useless?)
    //   image data
    unsigned char *tga_data;
    unsigned char *tga_palette = NULL;
    int i, j;
    unsigned char raw_data[4] = {0};
    int RLE_count = 0;
    int RLE_repeating = 0;
    int read_next_pixel = 1;
    STBI_NOTUSED(ri);
 
    //   do a tiny bit of precessing
    if ( tga_image_type >= 8 )
    {
       tga_image_type -= 8;
       tga_is_RLE = 1;
    }
    tga_inverted = 1 - ((tga_inverted >> 5) & 1);
 
    //   If I'm paletted, then I'll use the number of bits from the palette
    if ( tga_indexed ) tga_comp = stbi__tga_get_comp(tga_palette_bits, 0, &tga_rgb16);
    else tga_comp = stbi__tga_get_comp(tga_bits_per_pixel, (tga_image_type == 3), &tga_rgb16);
 
    if(!tga_comp) // shouldn't really happen, stbi__tga_test() should have ensured basic consistency
       return stbi__errpuc("bad format", "Can't find out TGA pixelformat");
 
    //   tga info
    *x = tga_width;
    *y = tga_height;
    if (comp) *comp = tga_comp;
 
    if (!stbi__mad3sizes_valid(tga_width, tga_height, tga_comp, 0))
       return stbi__errpuc("too large", "Corrupt TGA");
 
    tga_data = (unsigned char*)stbi__malloc_mad3(tga_width, tga_height, tga_comp, 0);
    if (!tga_data) return stbi__errpuc("outofmem", "Out of memory");
 
    // skip to the data's starting position (offset usually = 0)
    stbi__skip(s, tga_offset );
 
    if ( !tga_indexed && !tga_is_RLE && !tga_rgb16 ) {
       for (i=0; i < tga_height; ++i) {
          int row = tga_inverted ? tga_height -i - 1 : i;
          stbi_uc *tga_row = tga_data + row*tga_width*tga_comp;
          stbi__getn(s, tga_row, tga_width * tga_comp);
       }
    } else  {
       //   do I need to load a palette?
       if ( tga_indexed)
       {
          //   any data to skip? (offset usually = 0)
          stbi__skip(s, tga_palette_start );
          //   load the palette
          tga_palette = (unsigned char*)stbi__malloc_mad2(tga_palette_len, tga_comp, 0);
          if (!tga_palette) {
             STBI_FREE(tga_data);
             return stbi__errpuc("outofmem", "Out of memory");
          }
          if (tga_rgb16) {
             stbi_uc *pal_entry = tga_palette;
             STBI_ASSERT(tga_comp == STBI_rgb);
             for (i=0; i < tga_palette_len; ++i) {
                stbi__tga_read_rgb16(s, pal_entry);
                pal_entry += tga_comp;
             }
          } else if (!stbi__getn(s, tga_palette, tga_palette_len * tga_comp)) {
                STBI_FREE(tga_data);
                STBI_FREE(tga_palette);
                return stbi__errpuc("bad palette", "Corrupt TGA");
          }
       }
       //   load the data
       for (i=0; i < tga_width * tga_height; ++i)
       {
          //   if I'm in RLE mode, do I need to get a RLE stbi__pngchunk?
          if ( tga_is_RLE )
          {
             if ( RLE_count == 0 )
             {
                //   yep, get the next byte as a RLE command
                int RLE_cmd = stbi__get8(s);
                RLE_count = 1 + (RLE_cmd & 127);
                RLE_repeating = RLE_cmd >> 7;
                read_next_pixel = 1;
             } else if ( !RLE_repeating )
             {
                read_next_pixel = 1;
             }
          } else
          {
             read_next_pixel = 1;
          }
          //   OK, if I need to read a pixel, do it now
          if ( read_next_pixel )
          {
             //   load however much data we did have
             if ( tga_indexed )
             {
                // read in index, then perform the lookup
                int pal_idx = (tga_bits_per_pixel == 8) ? stbi__get8(s) : stbi__get16le(s);
                if ( pal_idx >= tga_palette_len ) {
                   // invalid index
                   pal_idx = 0;
                }
                pal_idx *= tga_comp;
                for (j = 0; j < tga_comp; ++j) {
                   raw_data[j] = tga_palette[pal_idx+j];
                }
             } else if(tga_rgb16) {
                STBI_ASSERT(tga_comp == STBI_rgb);
                stbi__tga_read_rgb16(s, raw_data);
             } else {
                //   read in the data raw
                for (j = 0; j < tga_comp; ++j) {
                   raw_data[j] = stbi__get8(s);
                }
             }
             //   clear the reading flag for the next pixel
             read_next_pixel = 0;
          } // end of reading a pixel
 
          // copy data
          for (j = 0; j < tga_comp; ++j)
            tga_data[i*tga_comp+j] = raw_data[j];
 
          //   in case we're in RLE mode, keep counting down
          --RLE_count;
       }
       //   do I need to invert the image?
       if ( tga_inverted )
       {
          for (j = 0; j*2 < tga_height; ++j)
          {
             int index1 = j * tga_width * tga_comp;
             int index2 = (tga_height - 1 - j) * tga_width * tga_comp;
             for (i = tga_width * tga_comp; i > 0; --i)
             {
                unsigned char temp = tga_data[index1];
                tga_data[index1] = tga_data[index2];
                tga_data[index2] = temp;
                ++index1;
                ++index2;
             }
          }
       }
       //   clear my palette, if I had one
       if ( tga_palette != NULL )
       {
          STBI_FREE( tga_palette );
       }
    }
 
    // swap RGB - if the source data was RGB16, it already is in the right order
    if (tga_comp >= 3 && !tga_rgb16)
    {
       unsigned char* tga_pixel = tga_data;
       for (i=0; i < tga_width * tga_height; ++i)
       {
          unsigned char temp = tga_pixel[0];
          tga_pixel[0] = tga_pixel[2];
          tga_pixel[2] = temp;
          tga_pixel += tga_comp;
       }
    }
 
    // convert to target component count
    if (req_comp && req_comp != tga_comp)
       tga_data = stbi__convert_format(tga_data, tga_comp, req_comp, tga_width, tga_height);
 
    //   the things I do to get rid of an error message, and yet keep
    //   Microsoft's C compilers happy... [8^(
    tga_palette_start = tga_palette_len = tga_palette_bits =
          tga_x_origin = tga_y_origin = 0;
    //   OK, done
    return tga_data;
 }
 #endif
 
 // *************************************************************************************************
 // Photoshop PSD loader -- PD by Thatcher Ulrich, integration by Nicolas Schulz, tweaked by STB
 
 #ifndef STBI_NO_PSD
 static int stbi__psd_test(stbi__context *s)
 {
    int r = (stbi__get32be(s) == 0x38425053);
    stbi__rewind(s);
    return r;
 }
 
 static int stbi__psd_decode_rle(stbi__context *s, stbi_uc *p, int pixelCount)
 {
    int count, nleft, len;
 
    count = 0;
    while ((nleft = pixelCount - count) > 0) {
       len = stbi__get8(s);
       if (len == 128) {
          // No-op.
       } else if (len < 128) {
          // Copy next len+1 bytes literally.
          len++;
          if (len > nleft) return 0; // corrupt data
          count += len;
          while (len) {
             *p = stbi__get8(s);
             p += 4;
             len--;
          }
       } else if (len > 128) {
          stbi_uc   val;
          // Next -len+1 bytes in the dest are replicated from next source byte.
          // (Interpret len as a negative 8-bit int.)
          len = 257 - len;
          if (len > nleft) return 0; // corrupt data
          val = stbi__get8(s);
          count += len;
          while (len) {
             *p = val;
             p += 4;
             len--;
          }
       }
    }
 
    return 1;
 }
 
 static void *stbi__psd_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri, int bpc)
 {
    int pixelCount;
    int channelCount, compression;
    int channel, i;
    int bitdepth;
    int w,h;
    stbi_uc *out;
    STBI_NOTUSED(ri);
 
    // Check identifier
    if (stbi__get32be(s) != 0x38425053)   // "8BPS"
       return stbi__errpuc("not PSD", "Corrupt PSD image");
 
    // Check file type version.
    if (stbi__get16be(s) != 1)
       return stbi__errpuc("wrong version", "Unsupported version of PSD image");
 
    // Skip 6 reserved bytes.
    stbi__skip(s, 6 );
 
    // Read the number of channels (R, G, B, A, etc).
    channelCount = stbi__get16be(s);
    if (channelCount < 0 || channelCount > 16)
       return stbi__errpuc("wrong channel count", "Unsupported number of channels in PSD image");
 
    // Read the rows and columns of the image.
    h = stbi__get32be(s);
    w = stbi__get32be(s);
 
    // Make sure the depth is 8 bits.
    bitdepth = stbi__get16be(s);
    if (bitdepth != 8 && bitdepth != 16)
       return stbi__errpuc("unsupported bit depth", "PSD bit depth is not 8 or 16 bit");
 
    // Make sure the color mode is RGB.
    // Valid options are:
    //   0: Bitmap
    //   1: Grayscale
    //   2: Indexed color
    //   3: RGB color
    //   4: CMYK color
    //   7: Multichannel
    //   8: Duotone
    //   9: Lab color
    if (stbi__get16be(s) != 3)
       return stbi__errpuc("wrong color format", "PSD is not in RGB color format");
 
    // Skip the Mode Data.  (It's the palette for indexed color; other info for other modes.)
    stbi__skip(s,stbi__get32be(s) );
 
    // Skip the image resources.  (resolution, pen tool paths, etc)
    stbi__skip(s, stbi__get32be(s) );
 
    // Skip the reserved data.
    stbi__skip(s, stbi__get32be(s) );
 
    // Find out if the data is compressed.
    // Known values:
    //   0: no compression
    //   1: RLE compressed
    compression = stbi__get16be(s);
    if (compression > 1)
       return stbi__errpuc("bad compression", "PSD has an unknown compression format");
 
    // Check size
    if (!stbi__mad3sizes_valid(4, w, h, 0))
       return stbi__errpuc("too large", "Corrupt PSD");
 
    // Create the destination image.
 
    if (!compression && bitdepth == 16 && bpc == 16) {
       out = (stbi_uc *) stbi__malloc_mad3(8, w, h, 0);
       ri->bits_per_channel = 16;
    } else
       out = (stbi_uc *) stbi__malloc(4 * w*h);
 
    if (!out) return stbi__errpuc("outofmem", "Out of memory");
    pixelCount = w*h;
 
    // Initialize the data to zero.
    //memset( out, 0, pixelCount * 4 );
 
    // Finally, the image data.
    if (compression) {
       // RLE as used by .PSD and .TIFF
       // Loop until you get the number of unpacked bytes you are expecting:
       //     Read the next source byte into n.
       //     If n is between 0 and 127 inclusive, copy the next n+1 bytes literally.
       //     Else if n is between -127 and -1 inclusive, copy the next byte -n+1 times.
       //     Else if n is 128, noop.
       // Endloop
 
       // The RLE-compressed data is preceeded by a 2-byte data count for each row in the data,
       // which we're going to just skip.
       stbi__skip(s, h * channelCount * 2 );
 
       // Read the RLE data by channel.
       for (channel = 0; channel < 4; channel++) {
          stbi_uc *p;
 
          p = out+channel;
          if (channel >= channelCount) {
             // Fill this channel with default data.
             for (i = 0; i < pixelCount; i++, p += 4)
                *p = (channel == 3 ? 255 : 0);
          } else {
             // Read the RLE data.
             if (!stbi__psd_decode_rle(s, p, pixelCount)) {
                STBI_FREE(out);
                return stbi__errpuc("corrupt", "bad RLE data");
             }
          }
       }
 
    } else {
       // We're at the raw image data.  It's each channel in order (Red, Green, Blue, Alpha, ...)
       // where each channel consists of an 8-bit (or 16-bit) value for each pixel in the image.
 
       // Read the data by channel.
       for (channel = 0; channel < 4; channel++) {
          if (channel >= channelCount) {
             // Fill this channel with default data.
             if (bitdepth == 16 && bpc == 16) {
                stbi__uint16 *q = ((stbi__uint16 *) out) + channel;
                stbi__uint16 val = channel == 3 ? 65535 : 0;
                for (i = 0; i < pixelCount; i++, q += 4)
                   *q = val;
             } else {
                stbi_uc *p = out+channel;
                stbi_uc val = channel == 3 ? 255 : 0;
                for (i = 0; i < pixelCount; i++, p += 4)
                   *p = val;
             }
          } else {
             if (ri->bits_per_channel == 16) {    // output bpc
                stbi__uint16 *q = ((stbi__uint16 *) out) + channel;
                for (i = 0; i < pixelCount; i++, q += 4)
                   *q = (stbi__uint16) stbi__get16be(s);
             } else {
                stbi_uc *p = out+channel;
                if (bitdepth == 16) {  // input bpc
                   for (i = 0; i < pixelCount; i++, p += 4)
                      *p = (stbi_uc) (stbi__get16be(s) >> 8);
                } else {
                   for (i = 0; i < pixelCount; i++, p += 4)
                      *p = stbi__get8(s);
                }
             }
          }
       }
    }
 
    // remove weird white matte from PSD
    if (channelCount >= 4) {
       if (ri->bits_per_channel == 16) {
          for (i=0; i < w*h; ++i) {
             stbi__uint16 *pixel = (stbi__uint16 *) out + 4*i;
             if (pixel[3] != 0 && pixel[3] != 65535) {
                float a = pixel[3] / 65535.0f;
                float ra = 1.0f / a;
                float inv_a = 65535.0f * (1 - ra);
                pixel[0] = (stbi__uint16) (pixel[0]*ra + inv_a);
                pixel[1] = (stbi__uint16) (pixel[1]*ra + inv_a);
                pixel[2] = (stbi__uint16) (pixel[2]*ra + inv_a);
             }
          }
       } else {
          for (i=0; i < w*h; ++i) {
             unsigned char *pixel = out + 4*i;
             if (pixel[3] != 0 && pixel[3] != 255) {
                float a = pixel[3] / 255.0f;
                float ra = 1.0f / a;
                float inv_a = 255.0f * (1 - ra);
                pixel[0] = (unsigned char) (pixel[0]*ra + inv_a);
                pixel[1] = (unsigned char) (pixel[1]*ra + inv_a);
                pixel[2] = (unsigned char) (pixel[2]*ra + inv_a);
             }
          }
       }
    }
 
    // convert to desired output format
    if (req_comp && req_comp != 4) {
       if (ri->bits_per_channel == 16)
          out = (stbi_uc *) stbi__convert_format16((stbi__uint16 *) out, 4, req_comp, w, h);
       else
          out = stbi__convert_format(out, 4, req_comp, w, h);
       if (out == NULL) return out; // stbi__convert_format frees input on failure
    }
 
    if (comp) *comp = 4;
    *y = h;
    *x = w;
 
    return out;
 }
 #endif
 
 // *************************************************************************************************
 // Softimage PIC loader
 // by Tom Seddon
 //
 // See http://softimage.wiki.softimage.com/index.php/INFO:_PIC_file_format
 // See http://ozviz.wasp.uwa.edu.au/~pbourke/dataformats/softimagepic/
 
 #ifndef STBI_NO_PIC
 static int stbi__pic_is4(stbi__context *s,const char *str)
 {
    int i;
    for (i=0; i<4; ++i)
       if (stbi__get8(s) != (stbi_uc)str[i])
          return 0;
 
    return 1;
 }
 
 static int stbi__pic_test_core(stbi__context *s)
 {
    int i;
 
    if (!stbi__pic_is4(s,"\x53\x80\xF6\x34"))
       return 0;
 
    for(i=0;i<84;++i)
       stbi__get8(s);
 
    if (!stbi__pic_is4(s,"PICT"))
       return 0;
 
    return 1;
 }
 
 typedef struct
 {
    stbi_uc size,type,channel;
 } stbi__pic_packet;
 
 static stbi_uc *stbi__readval(stbi__context *s, int channel, stbi_uc *dest)
 {
    int mask=0x80, i;
 
    for (i=0; i<4; ++i, mask>>=1) {
       if (channel & mask) {
          if (stbi__at_eof(s)) return stbi__errpuc("bad file","PIC file too short");
          dest[i]=stbi__get8(s);
       }
    }
 
    return dest;
 }
 
 static void stbi__copyval(int channel,stbi_uc *dest,const stbi_uc *src)
 {
    int mask=0x80,i;
 
    for (i=0;i<4; ++i, mask>>=1)
       if (channel&mask)
          dest[i]=src[i];
 }
 
 static stbi_uc *stbi__pic_load_core(stbi__context *s,int width,int height,int *comp, stbi_uc *result)
 {
    int act_comp=0,num_packets=0,y,chained;
    stbi__pic_packet packets[10];
 
    // this will (should...) cater for even some bizarre stuff like having data
     // for the same channel in multiple packets.
    do {
       stbi__pic_packet *packet;
 
       if (num_packets==sizeof(packets)/sizeof(packets[0]))
          return stbi__errpuc("bad format","too many packets");
 
       packet = &packets[num_packets++];
 
       chained = stbi__get8(s);
       packet->size    = stbi__get8(s);
       packet->type    = stbi__get8(s);
       packet->channel = stbi__get8(s);
 
       act_comp |= packet->channel;
 
       if (stbi__at_eof(s))          return stbi__errpuc("bad file","file too short (reading packets)");
       if (packet->size != 8)  return stbi__errpuc("bad format","packet isn't 8bpp");
    } while (chained);
 
    *comp = (act_comp & 0x10 ? 4 : 3); // has alpha channel?
 
    for(y=0; y<height; ++y) {
       int packet_idx;
 
       for(packet_idx=0; packet_idx < num_packets; ++packet_idx) {
          stbi__pic_packet *packet = &packets[packet_idx];
          stbi_uc *dest = result+y*width*4;
 
          switch (packet->type) {
             default:
                return stbi__errpuc("bad format","packet has bad compression type");
 
             case 0: {//uncompressed
                int x;
 
                for(x=0;x<width;++x, dest+=4)
                   if (!stbi__readval(s,packet->channel,dest))
                      return 0;
                break;
             }
 
             case 1://Pure RLE
                {
                   int left=width, i;
 
                   while (left>0) {
                      stbi_uc count,value[4];
 
                      count=stbi__get8(s);
                      if (stbi__at_eof(s))   return stbi__errpuc("bad file","file too short (pure read count)");
 
                      if (count > left)
                         count = (stbi_uc) left;
 
                      if (!stbi__readval(s,packet->channel,value))  return 0;
 
                      for(i=0; i<count; ++i,dest+=4)
                         stbi__copyval(packet->channel,dest,value);
                      left -= count;
                   }
                }
                break;
 
             case 2: {//Mixed RLE
                int left=width;
                while (left>0) {
                   int count = stbi__get8(s), i;
                   if (stbi__at_eof(s))  return stbi__errpuc("bad file","file too short (mixed read count)");
 
                   if (count >= 128) { // Repeated
                      stbi_uc value[4];
 
                      if (count==128)
                         count = stbi__get16be(s);
                      else
                         count -= 127;
                      if (count > left)
                         return stbi__errpuc("bad file","scanline overrun");
 
                      if (!stbi__readval(s,packet->channel,value))
                         return 0;
 
                      for(i=0;i<count;++i, dest += 4)
                         stbi__copyval(packet->channel,dest,value);
                   } else { // Raw
                      ++count;
                      if (count>left) return stbi__errpuc("bad file","scanline overrun");
 
                      for(i=0;i<count;++i, dest+=4)
                         if (!stbi__readval(s,packet->channel,dest))
                            return 0;
                   }
                   left-=count;
                }
                break;
             }
          }
       }
    }
 
    return result;
 }
 
 static void *stbi__pic_load(stbi__context *s,int *px,int *py,int *comp,int req_comp, stbi__result_info *ri)
 {
    stbi_uc *result;
    int i, x,y, internal_comp;
    STBI_NOTUSED(ri);
 
    if (!comp) comp = &internal_comp;
 
    for (i=0; i<92; ++i)
       stbi__get8(s);
 
    x = stbi__get16be(s);
    y = stbi__get16be(s);
    if (stbi__at_eof(s))  return stbi__errpuc("bad file","file too short (pic header)");
    if (!stbi__mad3sizes_valid(x, y, 4, 0)) return stbi__errpuc("too large", "PIC image too large to decode");
 
    stbi__get32be(s); //skip `ratio'
    stbi__get16be(s); //skip `fields'
    stbi__get16be(s); //skip `pad'
 
    // intermediate buffer is RGBA
    result = (stbi_uc *) stbi__malloc_mad3(x, y, 4, 0);
    memset(result, 0xff, x*y*4);
 
    if (!stbi__pic_load_core(s,x,y,comp, result)) {
       STBI_FREE(result);
       result=0;
    }
    *px = x;
    *py = y;
    if (req_comp == 0) req_comp = *comp;
    result=stbi__convert_format(result,4,req_comp,x,y);
 
    return result;
 }
 
 static int stbi__pic_test(stbi__context *s)
 {
    int r = stbi__pic_test_core(s);
    stbi__rewind(s);
    return r;
 }
 #endif
 
 // *************************************************************************************************
 // GIF loader -- public domain by Jean-Marc Lienher -- simplified/shrunk by stb
 
 #ifndef STBI_NO_GIF
 typedef struct
 {
    stbi__int16 prefix;
    stbi_uc first;
    stbi_uc suffix;
 } stbi__gif_lzw;
 
 typedef struct
 {
    int w,h;
    stbi_uc *out;                 // output buffer (always 4 components)
    stbi_uc *background;          // The current "background" as far as a gif is concerned
    stbi_uc *history; 
    int flags, bgindex, ratio, transparent, eflags;
    stbi_uc  pal[256][4];
    stbi_uc lpal[256][4];
    stbi__gif_lzw codes[8192];
    stbi_uc *color_table;
    int parse, step;
    int lflags;
    int start_x, start_y;
    int max_x, max_y;
    int cur_x, cur_y;
    int line_size;
    int delay;
 } stbi__gif;
 
 static int stbi__gif_test_raw(stbi__context *s)
 {
    int sz;
    if (stbi__get8(s) != 'G' || stbi__get8(s) != 'I' || stbi__get8(s) != 'F' || stbi__get8(s) != '8') return 0;
    sz = stbi__get8(s);
    if (sz != '9' && sz != '7') return 0;
    if (stbi__get8(s) != 'a') return 0;
    return 1;
 }
 
 static int stbi__gif_test(stbi__context *s)
 {
    int r = stbi__gif_test_raw(s);
    stbi__rewind(s);
    return r;
 }
 
 static void stbi__gif_parse_colortable(stbi__context *s, stbi_uc pal[256][4], int num_entries, int transp)
 {
    int i;
    for (i=0; i < num_entries; ++i) {
       pal[i][2] = stbi__get8(s);
       pal[i][1] = stbi__get8(s);
       pal[i][0] = stbi__get8(s);
       pal[i][3] = transp == i ? 0 : 255;
    }
 }
 
 static int stbi__gif_header(stbi__context *s, stbi__gif *g, int *comp, int is_info)
 {
    stbi_uc version;
    if (stbi__get8(s) != 'G' || stbi__get8(s) != 'I' || stbi__get8(s) != 'F' || stbi__get8(s) != '8')
       return stbi__err("not GIF", "Corrupt GIF");
 
    version = stbi__get8(s);
    if (version != '7' && version != '9')    return stbi__err("not GIF", "Corrupt GIF");
    if (stbi__get8(s) != 'a')                return stbi__err("not GIF", "Corrupt GIF");
 
    stbi__g_failure_reason = "";
    g->w = stbi__get16le(s);
    g->h = stbi__get16le(s);
    g->flags = stbi__get8(s);
    g->bgindex = stbi__get8(s);
    g->ratio = stbi__get8(s);
    g->transparent = -1;
 
    if (comp != 0) *comp = 4;  // can't actually tell whether it's 3 or 4 until we parse the comments
 
    if (is_info) return 1;
 
    if (g->flags & 0x80)
       stbi__gif_parse_colortable(s,g->pal, 2 << (g->flags & 7), -1);
 
    return 1;
 }
 
 static int stbi__gif_info_raw(stbi__context *s, int *x, int *y, int *comp)
 {
    stbi__gif* g = (stbi__gif*) stbi__malloc(sizeof(stbi__gif));
    if (!stbi__gif_header(s, g, comp, 1)) {
       STBI_FREE(g);
       stbi__rewind( s );
       return 0;
    }
    if (x) *x = g->w;
    if (y) *y = g->h;
    STBI_FREE(g);
    return 1;
 }
 
 static void stbi__out_gif_code(stbi__gif *g, stbi__uint16 code)
 {
    stbi_uc *p, *c;
    int idx; 
 
    // recurse to decode the prefixes, since the linked-list is backwards,
    // and working backwards through an interleaved image would be nasty
    if (g->codes[code].prefix >= 0)
       stbi__out_gif_code(g, g->codes[code].prefix);
 
    if (g->cur_y >= g->max_y) return;
 
    idx = g->cur_x + g->cur_y; 
    p = &g->out[idx];
    g->history[idx / 4] = 1;  
 
    c = &g->color_table[g->codes[code].suffix * 4];
    if (c[3] > 128) { // don't render transparent pixels; 
       p[0] = c[2];
       p[1] = c[1];
       p[2] = c[0];
       p[3] = c[3];
    }
    g->cur_x += 4;
 
    if (g->cur_x >= g->max_x) {
       g->cur_x = g->start_x;
       g->cur_y += g->step;
 
       while (g->cur_y >= g->max_y && g->parse > 0) {
          g->step = (1 << g->parse) * g->line_size;
          g->cur_y = g->start_y + (g->step >> 1);
          --g->parse;
       }
    }
 }
 
 static stbi_uc *stbi__process_gif_raster(stbi__context *s, stbi__gif *g)
 {
    stbi_uc lzw_cs;
    stbi__int32 len, init_code;
    stbi__uint32 first;
    stbi__int32 codesize, codemask, avail, oldcode, bits, valid_bits, clear;
    stbi__gif_lzw *p;
 
    lzw_cs = stbi__get8(s);
    if (lzw_cs > 12) return NULL;
    clear = 1 << lzw_cs;
    first = 1;
    codesize = lzw_cs + 1;
    codemask = (1 << codesize) - 1;
    bits = 0;
    valid_bits = 0;
    for (init_code = 0; init_code < clear; init_code++) {
       g->codes[init_code].prefix = -1;
       g->codes[init_code].first = (stbi_uc) init_code;
       g->codes[init_code].suffix = (stbi_uc) init_code;
    }
 
    // support no starting clear code
    avail = clear+2;
    oldcode = -1;
 
    len = 0;
    for(;;) {
       if (valid_bits < codesize) {
          if (len == 0) {
             len = stbi__get8(s); // start new block
             if (len == 0)
                return g->out;
          }
          --len;
          bits |= (stbi__int32) stbi__get8(s) << valid_bits;
          valid_bits += 8;
       } else {
          stbi__int32 code = bits & codemask;
          bits >>= codesize;
          valid_bits -= codesize;
          // @OPTIMIZE: is there some way we can accelerate the non-clear path?
          if (code == clear) {  // clear code
             codesize = lzw_cs + 1;
             codemask = (1 << codesize) - 1;
             avail = clear + 2;
             oldcode = -1;
             first = 0;
          } else if (code == clear + 1) { // end of stream code
             stbi__skip(s, len);
             while ((len = stbi__get8(s)) > 0)
                stbi__skip(s,len);
             return g->out;
          } else if (code <= avail) {
             if (first) {
                return stbi__errpuc("no clear code", "Corrupt GIF");
             }
 
             if (oldcode >= 0) {
                p = &g->codes[avail++];
                if (avail > 8192) {
                   return stbi__errpuc("too many codes", "Corrupt GIF");
                }
 
                p->prefix = (stbi__int16) oldcode;
                p->first = g->codes[oldcode].first;
                p->suffix = (code == avail) ? p->first : g->codes[code].first;
             } else if (code == avail)
                return stbi__errpuc("illegal code in raster", "Corrupt GIF");
 
             stbi__out_gif_code(g, (stbi__uint16) code);
 
             if ((avail & codemask) == 0 && avail <= 0x0FFF) {
                codesize++;
                codemask = (1 << codesize) - 1;
             }
 
             oldcode = code;
          } else {
             return stbi__errpuc("illegal code in raster", "Corrupt GIF");
          }
       }
    }
 }
 
 // this function is designed to support animated gifs, although stb_image doesn't support it
 // two back is the image from two frames ago, used for a very specific disposal format
 static stbi_uc *stbi__gif_load_next(stbi__context *s, stbi__gif *g, int *comp, int req_comp, stbi_uc *two_back)
 {
    int dispose; 
    int first_frame; 
    int pi; 
    int pcount; 
 
    // on first frame, any non-written pixels get the background colour (non-transparent)
    first_frame = 0; 
    if (g->out == 0) {
       if (!stbi__gif_header(s, g, comp,0))     return 0; // stbi__g_failure_reason set by stbi__gif_header
       g->out = (stbi_uc *) stbi__malloc(4 * g->w * g->h);
       g->background = (stbi_uc *) stbi__malloc(4 * g->w * g->h); 
       g->history = (stbi_uc *) stbi__malloc(g->w * g->h); 
       if (g->out == 0)                      return stbi__errpuc("outofmem", "Out of memory");
 
       // image is treated as "tranparent" at the start - ie, nothing overwrites the current background; 
       // background colour is only used for pixels that are not rendered first frame, after that "background"
       // color refers to teh color that was there the previous frame. 
       memset( g->out, 0x00, 4 * g->w * g->h ); 
       memset( g->background, 0x00, 4 * g->w * g->h ); // state of the background (starts transparent)
       memset( g->history, 0x00, g->w * g->h );        // pixels that were affected previous frame
       first_frame = 1; 
    } else {
       // second frame - how do we dispoase of the previous one?
       dispose = (g->eflags & 0x1C) >> 2; 
       pcount = g->w * g->h; 
 
       if ((dispose == 3) && (two_back == 0)) {
          dispose = 2; // if I don't have an image to revert back to, default to the old background
       }
 
       if (dispose == 3) { // use previous graphic
          for (pi = 0; pi < pcount; ++pi) {
             if (g->history[pi]) {
                memcpy( &g->out[pi * 4], &two_back[pi * 4], 4 ); 
             }
          }
       } else if (dispose == 2) { 
          // restore what was changed last frame to background before that frame; 
          for (pi = 0; pi < pcount; ++pi) {
             if (g->history[pi]) {
                memcpy( &g->out[pi * 4], &g->background[pi * 4], 4 ); 
             }
          }
       } else {
          // This is a non-disposal case eithe way, so just 
          // leave the pixels as is, and they will become the new background
          // 1: do not dispose
          // 0:  not specified.
       }
 
       // background is what out is after the undoing of the previou frame; 
       memcpy( g->background, g->out, 4 * g->w * g->h ); 
    }
 
    // clear my history; 
    memset( g->history, 0x00, g->w * g->h );        // pixels that were affected previous frame
 
    for (;;) {
       int tag = stbi__get8(s); 
       switch (tag) {
          case 0x2C: /* Image Descriptor */
          {
             stbi__int32 x, y, w, h;
             stbi_uc *o;
 
             x = stbi__get16le(s);
             y = stbi__get16le(s);
             w = stbi__get16le(s);
             h = stbi__get16le(s);
             if (((x + w) > (g->w)) || ((y + h) > (g->h)))
                return stbi__errpuc("bad Image Descriptor", "Corrupt GIF");
 
             g->line_size = g->w * 4;
             g->start_x = x * 4;
             g->start_y = y * g->line_size;
             g->max_x   = g->start_x + w * 4;
             g->max_y   = g->start_y + h * g->line_size;
             g->cur_x   = g->start_x;
             g->cur_y   = g->start_y;
 
             g->lflags = stbi__get8(s);
 
             if (g->lflags & 0x40) {
                g->step = 8 * g->line_size; // first interlaced spacing
                g->parse = 3;
             } else {
                g->step = g->line_size;
                g->parse = 0;
             }
 
             if (g->lflags & 0x80) {
                stbi__gif_parse_colortable(s,g->lpal, 2 << (g->lflags & 7), g->eflags & 0x01 ? g->transparent : -1);
                g->color_table = (stbi_uc *) g->lpal;
             } else if (g->flags & 0x80) {
                g->color_table = (stbi_uc *) g->pal;
             } else
                return stbi__errpuc("missing color table", "Corrupt GIF");            
             
             o = stbi__process_gif_raster(s, g);
             if (o == NULL) return NULL;
 
             // if this was the first frame, 
             pcount = g->w * g->h; 
             if (first_frame && (g->bgindex > 0)) {
                // if first frame, any pixel not drawn to gets the background color
                for (pi = 0; pi < pcount; ++pi) {
                   if (g->history[pi] == 0) {
                      g->pal[g->bgindex][3] = 255; // just in case it was made transparent, undo that; It will be reset next frame if need be; 
                      memcpy( &g->out[pi * 4], &g->pal[g->bgindex], 4 ); 
                   }
                }
             }
 
             return o;
          }
 
          case 0x21: // Comment Extension.
          {
             int len;
             int ext = stbi__get8(s); 
             if (ext == 0xF9) { // Graphic Control Extension.
                len = stbi__get8(s);
                if (len == 4) {
                   g->eflags = stbi__get8(s);
                   g->delay = 10 * stbi__get16le(s); // delay - 1/100th of a second, saving as 1/1000ths.
 
                   // unset old transparent
                   if (g->transparent >= 0) {
                      g->pal[g->transparent][3] = 255; 
                   } 
                   if (g->eflags & 0x01) {
                      g->transparent = stbi__get8(s);
                      if (g->transparent >= 0) {
                         g->pal[g->transparent][3] = 0; 
                      }
                   } else {
                      // don't need transparent
                      stbi__skip(s, 1); 
                      g->transparent = -1; 
                   }
                } else {
                   stbi__skip(s, len);
                   break;
                }
             } 
             while ((len = stbi__get8(s)) != 0) {
                stbi__skip(s, len);
             }
             break;
          }
 
          case 0x3B: // gif stream termination code
             return (stbi_uc *) s; // using '1' causes warning on some compilers
 
          default:
             return stbi__errpuc("unknown code", "Corrupt GIF");
       }
    }
 }
 
 static void *stbi__load_gif_main(stbi__context *s, int **delays, int *x, int *y, int *z, int *comp, int req_comp)
 {
    if (stbi__gif_test(s)) {
       int layers = 0; 
       stbi_uc *u = 0;
       stbi_uc *out = 0;
       stbi_uc *two_back = 0; 
       stbi__gif g;
       int stride; 
       memset(&g, 0, sizeof(g));
       if (delays) {
          *delays = 0; 
       }
 
       do {
          u = stbi__gif_load_next(s, &g, comp, req_comp, two_back);
          if (u == (stbi_uc *) s) u = 0;  // end of animated gif marker
 
          if (u) {
             *x = g.w;
             *y = g.h;
             ++layers; 
             stride = g.w * g.h * 4; 
          
             if (out) {
                out = (stbi_uc*) STBI_REALLOC( out, layers * stride ); 
                if (delays) {
                   *delays = (int*) STBI_REALLOC( *delays, sizeof(int) * layers ); 
                }
             } else {
                out = (stbi_uc*)stbi__malloc( layers * stride ); 
                if (delays) {
                   *delays = (int*) stbi__malloc( layers * sizeof(int) ); 
                }
             }
             memcpy( out + ((layers - 1) * stride), u, stride ); 
             if (layers >= 2) {
                two_back = out - 2 * stride; 
             }
 
             if (delays) {
                (*delays)[layers - 1U] = g.delay; 
             }
          }
       } while (u != 0); 
 
       // free temp buffer; 
       STBI_FREE(g.out); 
       STBI_FREE(g.history); 
       STBI_FREE(g.background); 
 
       // do the final conversion after loading everything; 
       if (req_comp && req_comp != 4)
          out = stbi__convert_format(out, 4, req_comp, layers * g.w, g.h);
 
       *z = layers; 
       return out;
    } else {
       return stbi__errpuc("not GIF", "Image was not as a gif type."); 
    }
 }
 
 static void *stbi__gif_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri)
 {
    stbi_uc *u = 0;
    stbi__gif g;
    memset(&g, 0, sizeof(g));
 
    u = stbi__gif_load_next(s, &g, comp, req_comp, 0);
    if (u == (stbi_uc *) s) u = 0;  // end of animated gif marker
    if (u) {
       *x = g.w;
       *y = g.h;
 
       // moved conversion to after successful load so that the same
       // can be done for multiple frames. 
       if (req_comp && req_comp != 4)
          u = stbi__convert_format(u, 4, req_comp, g.w, g.h);
    }
 
    // free buffers needed for multiple frame loading; 
    STBI_FREE(g.history);
    STBI_FREE(g.background); 
 
    return u;
 }
 
 static int stbi__gif_info(stbi__context *s, int *x, int *y, int *comp)
 {
    return stbi__gif_info_raw(s,x,y,comp);
 }
 #endif
 
 // *************************************************************************************************
 // Radiance RGBE HDR loader
 // originally by Nicolas Schulz
 #ifndef STBI_NO_HDR
 static int stbi__hdr_test_core(stbi__context *s, const char *signature)
 {
    int i;
    for (i=0; signature[i]; ++i)
       if (stbi__get8(s) != signature[i])
           return 0;
    stbi__rewind(s);
    return 1;
 }
 
 static int stbi__hdr_test(stbi__context* s)
 {
    int r = stbi__hdr_test_core(s, "#?RADIANCE\n");
    stbi__rewind(s);
    if(!r) {
        r = stbi__hdr_test_core(s, "#?RGBE\n");
        stbi__rewind(s);
    }
    return r;
 }
 
 #define STBI__HDR_BUFLEN  1024
 static char *stbi__hdr_gettoken(stbi__context *z, char *buffer)
 {
    int len=0;
    char c = '\0';
 
    c = (char) stbi__get8(z);
 
    while (!stbi__at_eof(z) && c != '\n') {
       buffer[len++] = c;
       if (len == STBI__HDR_BUFLEN-1) {
          // flush to end of line
          while (!stbi__at_eof(z) && stbi__get8(z) != '\n')
             ;
          break;
       }
       c = (char) stbi__get8(z);
    }
 
    buffer[len] = 0;
    return buffer;
 }
 
 static void stbi__hdr_convert(float *output, stbi_uc *input, int req_comp)
 {
    if ( input[3] != 0 ) {
       float f1;
       // Exponent
       f1 = (float) ldexp(1.0f, input[3] - (int)(128 + 8));
       if (req_comp <= 2)
          output[0] = (input[0] + input[1] + input[2]) * f1 / 3;
       else {
          output[0] = input[0] * f1;
          output[1] = input[1] * f1;
          output[2] = input[2] * f1;
       }
       if (req_comp == 2) output[1] = 1;
       if (req_comp == 4) output[3] = 1;
    } else {
       switch (req_comp) {
          case 4: output[3] = 1; /* fallthrough */
          case 3: output[0] = output[1] = output[2] = 0;
                  break;
          case 2: output[1] = 1; /* fallthrough */
          case 1: output[0] = 0;
                  break;
       }
    }
 }
 
 static float *stbi__hdr_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri)
 {
    char buffer[STBI__HDR_BUFLEN];
    char *token;
    int valid = 0;
    int width, height;
    stbi_uc *scanline;
    float *hdr_data;
    int len;
    unsigned char count, value;
    int i, j, k, c1,c2, z;
    const char *headerToken;
    STBI_NOTUSED(ri);
 
    // Check identifier
    headerToken = stbi__hdr_gettoken(s,buffer);
    if (strcmp(headerToken, "#?RADIANCE") != 0 && strcmp(headerToken, "#?RGBE") != 0)
       return stbi__errpf("not HDR", "Corrupt HDR image");
 
    // Parse header
    for(;;) {
       token = stbi__hdr_gettoken(s,buffer);
       if (token[0] == 0) break;
       if (strcmp(token, "FORMAT=32-bit_rle_rgbe") == 0) valid = 1;
    }
 
    if (!valid)    return stbi__errpf("unsupported format", "Unsupported HDR format");
 
    // Parse width and height
    // can't use sscanf() if we're not using stdio!
    token = stbi__hdr_gettoken(s,buffer);
    if (strncmp(token, "-Y ", 3))  return stbi__errpf("unsupported data layout", "Unsupported HDR format");
    token += 3;
    height = (int) strtol(token, &token, 10);
    while (*token == ' ') ++token;
    if (strncmp(token, "+X ", 3))  return stbi__errpf("unsupported data layout", "Unsupported HDR format");
    token += 3;
    width = (int) strtol(token, NULL, 10);
 
    *x = width;
    *y = height;
 
    if (comp) *comp = 3;
    if (req_comp == 0) req_comp = 3;
 
    if (!stbi__mad4sizes_valid(width, height, req_comp, sizeof(float), 0))
       return stbi__errpf("too large", "HDR image is too large");
 
    // Read data
    hdr_data = (float *) stbi__malloc_mad4(width, height, req_comp, sizeof(float), 0);
    if (!hdr_data)
       return stbi__errpf("outofmem", "Out of memory");
 
    // Load image data
    // image data is stored as some number of sca
    if ( width < 8 || width >= 32768) {
       // Read flat data
       for (j=0; j < height; ++j) {
          for (i=0; i < width; ++i) {
             stbi_uc rgbe[4];
            main_decode_loop:
             stbi__getn(s, rgbe, 4);
             stbi__hdr_convert(hdr_data + j * width * req_comp + i * req_comp, rgbe, req_comp);
          }
       }
    } else {
       // Read RLE-encoded data
       scanline = NULL;
 
       for (j = 0; j < height; ++j) {
          c1 = stbi__get8(s);
          c2 = stbi__get8(s);
          len = stbi__get8(s);
          if (c1 != 2 || c2 != 2 || (len & 0x80)) {
             // not run-length encoded, so we have to actually use THIS data as a decoded
             // pixel (note this can't be a valid pixel--one of RGB must be >= 128)
             stbi_uc rgbe[4];
             rgbe[0] = (stbi_uc) c1;
             rgbe[1] = (stbi_uc) c2;
             rgbe[2] = (stbi_uc) len;
             rgbe[3] = (stbi_uc) stbi__get8(s);
             stbi__hdr_convert(hdr_data, rgbe, req_comp);
             i = 1;
             j = 0;
             STBI_FREE(scanline);
             goto main_decode_loop; // yes, this makes no sense
          }
          len <<= 8;
          len |= stbi__get8(s);
          if (len != width) { STBI_FREE(hdr_data); STBI_FREE(scanline); return stbi__errpf("invalid decoded scanline length", "corrupt HDR"); }
          if (scanline == NULL) {
             scanline = (stbi_uc *) stbi__malloc_mad2(width, 4, 0);
             if (!scanline) {
                STBI_FREE(hdr_data);
                return stbi__errpf("outofmem", "Out of memory");
             }
          }
 
          for (k = 0; k < 4; ++k) {
             int nleft;
             i = 0;
             while ((nleft = width - i) > 0) {
                count = stbi__get8(s);
                if (count > 128) {
                   // Run
                   value = stbi__get8(s);
                   count -= 128;
                   if (count > nleft) { STBI_FREE(hdr_data); STBI_FREE(scanline); return stbi__errpf("corrupt", "bad RLE data in HDR"); }
                   for (z = 0; z < count; ++z)
                      scanline[i++ * 4 + k] = value;
                } else {
                   // Dump
                   if (count > nleft) { STBI_FREE(hdr_data); STBI_FREE(scanline); return stbi__errpf("corrupt", "bad RLE data in HDR"); }
                   for (z = 0; z < count; ++z)
                      scanline[i++ * 4 + k] = stbi__get8(s);
                }
             }
          }
          for (i=0; i < width; ++i)
             stbi__hdr_convert(hdr_data+(j*width + i)*req_comp, scanline + i*4, req_comp);
       }
       if (scanline)
          STBI_FREE(scanline);
    }
 
    return hdr_data;
 }
 
 static int stbi__hdr_info(stbi__context *s, int *x, int *y, int *comp)
 {
    char buffer[STBI__HDR_BUFLEN];
    char *token;
    int valid = 0;
    int dummy;
 
    if (!x) x = &dummy;
    if (!y) y = &dummy;
    if (!comp) comp = &dummy;
 
    if (stbi__hdr_test(s) == 0) {
        stbi__rewind( s );
        return 0;
    }
 
    for(;;) {
       token = stbi__hdr_gettoken(s,buffer);
       if (token[0] == 0) break;
       if (strcmp(token, "FORMAT=32-bit_rle_rgbe") == 0) valid = 1;
    }
 
    if (!valid) {
        stbi__rewind( s );
        return 0;
    }
    token = stbi__hdr_gettoken(s,buffer);
    if (strncmp(token, "-Y ", 3)) {
        stbi__rewind( s );
        return 0;
    }
    token += 3;
    *y = (int) strtol(token, &token, 10);
    while (*token == ' ') ++token;
    if (strncmp(token, "+X ", 3)) {
        stbi__rewind( s );
        return 0;
    }
    token += 3;
    *x = (int) strtol(token, NULL, 10);
    *comp = 3;
    return 1;
 }
 #endif // STBI_NO_HDR
 
 #ifndef STBI_NO_BMP
 static int stbi__bmp_info(stbi__context *s, int *x, int *y, int *comp)
 {
    void *p;
    stbi__bmp_data info;
 
    info.all_a = 255;
    p = stbi__bmp_parse_header(s, &info);
    stbi__rewind( s );
    if (p == NULL)
       return 0;
    if (x) *x = s->img_x;
    if (y) *y = s->img_y;
    if (comp) *comp = info.ma ? 4 : 3;
    return 1;
 }
 #endif
 
 #ifndef STBI_NO_PSD
 static int stbi__psd_info(stbi__context *s, int *x, int *y, int *comp)
 {
    int channelCount, dummy, depth;
    if (!x) x = &dummy;
    if (!y) y = &dummy;
    if (!comp) comp = &dummy;
    if (stbi__get32be(s) != 0x38425053) {
        stbi__rewind( s );
        return 0;
    }
    if (stbi__get16be(s) != 1) {
        stbi__rewind( s );
        return 0;
    }
    stbi__skip(s, 6);
    channelCount = stbi__get16be(s);
    if (channelCount < 0 || channelCount > 16) {
        stbi__rewind( s );
        return 0;
    }
    *y = stbi__get32be(s);
    *x = stbi__get32be(s);
    depth = stbi__get16be(s);
    if (depth != 8 && depth != 16) {
        stbi__rewind( s );
        return 0;
    }
    if (stbi__get16be(s) != 3) {
        stbi__rewind( s );
        return 0;
    }
    *comp = 4;
    return 1;
 }
 
 static int stbi__psd_is16(stbi__context *s)
 {
    int channelCount, depth;
    if (stbi__get32be(s) != 0x38425053) {
        stbi__rewind( s );
        return 0;
    }
    if (stbi__get16be(s) != 1) {
        stbi__rewind( s );
        return 0;
    }
    stbi__skip(s, 6);
    channelCount = stbi__get16be(s);
    if (channelCount < 0 || channelCount > 16) {
        stbi__rewind( s );
        return 0;
    }
    (void) stbi__get32be(s);
    (void) stbi__get32be(s);
    depth = stbi__get16be(s);
    if (depth != 16) {
        stbi__rewind( s );
        return 0;
    }
    return 1;
 }
 #endif
 
 #ifndef STBI_NO_PIC
 static int stbi__pic_info(stbi__context *s, int *x, int *y, int *comp)
 {
    int act_comp=0,num_packets=0,chained,dummy;
    stbi__pic_packet packets[10];
 
    if (!x) x = &dummy;
    if (!y) y = &dummy;
    if (!comp) comp = &dummy;
 
    if (!stbi__pic_is4(s,"\x53\x80\xF6\x34")) {
       stbi__rewind(s);
       return 0;
    }
 
    stbi__skip(s, 88);
 
    *x = stbi__get16be(s);
    *y = stbi__get16be(s);
    if (stbi__at_eof(s)) {
       stbi__rewind( s);
       return 0;
    }
    if ( (*x) != 0 && (1 << 28) / (*x) < (*y)) {
       stbi__rewind( s );
       return 0;
    }
 
    stbi__skip(s, 8);
 
    do {
       stbi__pic_packet *packet;
 
       if (num_packets==sizeof(packets)/sizeof(packets[0]))
          return 0;
 
       packet = &packets[num_packets++];
       chained = stbi__get8(s);
       packet->size    = stbi__get8(s);
       packet->type    = stbi__get8(s);
       packet->channel = stbi__get8(s);
       act_comp |= packet->channel;
 
       if (stbi__at_eof(s)) {
           stbi__rewind( s );
           return 0;
       }
       if (packet->size != 8) {
           stbi__rewind( s );
           return 0;
       }
    } while (chained);
 
    *comp = (act_comp & 0x10 ? 4 : 3);
 
    return 1;
 }
 #endif
 
 // *************************************************************************************************
 // Portable Gray Map and Portable Pixel Map loader
 // by Ken Miller
 //
 // PGM: http://netpbm.sourceforge.net/doc/pgm.html
 // PPM: http://netpbm.sourceforge.net/doc/ppm.html
 //
 // Known limitations:
 //    Does not support comments in the header section
 //    Does not support ASCII image data (formats P2 and P3)
 //    Does not support 16-bit-per-channel
 
 #ifndef STBI_NO_PNM
 
 static int      stbi__pnm_test(stbi__context *s)
 {
    char p, t;
    p = (char) stbi__get8(s);
    t = (char) stbi__get8(s);
    if (p != 'P' || (t != '5' && t != '6')) {
        stbi__rewind( s );
        return 0;
    }
    return 1;
 }
 
 static void *stbi__pnm_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri)
 {
    stbi_uc *out;
    STBI_NOTUSED(ri);
 
    if (!stbi__pnm_info(s, (int *)&s->img_x, (int *)&s->img_y, (int *)&s->img_n))
       return 0;
 
    *x = s->img_x;
    *y = s->img_y;
    if (comp) *comp = s->img_n;
 
    if (!stbi__mad3sizes_valid(s->img_n, s->img_x, s->img_y, 0))
       return stbi__errpuc("too large", "PNM too large");
 
    out = (stbi_uc *) stbi__malloc_mad3(s->img_n, s->img_x, s->img_y, 0);
    if (!out) return stbi__errpuc("outofmem", "Out of memory");
    stbi__getn(s, out, s->img_n * s->img_x * s->img_y);
 
    if (req_comp && req_comp != s->img_n) {
       out = stbi__convert_format(out, s->img_n, req_comp, s->img_x, s->img_y);
       if (out == NULL) return out; // stbi__convert_format frees input on failure
    }
    return out;
 }
 
 static int      stbi__pnm_isspace(char c)
 {
    return c == ' ' || c == '\t' || c == '\n' || c == '\v' || c == '\f' || c == '\r';
 }
 
 static void     stbi__pnm_skip_whitespace(stbi__context *s, char *c)
 {
    for (;;) {
       while (!stbi__at_eof(s) && stbi__pnm_isspace(*c))
          *c = (char) stbi__get8(s);
 
       if (stbi__at_eof(s) || *c != '#')
          break;
 
       while (!stbi__at_eof(s) && *c != '\n' && *c != '\r' )
          *c = (char) stbi__get8(s);
    }
 }
 
 static int      stbi__pnm_isdigit(char c)
 {
    return c >= '0' && c <= '9';
 }
 
 static int      stbi__pnm_getinteger(stbi__context *s, char *c)
 {
    int value = 0;
 
    while (!stbi__at_eof(s) && stbi__pnm_isdigit(*c)) {
       value = value*10 + (*c - '0');
       *c = (char) stbi__get8(s);
    }
 
    return value;
 }
 
 static int      stbi__pnm_info(stbi__context *s, int *x, int *y, int *comp)
 {
    int maxv, dummy;
    char c, p, t;
 
    if (!x) x = &dummy;
    if (!y) y = &dummy;
    if (!comp) comp = &dummy;
 
    stbi__rewind(s);
 
    // Get identifier
    p = (char) stbi__get8(s);
    t = (char) stbi__get8(s);
    if (p != 'P' || (t != '5' && t != '6')) {
        stbi__rewind(s);
        return 0;
    }
 
    *comp = (t == '6') ? 3 : 1;  // '5' is 1-component .pgm; '6' is 3-component .ppm
 
    c = (char) stbi__get8(s);
    stbi__pnm_skip_whitespace(s, &c);
 
    *x = stbi__pnm_getinteger(s, &c); // read width
    stbi__pnm_skip_whitespace(s, &c);
 
    *y = stbi__pnm_getinteger(s, &c); // read height
    stbi__pnm_skip_whitespace(s, &c);
 
    maxv = stbi__pnm_getinteger(s, &c);  // read max value
 
    if (maxv > 255)
       return stbi__err("max value > 255", "PPM image not 8-bit");
    else
       return 1;
 }
 #endif
 
 static int stbi__info_main(stbi__context *s, int *x, int *y, int *comp)
 {
    #ifndef STBI_NO_JPEG
    if (stbi__jpeg_info(s, x, y, comp)) return 1;
    #endif
 
    #ifndef STBI_NO_PNG
    if (stbi__png_info(s, x, y, comp))  return 1;
    #endif
 
    #ifndef STBI_NO_GIF
    if (stbi__gif_info(s, x, y, comp))  return 1;
    #endif
 
    #ifndef STBI_NO_BMP
    if (stbi__bmp_info(s, x, y, comp))  return 1;
    #endif
 
    #ifndef STBI_NO_PSD
    if (stbi__psd_info(s, x, y, comp))  return 1;
    #endif
 
    #ifndef STBI_NO_PIC
    if (stbi__pic_info(s, x, y, comp))  return 1;
    #endif
 
    #ifndef STBI_NO_PNM
    if (stbi__pnm_info(s, x, y, comp))  return 1;
    #endif
 
    #ifndef STBI_NO_HDR
    if (stbi__hdr_info(s, x, y, comp))  return 1;
    #endif
 
    // test tga last because it's a crappy test!
    #ifndef STBI_NO_TGA
    if (stbi__tga_info(s, x, y, comp))
        return 1;
    #endif
    return stbi__err("unknown image type", "Image not of any known type, or corrupt");
 }
 
 static int stbi__is_16_main(stbi__context *s)
 {
    #ifndef STBI_NO_PNG
    if (stbi__png_is16(s))  return 1;
    #endif
 
    #ifndef STBI_NO_PSD
    if (stbi__psd_is16(s))  return 1;
    #endif
 
    return 0;
 }
 
 #ifndef STBI_NO_STDIO
 STBIDEF int stbi_info(char const *filename, int *x, int *y, int *comp)
 {
     FILE *f = stbi__fopen(filename, "rb");
     int result;
     if (!f) return stbi__err("can't fopen", "Unable to open file");
     result = stbi_info_from_file(f, x, y, comp);
     fclose(f);
     return result;
 }
 
 STBIDEF int stbi_info_from_file(FILE *f, int *x, int *y, int *comp)
 {
    int r;
    stbi__context s;
    long pos = ftell(f);
    stbi__start_file(&s, f);
    r = stbi__info_main(&s,x,y,comp);
    fseek(f,pos,SEEK_SET);
    return r;
 }
 
 STBIDEF int stbi_is_16_bit(char const *filename)
 {
     FILE *f = stbi__fopen(filename, "rb");
     int result;
     if (!f) return stbi__err("can't fopen", "Unable to open file");
     result = stbi_is_16_bit_from_file(f);
     fclose(f);
     return result;
 }
 
 STBIDEF int stbi_is_16_bit_from_file(FILE *f)
 {
    int r;
    stbi__context s;
    long pos = ftell(f);
    stbi__start_file(&s, f);
    r = stbi__is_16_main(&s);
    fseek(f,pos,SEEK_SET);
    return r;
 }
 #endif // !STBI_NO_STDIO
 
 STBIDEF int stbi_info_from_memory(stbi_uc const *buffer, int len, int *x, int *y, int *comp)
 {
    stbi__context s;
    stbi__start_mem(&s,buffer,len);
    return stbi__info_main(&s,x,y,comp);
 }
 
 STBIDEF int stbi_info_from_callbacks(stbi_io_callbacks const *c, void *user, int *x, int *y, int *comp)
 {
    stbi__context s;
    stbi__start_callbacks(&s, (stbi_io_callbacks *) c, user);
    return stbi__info_main(&s,x,y,comp);
 }
 
 STBIDEF int stbi_is_16_bit_from_memory(stbi_uc const *buffer, int len)
 {
    stbi__context s;
    stbi__start_mem(&s,buffer,len);
    return stbi__is_16_main(&s);
 }
 
 STBIDEF int stbi_is_16_bit_from_callbacks(stbi_io_callbacks const *c, void *user)
 {
    stbi__context s;
    stbi__start_callbacks(&s, (stbi_io_callbacks *) c, user);
    return stbi__is_16_main(&s);
 }