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memchr.h (1462B)


      1 
      2 
      3 #ifndef FAST_MEMCHR_H
      4 #define FAST_MEMCHR_H
      5 
      6 #include <string.h>
      7 
      8 #ifdef __ARM_NEON
      9 #define vector_strchr neon_strchr
     10 #else
     11 #define vector_strchr native_memchr
     12 #endif
     13 
     14 #ifdef __ARM_NEON
     15 #include <arm_neon.h>
     16 static const char *neon_strchr(const char *str, char c, size_t length) {
     17 	const char* end = str + length;
     18 
     19 	// Alignment handling
     20 	while (str < end && ((size_t)str & 0xF)) {
     21 		if (*str == c) 
     22 			return str;
     23 		++str;
     24 	}
     25 
     26 	uint8x16_t searchChar = vdupq_n_u8(c);
     27 
     28 	while (str + 16 <= end) {
     29 		uint8x16_t chunk = vld1q_u8((const uint8_t*)str);
     30 		uint8x16_t comparison = vceqq_u8(chunk, searchChar);
     31 
     32 		// Check first 64 bits
     33 		uint64_t result0 =
     34 			vgetq_lane_u64(vreinterpretq_u64_u8(comparison), 0);
     35 
     36 		if (result0)
     37 			return str + __builtin_ctzll(result0)/8;
     38 	
     39 		// Check second 64 bits
     40 		uint64_t result1 = vgetq_lane_u64(vreinterpretq_u64_u8(comparison), 1);
     41 		if (result1)
     42 			return str + 8 + __builtin_ctzll(result1)/8;
     43 
     44 		str += 16;
     45 	}
     46 
     47 	// Handle remaining unaligned characters
     48 	for (; str < end; ++str) {
     49 		if (*str == c)
     50 			return str;
     51 	}
     52 
     53 	return NULL;
     54 }
     55 #endif
     56 
     57 static inline const char *native_memchr(const char *str, char c, size_t length) {
     58     const void *result = memchr(str, c, length);
     59     return (const char *) result;
     60 }
     61 
     62 static inline const char *fast_strchr(const char *str, char c, size_t length)
     63 {
     64 	if (length >= 16) {
     65 		return vector_strchr(str, c, length);
     66 	}
     67 	
     68 	return native_memchr(str, c, length);
     69 }
     70 
     71 
     72 #endif // FAST_MEMCHR_H