1#include "native.h"
2
3/**
4 * @brief uppercase to lowercase
5 * @param[in] src original string
6 * @param[in, out] dst lowercase string
7 * @param[in] len length of the string
8*/
9void to_lower(char* dst, const char* src, size_t len) {
10 const __m128i _A = _mm_set1_epi8('A' - 1);
11 const __m128i Z_ = _mm_set1_epi8('Z' + 1);
12 const __m128i delta = _mm_set1_epi8('a' - 'A');
13 char* q = dst;
14
15 while (len >= 16){
16 __m128i op = _mm_loadu_si128((__m128i*)src);
17 __m128i gt = _mm_cmpgt_epi8(op, _A);
18 __m128i lt = _mm_cmplt_epi8(op, Z_);
19 __m128i mingle = _mm_and_si128(gt, lt);
20 __m128i add = _mm_and_si128(mingle, delta);
21 __m128i lower = _mm_add_epi8(op, add);
22 _mm_storeu_si128((__m128i *)q, lower);
23 src += 16;
24 q += 16;
25 len -= 16;
26 };
27
28 while(len > 0) {
29 len--;
30 bool isUpper = (*src >= 'A' && *src <= 'Z');
31 *q = isUpper? (*src + 32): *src;
32 src++;
33 q++;
34 }
35}View as plain text