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Daniel Lemire 2018-09-30 14:44:30 -04:00
parent 314356d561
commit 37adea9387
1 changed files with 5 additions and 0 deletions
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5
include/jsonparser/numberparsing.h
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@ -111,11 +111,16 @@ is_not_structural_or_whitespace_or_exponent_or_decimal(unsigned char c) {
static inline bool is_made_of_eight_digits_fast(const char *chars) {
uint64_t val;
memcpy(&val, chars, 8);
// a branchy method might be faster:
//return (( val & 0xF0F0F0F0F0F0F0F0 ) == 0x3030303030303030)
// && (( (val + 0x0606060606060606) & 0xF0F0F0F0F0F0F0F0 ) == 0x3030303030303030);
return (((val & 0xF0F0F0F0F0F0F0F0) |
(((val + 0x0606060606060606) & 0xF0F0F0F0F0F0F0F0) >> 4)) ==
0x3333333333333333);
}
static inline uint32_t parse_eight_digits_unrolled(const char *chars) {
// this actually computes *16* values so we are being wasteful.
const __m128i ascii0 = _mm_set1_epi8('0');