diff options
Diffstat (limited to 'src/mem/ft_memchr.c')
| -rw-r--r-- | src/mem/ft_memchr.c | 44 |
1 files changed, 37 insertions, 7 deletions
diff --git a/src/mem/ft_memchr.c b/src/mem/ft_memchr.c index 4fd8689..54780fe 100644 --- a/src/mem/ft_memchr.c +++ b/src/mem/ft_memchr.c @@ -12,15 +12,45 @@ #include "libft.h" +/* +** Determining if a long word contain byte n +** +** xor all bytes with n, then check for zero byte like in ft_strlen. +*/ + +#define HIMAGIC 0x8080808080808080L +#define LOMAGIC 0x0101010101010101L + void *ft_memchr(const void *s, int c, size_t n) { - size_t i; - t_ftbyte *cast_s; + uint64_t buf; + uint64_t lw; - cast_s = (t_ftbyte*)s; - i = -1; - while (++i < n) - if (cast_s[i] == (unsigned char)c) - return (cast_s + i); + c = (uint8_t)c; + while (((uint64_t)s & 0b111) != 0) + { + n--; + if (*(uint8_t*)s == (uint8_t)c) + return ((uint8_t*)s); + s++; + } + buf = (uint64_t)c | (uint64_t)c << 8 | (uint64_t)c << 16 + | (uint64_t)c << 24 | (uint64_t)c << 32 | (uint64_t)c << 40 + | (uint64_t)c << 48 | (uint64_t)c << 56; + while (n >= 8) + { + lw = *(uint64_t*)s ^ buf; + if ((lw - LOMAGIC) & ~lw & HIMAGIC) + break; + n -= 8; + s += 8; + } + while (n > 0) + { + if (*(uint8_t*)s == (uint8_t)c) + return ((uint8_t*)s); + n--; + s++; + } return (NULL); } |