cosmopolitan/libc/intrin/strlen.c
Justine Tunney 7061c79c22 Make fixes, improvements, and chibicc python bindings
- python now mixes audio 10x faster
- python octal notation is restored
- chibicc now builds code 3x faster
- chibicc now has help documentation
- chibicc can now generate basic python bindings
- linenoise now supports some paredit-like features

See #141
2021-10-08 08:41:57 -07:00

43 lines
2.5 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2021 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/dce.h"
#include "libc/intrin/asan.internal.h"
#include "libc/str/str.h"
typedef char xmm_t __attribute__((__vector_size__(16), __aligned__(16)));
/**
* Returns length of NUL-terminated string.
*
* @param s is non-null NUL-terminated string pointer
* @return number of bytes (excluding NUL)
* @asyncsignalsafe
*/
noasan size_t strlen(const char *s) {
size_t n;
xmm_t v, z = {0};
unsigned m, k = (uintptr_t)s & 15;
const xmm_t *p = (const xmm_t *)((uintptr_t)s & -16);
if (IsAsan()) __asan_verify(s, 1);
m = __builtin_ia32_pmovmskb128(*p == z) >> k << k;
while (!m) m = __builtin_ia32_pmovmskb128(*++p == z);
n = (const char *)p + __builtin_ctzl(m) - s;
if (IsAsan()) __asan_verify(s, n);
return n;
}