cosmopolitan/libc/intrin/memchr.c
Justine Tunney f531acc8f9
Make improvements
- Invent openatemp() API
- Invent O_UNLINK open flag
- Introduce getenv_secure() API
- Remove `git pull` from cosmocc
- Fix utimes() when path is NULL
- Fix mktemp() to never return NULL
- Fix utimensat() UTIME_OMIT on XNU
- Improve utimensat() code for RHEL5
- Turn `argv[0]` C:/ to /C/ on Windows
- Introduce tmpnam() and tmpnam_r() APIs
- Fix more const issues with internal APIs
- Permit utimes() on WIN32 in O_RDONLY mode
- Fix fdopendir() to check fd is a directory
- Fix recent crash regression in landlock make
- Fix futimens(AT_FDCWD, NULL) to return EBADF
- Use workaround so `make -j` doesn't fork bomb
- Rename dontdiscard to __wur (just like glibc)
- Fix st_size for WIN32 symlinks containing UTF-8
- Introduce stdio ext APIs needed by GNU coreutils
- Fix lstat() on WIN32 for symlinks to directories
- Move some constants from normalize.inc to limits.h
- Fix segv with memchr() and memcmp() overlapping page
- Implement POSIX fflush() behavior for reader streams
- Implement AT_SYMLINK_NOFOLLOW for utimensat() on WIN32
- Don't change read-only status of existing files on WIN32
- Correctly handle `0x[^[:xdigit:]]` case in strtol() functions
2023-09-06 12:34:59 -07:00

90 lines
3.6 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/nexgen32e/x86feature.h"
#include "libc/str/str.h"
#ifndef __aarch64__
typedef char xmm_t __attribute__((__vector_size__(16), __aligned__(16)));
static inline const unsigned char *memchr_pure(const unsigned char *s,
unsigned char c, size_t n) {
size_t i;
for (i = 0; i < n; ++i) {
if (s[i] == c) {
return s + i;
}
}
return 0;
}
#if defined(__x86_64__) && !defined(__chibicc__)
dontasan static inline const unsigned char *memchr_sse(const unsigned char *s,
unsigned char c,
size_t n) {
size_t i;
unsigned m;
xmm_t v, t = {c, c, c, c, c, c, c, c, c, c, c, c, c, c, c, c};
for (; n >= 16; n -= 16, s += 16) {
v = *(const xmm_t *)s;
m = __builtin_ia32_pmovmskb128(v == t);
if (m) {
m = __builtin_ctzll(m);
return s + m;
}
}
for (i = 0; i < n; ++i) {
if (s[i] == c) {
return s + i;
}
}
return 0;
}
#endif
/**
* Returns pointer to first instance of character.
*
* @param s is memory to search
* @param c is search byte which is masked with 255
* @param n is byte length of p
* @return is pointer to first instance of c or NULL if not found
* @asyncsignalsafe
*/
dontasan void *memchr(const void *s, int c, size_t n) {
#if defined(__x86_64__) && !defined(__chibicc__)
const void *r;
if (IsAsan()) __asan_verify(s, n);
const unsigned char *p = (const unsigned char *)s;
while (n && ((intptr_t)p & 15)) {
if (*p == (unsigned char)c) {
return (void *)p;
}
++p;
--n;
}
r = memchr_sse(p, c, n);
return (void *)r;
#else
return (void *)memchr_pure(s, c, n);
#endif
}
#endif /* __aarch64__ */