mirror of
https://github.com/jart/cosmopolitan.git
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2ab9e9f7fd
- Introduce portable sched_getcpu() api - Support GCC's __target_clones__ feature - Make fma() go faster on x86 in default mode - Remove some asan checks from core libraries - WinMain() now ensures $HOME and $USER are defined
81 lines
3.6 KiB
C
81 lines
3.6 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/str/str.h"
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#include "libc/dce.h"
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typedef char xmm_t __attribute__((__vector_size__(16), __aligned__(16)));
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/**
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* Searches for substring.
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*
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* @param haystack is the search area, as a NUL-terminated string
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* @param needle is the desired substring, also NUL-terminated
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* @return pointer to first substring within haystack, or NULL
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* @note this implementation goes fast in practice but isn't hardened
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* against pathological cases, and therefore shouldn't be used on
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* untrustworthy data
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* @asyncsignalsafe
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* @see strcasestr()
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* @see memmem()
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*/
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__vex char *strstr(const char *haystack, const char *needle) {
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#if defined(__x86_64__) && !defined(__chibicc__)
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size_t i;
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unsigned k, m;
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const xmm_t *p;
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xmm_t v, n, z = {0};
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if (haystack == needle || !*needle) return (char *)haystack;
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n = (xmm_t){*needle, *needle, *needle, *needle, *needle, *needle,
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*needle, *needle, *needle, *needle, *needle, *needle,
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*needle, *needle, *needle, *needle};
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for (;;) {
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k = (uintptr_t)haystack & 15;
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p = (const xmm_t *)((uintptr_t)haystack & -16);
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v = *p;
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m = __builtin_ia32_pmovmskb128((v == z) | (v == n));
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m >>= k;
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m <<= k;
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while (!m) {
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v = *++p;
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m = __builtin_ia32_pmovmskb128((v == z) | (v == n));
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}
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haystack = (const char *)p + __builtin_ctzl(m);
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for (i = 0;; ++i) {
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if (!needle[i]) return (/*unconst*/ char *)haystack;
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if (!haystack[i]) break;
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if (needle[i] != haystack[i]) break;
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}
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if (!*haystack++) break;
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}
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return 0;
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#else
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size_t i;
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if (haystack == needle || !*needle) return (void *)haystack;
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for (;;) {
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for (i = 0;; ++i) {
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if (!needle[i]) return (/*unconst*/ char *)haystack;
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if (!haystack[i]) break;
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if (needle[i] != haystack[i]) break;
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}
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if (!*haystack++) break;
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}
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return 0;
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#endif
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}
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