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
85 lines
3.6 KiB
C
85 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/dce.h"
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#include "libc/intrin/likely.h"
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#include "libc/str/str.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 fixed-length substring in memory region.
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*
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* @param haystack is the region of memory to be searched
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* @param haystacklen is its character count
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* @param needle contains the memory for which we're searching
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* @param needlelen is its character count
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* @return pointer to first result or NULL if not found
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*/
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__vex void *memmem(const void *haystack, size_t haystacklen, const void *needle,
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size_t needlelen) {
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#if defined(__x86_64__) && !defined(__chibicc__)
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char c;
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xmm_t n;
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const xmm_t *v;
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unsigned i, k, m;
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const char *p, *q, *e;
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if (!needlelen) return (void *)haystack;
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if (UNLIKELY(needlelen > haystacklen)) return 0;
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q = needle;
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c = *q;
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n = (xmm_t){c, c, c, c, c, c, c, c, c, c, c, c, c, c, c, c};
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p = haystack;
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e = p + haystacklen;
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k = (uintptr_t)p & 15;
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v = (const xmm_t *)((uintptr_t)p & -16);
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m = __builtin_ia32_pmovmskb128(*v == n);
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m >>= k;
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m <<= k;
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for (;;) {
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while (!m) {
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++v;
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if ((const char *)v >= e) return 0;
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m = __builtin_ia32_pmovmskb128(*v == n);
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}
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do {
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k = __builtin_ctzl(m);
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p = (const char *)v + k;
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if (UNLIKELY(p + needlelen > e)) return 0;
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for (i = 1;; ++i) {
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if (i == needlelen) return (/*unconst*/ char *)p;
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if (p[i] != q[i]) break;
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}
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m &= ~(1 << k);
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} while (m);
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}
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#else
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size_t i, j;
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if (!needlelen) return (void *)haystack;
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if (needlelen > haystacklen) return 0;
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for (i = 0; i < haystacklen; ++i) {
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for (j = 0;; ++j) {
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if (j == needlelen) return (/*unconst*/ char *)haystack + i;
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if (i + j == haystacklen) break;
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if (((char *)haystack)[i + j] != ((char *)needle)[j]) break;
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}
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}
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return 0;
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#endif
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}
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