mirror of
https://github.com/jart/cosmopolitan.git
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83 lines
3.4 KiB
C
83 lines
3.4 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2021 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/asan.internal.h"
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#include "libc/nexgen32e/x86feature.h"
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#include "libc/stdckdint.h"
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#include "libc/str/str.h"
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typedef wchar_t xmm_t __attribute__((__vector_size__(16), __aligned__(4)));
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static inline const wchar_t *wmemrchr_pure(const wchar_t *s, wchar_t c,
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size_t n) {
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size_t i;
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for (i = n; i--;) {
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if (s[i] == c) {
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return s + i;
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}
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}
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return 0;
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}
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#if defined(__x86_64__) && !defined(__chibicc__)
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dontasan static inline const wchar_t *wmemrchr_sse(const wchar_t *s, wchar_t c,
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size_t n) {
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size_t i;
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unsigned k, m;
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xmm_t v, t = {c, c, c, c};
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for (i = n; i >= 4;) {
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v = *(const xmm_t *)(s + (i -= 4));
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m = __builtin_ia32_pmovmskb128(v == t);
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if (m) {
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m = __builtin_clzl(m) ^ (sizeof(long) * CHAR_BIT - 1);
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return s + i + m / 4;
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}
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}
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while (i--) {
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if (s[i] == c) {
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return s + i;
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}
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}
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return 0;
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}
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#endif
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/**
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* Returns pointer to first instance of character.
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*
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* @param s is memory to search
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* @param c is search word
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* @param n is number of wchar_t elements in `s`
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* @return is pointer to first instance of c or NULL if not found
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* @asyncsignalsafe
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*/
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void *wmemrchr(const wchar_t *s, wchar_t c, size_t n) {
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#if defined(__x86_64__) && !defined(__chibicc__)
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size_t bytes;
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const void *r;
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if (IsAsan()) {
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if (ckd_mul(&bytes, n, sizeof(wchar_t))) bytes = -1;
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__asan_verify(s, bytes);
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}
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r = wmemrchr_sse(s, c, n);
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return (void *)r;
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#else
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return wmemrchr_pure(s, c, n);
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#endif
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}
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