mirror of
https://github.com/jart/cosmopolitan.git
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d7733579d3
The amalgamated release is now confirmed to be working with Clang, including its integrated assembler. Fixes #41
50 lines
2.6 KiB
C
50 lines
2.6 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set 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/assert.h"
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#include "libc/str/str.h"
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static noasan size_t strlen_pure_x64(const char *s, size_t i) {
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uint64_t w;
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const unsigned char *p;
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for (;;) {
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p = (const unsigned char *)s + i;
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w = (uint64_t)p[7] << 070 | (uint64_t)p[6] << 060 | (uint64_t)p[5] << 050 |
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(uint64_t)p[4] << 040 | (uint64_t)p[3] << 030 | (uint64_t)p[2] << 020 |
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(uint64_t)p[1] << 010 | (uint64_t)p[0] << 000;
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if ((w = ~w & (w - 0x0101010101010101) & 0x8080808080808080)) {
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return i + ((unsigned)__builtin_ctzll(w) >> 3);
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} else {
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i += 8;
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}
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}
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}
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/**
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* Returns length of NUL-terminated string.
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*/
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size_t strlen_pure(const char *s) {
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size_t i;
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for (i = 0; (uintptr_t)(s + i) & 7; ++i) {
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if (!s[i]) return i;
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}
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i = strlen_pure_x64(s, i);
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assert(!i || s[0]);
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assert(!s[i]);
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return i;
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}
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