mirror of
https://github.com/jart/cosmopolitan.git
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72 lines
3.4 KiB
C
72 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 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/assert.h"
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#include "libc/intrin/safemacros.internal.h"
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#include "libc/dce.h"
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#include "libc/intrin/asan.internal.h"
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#include "libc/macros.internal.h"
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#include "libc/nexgen32e/crc32.h"
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#include "libc/nexgen32e/x86feature.h"
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#include "libc/str/str.h"
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static inline noasan uint64_t WildRead64(const signed char *p) {
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return (uint64_t)(255 & p[7]) << 070 | (uint64_t)(255 & p[6]) << 060 |
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(uint64_t)(255 & p[5]) << 050 | (uint64_t)(255 & p[4]) << 040 |
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(uint64_t)(255 & p[3]) << 030 | (uint64_t)(255 & p[2]) << 020 |
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(uint64_t)(255 & p[1]) << 010 | (uint64_t)(255 & p[0]) << 000;
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}
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/**
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* Computes Phil Katz CRC-32 used by zip/zlib/gzip/etc.
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*
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* x^32+x^26+x^23+x^22+x^16+x^12+x^11+x^10+x^8+x^7+x^5+x^4+x^2+x+1
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* 0b100000100110000010001110110110111
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* bitreverse32(0x104c11db7)
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*
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* This implementation takes 32 picoseconds per byte or 30 gibibyte/s.
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*
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* @param h is initial value
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*/
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uint32_t crc32_z(uint32_t h, const void *data, size_t size) {
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size_t n;
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static bool once;
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const unsigned char *p, *e;
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static uint32_t kCrc32Tab[256];
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if (!once) {
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crc32init(kCrc32Tab, 0xedb88320);
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once = 0;
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}
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if (size == -1) {
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size = data ? strlen(data) : 0;
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}
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p = data;
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e = p + size;
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h ^= 0xffffffff;
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if (X86_HAVE(PCLMUL)) {
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while (((intptr_t)p & 15) && p < e)
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h = h >> 8 ^ kCrc32Tab[(h & 0xff) ^ *p++];
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if ((n = ROUNDDOWN(e - p, 16)) >= 64) {
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if (IsAsan()) __asan_verify(p, n);
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h = crc32_pclmul(h, p, n); /* 51x faster */
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p += n;
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}
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}
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while (p < e) h = h >> 8 ^ kCrc32Tab[(h & 0xff) ^ *p++];
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return h ^ 0xffffffff;
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}
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