48 lines
2.6 KiB
C
48 lines
2.6 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
|
|
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
|
|
╞══════════════════════════════════════════════════════════════════════════════╡
|
|
│ Copyright 2020 Justine Alexandra Roberts Tunney │
|
|
│ │
|
|
│ This program is free software; you can redistribute it and/or modify │
|
|
│ it under the terms of the GNU General Public License as published by │
|
|
│ the Free Software Foundation; version 2 of the License. │
|
|
│ │
|
|
│ This program is distributed in the hope that it will be useful, but │
|
|
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
|
|
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
|
|
│ General Public License for more details. │
|
|
│ │
|
|
│ You should have received a copy of the GNU General Public License │
|
|
│ along with this program; if not, write to the Free Software │
|
|
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
|
|
│ 02110-1301 USA │
|
|
╚─────────────────────────────────────────────────────────────────────────────*/
|
|
#include "libc/bits/safemacros.h"
|
|
#include "libc/nexgen32e/crc32.h"
|
|
#include "libc/nexgen32e/x86feature.h"
|
|
|
|
/**
|
|
* Computes Phil Katz CRC-32 used by zip/zlib/gzip/etc.
|
|
*/
|
|
uint32_t crc32_z(uint32_t h, const void *data, size_t size) {
|
|
const unsigned char *p, *pe;
|
|
size_t skip;
|
|
if (data) {
|
|
h ^= 0xffffffff;
|
|
if (size >= 64 && X86_HAVE(PCLMUL)) {
|
|
h = crc32$pclmul(h, data, size); /* 51x faster */
|
|
skip = rounddown(size, 16);
|
|
} else {
|
|
skip = 0;
|
|
}
|
|
p = (const unsigned char *)data + skip;
|
|
pe = (const unsigned char *)data + size;
|
|
while (p < pe) {
|
|
h = h >> 8 ^ kCrc32Tab[(h & 0xff) ^ *p++];
|
|
}
|
|
return h ^ 0xffffffff;
|
|
} else {
|
|
return 0;
|
|
}
|
|
}
|