61 lines
2.9 KiB
C
61 lines
2.9 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/bits/bits.h"
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#include "libc/bits/pushpop.h"
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#include "libc/intrin/repmovsb.h"
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#include "libc/nexgen32e/kompressor.h"
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#include "libc/str/str.h"
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/**
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* Decompresses LZ4 block.
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*
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* This is a 103 byte implementation of the LZ4 algorithm. Please note
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* LZ4 files are comprised of multiple frames, which may be decoded
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* together using the wrapper function lz4decode().
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*
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* @see rldecode() for a 16-byte decompressor
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*/
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textstartup void *lz4cpy(void *dest, const void *blockdata, size_t blocksize) {
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unsigned char *op, *ip, *ipe, *match;
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unsigned token, length, fifteen, offset, matchlen;
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for (op = dest, ip = blockdata, ipe = ip + blocksize;;) {
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token = *ip++;
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length = token >> 4;
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fifteen = pushpop(15);
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if (length == fifteen) {
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do {
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length += *ip;
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} while (*ip++ == 255);
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}
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repmovsb(&op, &ip, length);
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if (ip >= ipe) break;
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offset = read16le(ip);
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matchlen = token & fifteen;
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ip += 2;
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if (matchlen == fifteen) {
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do {
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matchlen += *ip;
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} while (*ip++ == 255);
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}
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match = op - offset;
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repmovsb(&op, &match, (matchlen += 4));
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}
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return op;
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}
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