62 lines
3.0 KiB
C
62 lines
3.0 KiB
C
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/*-*- 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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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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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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