91 lines
2.4 KiB
C
91 lines
2.4 KiB
C
/*
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* lzf decompression algorithm
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* Copyright (c) 2015 Luca Barbato
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but 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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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* lzf decompression
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*
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* LZF is a fast compression/decompression algorithm that takes very little
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* code space and working memory, ideal for real-time and block compression.
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*
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* https://en.wikibooks.org/wiki/Data_Compression/Dictionary_compression#LZF
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*/
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#include "libavutil/mem.h"
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#include "bytestream.h"
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#include "lzf.h"
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#define LZF_LITERAL_MAX (1 << 5)
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#define LZF_LONG_BACKREF 7 + 2
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int ff_lzf_uncompress(GetByteContext *gb, uint8_t **buf, int64_t *size)
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{
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int ret = 0;
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uint8_t *p = *buf;
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int64_t len = 0;
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while (bytestream2_get_bytes_left(gb) > 2) {
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uint8_t s = bytestream2_get_byte(gb);
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if (s < LZF_LITERAL_MAX) {
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s++;
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if (s > *size - len) {
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*size += *size /2;
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ret = av_reallocp(buf, *size);
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if (ret < 0)
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return ret;
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}
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bytestream2_get_buffer(gb, p, s);
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p += s;
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len += s;
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} else {
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int l = 2 + (s >> 5);
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int off = ((s & 0x1f) << 8) + 1;
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if (l == LZF_LONG_BACKREF)
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l += bytestream2_get_byte(gb);
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off += bytestream2_get_byte(gb);
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if (off > len)
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return AVERROR_INVALIDDATA;
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if (l > *size - len) {
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*size += *size / 2;
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ret = av_reallocp(buf, *size);
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if (ret < 0)
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return ret;
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}
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av_memcpy_backptr(p, off, l);
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p += l;
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len += l;
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}
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}
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*size = len;
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return 0;
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}
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