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/*
* lzf decompression algorithm
* Copyright (c) 2015 Luca Barbato
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* lzf decompression
*
* LZF is a fast compression/decompression algorithm that takes very little
* code space and working memory, ideal for real-time and block compression.
*
* https://en.wikibooks.org/wiki/Data_Compression/Dictionary_compression#LZF
*/
#include "libavutil/mem.h"
#include "bytestream.h"
#include "lzf.h"
#define LZF_LITERAL_MAX (1 << 5)
#define LZF_LONG_BACKREF 7 + 2
static inline int lzf_realloc(uint8_t **buf, size_t *size, int addition, unsigned *allocated_size)
{
void *ptr = av_fast_realloc(*buf, allocated_size, *size + addition);
if (!ptr) {
av_freep(buf); //probably not needed
return AVERROR(ENOMEM);
}
*buf = ptr;
*size += addition;
return 0;
}
int ff_lzf_uncompress(GetByteContext *gb, uint8_t **buf, size_t *size, unsigned *allocated_size)
{
int ret = 0;
uint8_t *p = *buf;
int64_t len = 0;
while (bytestream2_get_bytes_left(gb) > 2) {
uint8_t s = bytestream2_get_byte(gb);
if (s < LZF_LITERAL_MAX) {
s++;
if (s > *size - len) {
ret = lzf_realloc(buf, size, s, allocated_size);
if (ret < 0)
return ret;
p = *buf + len;
}
int s2 = bytestream2_get_buffer(gb, p, s);
if (s2 != s)
return AVERROR_INVALIDDATA;
p += s;
len += s;
} else {
int l = 2 + (s >> 5);
int off = ((s & 0x1f) << 8) + 1;
if (l == LZF_LONG_BACKREF)
l += bytestream2_get_byte(gb);
off += bytestream2_get_byte(gb);
if (off > len)
return AVERROR_INVALIDDATA;
if (l > *size - len) {
ret = lzf_realloc(buf, size, l, allocated_size);
if (ret < 0)
return ret;
p = *buf + len;
}
av_memcpy_backptr(p, off, l);
p += l;
len += l;
}
}
*size = len;
return 0;
}
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