| /* |
| * 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 |
| |
| int ff_lzf_uncompress(GetByteContext *gb, uint8_t **buf, int64_t *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) { |
| *size += s + *size /2; |
| ret = av_reallocp(buf, *size); |
| if (ret < 0) |
| return ret; |
| p = *buf + len; |
| } |
| |
| bytestream2_get_buffer(gb, p, s); |
| 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) { |
| *size += l + *size / 2; |
| ret = av_reallocp(buf, *size); |
| if (ret < 0) |
| return ret; |
| p = *buf + len; |
| } |
| |
| av_memcpy_backptr(p, off, l); |
| |
| p += l; |
| len += l; |
| } |
| } |
| |
| *size = len; |
| |
| return 0; |
| } |