FFmpeg
libavcodec
lzf.c
Go to the documentation of this file.
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/*
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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 FFmpeg.
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*
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* FFmpeg 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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* FFmpeg 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 FFmpeg; 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
+=
s
+ *
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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p = *buf +
len
;
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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
+= l + *
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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p = *buf +
len
;
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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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}
GetByteContext
Definition:
bytestream.h:33
av_memcpy_backptr
void av_memcpy_backptr(uint8_t *dst, int back, int cnt)
Overlapping memcpy() implementation.
Definition:
mem.c:445
s
#define s(width, name)
Definition:
cbs_vp9.c:198
LZF_LITERAL_MAX
#define LZF_LITERAL_MAX
Definition:
lzf.c:37
bytestream2_get_buffer
static av_always_inline unsigned int bytestream2_get_buffer(GetByteContext *g, uint8_t *dst, unsigned int size)
Definition:
bytestream.h:267
bytestream2_get_bytes_left
static av_always_inline int bytestream2_get_bytes_left(GetByteContext *g)
Definition:
bytestream.h:158
size
int size
Definition:
twinvq_data.h:10344
av_reallocp
int av_reallocp(void *ptr, size_t size)
Allocate, reallocate, or free a block of memory through a pointer to a pointer.
Definition:
mem.c:186
ff_lzf_uncompress
int ff_lzf_uncompress(GetByteContext *gb, uint8_t **buf, int64_t *size)
Definition:
lzf.c:40
LZF_LONG_BACKREF
#define LZF_LONG_BACKREF
Definition:
lzf.c:38
len
int len
Definition:
vorbis_enc_data.h:426
ret
ret
Definition:
filter_design.txt:187
mem.h
bytestream.h
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition:
error.h:61
lzf.h
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