0,0 → 1,657 |
/* |
* copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at> |
* |
* 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 |
* bitstream reader API header. |
*/ |
|
#ifndef AVCODEC_GET_BITS_H |
#define AVCODEC_GET_BITS_H |
|
#include <stdint.h> |
|
#include "libavutil/common.h" |
#include "libavutil/intreadwrite.h" |
#include "libavutil/log.h" |
#include "libavutil/avassert.h" |
#include "mathops.h" |
|
/* |
* Safe bitstream reading: |
* optionally, the get_bits API can check to ensure that we |
* don't read past input buffer boundaries. This is protected |
* with CONFIG_SAFE_BITSTREAM_READER at the global level, and |
* then below that with UNCHECKED_BITSTREAM_READER at the per- |
* decoder level. This means that decoders that check internally |
* can "#define UNCHECKED_BITSTREAM_READER 1" to disable |
* overread checks. |
* Boundary checking causes a minor performance penalty so for |
* applications that won't want/need this, it can be disabled |
* globally using "#define CONFIG_SAFE_BITSTREAM_READER 0". |
*/ |
#ifndef UNCHECKED_BITSTREAM_READER |
#define UNCHECKED_BITSTREAM_READER !CONFIG_SAFE_BITSTREAM_READER |
#endif |
|
typedef struct GetBitContext { |
const uint8_t *buffer, *buffer_end; |
int index; |
int size_in_bits; |
int size_in_bits_plus8; |
} GetBitContext; |
|
#define VLC_TYPE int16_t |
|
typedef struct VLC { |
int bits; |
VLC_TYPE (*table)[2]; ///< code, bits |
int table_size, table_allocated; |
void * volatile init_state; |
} VLC; |
|
typedef struct RL_VLC_ELEM { |
int16_t level; |
int8_t len; |
uint8_t run; |
} RL_VLC_ELEM; |
|
/* Bitstream reader API docs: |
* name |
* arbitrary name which is used as prefix for the internal variables |
* |
* gb |
* getbitcontext |
* |
* OPEN_READER(name, gb) |
* load gb into local variables |
* |
* CLOSE_READER(name, gb) |
* store local vars in gb |
* |
* UPDATE_CACHE(name, gb) |
* Refill the internal cache from the bitstream. |
* After this call at least MIN_CACHE_BITS will be available. |
* |
* GET_CACHE(name, gb) |
* Will output the contents of the internal cache, |
* next bit is MSB of 32 or 64 bit (FIXME 64bit). |
* |
* SHOW_UBITS(name, gb, num) |
* Will return the next num bits. |
* |
* SHOW_SBITS(name, gb, num) |
* Will return the next num bits and do sign extension. |
* |
* SKIP_BITS(name, gb, num) |
* Will skip over the next num bits. |
* Note, this is equivalent to SKIP_CACHE; SKIP_COUNTER. |
* |
* SKIP_CACHE(name, gb, num) |
* Will remove the next num bits from the cache (note SKIP_COUNTER |
* MUST be called before UPDATE_CACHE / CLOSE_READER). |
* |
* SKIP_COUNTER(name, gb, num) |
* Will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS). |
* |
* LAST_SKIP_BITS(name, gb, num) |
* Like SKIP_BITS, to be used if next call is UPDATE_CACHE or CLOSE_READER. |
* |
* For examples see get_bits, show_bits, skip_bits, get_vlc. |
*/ |
|
#ifdef LONG_BITSTREAM_READER |
# define MIN_CACHE_BITS 32 |
#else |
# define MIN_CACHE_BITS 25 |
#endif |
|
#if UNCHECKED_BITSTREAM_READER |
#define OPEN_READER(name, gb) \ |
unsigned int name ## _index = (gb)->index; \ |
unsigned int av_unused name ## _cache |
|
#define HAVE_BITS_REMAINING(name, gb) 1 |
#else |
#define OPEN_READER(name, gb) \ |
unsigned int name ## _index = (gb)->index; \ |
unsigned int av_unused name ## _cache = 0; \ |
unsigned int av_unused name ## _size_plus8 = (gb)->size_in_bits_plus8 |
|
#define HAVE_BITS_REMAINING(name, gb) name ## _index < name ## _size_plus8 |
#endif |
|
#define CLOSE_READER(name, gb) (gb)->index = name ## _index |
|
# ifdef LONG_BITSTREAM_READER |
|
# define UPDATE_CACHE_LE(name, gb) name ## _cache = \ |
AV_RL64((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7) |
|
# define UPDATE_CACHE_BE(name, gb) name ## _cache = \ |
AV_RB64((gb)->buffer + (name ## _index >> 3)) >> (32 - (name ## _index & 7)) |
|
#else |
|
# define UPDATE_CACHE_LE(name, gb) name ## _cache = \ |
AV_RL32((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7) |
|
# define UPDATE_CACHE_BE(name, gb) name ## _cache = \ |
AV_RB32((gb)->buffer + (name ## _index >> 3)) << (name ## _index & 7) |
|
#endif |
|
|
#ifdef BITSTREAM_READER_LE |
|
# define UPDATE_CACHE(name, gb) UPDATE_CACHE_LE(name, gb) |
|
# define SKIP_CACHE(name, gb, num) name ## _cache >>= (num) |
|
#else |
|
# define UPDATE_CACHE(name, gb) UPDATE_CACHE_BE(name, gb) |
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# define SKIP_CACHE(name, gb, num) name ## _cache <<= (num) |
|
#endif |
|
#if UNCHECKED_BITSTREAM_READER |
# define SKIP_COUNTER(name, gb, num) name ## _index += (num) |
#else |
# define SKIP_COUNTER(name, gb, num) \ |
name ## _index = FFMIN(name ## _size_plus8, name ## _index + (num)) |
#endif |
|
#define SKIP_BITS(name, gb, num) \ |
do { \ |
SKIP_CACHE(name, gb, num); \ |
SKIP_COUNTER(name, gb, num); \ |
} while (0) |
|
#define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num) |
|
#define SHOW_UBITS_LE(name, gb, num) zero_extend(name ## _cache, num) |
#define SHOW_SBITS_LE(name, gb, num) sign_extend(name ## _cache, num) |
|
#define SHOW_UBITS_BE(name, gb, num) NEG_USR32(name ## _cache, num) |
#define SHOW_SBITS_BE(name, gb, num) NEG_SSR32(name ## _cache, num) |
|
#ifdef BITSTREAM_READER_LE |
# define SHOW_UBITS(name, gb, num) SHOW_UBITS_LE(name, gb, num) |
# define SHOW_SBITS(name, gb, num) SHOW_SBITS_LE(name, gb, num) |
#else |
# define SHOW_UBITS(name, gb, num) SHOW_UBITS_BE(name, gb, num) |
# define SHOW_SBITS(name, gb, num) SHOW_SBITS_BE(name, gb, num) |
#endif |
|
#define GET_CACHE(name, gb) ((uint32_t) name ## _cache) |
|
static inline int get_bits_count(const GetBitContext *s) |
{ |
return s->index; |
} |
|
static inline void skip_bits_long(GetBitContext *s, int n) |
{ |
#if UNCHECKED_BITSTREAM_READER |
s->index += n; |
#else |
s->index += av_clip(n, -s->index, s->size_in_bits_plus8 - s->index); |
#endif |
} |
|
/** |
* read mpeg1 dc style vlc (sign bit + mantisse with no MSB). |
* if MSB not set it is negative |
* @param n length in bits |
*/ |
static inline int get_xbits(GetBitContext *s, int n) |
{ |
register int sign; |
register int32_t cache; |
OPEN_READER(re, s); |
av_assert2(n>0 && n<=25); |
UPDATE_CACHE(re, s); |
cache = GET_CACHE(re, s); |
sign = ~cache >> 31; |
LAST_SKIP_BITS(re, s, n); |
CLOSE_READER(re, s); |
return (NEG_USR32(sign ^ cache, n) ^ sign) - sign; |
} |
|
static inline int get_sbits(GetBitContext *s, int n) |
{ |
register int tmp; |
OPEN_READER(re, s); |
av_assert2(n>0 && n<=25); |
UPDATE_CACHE(re, s); |
tmp = SHOW_SBITS(re, s, n); |
LAST_SKIP_BITS(re, s, n); |
CLOSE_READER(re, s); |
return tmp; |
} |
|
/** |
* Read 1-25 bits. |
*/ |
static inline unsigned int get_bits(GetBitContext *s, int n) |
{ |
register int tmp; |
OPEN_READER(re, s); |
av_assert2(n>0 && n<=25); |
UPDATE_CACHE(re, s); |
tmp = SHOW_UBITS(re, s, n); |
LAST_SKIP_BITS(re, s, n); |
CLOSE_READER(re, s); |
return tmp; |
} |
|
static inline unsigned int get_bits_le(GetBitContext *s, int n) |
{ |
register int tmp; |
OPEN_READER(re, s); |
av_assert2(n>0 && n<=25); |
UPDATE_CACHE_LE(re, s); |
tmp = SHOW_UBITS_LE(re, s, n); |
LAST_SKIP_BITS(re, s, n); |
CLOSE_READER(re, s); |
return tmp; |
} |
|
/** |
* Show 1-25 bits. |
*/ |
static inline unsigned int show_bits(GetBitContext *s, int n) |
{ |
register int tmp; |
OPEN_READER(re, s); |
av_assert2(n>0 && n<=25); |
UPDATE_CACHE(re, s); |
tmp = SHOW_UBITS(re, s, n); |
return tmp; |
} |
|
static inline void skip_bits(GetBitContext *s, int n) |
{ |
OPEN_READER(re, s); |
LAST_SKIP_BITS(re, s, n); |
CLOSE_READER(re, s); |
} |
|
static inline unsigned int get_bits1(GetBitContext *s) |
{ |
unsigned int index = s->index; |
uint8_t result = s->buffer[index >> 3]; |
#ifdef BITSTREAM_READER_LE |
result >>= index & 7; |
result &= 1; |
#else |
result <<= index & 7; |
result >>= 8 - 1; |
#endif |
#if !UNCHECKED_BITSTREAM_READER |
if (s->index < s->size_in_bits_plus8) |
#endif |
index++; |
s->index = index; |
|
return result; |
} |
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static inline unsigned int show_bits1(GetBitContext *s) |
{ |
return show_bits(s, 1); |
} |
|
static inline void skip_bits1(GetBitContext *s) |
{ |
skip_bits(s, 1); |
} |
|
/** |
* Read 0-32 bits. |
*/ |
static inline unsigned int get_bits_long(GetBitContext *s, int n) |
{ |
if (!n) { |
return 0; |
} else if (n <= MIN_CACHE_BITS) { |
return get_bits(s, n); |
} else { |
#ifdef BITSTREAM_READER_LE |
unsigned ret = get_bits(s, 16); |
return ret | (get_bits(s, n - 16) << 16); |
#else |
unsigned ret = get_bits(s, 16) << (n - 16); |
return ret | get_bits(s, n - 16); |
#endif |
} |
} |
|
/** |
* Read 0-64 bits. |
*/ |
static inline uint64_t get_bits64(GetBitContext *s, int n) |
{ |
if (n <= 32) { |
return get_bits_long(s, n); |
} else { |
#ifdef BITSTREAM_READER_LE |
uint64_t ret = get_bits_long(s, 32); |
return ret | (uint64_t) get_bits_long(s, n - 32) << 32; |
#else |
uint64_t ret = (uint64_t) get_bits_long(s, n - 32) << 32; |
return ret | get_bits_long(s, 32); |
#endif |
} |
} |
|
/** |
* Read 0-32 bits as a signed integer. |
*/ |
static inline int get_sbits_long(GetBitContext *s, int n) |
{ |
return sign_extend(get_bits_long(s, n), n); |
} |
|
/** |
* Show 0-32 bits. |
*/ |
static inline unsigned int show_bits_long(GetBitContext *s, int n) |
{ |
if (n <= MIN_CACHE_BITS) { |
return show_bits(s, n); |
} else { |
GetBitContext gb = *s; |
return get_bits_long(&gb, n); |
} |
} |
|
static inline int check_marker(GetBitContext *s, const char *msg) |
{ |
int bit = get_bits1(s); |
if (!bit) |
av_log(NULL, AV_LOG_INFO, "Marker bit missing %s\n", msg); |
|
return bit; |
} |
|
/** |
* Initialize GetBitContext. |
* @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes |
* larger than the actual read bits because some optimized bitstream |
* readers read 32 or 64 bit at once and could read over the end |
* @param bit_size the size of the buffer in bits |
* @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow. |
*/ |
static inline int init_get_bits(GetBitContext *s, const uint8_t *buffer, |
int bit_size) |
{ |
int buffer_size; |
int ret = 0; |
|
if (bit_size >= INT_MAX - 7 || bit_size < 0 || !buffer) { |
buffer_size = bit_size = 0; |
buffer = NULL; |
ret = AVERROR_INVALIDDATA; |
} |
|
buffer_size = (bit_size + 7) >> 3; |
|
s->buffer = buffer; |
s->size_in_bits = bit_size; |
s->size_in_bits_plus8 = bit_size + 8; |
s->buffer_end = buffer + buffer_size; |
s->index = 0; |
|
return ret; |
} |
|
/** |
* Initialize GetBitContext. |
* @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes |
* larger than the actual read bits because some optimized bitstream |
* readers read 32 or 64 bit at once and could read over the end |
* @param byte_size the size of the buffer in bytes |
* @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow. |
*/ |
static inline int init_get_bits8(GetBitContext *s, const uint8_t *buffer, |
int byte_size) |
{ |
if (byte_size > INT_MAX / 8 || byte_size < 0) |
byte_size = -1; |
return init_get_bits(s, buffer, byte_size * 8); |
} |
|
static inline const uint8_t *align_get_bits(GetBitContext *s) |
{ |
int n = -get_bits_count(s) & 7; |
if (n) |
skip_bits(s, n); |
return s->buffer + (s->index >> 3); |
} |
|
#define init_vlc(vlc, nb_bits, nb_codes, \ |
bits, bits_wrap, bits_size, \ |
codes, codes_wrap, codes_size, \ |
flags) \ |
ff_init_vlc_sparse(vlc, nb_bits, nb_codes, \ |
bits, bits_wrap, bits_size, \ |
codes, codes_wrap, codes_size, \ |
NULL, 0, 0, flags) |
|
int ff_init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes, |
const void *bits, int bits_wrap, int bits_size, |
const void *codes, int codes_wrap, int codes_size, |
const void *symbols, int symbols_wrap, int symbols_size, |
int flags); |
void ff_free_vlc(VLC *vlc); |
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#define INIT_VLC_LE 2 |
#define INIT_VLC_USE_NEW_STATIC 4 |
|
#define INIT_VLC_STATIC(vlc, bits, a, b, c, d, e, f, g, static_size) \ |
do { \ |
static VLC_TYPE table[static_size][2]; \ |
(vlc)->table = table; \ |
(vlc)->table_allocated = static_size; \ |
init_vlc(vlc, bits, a, b, c, d, e, f, g, INIT_VLC_USE_NEW_STATIC); \ |
} while (0) |
|
/** |
* If the vlc code is invalid and max_depth=1, then no bits will be removed. |
* If the vlc code is invalid and max_depth>1, then the number of bits removed |
* is undefined. |
*/ |
#define GET_VLC(code, name, gb, table, bits, max_depth) \ |
do { \ |
int n, nb_bits; \ |
unsigned int index; \ |
\ |
index = SHOW_UBITS(name, gb, bits); \ |
code = table[index][0]; \ |
n = table[index][1]; \ |
\ |
if (max_depth > 1 && n < 0) { \ |
LAST_SKIP_BITS(name, gb, bits); \ |
UPDATE_CACHE(name, gb); \ |
\ |
nb_bits = -n; \ |
\ |
index = SHOW_UBITS(name, gb, nb_bits) + code; \ |
code = table[index][0]; \ |
n = table[index][1]; \ |
if (max_depth > 2 && n < 0) { \ |
LAST_SKIP_BITS(name, gb, nb_bits); \ |
UPDATE_CACHE(name, gb); \ |
\ |
nb_bits = -n; \ |
\ |
index = SHOW_UBITS(name, gb, nb_bits) + code; \ |
code = table[index][0]; \ |
n = table[index][1]; \ |
} \ |
} \ |
SKIP_BITS(name, gb, n); \ |
} while (0) |
|
#define GET_RL_VLC(level, run, name, gb, table, bits, \ |
max_depth, need_update) \ |
do { \ |
int n, nb_bits; \ |
unsigned int index; \ |
\ |
index = SHOW_UBITS(name, gb, bits); \ |
level = table[index].level; \ |
n = table[index].len; \ |
\ |
if (max_depth > 1 && n < 0) { \ |
SKIP_BITS(name, gb, bits); \ |
if (need_update) { \ |
UPDATE_CACHE(name, gb); \ |
} \ |
\ |
nb_bits = -n; \ |
\ |
index = SHOW_UBITS(name, gb, nb_bits) + level; \ |
level = table[index].level; \ |
n = table[index].len; \ |
} \ |
run = table[index].run; \ |
SKIP_BITS(name, gb, n); \ |
} while (0) |
|
/** |
* Parse a vlc code. |
* @param bits is the number of bits which will be read at once, must be |
* identical to nb_bits in init_vlc() |
* @param max_depth is the number of times bits bits must be read to completely |
* read the longest vlc code |
* = (max_vlc_length + bits - 1) / bits |
*/ |
static av_always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2], |
int bits, int max_depth) |
{ |
int code; |
|
OPEN_READER(re, s); |
UPDATE_CACHE(re, s); |
|
GET_VLC(code, re, s, table, bits, max_depth); |
|
CLOSE_READER(re, s); |
|
return code; |
} |
|
static inline int decode012(GetBitContext *gb) |
{ |
int n; |
n = get_bits1(gb); |
if (n == 0) |
return 0; |
else |
return get_bits1(gb) + 1; |
} |
|
static inline int decode210(GetBitContext *gb) |
{ |
if (get_bits1(gb)) |
return 0; |
else |
return 2 - get_bits1(gb); |
} |
|
static inline int get_bits_left(GetBitContext *gb) |
{ |
return gb->size_in_bits - get_bits_count(gb); |
} |
|
//#define TRACE |
|
#ifdef TRACE |
static inline void print_bin(int bits, int n) |
{ |
int i; |
|
for (i = n - 1; i >= 0; i--) |
av_log(NULL, AV_LOG_DEBUG, "%d", (bits >> i) & 1); |
for (i = n; i < 24; i++) |
av_log(NULL, AV_LOG_DEBUG, " "); |
} |
|
static inline int get_bits_trace(GetBitContext *s, int n, const char *file, |
const char *func, int line) |
{ |
int r = get_bits(s, n); |
|
print_bin(r, n); |
av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d bit @%5d in %s %s:%d\n", |
r, n, r, get_bits_count(s) - n, file, func, line); |
|
return r; |
} |
|
static inline int get_vlc_trace(GetBitContext *s, VLC_TYPE (*table)[2], |
int bits, int max_depth, const char *file, |
const char *func, int line) |
{ |
int show = show_bits(s, 24); |
int pos = get_bits_count(s); |
int r = get_vlc2(s, table, bits, max_depth); |
int len = get_bits_count(s) - pos; |
int bits2 = show >> (24 - len); |
|
print_bin(bits2, len); |
|
av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d vlc @%5d in %s %s:%d\n", |
bits2, len, r, pos, file, func, line); |
|
return r; |
} |
|
static inline int get_xbits_trace(GetBitContext *s, int n, const char *file, |
const char *func, int line) |
{ |
int show = show_bits(s, n); |
int r = get_xbits(s, n); |
|
print_bin(show, n); |
av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d xbt @%5d in %s %s:%d\n", |
show, n, r, get_bits_count(s) - n, file, func, line); |
|
return r; |
} |
|
#define get_bits(s, n) get_bits_trace(s , n, __FILE__, __PRETTY_FUNCTION__, __LINE__) |
#define get_bits1(s) get_bits_trace(s, 1, __FILE__, __PRETTY_FUNCTION__, __LINE__) |
#define get_xbits(s, n) get_xbits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__) |
|
#define get_vlc(s, vlc) get_vlc_trace(s, (vlc)->table, (vlc)->bits, 3, __FILE__, __PRETTY_FUNCTION__, __LINE__) |
#define get_vlc2(s, tab, bits, max) get_vlc_trace(s, tab, bits, max, __FILE__, __PRETTY_FUNCTION__, __LINE__) |
|
#define tprintf(p, ...) av_log(p, AV_LOG_DEBUG, __VA_ARGS__) |
|
#else //TRACE |
#define tprintf(p, ...) { } |
#endif |
|
#endif /* AVCODEC_GET_BITS_H */ |