get_bits.h File Reference

#include <stdint.h>
#include "config-adpcm.h"
#include "intreadwrite.h"
#include "adpcm.h"

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Classes
struct	adpcm_ffmpeg::GetBitContext

Macros
#define	UNCHECKED_BITSTREAM_READER   !CONFIG_SAFE_BITSTREAM_READER
#define	MIN_CACHE_BITS   25
#define	OPEN_READER_NOSIZE(name, gb)
#define	OPEN_READER(name, gb)   OPEN_READER_NOSIZE(name, gb)
#define	BITS_AVAILABLE(name, gb)   1
#define	CLOSE_READER(name, gb)   (gb)->index = name ## _index
#define	UPDATE_CACHE_LE(name, gb)
#define	UPDATE_CACHE_BE(name, gb)
#define	UPDATE_CACHE(name, gb)   UPDATE_CACHE_LE(name, gb)
#define	SKIP_CACHE(name, gb, num)   name ## _cache >>= (num)
#define	SKIP_COUNTER(name, gb, num)   name ## _index += (num)
#define	BITS_LEFT(name, gb)   ((int)((gb)->size_in_bits - name ## _index))
#define	SKIP_BITS(name, gb, num)
#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)
#define	SHOW_UBITS(name, gb, num)   SHOW_UBITS_LE(name, gb, num)
#define	SHOW_SBITS(name, gb, num)   SHOW_SBITS_LE(name, gb, num)
#define	GET_CACHE(name, gb)   ((uint32_t) name ## _cache)
#define	GET_VLC(code, name, gb, table, bits, max_depth)
#define	GET_RL_VLC(level, run, name, gb, table, bits, max_depth, need_update)

Detailed Description

bitstream reader API header.

Macro Definition Documentation

GET_VLC

#define GET_VLC	(		code,
			name,
			gb,
			table,
			bits,
			max_depth
	)

Value:

    do {                                                        \
        int n, nb_bits;                                         \
        unsigned int index;                                     \
                                                                \
        index = SHOW_UBITS(name, gb, bits);                     \
        code  = table[index].sym;                               \
        n     = table[index].len;                               \
                                                                \
        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].sym;                           \
            n     = table[index].len;                           \
            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].sym;                       \
                n     = table[index].len;                       \
            }                                                   \
        }                                                       \
        SKIP_BITS(name, gb, n);                                 \
    } 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.

OPEN_READER_NOSIZE

#define OPEN_READER_NOSIZE	(		name,
			gb
	)

Value:

    unsigned int name ## _index = (gb)->index;  \
    unsigned int av_unused name ## _cache

SKIP_BITS

#define SKIP_BITS	(		name,
			gb,
			num
	)

Value:

    do {                                        \
        SKIP_CACHE(name, gb, num);              \
        SKIP_COUNTER(name, gb, num);            \
    } while (0)

UPDATE_CACHE_BE

#define UPDATE_CACHE_BE	(		name,
			gb
	)

Value:

      name ## _cache = \
      AV_RB32((gb)->buffer + (name ## _index >> 3)) << (name ## _index & 7)

UPDATE_CACHE_LE

#define UPDATE_CACHE_LE	(		name,
			gb
	)

Value:

      name ## _cache = \
      AV_RL32((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7)