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bitstream: Move VLC reading functions into the vlc.h header

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This makes the bitstream.h header leaner.

Signed-off-by: Diego Biurrun <diego@biurrun.de>
This commit is contained in:
Luca Barbato 2017-04-29 00:34:12 +00:00 committed by Diego Biurrun
parent 73fc82f343
commit 0ac1fec1c3
2 changed files with 74 additions and 73 deletions
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73
libavcodec/bitstream.h
View File

@ -33,7 +33,6 @@
#include "libavutil/log.h"
#include "mathops.h"
#include "vlc.h"
typedef struct BitstreamContext {
uint64_t bits; // stores bits read from the buffer
@ -287,78 +286,6 @@ static inline int bitstream_read_xbits(BitstreamContext *bc, unsigned length)
return ((((uint32_t)(sign ^ cache)) >> (32 - length)) ^ sign) - sign;
}
/* Return the LUT element for the given bitstream configuration. */
static inline int set_idx(BitstreamContext *bc, int code, int *n, int *nb_bits,
VLC_TYPE (*table)[2])
{
unsigned idx;
*nb_bits = -*n;
idx = bitstream_peek(bc, *nb_bits) + code;
*n = table[idx][1];
return table[idx][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
* 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. */
static inline int bitstream_read_vlc(BitstreamContext *bc, VLC_TYPE (*table)[2],
int bits, int max_depth)
{
int nb_bits;
unsigned idx = bitstream_peek(bc, bits);
int code = table[idx][0];
int n = table[idx][1];
if (max_depth > 1 && n < 0) {
skip_remaining(bc, bits);
code = set_idx(bc, code, &n, &nb_bits, table);
if (max_depth > 2 && n < 0) {
skip_remaining(bc, nb_bits);
code = set_idx(bc, code, &n, &nb_bits, table);
}
}
skip_remaining(bc, n);
return code;
}
#define BITSTREAM_RL_VLC(level, run, bc, table, bits, max_depth) \
do { \
int n, nb_bits; \
unsigned index = bitstream_peek(bc, bits); \
level = table[index].level; \
n = table[index].len; \
\
if (max_depth > 1 && n < 0) { \
bitstream_skip(bc, bits); \
\
nb_bits = -n; \
\
index = bitstream_peek(bc, nb_bits) + level; \
level = table[index].level; \
n = table[index].len; \
if (max_depth > 2 && n < 0) { \
bitstream_skip(bc, nb_bits); \
nb_bits = -n; \
\
index = bitstream_peek(bc, nb_bits) + level; \
level = table[index].level; \
n = table[index].len; \
} \
} \
run = table[index].run; \
bitstream_skip(bc, n); \
} while (0)
/* Return decoded truncated unary code for the values 0, 1, 2. */
static inline int bitstream_decode012(BitstreamContext *bc)
{

74
libavcodec/vlc.h
View File

@ -21,6 +21,8 @@
#include <stdint.h>
#include "bitstream.h"
#define VLC_TYPE int16_t
typedef struct VLC {
@ -62,4 +64,76 @@ void ff_free_vlc(VLC *vlc);
init_vlc(vlc, bits, a, b, c, d, e, f, g, INIT_VLC_USE_NEW_STATIC); \
} while (0)
/* Return the LUT element for the given bitstream configuration. */
static inline int set_idx(BitstreamContext *bc, int code, int *n, int *nb_bits,
VLC_TYPE (*table)[2])
{
unsigned idx;
*nb_bits = -*n;
idx = bitstream_peek(bc, *nb_bits) + code;
*n = table[idx][1];
return table[idx][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
* 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. */
static inline int bitstream_read_vlc(BitstreamContext *bc, VLC_TYPE (*table)[2],
int bits, int max_depth)
{
int nb_bits;
unsigned idx = bitstream_peek(bc, bits);
int code = table[idx][0];
int n = table[idx][1];
if (max_depth > 1 && n < 0) {
skip_remaining(bc, bits);
code = set_idx(bc, code, &n, &nb_bits, table);
if (max_depth > 2 && n < 0) {
skip_remaining(bc, nb_bits);
code = set_idx(bc, code, &n, &nb_bits, table);
}
}
skip_remaining(bc, n);
return code;
}
#define BITSTREAM_RL_VLC(level, run, bc, table, bits, max_depth) \
do { \
int n, nb_bits; \
unsigned index = bitstream_peek(bc, bits); \
level = table[index].level; \
n = table[index].len; \
\
if (max_depth > 1 && n < 0) { \
bitstream_skip(bc, bits); \
\
nb_bits = -n; \
\
index = bitstream_peek(bc, nb_bits) + level; \
level = table[index].level; \
n = table[index].len; \
if (max_depth > 2 && n < 0) { \
bitstream_skip(bc, nb_bits); \
nb_bits = -n; \
\
index = bitstream_peek(bc, nb_bits) + level; \
level = table[index].level; \
n = table[index].len; \
} \
} \
run = table[index].run; \
bitstream_skip(bc, n); \
} while (0)
#endif /* AVCODEC_VLC_H */