2025-04-28 08:47:28 +08:00

310 lines
8.7 KiB
C

/*****************************************************************************
* bitstream.h: bitstream writing
*****************************************************************************
* Copyright (C) 2003-2025 x264 project
*
* Authors: Loren Merritt <lorenm@u.washington.edu>
* Fiona Glaser <fiona@x264.com>
* Laurent Aimar <fenrir@via.ecp.fr>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02111, USA.
*
* This program is also available under a commercial proprietary license.
* For more information, contact us at licensing@x264.com.
*****************************************************************************/
#ifndef X264_BS_H
#define X264_BS_H
typedef struct
{
uint16_t i_bits;
uint8_t i_size;
/* Next level table to use */
uint8_t i_next;
} vlc_large_t;
typedef struct bs_s
{
uint8_t *p_start;
uint8_t *p;
uint8_t *p_end;
uintptr_t cur_bits;
int i_left; /* i_count number of available bits */
int i_bits_encoded; /* RD only */
} bs_t;
typedef struct
{
int32_t last;
int32_t mask;
ALIGNED_16( dctcoef level[18] );
} x264_run_level_t;
typedef struct
{
uint8_t *(*nal_escape)( uint8_t *dst, uint8_t *src, uint8_t *end );
void (*cabac_block_residual_internal)( dctcoef *l, int b_interlaced,
intptr_t ctx_block_cat, x264_cabac_t *cb );
void (*cabac_block_residual_rd_internal)( dctcoef *l, int b_interlaced,
intptr_t ctx_block_cat, x264_cabac_t *cb );
void (*cabac_block_residual_8x8_rd_internal)( dctcoef *l, int b_interlaced,
intptr_t ctx_block_cat, x264_cabac_t *cb );
} x264_bitstream_function_t;
#define x264_bitstream_init x264_template(bitstream_init)
void x264_bitstream_init( uint32_t cpu, x264_bitstream_function_t *pf );
/* A larger level table size theoretically could help a bit at extremely
* high bitrates, but the cost in cache is usually too high for it to be
* useful.
* This size appears to be optimal for QP18 encoding on a Nehalem CPU.
* FIXME: Do further testing? */
#define LEVEL_TABLE_SIZE 128
#define x264_level_token x264_template(level_token)
extern vlc_large_t x264_level_token[7][LEVEL_TABLE_SIZE];
/* The longest possible set of zero run codes sums to 25 bits. This leaves
* plenty of room for both the code (25 bits) and size (5 bits) in a uint32_t. */
#define x264_run_before x264_template(run_before)
extern uint32_t x264_run_before[1<<16];
static inline void bs_init( bs_t *s, void *p_data, int i_data )
{
int offset = ((intptr_t)p_data & 3);
s->p = s->p_start = (uint8_t*)p_data - offset;
s->p_end = (uint8_t*)p_data + i_data;
s->i_left = (WORD_SIZE - offset)*8;
if( offset )
{
s->cur_bits = endian_fix32( M32(s->p) );
s->cur_bits >>= (4-offset)*8;
}
else
s->cur_bits = 0;
}
static inline int bs_pos( bs_t *s )
{
return( 8 * (s->p - s->p_start) + (WORD_SIZE*8) - s->i_left );
}
/* Write the rest of cur_bits to the bitstream; results in a bitstream no longer 32-bit aligned. */
static inline void bs_flush( bs_t *s )
{
M32( s->p ) = endian_fix32( s->cur_bits << (s->i_left&31) );
s->p += WORD_SIZE - (s->i_left >> 3);
s->i_left = WORD_SIZE*8;
}
/* The inverse of bs_flush: prepare the bitstream to be written to again. */
static inline void bs_realign( bs_t *s )
{
int offset = ((intptr_t)s->p & 3);
if( offset )
{
s->p = (uint8_t*)s->p - offset;
s->i_left = (WORD_SIZE - offset)*8;
s->cur_bits = endian_fix32( M32(s->p) );
s->cur_bits >>= (4-offset)*8;
}
}
static inline void bs_write( bs_t *s, int i_count, uint32_t i_bits )
{
if( WORD_SIZE == 8 )
{
s->cur_bits = (s->cur_bits << i_count) | i_bits;
s->i_left -= i_count;
if( s->i_left <= 32 )
{
#if WORDS_BIGENDIAN
M32( s->p ) = s->cur_bits >> (32 - s->i_left);
#else
M32( s->p ) = endian_fix( s->cur_bits << s->i_left );
#endif
s->i_left += 32;
s->p += 4;
}
}
else
{
if( i_count < s->i_left )
{
s->cur_bits = (s->cur_bits << i_count) | i_bits;
s->i_left -= i_count;
}
else
{
i_count -= s->i_left;
s->cur_bits = (s->cur_bits << s->i_left) | (i_bits >> i_count);
M32( s->p ) = endian_fix( s->cur_bits );
s->p += 4;
s->cur_bits = i_bits;
s->i_left = 32 - i_count;
}
}
}
/* Special case to eliminate branch in normal bs_write. */
/* Golomb never writes an even-size code, so this is only used in slice headers. */
static inline void bs_write32( bs_t *s, uint32_t i_bits )
{
bs_write( s, 16, i_bits >> 16 );
bs_write( s, 16, i_bits );
}
static inline void bs_write1( bs_t *s, uint32_t i_bit )
{
s->cur_bits <<= 1;
s->cur_bits |= i_bit;
s->i_left--;
if( s->i_left == WORD_SIZE*8-32 )
{
M32( s->p ) = endian_fix32( s->cur_bits );
s->p += 4;
s->i_left = WORD_SIZE*8;
}
}
static inline void bs_align_0( bs_t *s )
{
bs_write( s, s->i_left&7, 0 );
bs_flush( s );
}
static inline void bs_align_1( bs_t *s )
{
bs_write( s, s->i_left&7, (1 << (s->i_left&7)) - 1 );
bs_flush( s );
}
static inline void bs_align_10( bs_t *s )
{
if( s->i_left&7 )
bs_write( s, s->i_left&7, 1 << ( (s->i_left&7) - 1 ) );
bs_flush( s );
}
/* golomb functions */
static const uint8_t x264_ue_size_tab[256] =
{
1, 1, 3, 3, 5, 5, 5, 5, 7, 7, 7, 7, 7, 7, 7, 7,
9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,
11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,
13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,
13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,
13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,
13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,
15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,
15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,
15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,
15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,
15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,
15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,
15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,
15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,
};
static inline void bs_write_ue_big( bs_t *s, unsigned int val )
{
int size = 0;
int tmp = ++val;
if( tmp >= 0x10000 )
{
size = 32;
tmp >>= 16;
}
if( tmp >= 0x100 )
{
size += 16;
tmp >>= 8;
}
size += x264_ue_size_tab[tmp];
bs_write( s, size>>1, 0 );
bs_write( s, (size>>1)+1, val );
}
/* Only works on values under 255. */
static inline void bs_write_ue( bs_t *s, int val )
{
bs_write( s, x264_ue_size_tab[val+1], val+1 );
}
static inline void bs_write_se( bs_t *s, int val )
{
int size = 0;
/* Faster than (val <= 0 ? -val*2+1 : val*2) */
/* 4 instructions on x86, 3 on ARM */
int tmp = 1 - val*2;
if( tmp < 0 ) tmp = val*2;
val = tmp;
if( tmp >= 0x100 )
{
size = 16;
tmp >>= 8;
}
size += x264_ue_size_tab[tmp];
bs_write( s, size, val );
}
static inline void bs_write_te( bs_t *s, int x, int val )
{
if( x == 1 )
bs_write1( s, 1^val );
else //if( x > 1 )
bs_write_ue( s, val );
}
static inline void bs_rbsp_trailing( bs_t *s )
{
bs_write1( s, 1 );
bs_write( s, s->i_left&7, 0 );
}
static ALWAYS_INLINE int bs_size_ue( unsigned int val )
{
return x264_ue_size_tab[val+1];
}
static ALWAYS_INLINE int bs_size_ue_big( unsigned int val )
{
if( val < 255 )
return x264_ue_size_tab[val+1];
else
return x264_ue_size_tab[(val+1)>>8] + 16;
}
static ALWAYS_INLINE int bs_size_se( int val )
{
int tmp = 1 - val*2;
if( tmp < 0 ) tmp = val*2;
if( tmp < 256 )
return x264_ue_size_tab[tmp];
else
return x264_ue_size_tab[tmp>>8]+16;
}
static ALWAYS_INLINE int bs_size_te( int x, int val )
{
if( x == 1 )
return 1;
else //if( x > 1 )
return x264_ue_size_tab[val+1];
}
#endif