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FFmpeg/libavcodec/cabac_functions.h
Roland Scheidegger 14e9ffc1e4 h264: use one table instead of several for cabac functions
The reason is this is easier for PIC code (in particular on darwin...).
Keep the old names as pointers (static in cabac_functions.h so gcc
knows these are just immediate offsets) so the c code can nicely stay the same
(alternatively could use offsets directly in the functions needing the
tables). This should produce the same code as before with non-pic and better
code (confirmed) with pic.

The assembly uses the new table but still won't work for PIC case.

Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
2012-04-28 08:26:12 -07:00

165 lines
4.3 KiB
C

/*
* H.26L/H.264/AVC/JVT/14496-10/... encoder/decoder
* Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
*
* This file is part of Libav.
*
* Libav 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.
*
* Libav 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 Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* Context Adaptive Binary Arithmetic Coder inline functions
*/
#ifndef AVCODEC_CABAC_FUNCTIONS_H
#define AVCODEC_CABAC_FUNCTIONS_H
#include <stdint.h>
#include "cabac.h"
#include "config.h"
#if ARCH_X86
# include "x86/cabac.h"
#endif
extern uint8_t ff_h264_cabac_tables[512 + 4*2*64 + 4*64 + 63];
static uint8_t * const ff_h264_norm_shift = ff_h264_cabac_tables + H264_NORM_SHIFT_OFFSET;
static uint8_t * const ff_h264_lps_range = ff_h264_cabac_tables + H264_LPS_RANGE_OFFSET;
static uint8_t * const ff_h264_mlps_state = ff_h264_cabac_tables + H264_MLPS_STATE_OFFSET;
static uint8_t * const ff_h264_last_coeff_flag_offset_8x8 = ff_h264_cabac_tables + H264_LAST_COEFF_FLAG_OFFSET_8x8_OFFSET;
static void refill(CABACContext *c){
#if CABAC_BITS == 16
c->low+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1);
#else
c->low+= c->bytestream[0]<<1;
#endif
c->low -= CABAC_MASK;
if (c->bytestream < c->bytestream_end)
c->bytestream += CABAC_BITS / 8;
}
static inline void renorm_cabac_decoder_once(CABACContext *c){
int shift= (uint32_t)(c->range - 0x100)>>31;
c->range<<= shift;
c->low <<= shift;
if(!(c->low & CABAC_MASK))
refill(c);
}
#ifndef get_cabac_inline
static void refill2(CABACContext *c){
int i, x;
x= c->low ^ (c->low-1);
i= 7 - ff_h264_norm_shift[x>>(CABAC_BITS-1)];
x= -CABAC_MASK;
#if CABAC_BITS == 16
x+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1);
#else
x+= c->bytestream[0]<<1;
#endif
c->low += x<<i;
if (c->bytestream < c->bytestream_end)
c->bytestream += CABAC_BITS/8;
}
static av_always_inline int get_cabac_inline(CABACContext *c, uint8_t * const state){
int s = *state;
int RangeLPS= ff_h264_lps_range[2*(c->range&0xC0) + s];
int bit, lps_mask;
c->range -= RangeLPS;
lps_mask= ((c->range<<(CABAC_BITS+1)) - c->low)>>31;
c->low -= (c->range<<(CABAC_BITS+1)) & lps_mask;
c->range += (RangeLPS - c->range) & lps_mask;
s^=lps_mask;
*state= (ff_h264_mlps_state+128)[s];
bit= s&1;
lps_mask= ff_h264_norm_shift[c->range];
c->range<<= lps_mask;
c->low <<= lps_mask;
if(!(c->low & CABAC_MASK))
refill2(c);
return bit;
}
#endif
static int av_noinline av_unused get_cabac_noinline(CABACContext *c, uint8_t * const state){
return get_cabac_inline(c,state);
}
static int av_unused get_cabac(CABACContext *c, uint8_t * const state){
return get_cabac_inline(c,state);
}
static int av_unused get_cabac_bypass(CABACContext *c){
int range;
c->low += c->low;
if(!(c->low & CABAC_MASK))
refill(c);
range= c->range<<(CABAC_BITS+1);
if(c->low < range){
return 0;
}else{
c->low -= range;
return 1;
}
}
#ifndef get_cabac_bypass_sign
static av_always_inline int get_cabac_bypass_sign(CABACContext *c, int val){
int range, mask;
c->low += c->low;
if(!(c->low & CABAC_MASK))
refill(c);
range= c->range<<(CABAC_BITS+1);
c->low -= range;
mask= c->low >> 31;
range &= mask;
c->low += range;
return (val^mask)-mask;
}
#endif
/**
*
* @return the number of bytes read or 0 if no end
*/
static int av_unused get_cabac_terminate(CABACContext *c){
c->range -= 2;
if(c->low < c->range<<(CABAC_BITS+1)){
renorm_cabac_decoder_once(c);
return 0;
}else{
return c->bytestream - c->bytestream_start;
}
}
#endif /* AVCODEC_CABAC_FUNCTIONS_H */