2 * H.26L/H.264/AVC/JVT/14496-10/... encoder/decoder
3 * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
5 * This file is part of FFmpeg.
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 * Context Adaptive Binary Arithmetic Coder inline functions
27 #ifndef AVCODEC_CABAC_FUNCTIONS_H
28 #define AVCODEC_CABAC_FUNCTIONS_H
36 # include "x86/cabac.h"
39 extern uint8_t ff_h264_cabac_tables[512 + 4*2*64 + 4*64 + 63];
40 static uint8_t * const ff_h264_norm_shift = ff_h264_cabac_tables + H264_NORM_SHIFT_OFFSET;
41 static uint8_t * const ff_h264_lps_range = ff_h264_cabac_tables + H264_LPS_RANGE_OFFSET;
42 static uint8_t * const ff_h264_mlps_state = ff_h264_cabac_tables + H264_MLPS_STATE_OFFSET;
43 static uint8_t * const ff_h264_last_coeff_flag_offset_8x8 = ff_h264_cabac_tables + H264_LAST_COEFF_FLAG_OFFSET_8x8_OFFSET;
45 static void refill(CABACContext *c){
47 c->low+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1);
49 c->low+= c->bytestream[0]<<1;
52 c->bytestream += CABAC_BITS / 8;
55 static inline void renorm_cabac_decoder_once(CABACContext *c){
56 int shift= (uint32_t)(c->range - 0x100)>>31;
59 if(!(c->low & CABAC_MASK))
63 #ifndef get_cabac_inline
64 static void refill2(CABACContext *c){
67 x= c->low ^ (c->low-1);
68 i= 7 - ff_h264_norm_shift[x>>(CABAC_BITS-1)];
73 x+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1);
75 x+= c->bytestream[0]<<1;
79 c->bytestream += CABAC_BITS/8;
82 static av_always_inline int get_cabac_inline(CABACContext *c, uint8_t * const state){
84 int RangeLPS= ff_h264_lps_range[2*(c->range&0xC0) + s];
88 lps_mask= ((c->range<<(CABAC_BITS+1)) - c->low)>>31;
90 c->low -= (c->range<<(CABAC_BITS+1)) & lps_mask;
91 c->range += (RangeLPS - c->range) & lps_mask;
94 *state= (ff_h264_mlps_state+128)[s];
97 lps_mask= ff_h264_norm_shift[c->range];
100 if(!(c->low & CABAC_MASK))
106 static int av_noinline av_unused get_cabac_noinline(CABACContext *c, uint8_t * const state){
107 return get_cabac_inline(c,state);
110 static int av_unused get_cabac(CABACContext *c, uint8_t * const state){
111 return get_cabac_inline(c,state);
114 #ifndef get_cabac_bypass
115 static int av_unused get_cabac_bypass(CABACContext *c){
119 if(!(c->low & CABAC_MASK))
122 range= c->range<<(CABAC_BITS+1);
132 #ifndef get_cabac_bypass_sign
133 static av_always_inline int get_cabac_bypass_sign(CABACContext *c, int val){
137 if(!(c->low & CABAC_MASK))
140 range= c->range<<(CABAC_BITS+1);
145 return (val^mask)-mask;
151 * @return the number of bytes read or 0 if no end
153 static int av_unused get_cabac_terminate(CABACContext *c){
155 if(c->low < c->range<<(CABAC_BITS+1)){
156 renorm_cabac_decoder_once(c);
159 return c->bytestream - c->bytestream_start;
164 * Skip @p n bytes and reset the decoder.
165 * @return the address of the first skipped byte or NULL if there's less than @p n bytes left
167 static av_unused const uint8_t* skip_bytes(CABACContext *c, int n) {
168 const uint8_t *ptr = c->bytestream;
176 if ((int) (c->bytestream_end - ptr) < n)
178 ff_init_cabac_decoder(c, ptr + n, c->bytestream_end - ptr - n);
183 #endif /* AVCODEC_CABAC_FUNCTIONS_H */