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
35 #ifndef UNCHECKED_BITSTREAM_READER
36 #define UNCHECKED_BITSTREAM_READER !CONFIG_SAFE_BITSTREAM_READER
40 # include "aarch64/cabac.h"
43 # include "arm/cabac.h"
46 # include "x86/cabac.h"
49 static const uint8_t * const ff_h264_norm_shift = ff_h264_cabac_tables + H264_NORM_SHIFT_OFFSET;
50 static const uint8_t * const ff_h264_lps_range = ff_h264_cabac_tables + H264_LPS_RANGE_OFFSET;
51 static const uint8_t * const ff_h264_mlps_state = ff_h264_cabac_tables + H264_MLPS_STATE_OFFSET;
52 static const uint8_t * const ff_h264_last_coeff_flag_offset_8x8 = ff_h264_cabac_tables + H264_LAST_COEFF_FLAG_OFFSET_8x8_OFFSET;
54 static void refill(CABACContext *c){
56 c->low+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1);
58 c->low+= c->bytestream[0]<<1;
61 #if !UNCHECKED_BITSTREAM_READER
62 if (c->bytestream < c->bytestream_end)
64 c->bytestream += CABAC_BITS / 8;
67 static inline void renorm_cabac_decoder_once(CABACContext *c){
68 int shift= (uint32_t)(c->range - 0x100)>>31;
71 if(!(c->low & CABAC_MASK))
75 #ifndef get_cabac_inline
76 static void refill2(CABACContext *c){
79 x= c->low ^ (c->low-1);
80 i= 7 - ff_h264_norm_shift[x>>(CABAC_BITS-1)];
85 x+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1);
87 x+= c->bytestream[0]<<1;
91 #if !UNCHECKED_BITSTREAM_READER
92 if (c->bytestream < c->bytestream_end)
94 c->bytestream += CABAC_BITS/8;
97 static av_always_inline int get_cabac_inline(CABACContext *c, uint8_t * const state){
99 int RangeLPS= ff_h264_lps_range[2*(c->range&0xC0) + s];
102 c->range -= RangeLPS;
103 lps_mask= ((c->range<<(CABAC_BITS+1)) - c->low)>>31;
105 c->low -= (c->range<<(CABAC_BITS+1)) & lps_mask;
106 c->range += (RangeLPS - c->range) & lps_mask;
109 *state= (ff_h264_mlps_state+128)[s];
112 lps_mask= ff_h264_norm_shift[c->range];
113 c->range<<= lps_mask;
115 if(!(c->low & CABAC_MASK))
121 static int av_noinline av_unused get_cabac_noinline(CABACContext *c, uint8_t * const state){
122 return get_cabac_inline(c,state);
125 static int av_unused get_cabac(CABACContext *c, uint8_t * const state){
126 return get_cabac_inline(c,state);
129 #ifndef get_cabac_bypass
130 static int av_unused get_cabac_bypass(CABACContext *c){
134 if(!(c->low & CABAC_MASK))
137 range= c->range<<(CABAC_BITS+1);
147 #ifndef get_cabac_bypass_sign
148 static av_always_inline int get_cabac_bypass_sign(CABACContext *c, int val){
152 if(!(c->low & CABAC_MASK))
155 range= c->range<<(CABAC_BITS+1);
160 return (val^mask)-mask;
166 * @return the number of bytes read or 0 if no end
168 static int av_unused get_cabac_terminate(CABACContext *c){
170 if(c->low < c->range<<(CABAC_BITS+1)){
171 renorm_cabac_decoder_once(c);
174 return c->bytestream - c->bytestream_start;
179 * Skip @p n bytes and reset the decoder.
180 * @return the address of the first skipped byte or NULL if there's less than @p n bytes left
182 static av_unused const uint8_t* skip_bytes(CABACContext *c, int n) {
183 const uint8_t *ptr = c->bytestream;
191 if ((int) (c->bytestream_end - ptr) < n)
193 ff_init_cabac_decoder(c, ptr + n, c->bytestream_end - ptr - n);
198 #endif /* AVCODEC_CABAC_FUNCTIONS_H */