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 Libav.
7 * Libav 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 * Libav 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 Libav; 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 "aarch64/cabac.h"
39 # include "arm/cabac.h"
42 # include "x86/cabac.h"
45 static uint8_t * const ff_h264_norm_shift = ff_h264_cabac_tables + H264_NORM_SHIFT_OFFSET;
46 static uint8_t * const ff_h264_lps_range = ff_h264_cabac_tables + H264_LPS_RANGE_OFFSET;
47 static uint8_t * const ff_h264_mlps_state = ff_h264_cabac_tables + H264_MLPS_STATE_OFFSET;
48 static uint8_t * const ff_h264_last_coeff_flag_offset_8x8 = ff_h264_cabac_tables + H264_LAST_COEFF_FLAG_OFFSET_8x8_OFFSET;
50 static void refill(CABACContext *c){
52 c->low+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1);
54 c->low+= c->bytestream[0]<<1;
57 if (c->bytestream < c->bytestream_end)
58 c->bytestream += CABAC_BITS / 8;
61 static inline void renorm_cabac_decoder_once(CABACContext *c){
62 int shift= (uint32_t)(c->range - 0x100)>>31;
65 if(!(c->low & CABAC_MASK))
69 #ifndef get_cabac_inline
70 static void refill2(CABACContext *c){
73 x= c->low ^ (c->low-1);
74 i= 7 - ff_h264_norm_shift[x>>(CABAC_BITS-1)];
79 x+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1);
81 x+= c->bytestream[0]<<1;
85 if (c->bytestream < c->bytestream_end)
86 c->bytestream += CABAC_BITS/8;
89 static av_always_inline int get_cabac_inline(CABACContext *c, uint8_t * const state){
91 int RangeLPS= ff_h264_lps_range[2*(c->range&0xC0) + s];
95 lps_mask= ((c->range<<(CABAC_BITS+1)) - c->low)>>31;
97 c->low -= (c->range<<(CABAC_BITS+1)) & lps_mask;
98 c->range += (RangeLPS - c->range) & lps_mask;
101 *state= (ff_h264_mlps_state+128)[s];
104 lps_mask= ff_h264_norm_shift[c->range];
105 c->range<<= lps_mask;
107 if(!(c->low & CABAC_MASK))
113 static int av_noinline av_unused get_cabac_noinline(CABACContext *c, uint8_t * const state){
114 return get_cabac_inline(c,state);
117 static int av_unused get_cabac(CABACContext *c, uint8_t * const state){
118 return get_cabac_inline(c,state);
121 #ifndef get_cabac_bypass
122 static int av_unused get_cabac_bypass(CABACContext *c){
126 if(!(c->low & CABAC_MASK))
129 range= c->range<<(CABAC_BITS+1);
139 #ifndef get_cabac_bypass_sign
140 static av_always_inline int get_cabac_bypass_sign(CABACContext *c, int val){
144 if(!(c->low & CABAC_MASK))
147 range= c->range<<(CABAC_BITS+1);
152 return (val^mask)-mask;
158 * @return the number of bytes read or 0 if no end
160 static int av_unused get_cabac_terminate(CABACContext *c){
162 if(c->low < c->range<<(CABAC_BITS+1)){
163 renorm_cabac_decoder_once(c);
166 return c->bytestream - c->bytestream_start;
171 * Skip @p n bytes and reset the decoder.
172 * @return the address of the first skipped byte or NULL if there's less than @p n bytes left
174 static av_unused const uint8_t* skip_bytes(CABACContext *c, int n) {
175 const uint8_t *ptr = c->bytestream;
183 if ((int) (c->bytestream_end - ptr) < n)
185 ff_init_cabac_decoder(c, ptr + n, c->bytestream_end - ptr - n);
190 #endif /* AVCODEC_CABAC_FUNCTIONS_H */