1/* 2 * H.26L/H.264/AVC/JVT/14496-10/... encoder/decoder 3 * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at> 4 * 5 * This file is part of FFmpeg. 6 * 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. 11 * 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. 16 * 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 20 */ 21 22/** 23 * @file 24 * Context Adaptive Binary Arithmetic Coder inline functions 25 */ 26 27#ifndef AVCODEC_CABAC_FUNCTIONS_H 28#define AVCODEC_CABAC_FUNCTIONS_H 29 30#include <stdint.h> 31 32#include "cabac.h" 33#include "config.h" 34 35#ifndef UNCHECKED_BITSTREAM_READER 36#define UNCHECKED_BITSTREAM_READER !CONFIG_SAFE_BITSTREAM_READER 37#endif 38 39#if ARCH_AARCH64 40# include "aarch64/cabac.h" 41#endif 42#if ARCH_ARM 43# include "arm/cabac.h" 44#endif 45#if ARCH_X86 46# include "x86/cabac.h" 47#endif 48 49static uint8_t * const ff_h264_norm_shift = ff_h264_cabac_tables + H264_NORM_SHIFT_OFFSET; 50static uint8_t * const ff_h264_lps_range = ff_h264_cabac_tables + H264_LPS_RANGE_OFFSET; 51static uint8_t * const ff_h264_mlps_state = ff_h264_cabac_tables + H264_MLPS_STATE_OFFSET; 52static uint8_t * const ff_h264_last_coeff_flag_offset_8x8 = ff_h264_cabac_tables + H264_LAST_COEFF_FLAG_OFFSET_8x8_OFFSET; 53 54static void refill(CABACContext *c){ 55#if CABAC_BITS == 16 56 c->low+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1); 57#else 58 c->low+= c->bytestream[0]<<1; 59#endif 60 c->low -= CABAC_MASK; 61#if !UNCHECKED_BITSTREAM_READER 62 if (c->bytestream < c->bytestream_end) 63#endif 64 c->bytestream += CABAC_BITS / 8; 65} 66 67static inline void renorm_cabac_decoder_once(CABACContext *c){ 68 int shift= (uint32_t)(c->range - 0x100)>>31; 69 c->range<<= shift; 70 c->low <<= shift; 71 if(!(c->low & CABAC_MASK)) 72 refill(c); 73} 74 75#ifndef get_cabac_inline 76static void refill2(CABACContext *c){ 77 int i, x; 78 79 x= c->low ^ (c->low-1); 80 i= 7 - ff_h264_norm_shift[x>>(CABAC_BITS-1)]; 81 82 x= -CABAC_MASK; 83 84#if CABAC_BITS == 16 85 x+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1); 86#else 87 x+= c->bytestream[0]<<1; 88#endif 89 90 c->low += x<<i; 91#if !UNCHECKED_BITSTREAM_READER 92 if (c->bytestream < c->bytestream_end) 93#endif 94 c->bytestream += CABAC_BITS/8; 95} 96 97static av_always_inline int get_cabac_inline(CABACContext *c, uint8_t * const state){ 98 int s = *state; 99 int RangeLPS= ff_h264_lps_range[2*(c->range&0xC0) + s]; 100 int bit, lps_mask; 101 102 c->range -= RangeLPS; 103 lps_mask= ((c->range<<(CABAC_BITS+1)) - c->low)>>31; 104 105 c->low -= (c->range<<(CABAC_BITS+1)) & lps_mask; 106 c->range += (RangeLPS - c->range) & lps_mask; 107 108 s^=lps_mask; 109 *state= (ff_h264_mlps_state+128)[s]; 110 bit= s&1; 111 112 lps_mask= ff_h264_norm_shift[c->range]; 113 c->range<<= lps_mask; 114 c->low <<= lps_mask; 115 if(!(c->low & CABAC_MASK)) 116 refill2(c); 117 return bit; 118} 119#endif 120 121static int av_noinline av_unused get_cabac_noinline(CABACContext *c, uint8_t * const state){ 122 return get_cabac_inline(c,state); 123} 124 125static int av_unused get_cabac(CABACContext *c, uint8_t * const state){ 126 return get_cabac_inline(c,state); 127} 128 129#ifndef get_cabac_bypass 130static int av_unused get_cabac_bypass(CABACContext *c){ 131 int range; 132 c->low += c->low; 133 134 if(!(c->low & CABAC_MASK)) 135 refill(c); 136 137 range= c->range<<(CABAC_BITS+1); 138 if(c->low < range){ 139 return 0; 140 }else{ 141 c->low -= range; 142 return 1; 143 } 144} 145#endif 146 147#ifndef get_cabac_bypass_sign 148static av_always_inline int get_cabac_bypass_sign(CABACContext *c, int val){ 149 int range, mask; 150 c->low += c->low; 151 152 if(!(c->low & CABAC_MASK)) 153 refill(c); 154 155 range= c->range<<(CABAC_BITS+1); 156 c->low -= range; 157 mask= c->low >> 31; 158 range &= mask; 159 c->low += range; 160 return (val^mask)-mask; 161} 162#endif 163 164/** 165 * 166 * @return the number of bytes read or 0 if no end 167 */ 168static int av_unused get_cabac_terminate(CABACContext *c){ 169 c->range -= 2; 170 if(c->low < c->range<<(CABAC_BITS+1)){ 171 renorm_cabac_decoder_once(c); 172 return 0; 173 }else{ 174 return c->bytestream - c->bytestream_start; 175 } 176} 177 178/** 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 181 */ 182static av_unused const uint8_t* skip_bytes(CABACContext *c, int n) { 183 const uint8_t *ptr = c->bytestream; 184 185 if (c->low & 0x1) 186 ptr--; 187#if CABAC_BITS == 16 188 if (c->low & 0x1FF) 189 ptr--; 190#endif 191 if ((int) (c->bytestream_end - ptr) < n) 192 return NULL; 193 ff_init_cabac_decoder(c, ptr + n, c->bytestream_end - ptr - n); 194 195 return ptr; 196} 197 198#endif /* AVCODEC_CABAC_FUNCTIONS_H */ 199