| 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 | |
| 49 | static CABAC_TABLE_CONST uint8_t * const ff_h264_norm_shift = ff_h264_cabac_tables + H264_NORM_SHIFT_OFFSET; |
| 50 | static CABAC_TABLE_CONST uint8_t * const ff_h264_lps_range = ff_h264_cabac_tables + H264_LPS_RANGE_OFFSET; |
| 51 | static CABAC_TABLE_CONST uint8_t * const ff_h264_mlps_state = ff_h264_cabac_tables + H264_MLPS_STATE_OFFSET; |
| 52 | static CABAC_TABLE_CONST uint8_t * const ff_h264_last_coeff_flag_offset_8x8 = ff_h264_cabac_tables + H264_LAST_COEFF_FLAG_OFFSET_8x8_OFFSET; |
| 53 | |
| 54 | static 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 | |
| 67 | static 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 |
| 76 | static 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 | |
| 97 | static 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 | |
| 121 | static int av_noinline av_unused get_cabac_noinline(CABACContext *c, uint8_t * const state){ |
| 122 | return get_cabac_inline(c,state); |
| 123 | } |
| 124 | |
| 125 | static 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 |
| 130 | static 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 |
| 148 | static 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 | */ |
| 168 | static 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 | */ |
| 182 | static 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 */ |