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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 */ |