FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/cabac_functions.h
Date: 2021-09-16 08:47:15
Exec Total Coverage
Lines: 32 34 94.1%
Branches: 12 14 85.7%

Line Branch Exec Source
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 <stddef.h>
31 #include <stdint.h>
32
33 #include "cabac.h"
34 #include "config.h"
35
36 #ifndef UNCHECKED_BITSTREAM_READER
37 #define UNCHECKED_BITSTREAM_READER !CONFIG_SAFE_BITSTREAM_READER
38 #endif
39
40 #if ARCH_AARCH64
41 # include "aarch64/cabac.h"
42 #endif
43 #if ARCH_ARM
44 # include "arm/cabac.h"
45 #endif
46 #if ARCH_X86
47 # include "x86/cabac.h"
48 #endif
49 #if ARCH_MIPS
50 # include "mips/cabac.h"
51 #endif
52
53 static const uint8_t * const ff_h264_norm_shift = ff_h264_cabac_tables + H264_NORM_SHIFT_OFFSET;
54 static const uint8_t * const ff_h264_lps_range = ff_h264_cabac_tables + H264_LPS_RANGE_OFFSET;
55 static const uint8_t * const ff_h264_mlps_state = ff_h264_cabac_tables + H264_MLPS_STATE_OFFSET;
56 static const uint8_t * const ff_h264_last_coeff_flag_offset_8x8 = ff_h264_cabac_tables + H264_LAST_COEFF_FLAG_OFFSET_8x8_OFFSET;
57
58 #if !defined(get_cabac_bypass) || !defined(get_cabac_terminate)
59 23136 static void refill(CABACContext *c){
60 #if CABAC_BITS == 16
61 23136 c->low+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1);
62 #else
63 c->low+= c->bytestream[0]<<1;
64 #endif
65 23136 c->low -= CABAC_MASK;
66 #if !UNCHECKED_BITSTREAM_READER
67
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21066 if (c->bytestream < c->bytestream_end)
68 #endif
69 23090 c->bytestream += CABAC_BITS / 8;
70 23136 }
71 #endif
72
73 #ifndef get_cabac_terminate
74 10685256 static inline void renorm_cabac_decoder_once(CABACContext *c){
75 10685256 int shift= (uint32_t)(c->range - 0x100)>>31;
76 10685256 c->range<<= shift;
77 10685256 c->low <<= shift;
78
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10685256 if(!(c->low & CABAC_MASK))
79 23136 refill(c);
80 10685256 }
81 #endif
82
83 #ifndef get_cabac_inline
84 static void refill2(CABACContext *c){
85 int i;
86 unsigned x;
87 #if !HAVE_FAST_CLZ
88 x= c->low ^ (c->low-1);
89 i= 7 - ff_h264_norm_shift[x>>(CABAC_BITS-1)];
90 #else
91 i = ff_ctz(c->low) - CABAC_BITS;
92 #endif
93
94 x= -CABAC_MASK;
95
96 #if CABAC_BITS == 16
97 x+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1);
98 #else
99 x+= c->bytestream[0]<<1;
100 #endif
101
102 c->low += x<<i;
103 #if !UNCHECKED_BITSTREAM_READER
104 if (c->bytestream < c->bytestream_end)
105 #endif
106 c->bytestream += CABAC_BITS/8;
107 }
108 #endif
109
110 #ifndef get_cabac_inline
111 static av_always_inline int get_cabac_inline(CABACContext *c, uint8_t * const state){
112 int s = *state;
113 int RangeLPS= ff_h264_lps_range[2*(c->range&0xC0) + s];
114 int bit, lps_mask;
115
116 c->range -= RangeLPS;
117 lps_mask= ((c->range<<(CABAC_BITS+1)) - c->low)>>31;
118
119 c->low -= (c->range<<(CABAC_BITS+1)) & lps_mask;
120 c->range += (RangeLPS - c->range) & lps_mask;
121
122 s^=lps_mask;
123 *state= (ff_h264_mlps_state+128)[s];
124 bit= s&1;
125
126 lps_mask= ff_h264_norm_shift[c->range];
127 c->range<<= lps_mask;
128 c->low <<= lps_mask;
129 if(!(c->low & CABAC_MASK))
130 refill2(c);
131 return bit;
132 }
133 #endif
134
135 83350584 static int av_noinline av_unused get_cabac_noinline(CABACContext *c, uint8_t * const state){
136 83350584 return get_cabac_inline(c,state);
137 }
138
139 996780939 static int av_unused get_cabac(CABACContext *c, uint8_t * const state){
140 996780939 return get_cabac_inline(c,state);
141 }
142
143 #ifndef get_cabac_bypass
144 static int av_unused get_cabac_bypass(CABACContext *c){
145 int range;
146 c->low += c->low;
147
148 if(!(c->low & CABAC_MASK))
149 refill(c);
150
151 range= c->range<<(CABAC_BITS+1);
152 if(c->low < range){
153 return 0;
154 }else{
155 c->low -= range;
156 return 1;
157 }
158 }
159 #endif
160
161 #ifndef get_cabac_bypass_sign
162 static av_always_inline int get_cabac_bypass_sign(CABACContext *c, int val){
163 int range, mask;
164 c->low += c->low;
165
166 if(!(c->low & CABAC_MASK))
167 refill(c);
168
169 range= c->range<<(CABAC_BITS+1);
170 c->low -= range;
171 mask= c->low >> 31;
172 range &= mask;
173 c->low += range;
174 return (val^mask)-mask;
175 }
176 #endif
177
178 /**
179 * @return the number of bytes read or 0 if no end
180 */
181 #ifndef get_cabac_terminate
182 10752091 static int av_unused get_cabac_terminate(CABACContext *c){
183 10752091 c->range -= 2;
184
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10752091 if(c->low < c->range<<(CABAC_BITS+1)){
185 10685256 renorm_cabac_decoder_once(c);
186 10685256 return 0;
187 }else{
188 66835 return c->bytestream - c->bytestream_start;
189 }
190 }
191 #endif
192
193 /**
194 * Skip @p n bytes and reset the decoder.
195 * @return the address of the first skipped byte or NULL if there's less than @p n bytes left
196 */
197 #ifndef skip_bytes
198 20037 static av_unused const uint8_t* skip_bytes(CABACContext *c, int n) {
199 20037 const uint8_t *ptr = c->bytestream;
200
201
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20037 if (c->low & 0x1)
202 1145 ptr--;
203 #if CABAC_BITS == 16
204
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20037 if (c->low & 0x1FF)
205 10906 ptr--;
206 #endif
207
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20037 if ((int) (c->bytestream_end - ptr) < n)
208 return NULL;
209
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20037 if (ff_init_cabac_decoder(c, ptr + n, c->bytestream_end - ptr - n) < 0)
210 return NULL;
211
212 20037 return ptr;
213 }
214 #endif
215
216 #endif /* AVCODEC_CABAC_FUNCTIONS_H */
217