FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/cabac_functions.h
Date: 2022-07-06 18:02:43
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 "libavutil/attributes.h"
34 #include "libavutil/intmath.h"
35 #include "cabac.h"
36 #include "config.h"
37
38 #ifndef UNCHECKED_BITSTREAM_READER
39 #define UNCHECKED_BITSTREAM_READER !CONFIG_SAFE_BITSTREAM_READER
40 #endif
41
42 #if ARCH_AARCH64
43 # include "aarch64/cabac.h"
44 #endif
45 #if ARCH_ARM
46 # include "arm/cabac.h"
47 #endif
48 #if ARCH_X86
49 # include "x86/cabac.h"
50 #endif
51 #if ARCH_MIPS
52 # include "mips/cabac.h"
53 #endif
54 #if ARCH_LOONGARCH64
55 # include "loongarch/cabac.h"
56 #endif
57
58 static const uint8_t * const ff_h264_norm_shift = ff_h264_cabac_tables + H264_NORM_SHIFT_OFFSET;
59 static const uint8_t * const ff_h264_lps_range = ff_h264_cabac_tables + H264_LPS_RANGE_OFFSET;
60 static const uint8_t * const ff_h264_mlps_state = ff_h264_cabac_tables + H264_MLPS_STATE_OFFSET;
61 static const uint8_t * const ff_h264_last_coeff_flag_offset_8x8 = ff_h264_cabac_tables + H264_LAST_COEFF_FLAG_OFFSET_8x8_OFFSET;
62
63 #if !defined(get_cabac_bypass) || !defined(get_cabac_terminate)
64 23178 static void refill(CABACContext *c){
65 #if CABAC_BITS == 16
66 23178 c->low+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1);
67 #else
68 c->low+= c->bytestream[0]<<1;
69 #endif
70 23178 c->low -= CABAC_MASK;
71 #if !UNCHECKED_BITSTREAM_READER
72
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21108 if (c->bytestream < c->bytestream_end)
73 #endif
74 23132 c->bytestream += CABAC_BITS / 8;
75 23178 }
76 #endif
77
78 #ifndef get_cabac_terminate
79 10712071 static inline void renorm_cabac_decoder_once(CABACContext *c){
80 10712071 int shift= (uint32_t)(c->range - 0x100)>>31;
81 10712071 c->range<<= shift;
82 10712071 c->low <<= shift;
83
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10712071 if(!(c->low & CABAC_MASK))
84 23178 refill(c);
85 10712071 }
86 #endif
87
88 #ifndef get_cabac_inline
89 static void refill2(CABACContext *c){
90 int i;
91 unsigned x;
92 #if !HAVE_FAST_CLZ
93 x= c->low ^ (c->low-1);
94 i= 7 - ff_h264_norm_shift[x>>(CABAC_BITS-1)];
95 #else
96 i = ff_ctz(c->low) - CABAC_BITS;
97 #endif
98
99 x= -CABAC_MASK;
100
101 #if CABAC_BITS == 16
102 x+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1);
103 #else
104 x+= c->bytestream[0]<<1;
105 #endif
106
107 c->low += x<<i;
108 #if !UNCHECKED_BITSTREAM_READER
109 if (c->bytestream < c->bytestream_end)
110 #endif
111 c->bytestream += CABAC_BITS/8;
112 }
113 #endif
114
115 #ifndef get_cabac_inline
116 static av_always_inline int get_cabac_inline(CABACContext *c, uint8_t * const state){
117 int s = *state;
118 int RangeLPS= ff_h264_lps_range[2*(c->range&0xC0) + s];
119 int bit, lps_mask;
120
121 c->range -= RangeLPS;
122 lps_mask= ((c->range<<(CABAC_BITS+1)) - c->low)>>31;
123
124 c->low -= (c->range<<(CABAC_BITS+1)) & lps_mask;
125 c->range += (RangeLPS - c->range) & lps_mask;
126
127 s^=lps_mask;
128 *state= (ff_h264_mlps_state+128)[s];
129 bit= s&1;
130
131 lps_mask= ff_h264_norm_shift[c->range];
132 c->range<<= lps_mask;
133 c->low <<= lps_mask;
134 if(!(c->low & CABAC_MASK))
135 refill2(c);
136 return bit;
137 }
138 #endif
139
140 83483484 static int av_noinline av_unused get_cabac_noinline(CABACContext *c, uint8_t * const state){
141 83483484 return get_cabac_inline(c,state);
142 }
143
144 999560938 static int av_unused get_cabac(CABACContext *c, uint8_t * const state){
145 999560938 return get_cabac_inline(c,state);
146 }
147
148 #ifndef get_cabac_bypass
149 static int av_unused get_cabac_bypass(CABACContext *c){
150 int range;
151 c->low += c->low;
152
153 if(!(c->low & CABAC_MASK))
154 refill(c);
155
156 range= c->range<<(CABAC_BITS+1);
157 if(c->low < range){
158 return 0;
159 }else{
160 c->low -= range;
161 return 1;
162 }
163 }
164 #endif
165
166 #ifndef get_cabac_bypass_sign
167 static av_always_inline int get_cabac_bypass_sign(CABACContext *c, int val){
168 int range, mask;
169 c->low += c->low;
170
171 if(!(c->low & CABAC_MASK))
172 refill(c);
173
174 range= c->range<<(CABAC_BITS+1);
175 c->low -= range;
176 mask= c->low >> 31;
177 range &= mask;
178 c->low += range;
179 return (val^mask)-mask;
180 }
181 #endif
182
183 /**
184 * @return the number of bytes read or 0 if no end
185 */
186 #ifndef get_cabac_terminate
187 10779120 static int av_unused get_cabac_terminate(CABACContext *c){
188 10779120 c->range -= 2;
189
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10779120 if(c->low < c->range<<(CABAC_BITS+1)){
190 10712071 renorm_cabac_decoder_once(c);
191 10712071 return 0;
192 }else{
193 67049 return c->bytestream - c->bytestream_start;
194 }
195 }
196 #endif
197
198 /**
199 * Skip @p n bytes and reset the decoder.
200 * @return the address of the first skipped byte or NULL if there's less than @p n bytes left
201 */
202 #ifndef skip_bytes
203 20169 static av_unused const uint8_t* skip_bytes(CABACContext *c, int n) {
204 20169 const uint8_t *ptr = c->bytestream;
205
206
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20169 if (c->low & 0x1)
207 1151 ptr--;
208 #if CABAC_BITS == 16
209
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20169 if (c->low & 0x1FF)
210 10983 ptr--;
211 #endif
212
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20169 if ((int) (c->bytestream_end - ptr) < n)
213 return NULL;
214
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20169 if (ff_init_cabac_decoder(c, ptr + n, c->bytestream_end - ptr - n) < 0)
215 return NULL;
216
217 20169 return ptr;
218 }
219 #endif
220
221 #endif /* AVCODEC_CABAC_FUNCTIONS_H */
222