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1 // Copyright 2010 Google Inc. All Rights Reserved.
2 //
3 // Use of this source code is governed by a BSD-style license
4 // that can be found in the COPYING file in the root of the source
5 // tree. An additional intellectual property rights grant can be found
6 // in the file PATENTS. All contributing project authors may
7 // be found in the AUTHORS file in the root of the source tree.
8 // -----------------------------------------------------------------------------
9 //
10 // Coding trees and probas
11 //
12 // Author: Skal (pascal.massimino@gmail.com)
13 
14 #include "src/dec/vp8i_dec.h"
15 #include "src/utils/bit_reader_inl_utils.h"
16 
17 #if !defined(USE_GENERIC_TREE)
18 #if !defined(__arm__) && !defined(_M_ARM) && !defined(__aarch64__)
19 // using a table is ~1-2% slower on ARM. Prefer the coded-tree approach then.
20 #define USE_GENERIC_TREE 1   // ALTERNATE_CODE
21 #else
22 #define USE_GENERIC_TREE 0
23 #endif
24 #endif  // USE_GENERIC_TREE
25 
26 #if (USE_GENERIC_TREE == 1)
27 static const int8_t kYModesIntra4[18] = {
28   -B_DC_PRED, 1,
29     -B_TM_PRED, 2,
30       -B_VE_PRED, 3,
31         4, 6,
32           -B_HE_PRED, 5,
33             -B_RD_PRED, -B_VR_PRED,
34         -B_LD_PRED, 7,
35           -B_VL_PRED, 8,
36             -B_HD_PRED, -B_HU_PRED
37 };
38 #endif
39 
40 //------------------------------------------------------------------------------
41 // Default probabilities
42 
43 // Paragraph 13.5
44 static const uint8_t
45   CoeffsProba0[NUM_TYPES][NUM_BANDS][NUM_CTX][NUM_PROBAS] = {
46   { { { 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 },
47       { 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 },
48       { 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 }
49     },
50     { { 253, 136, 254, 255, 228, 219, 128, 128, 128, 128, 128 },
51       { 189, 129, 242, 255, 227, 213, 255, 219, 128, 128, 128 },
52       { 106, 126, 227, 252, 214, 209, 255, 255, 128, 128, 128 }
53     },
54     { { 1, 98, 248, 255, 236, 226, 255, 255, 128, 128, 128 },
55       { 181, 133, 238, 254, 221, 234, 255, 154, 128, 128, 128 },
56       { 78, 134, 202, 247, 198, 180, 255, 219, 128, 128, 128 },
57     },
58     { { 1, 185, 249, 255, 243, 255, 128, 128, 128, 128, 128 },
59       { 184, 150, 247, 255, 236, 224, 128, 128, 128, 128, 128 },
60       { 77, 110, 216, 255, 236, 230, 128, 128, 128, 128, 128 },
61     },
62     { { 1, 101, 251, 255, 241, 255, 128, 128, 128, 128, 128 },
63       { 170, 139, 241, 252, 236, 209, 255, 255, 128, 128, 128 },
64       { 37, 116, 196, 243, 228, 255, 255, 255, 128, 128, 128 }
65     },
66     { { 1, 204, 254, 255, 245, 255, 128, 128, 128, 128, 128 },
67       { 207, 160, 250, 255, 238, 128, 128, 128, 128, 128, 128 },
68       { 102, 103, 231, 255, 211, 171, 128, 128, 128, 128, 128 }
69     },
70     { { 1, 152, 252, 255, 240, 255, 128, 128, 128, 128, 128 },
71       { 177, 135, 243, 255, 234, 225, 128, 128, 128, 128, 128 },
72       { 80, 129, 211, 255, 194, 224, 128, 128, 128, 128, 128 }
73     },
74     { { 1, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
75       { 246, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
76       { 255, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 }
77     }
78   },
79   { { { 198, 35, 237, 223, 193, 187, 162, 160, 145, 155, 62 },
80       { 131, 45, 198, 221, 172, 176, 220, 157, 252, 221, 1 },
81       { 68, 47, 146, 208, 149, 167, 221, 162, 255, 223, 128 }
82     },
83     { { 1, 149, 241, 255, 221, 224, 255, 255, 128, 128, 128 },
84       { 184, 141, 234, 253, 222, 220, 255, 199, 128, 128, 128 },
85       { 81, 99, 181, 242, 176, 190, 249, 202, 255, 255, 128 }
86     },
87     { { 1, 129, 232, 253, 214, 197, 242, 196, 255, 255, 128 },
88       { 99, 121, 210, 250, 201, 198, 255, 202, 128, 128, 128 },
89       { 23, 91, 163, 242, 170, 187, 247, 210, 255, 255, 128 }
90     },
91     { { 1, 200, 246, 255, 234, 255, 128, 128, 128, 128, 128 },
92       { 109, 178, 241, 255, 231, 245, 255, 255, 128, 128, 128 },
93       { 44, 130, 201, 253, 205, 192, 255, 255, 128, 128, 128 }
94     },
95     { { 1, 132, 239, 251, 219, 209, 255, 165, 128, 128, 128 },
96       { 94, 136, 225, 251, 218, 190, 255, 255, 128, 128, 128 },
97       { 22, 100, 174, 245, 186, 161, 255, 199, 128, 128, 128 }
98     },
99     { { 1, 182, 249, 255, 232, 235, 128, 128, 128, 128, 128 },
100       { 124, 143, 241, 255, 227, 234, 128, 128, 128, 128, 128 },
101       { 35, 77, 181, 251, 193, 211, 255, 205, 128, 128, 128 }
102     },
103     { { 1, 157, 247, 255, 236, 231, 255, 255, 128, 128, 128 },
104       { 121, 141, 235, 255, 225, 227, 255, 255, 128, 128, 128 },
105       { 45, 99, 188, 251, 195, 217, 255, 224, 128, 128, 128 }
106     },
107     { { 1, 1, 251, 255, 213, 255, 128, 128, 128, 128, 128 },
108       { 203, 1, 248, 255, 255, 128, 128, 128, 128, 128, 128 },
109       { 137, 1, 177, 255, 224, 255, 128, 128, 128, 128, 128 }
110     }
111   },
112   { { { 253, 9, 248, 251, 207, 208, 255, 192, 128, 128, 128 },
113       { 175, 13, 224, 243, 193, 185, 249, 198, 255, 255, 128 },
114       { 73, 17, 171, 221, 161, 179, 236, 167, 255, 234, 128 }
115     },
116     { { 1, 95, 247, 253, 212, 183, 255, 255, 128, 128, 128 },
117       { 239, 90, 244, 250, 211, 209, 255, 255, 128, 128, 128 },
118       { 155, 77, 195, 248, 188, 195, 255, 255, 128, 128, 128 }
119     },
120     { { 1, 24, 239, 251, 218, 219, 255, 205, 128, 128, 128 },
121       { 201, 51, 219, 255, 196, 186, 128, 128, 128, 128, 128 },
122       { 69, 46, 190, 239, 201, 218, 255, 228, 128, 128, 128 }
123     },
124     { { 1, 191, 251, 255, 255, 128, 128, 128, 128, 128, 128 },
125       { 223, 165, 249, 255, 213, 255, 128, 128, 128, 128, 128 },
126       { 141, 124, 248, 255, 255, 128, 128, 128, 128, 128, 128 }
127     },
128     { { 1, 16, 248, 255, 255, 128, 128, 128, 128, 128, 128 },
129       { 190, 36, 230, 255, 236, 255, 128, 128, 128, 128, 128 },
130       { 149, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 }
131     },
132     { { 1, 226, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
133       { 247, 192, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
134       { 240, 128, 255, 128, 128, 128, 128, 128, 128, 128, 128 }
135     },
136     { { 1, 134, 252, 255, 255, 128, 128, 128, 128, 128, 128 },
137       { 213, 62, 250, 255, 255, 128, 128, 128, 128, 128, 128 },
138       { 55, 93, 255, 128, 128, 128, 128, 128, 128, 128, 128 }
139     },
140     { { 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 },
141       { 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 },
142       { 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 }
143     }
144   },
145   { { { 202, 24, 213, 235, 186, 191, 220, 160, 240, 175, 255 },
146       { 126, 38, 182, 232, 169, 184, 228, 174, 255, 187, 128 },
147       { 61, 46, 138, 219, 151, 178, 240, 170, 255, 216, 128 }
148     },
149     { { 1, 112, 230, 250, 199, 191, 247, 159, 255, 255, 128 },
150       { 166, 109, 228, 252, 211, 215, 255, 174, 128, 128, 128 },
151       { 39, 77, 162, 232, 172, 180, 245, 178, 255, 255, 128 }
152     },
153     { { 1, 52, 220, 246, 198, 199, 249, 220, 255, 255, 128 },
154       { 124, 74, 191, 243, 183, 193, 250, 221, 255, 255, 128 },
155       { 24, 71, 130, 219, 154, 170, 243, 182, 255, 255, 128 }
156     },
157     { { 1, 182, 225, 249, 219, 240, 255, 224, 128, 128, 128 },
158       { 149, 150, 226, 252, 216, 205, 255, 171, 128, 128, 128 },
159       { 28, 108, 170, 242, 183, 194, 254, 223, 255, 255, 128 }
160     },
161     { { 1, 81, 230, 252, 204, 203, 255, 192, 128, 128, 128 },
162       { 123, 102, 209, 247, 188, 196, 255, 233, 128, 128, 128 },
163       { 20, 95, 153, 243, 164, 173, 255, 203, 128, 128, 128 }
164     },
165     { { 1, 222, 248, 255, 216, 213, 128, 128, 128, 128, 128 },
166       { 168, 175, 246, 252, 235, 205, 255, 255, 128, 128, 128 },
167       { 47, 116, 215, 255, 211, 212, 255, 255, 128, 128, 128 }
168     },
169     { { 1, 121, 236, 253, 212, 214, 255, 255, 128, 128, 128 },
170       { 141, 84, 213, 252, 201, 202, 255, 219, 128, 128, 128 },
171       { 42, 80, 160, 240, 162, 185, 255, 205, 128, 128, 128 }
172     },
173     { { 1, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
174       { 244, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
175       { 238, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 }
176     }
177   }
178 };
179 
180 // Paragraph 11.5
181 static const uint8_t kBModesProba[NUM_BMODES][NUM_BMODES][NUM_BMODES - 1] = {
182   { { 231, 120, 48, 89, 115, 113, 120, 152, 112 },
183     { 152, 179, 64, 126, 170, 118, 46, 70, 95 },
184     { 175, 69, 143, 80, 85, 82, 72, 155, 103 },
185     { 56, 58, 10, 171, 218, 189, 17, 13, 152 },
186     { 114, 26, 17, 163, 44, 195, 21, 10, 173 },
187     { 121, 24, 80, 195, 26, 62, 44, 64, 85 },
188     { 144, 71, 10, 38, 171, 213, 144, 34, 26 },
189     { 170, 46, 55, 19, 136, 160, 33, 206, 71 },
190     { 63, 20, 8, 114, 114, 208, 12, 9, 226 },
191     { 81, 40, 11, 96, 182, 84, 29, 16, 36 } },
192   { { 134, 183, 89, 137, 98, 101, 106, 165, 148 },
193     { 72, 187, 100, 130, 157, 111, 32, 75, 80 },
194     { 66, 102, 167, 99, 74, 62, 40, 234, 128 },
195     { 41, 53, 9, 178, 241, 141, 26, 8, 107 },
196     { 74, 43, 26, 146, 73, 166, 49, 23, 157 },
197     { 65, 38, 105, 160, 51, 52, 31, 115, 128 },
198     { 104, 79, 12, 27, 217, 255, 87, 17, 7 },
199     { 87, 68, 71, 44, 114, 51, 15, 186, 23 },
200     { 47, 41, 14, 110, 182, 183, 21, 17, 194 },
201     { 66, 45, 25, 102, 197, 189, 23, 18, 22 } },
202   { { 88, 88, 147, 150, 42, 46, 45, 196, 205 },
203     { 43, 97, 183, 117, 85, 38, 35, 179, 61 },
204     { 39, 53, 200, 87, 26, 21, 43, 232, 171 },
205     { 56, 34, 51, 104, 114, 102, 29, 93, 77 },
206     { 39, 28, 85, 171, 58, 165, 90, 98, 64 },
207     { 34, 22, 116, 206, 23, 34, 43, 166, 73 },
208     { 107, 54, 32, 26, 51, 1, 81, 43, 31 },
209     { 68, 25, 106, 22, 64, 171, 36, 225, 114 },
210     { 34, 19, 21, 102, 132, 188, 16, 76, 124 },
211     { 62, 18, 78, 95, 85, 57, 50, 48, 51 } },
212   { { 193, 101, 35, 159, 215, 111, 89, 46, 111 },
213     { 60, 148, 31, 172, 219, 228, 21, 18, 111 },
214     { 112, 113, 77, 85, 179, 255, 38, 120, 114 },
215     { 40, 42, 1, 196, 245, 209, 10, 25, 109 },
216     { 88, 43, 29, 140, 166, 213, 37, 43, 154 },
217     { 61, 63, 30, 155, 67, 45, 68, 1, 209 },
218     { 100, 80, 8, 43, 154, 1, 51, 26, 71 },
219     { 142, 78, 78, 16, 255, 128, 34, 197, 171 },
220     { 41, 40, 5, 102, 211, 183, 4, 1, 221 },
221     { 51, 50, 17, 168, 209, 192, 23, 25, 82 } },
222   { { 138, 31, 36, 171, 27, 166, 38, 44, 229 },
223     { 67, 87, 58, 169, 82, 115, 26, 59, 179 },
224     { 63, 59, 90, 180, 59, 166, 93, 73, 154 },
225     { 40, 40, 21, 116, 143, 209, 34, 39, 175 },
226     { 47, 15, 16, 183, 34, 223, 49, 45, 183 },
227     { 46, 17, 33, 183, 6, 98, 15, 32, 183 },
228     { 57, 46, 22, 24, 128, 1, 54, 17, 37 },
229     { 65, 32, 73, 115, 28, 128, 23, 128, 205 },
230     { 40, 3, 9, 115, 51, 192, 18, 6, 223 },
231     { 87, 37, 9, 115, 59, 77, 64, 21, 47 } },
232   { { 104, 55, 44, 218, 9, 54, 53, 130, 226 },
233     { 64, 90, 70, 205, 40, 41, 23, 26, 57 },
234     { 54, 57, 112, 184, 5, 41, 38, 166, 213 },
235     { 30, 34, 26, 133, 152, 116, 10, 32, 134 },
236     { 39, 19, 53, 221, 26, 114, 32, 73, 255 },
237     { 31, 9, 65, 234, 2, 15, 1, 118, 73 },
238     { 75, 32, 12, 51, 192, 255, 160, 43, 51 },
239     { 88, 31, 35, 67, 102, 85, 55, 186, 85 },
240     { 56, 21, 23, 111, 59, 205, 45, 37, 192 },
241     { 55, 38, 70, 124, 73, 102, 1, 34, 98 } },
242   { { 125, 98, 42, 88, 104, 85, 117, 175, 82 },
243     { 95, 84, 53, 89, 128, 100, 113, 101, 45 },
244     { 75, 79, 123, 47, 51, 128, 81, 171, 1 },
245     { 57, 17, 5, 71, 102, 57, 53, 41, 49 },
246     { 38, 33, 13, 121, 57, 73, 26, 1, 85 },
247     { 41, 10, 67, 138, 77, 110, 90, 47, 114 },
248     { 115, 21, 2, 10, 102, 255, 166, 23, 6 },
249     { 101, 29, 16, 10, 85, 128, 101, 196, 26 },
250     { 57, 18, 10, 102, 102, 213, 34, 20, 43 },
251     { 117, 20, 15, 36, 163, 128, 68, 1, 26 } },
252   { { 102, 61, 71, 37, 34, 53, 31, 243, 192 },
253     { 69, 60, 71, 38, 73, 119, 28, 222, 37 },
254     { 68, 45, 128, 34, 1, 47, 11, 245, 171 },
255     { 62, 17, 19, 70, 146, 85, 55, 62, 70 },
256     { 37, 43, 37, 154, 100, 163, 85, 160, 1 },
257     { 63, 9, 92, 136, 28, 64, 32, 201, 85 },
258     { 75, 15, 9, 9, 64, 255, 184, 119, 16 },
259     { 86, 6, 28, 5, 64, 255, 25, 248, 1 },
260     { 56, 8, 17, 132, 137, 255, 55, 116, 128 },
261     { 58, 15, 20, 82, 135, 57, 26, 121, 40 } },
262   { { 164, 50, 31, 137, 154, 133, 25, 35, 218 },
263     { 51, 103, 44, 131, 131, 123, 31, 6, 158 },
264     { 86, 40, 64, 135, 148, 224, 45, 183, 128 },
265     { 22, 26, 17, 131, 240, 154, 14, 1, 209 },
266     { 45, 16, 21, 91, 64, 222, 7, 1, 197 },
267     { 56, 21, 39, 155, 60, 138, 23, 102, 213 },
268     { 83, 12, 13, 54, 192, 255, 68, 47, 28 },
269     { 85, 26, 85, 85, 128, 128, 32, 146, 171 },
270     { 18, 11, 7, 63, 144, 171, 4, 4, 246 },
271     { 35, 27, 10, 146, 174, 171, 12, 26, 128 } },
272   { { 190, 80, 35, 99, 180, 80, 126, 54, 45 },
273     { 85, 126, 47, 87, 176, 51, 41, 20, 32 },
274     { 101, 75, 128, 139, 118, 146, 116, 128, 85 },
275     { 56, 41, 15, 176, 236, 85, 37, 9, 62 },
276     { 71, 30, 17, 119, 118, 255, 17, 18, 138 },
277     { 101, 38, 60, 138, 55, 70, 43, 26, 142 },
278     { 146, 36, 19, 30, 171, 255, 97, 27, 20 },
279     { 138, 45, 61, 62, 219, 1, 81, 188, 64 },
280     { 32, 41, 20, 117, 151, 142, 20, 21, 163 },
281     { 112, 19, 12, 61, 195, 128, 48, 4, 24 } }
282 };
283 
VP8ResetProba(VP8Proba * const proba)284 void VP8ResetProba(VP8Proba* const proba) {
285   memset(proba->segments_, 255u, sizeof(proba->segments_));
286   // proba->bands_[][] is initialized later
287 }
288 
ParseIntraMode(VP8BitReader * const br,VP8Decoder * const dec,int mb_x)289 static void ParseIntraMode(VP8BitReader* const br,
290                            VP8Decoder* const dec, int mb_x) {
291   uint8_t* const top = dec->intra_t_ + 4 * mb_x;
292   uint8_t* const left = dec->intra_l_;
293   VP8MBData* const block = dec->mb_data_ + mb_x;
294 
295   // Note: we don't save segment map (yet), as we don't expect
296   // to decode more than 1 keyframe.
297   if (dec->segment_hdr_.update_map_) {
298     // Hardcoded tree parsing
299     block->segment_ = !VP8GetBit(br, dec->proba_.segments_[0])
300                     ? VP8GetBit(br, dec->proba_.segments_[1])
301                     : 2 + VP8GetBit(br, dec->proba_.segments_[2]);
302   } else {
303     block->segment_ = 0;  // default for intra
304   }
305   if (dec->use_skip_proba_) block->skip_ = VP8GetBit(br, dec->skip_p_);
306 
307   block->is_i4x4_ = !VP8GetBit(br, 145);   // decide for B_PRED first
308   if (!block->is_i4x4_) {
309     // Hardcoded 16x16 intra-mode decision tree.
310     const int ymode =
311         VP8GetBit(br, 156) ? (VP8GetBit(br, 128) ? TM_PRED : H_PRED)
312                            : (VP8GetBit(br, 163) ? V_PRED : DC_PRED);
313     block->imodes_[0] = ymode;
314     memset(top, ymode, 4 * sizeof(*top));
315     memset(left, ymode, 4 * sizeof(*left));
316   } else {
317     uint8_t* modes = block->imodes_;
318     int y;
319     for (y = 0; y < 4; ++y) {
320       int ymode = left[y];
321       int x;
322       for (x = 0; x < 4; ++x) {
323         const uint8_t* const prob = kBModesProba[top[x]][ymode];
324 #if (USE_GENERIC_TREE == 1)
325         // Generic tree-parsing
326         int i = kYModesIntra4[VP8GetBit(br, prob[0])];
327         while (i > 0) {
328           i = kYModesIntra4[2 * i + VP8GetBit(br, prob[i])];
329         }
330         ymode = -i;
331 #else
332         // Hardcoded tree parsing
333         ymode = !VP8GetBit(br, prob[0]) ? B_DC_PRED :
334                   !VP8GetBit(br, prob[1]) ? B_TM_PRED :
335                     !VP8GetBit(br, prob[2]) ? B_VE_PRED :
336                       !VP8GetBit(br, prob[3]) ?
337                         (!VP8GetBit(br, prob[4]) ? B_HE_PRED :
338                           (!VP8GetBit(br, prob[5]) ? B_RD_PRED : B_VR_PRED)) :
339                         (!VP8GetBit(br, prob[6]) ? B_LD_PRED :
340                           (!VP8GetBit(br, prob[7]) ? B_VL_PRED :
341                             (!VP8GetBit(br, prob[8]) ? B_HD_PRED : B_HU_PRED)));
342 #endif  // USE_GENERIC_TREE
343         top[x] = ymode;
344       }
345       memcpy(modes, top, 4 * sizeof(*top));
346       modes += 4;
347       left[y] = ymode;
348     }
349   }
350   // Hardcoded UVMode decision tree
351   block->uvmode_ = !VP8GetBit(br, 142) ? DC_PRED
352                  : !VP8GetBit(br, 114) ? V_PRED
353                  : VP8GetBit(br, 183) ? TM_PRED : H_PRED;
354 }
355 
VP8ParseIntraModeRow(VP8BitReader * const br,VP8Decoder * const dec)356 int VP8ParseIntraModeRow(VP8BitReader* const br, VP8Decoder* const dec) {
357   int mb_x;
358   for (mb_x = 0; mb_x < dec->mb_w_; ++mb_x) {
359     ParseIntraMode(br, dec, mb_x);
360   }
361   return !dec->br_.eof_;
362 }
363 
364 //------------------------------------------------------------------------------
365 // Paragraph 13
366 
367 static const uint8_t
368     CoeffsUpdateProba[NUM_TYPES][NUM_BANDS][NUM_CTX][NUM_PROBAS] = {
369   { { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
370       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
371       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
372     },
373     { { 176, 246, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
374       { 223, 241, 252, 255, 255, 255, 255, 255, 255, 255, 255 },
375       { 249, 253, 253, 255, 255, 255, 255, 255, 255, 255, 255 }
376     },
377     { { 255, 244, 252, 255, 255, 255, 255, 255, 255, 255, 255 },
378       { 234, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
379       { 253, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
380     },
381     { { 255, 246, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
382       { 239, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
383       { 254, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255 }
384     },
385     { { 255, 248, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
386       { 251, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
387       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
388     },
389     { { 255, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
390       { 251, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
391       { 254, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255 }
392     },
393     { { 255, 254, 253, 255, 254, 255, 255, 255, 255, 255, 255 },
394       { 250, 255, 254, 255, 254, 255, 255, 255, 255, 255, 255 },
395       { 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
396     },
397     { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
398       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
399       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
400     }
401   },
402   { { { 217, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
403       { 225, 252, 241, 253, 255, 255, 254, 255, 255, 255, 255 },
404       { 234, 250, 241, 250, 253, 255, 253, 254, 255, 255, 255 }
405     },
406     { { 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
407       { 223, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
408       { 238, 253, 254, 254, 255, 255, 255, 255, 255, 255, 255 }
409     },
410     { { 255, 248, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
411       { 249, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
412       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
413     },
414     { { 255, 253, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
415       { 247, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
416       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
417     },
418     { { 255, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
419       { 252, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
420       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
421     },
422     { { 255, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
423       { 253, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
424       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
425     },
426     { { 255, 254, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
427       { 250, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
428       { 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
429     },
430     { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
431       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
432       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
433     }
434   },
435   { { { 186, 251, 250, 255, 255, 255, 255, 255, 255, 255, 255 },
436       { 234, 251, 244, 254, 255, 255, 255, 255, 255, 255, 255 },
437       { 251, 251, 243, 253, 254, 255, 254, 255, 255, 255, 255 }
438     },
439     { { 255, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
440       { 236, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
441       { 251, 253, 253, 254, 254, 255, 255, 255, 255, 255, 255 }
442     },
443     { { 255, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
444       { 254, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
445       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
446     },
447     { { 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
448       { 254, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
449       { 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
450     },
451     { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
452       { 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
453       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
454     },
455     { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
456       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
457       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
458     },
459     { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
460       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
461       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
462     },
463     { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
464       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
465       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
466     }
467   },
468   { { { 248, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
469       { 250, 254, 252, 254, 255, 255, 255, 255, 255, 255, 255 },
470       { 248, 254, 249, 253, 255, 255, 255, 255, 255, 255, 255 }
471     },
472     { { 255, 253, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
473       { 246, 253, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
474       { 252, 254, 251, 254, 254, 255, 255, 255, 255, 255, 255 }
475     },
476     { { 255, 254, 252, 255, 255, 255, 255, 255, 255, 255, 255 },
477       { 248, 254, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
478       { 253, 255, 254, 254, 255, 255, 255, 255, 255, 255, 255 }
479     },
480     { { 255, 251, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
481       { 245, 251, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
482       { 253, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 }
483     },
484     { { 255, 251, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
485       { 252, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
486       { 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
487     },
488     { { 255, 252, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
489       { 249, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
490       { 255, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255 }
491     },
492     { { 255, 255, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
493       { 250, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
494       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
495     },
496     { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
497       { 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
498       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
499     }
500   }
501 };
502 
503 // Paragraph 9.9
504 
505 static const uint8_t kBands[16 + 1] = {
506   0, 1, 2, 3, 6, 4, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7,
507   0  // extra entry as sentinel
508 };
509 
VP8ParseProba(VP8BitReader * const br,VP8Decoder * const dec)510 void VP8ParseProba(VP8BitReader* const br, VP8Decoder* const dec) {
511   VP8Proba* const proba = &dec->proba_;
512   int t, b, c, p;
513   for (t = 0; t < NUM_TYPES; ++t) {
514     for (b = 0; b < NUM_BANDS; ++b) {
515       for (c = 0; c < NUM_CTX; ++c) {
516         for (p = 0; p < NUM_PROBAS; ++p) {
517           const int v = VP8GetBit(br, CoeffsUpdateProba[t][b][c][p]) ?
518                         VP8GetValue(br, 8) : CoeffsProba0[t][b][c][p];
519           proba->bands_[t][b].probas_[c][p] = v;
520         }
521       }
522     }
523     for (b = 0; b < 16 + 1; ++b) {
524       proba->bands_ptr_[t][b] = &proba->bands_[t][kBands[b]];
525     }
526   }
527   dec->use_skip_proba_ = VP8Get(br);
528   if (dec->use_skip_proba_) {
529     dec->skip_p_ = VP8GetValue(br, 8);
530   }
531 }
532 
533