media/libvpx/vp8/decoder/detokenize.c@ac0c01689b40
media/libvpx/vp8/decoder/detokenize.c
Thu, 15 Jan 2015 15:59:08 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Thu, 15 Jan 2015 15:59:08 +0100
- branch
- TOR_BUG_9701
- changeset 10
- ac0c01689b40
- permissions
- -rw-r--r--
Implement a real Private Browsing Mode condition by changing the API/ABI;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.
1 /*
2 * Copyright (c) 2010 The WebM project authors. All Rights Reserved.
3 *
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
12 #include "vp8/common/blockd.h"
13 #include "onyxd_int.h"
14 #include "vpx_mem/vpx_mem.h"
15 #include "vpx_ports/mem.h"
16 #include "detokenize.h"
18 void vp8_reset_mb_tokens_context(MACROBLOCKD *x)
19 {
20 ENTROPY_CONTEXT *a_ctx = ((ENTROPY_CONTEXT *)x->above_context);
21 ENTROPY_CONTEXT *l_ctx = ((ENTROPY_CONTEXT *)x->left_context);
23 vpx_memset(a_ctx, 0, sizeof(ENTROPY_CONTEXT_PLANES)-1);
24 vpx_memset(l_ctx, 0, sizeof(ENTROPY_CONTEXT_PLANES)-1);
26 /* Clear entropy contexts for Y2 blocks */
27 if (!x->mode_info_context->mbmi.is_4x4)
28 {
29 a_ctx[8] = l_ctx[8] = 0;
30 }
31 }
33 /*
34 ------------------------------------------------------------------------------
35 Residual decoding (Paragraph 13.2 / 13.3)
36 */
37 static const uint8_t kBands[16 + 1] = {
38 0, 1, 2, 3, 6, 4, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7,
39 0 /* extra entry as sentinel */
40 };
42 static const uint8_t kCat3[] = { 173, 148, 140, 0 };
43 static const uint8_t kCat4[] = { 176, 155, 140, 135, 0 };
44 static const uint8_t kCat5[] = { 180, 157, 141, 134, 130, 0 };
45 static const uint8_t kCat6[] =
46 { 254, 254, 243, 230, 196, 177, 153, 140, 133, 130, 129, 0 };
47 static const uint8_t* const kCat3456[] = { kCat3, kCat4, kCat5, kCat6 };
48 static const uint8_t kZigzag[16] = {
49 0, 1, 4, 8, 5, 2, 3, 6, 9, 12, 13, 10, 7, 11, 14, 15
50 };
52 #define VP8GetBit vp8dx_decode_bool
53 #define NUM_PROBAS 11
54 #define NUM_CTX 3
56 /* for const-casting */
57 typedef const uint8_t (*ProbaArray)[NUM_CTX][NUM_PROBAS];
59 static int GetSigned(BOOL_DECODER *br, int value_to_sign)
60 {
61 int split = (br->range + 1) >> 1;
62 VP8_BD_VALUE bigsplit = (VP8_BD_VALUE)split << (VP8_BD_VALUE_SIZE - 8);
63 int v;
65 if(br->count < 0)
66 vp8dx_bool_decoder_fill(br);
68 if ( br->value < bigsplit )
69 {
70 br->range = split;
71 v= value_to_sign;
72 }
73 else
74 {
75 br->range = br->range-split;
76 br->value = br->value-bigsplit;
77 v = -value_to_sign;
78 }
79 br->range +=br->range;
80 br->value +=br->value;
81 br->count--;
83 return v;
84 }
85 /*
86 Returns the position of the last non-zero coeff plus one
87 (and 0 if there's no coeff at all)
88 */
89 static int GetCoeffs(BOOL_DECODER *br, ProbaArray prob,
90 int ctx, int n, int16_t* out)
91 {
92 const uint8_t* p = prob[n][ctx];
93 if (!VP8GetBit(br, p[0]))
94 { /* first EOB is more a 'CBP' bit. */
95 return 0;
96 }
97 while (1)
98 {
99 ++n;
100 if (!VP8GetBit(br, p[1]))
101 {
102 p = prob[kBands[n]][0];
103 }
104 else
105 { /* non zero coeff */
106 int v, j;
107 if (!VP8GetBit(br, p[2]))
108 {
109 p = prob[kBands[n]][1];
110 v = 1;
111 }
112 else
113 {
114 if (!VP8GetBit(br, p[3]))
115 {
116 if (!VP8GetBit(br, p[4]))
117 {
118 v = 2;
119 }
120 else
121 {
122 v = 3 + VP8GetBit(br, p[5]);
123 }
124 }
125 else
126 {
127 if (!VP8GetBit(br, p[6]))
128 {
129 if (!VP8GetBit(br, p[7]))
130 {
131 v = 5 + VP8GetBit(br, 159);
132 } else
133 {
134 v = 7 + 2 * VP8GetBit(br, 165);
135 v += VP8GetBit(br, 145);
136 }
137 }
138 else
139 {
140 const uint8_t* tab;
141 const int bit1 = VP8GetBit(br, p[8]);
142 const int bit0 = VP8GetBit(br, p[9 + bit1]);
143 const int cat = 2 * bit1 + bit0;
144 v = 0;
145 for (tab = kCat3456[cat]; *tab; ++tab)
146 {
147 v += v + VP8GetBit(br, *tab);
148 }
149 v += 3 + (8 << cat);
150 }
151 }
152 p = prob[kBands[n]][2];
153 }
154 j = kZigzag[n - 1];
156 out[j] = GetSigned(br, v);
158 if (n == 16 || !VP8GetBit(br, p[0]))
159 { /* EOB */
160 return n;
161 }
162 }
163 if (n == 16)
164 {
165 return 16;
166 }
167 }
168 }
170 int vp8_decode_mb_tokens(VP8D_COMP *dx, MACROBLOCKD *x)
171 {
172 BOOL_DECODER *bc = x->current_bc;
173 const FRAME_CONTEXT * const fc = &dx->common.fc;
174 char *eobs = x->eobs;
176 int i;
177 int nonzeros;
178 int eobtotal = 0;
180 short *qcoeff_ptr;
181 ProbaArray coef_probs;
182 ENTROPY_CONTEXT *a_ctx = ((ENTROPY_CONTEXT *)x->above_context);
183 ENTROPY_CONTEXT *l_ctx = ((ENTROPY_CONTEXT *)x->left_context);
184 ENTROPY_CONTEXT *a;
185 ENTROPY_CONTEXT *l;
186 int skip_dc = 0;
188 qcoeff_ptr = &x->qcoeff[0];
190 if (!x->mode_info_context->mbmi.is_4x4)
191 {
192 a = a_ctx + 8;
193 l = l_ctx + 8;
195 coef_probs = fc->coef_probs [1];
197 nonzeros = GetCoeffs(bc, coef_probs, (*a + *l), 0, qcoeff_ptr + 24 * 16);
198 *a = *l = (nonzeros > 0);
200 eobs[24] = nonzeros;
201 eobtotal += nonzeros - 16;
203 coef_probs = fc->coef_probs [0];
204 skip_dc = 1;
205 }
206 else
207 {
208 coef_probs = fc->coef_probs [3];
209 skip_dc = 0;
210 }
212 for (i = 0; i < 16; ++i)
213 {
214 a = a_ctx + (i&3);
215 l = l_ctx + ((i&0xc)>>2);
217 nonzeros = GetCoeffs(bc, coef_probs, (*a + *l), skip_dc, qcoeff_ptr);
218 *a = *l = (nonzeros > 0);
220 nonzeros += skip_dc;
221 eobs[i] = nonzeros;
222 eobtotal += nonzeros;
223 qcoeff_ptr += 16;
224 }
226 coef_probs = fc->coef_probs [2];
228 a_ctx += 4;
229 l_ctx += 4;
230 for (i = 16; i < 24; ++i)
231 {
232 a = a_ctx + ((i > 19)<<1) + (i&1);
233 l = l_ctx + ((i > 19)<<1) + ((i&3)>1);
235 nonzeros = GetCoeffs(bc, coef_probs, (*a + *l), 0, qcoeff_ptr);
236 *a = *l = (nonzeros > 0);
238 eobs[i] = nonzeros;
239 eobtotal += nonzeros;
240 qcoeff_ptr += 16;
241 }
243 return eobtotal;
244 }
