media/libvpx/vp8/common/idctllm.c@ac0c01689b40
media/libvpx/vp8/common/idctllm.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 /****************************************************************************
13 * Notes:
14 *
15 * This implementation makes use of 16 bit fixed point verio of two multiply
16 * constants:
17 * 1. sqrt(2) * cos (pi/8)
18 * 2. sqrt(2) * sin (pi/8)
19 * Becuase the first constant is bigger than 1, to maintain the same 16 bit
20 * fixed point precision as the second one, we use a trick of
21 * x * a = x + x*(a-1)
22 * so
23 * x * sqrt(2) * cos (pi/8) = x + x * (sqrt(2) *cos(pi/8)-1).
24 **************************************************************************/
25 static const int cospi8sqrt2minus1 = 20091;
26 static const int sinpi8sqrt2 = 35468;
28 void vp8_short_idct4x4llm_c(short *input, unsigned char *pred_ptr,
29 int pred_stride, unsigned char *dst_ptr,
30 int dst_stride)
31 {
32 int i;
33 int r, c;
34 int a1, b1, c1, d1;
35 short output[16];
36 short *ip = input;
37 short *op = output;
38 int temp1, temp2;
39 int shortpitch = 4;
41 for (i = 0; i < 4; i++)
42 {
43 a1 = ip[0] + ip[8];
44 b1 = ip[0] - ip[8];
46 temp1 = (ip[4] * sinpi8sqrt2) >> 16;
47 temp2 = ip[12] + ((ip[12] * cospi8sqrt2minus1) >> 16);
48 c1 = temp1 - temp2;
50 temp1 = ip[4] + ((ip[4] * cospi8sqrt2minus1) >> 16);
51 temp2 = (ip[12] * sinpi8sqrt2) >> 16;
52 d1 = temp1 + temp2;
54 op[shortpitch*0] = a1 + d1;
55 op[shortpitch*3] = a1 - d1;
57 op[shortpitch*1] = b1 + c1;
58 op[shortpitch*2] = b1 - c1;
60 ip++;
61 op++;
62 }
64 ip = output;
65 op = output;
67 for (i = 0; i < 4; i++)
68 {
69 a1 = ip[0] + ip[2];
70 b1 = ip[0] - ip[2];
72 temp1 = (ip[1] * sinpi8sqrt2) >> 16;
73 temp2 = ip[3] + ((ip[3] * cospi8sqrt2minus1) >> 16);
74 c1 = temp1 - temp2;
76 temp1 = ip[1] + ((ip[1] * cospi8sqrt2minus1) >> 16);
77 temp2 = (ip[3] * sinpi8sqrt2) >> 16;
78 d1 = temp1 + temp2;
81 op[0] = (a1 + d1 + 4) >> 3;
82 op[3] = (a1 - d1 + 4) >> 3;
84 op[1] = (b1 + c1 + 4) >> 3;
85 op[2] = (b1 - c1 + 4) >> 3;
87 ip += shortpitch;
88 op += shortpitch;
89 }
91 ip = output;
92 for (r = 0; r < 4; r++)
93 {
94 for (c = 0; c < 4; c++)
95 {
96 int a = ip[c] + pred_ptr[c] ;
98 if (a < 0)
99 a = 0;
101 if (a > 255)
102 a = 255;
104 dst_ptr[c] = (unsigned char) a ;
105 }
106 ip += 4;
107 dst_ptr += dst_stride;
108 pred_ptr += pred_stride;
109 }
110 }
112 void vp8_dc_only_idct_add_c(short input_dc, unsigned char *pred_ptr,
113 int pred_stride, unsigned char *dst_ptr,
114 int dst_stride)
115 {
116 int a1 = ((input_dc + 4) >> 3);
117 int r, c;
119 for (r = 0; r < 4; r++)
120 {
121 for (c = 0; c < 4; c++)
122 {
123 int a = a1 + pred_ptr[c] ;
125 if (a < 0)
126 a = 0;
128 if (a > 255)
129 a = 255;
131 dst_ptr[c] = (unsigned char) a ;
132 }
134 dst_ptr += dst_stride;
135 pred_ptr += pred_stride;
136 }
138 }
140 void vp8_short_inv_walsh4x4_c(short *input, short *mb_dqcoeff)
141 {
142 short output[16];
143 int i;
144 int a1, b1, c1, d1;
145 int a2, b2, c2, d2;
146 short *ip = input;
147 short *op = output;
149 for (i = 0; i < 4; i++)
150 {
151 a1 = ip[0] + ip[12];
152 b1 = ip[4] + ip[8];
153 c1 = ip[4] - ip[8];
154 d1 = ip[0] - ip[12];
156 op[0] = a1 + b1;
157 op[4] = c1 + d1;
158 op[8] = a1 - b1;
159 op[12] = d1 - c1;
160 ip++;
161 op++;
162 }
164 ip = output;
165 op = output;
167 for (i = 0; i < 4; i++)
168 {
169 a1 = ip[0] + ip[3];
170 b1 = ip[1] + ip[2];
171 c1 = ip[1] - ip[2];
172 d1 = ip[0] - ip[3];
174 a2 = a1 + b1;
175 b2 = c1 + d1;
176 c2 = a1 - b1;
177 d2 = d1 - c1;
179 op[0] = (a2 + 3) >> 3;
180 op[1] = (b2 + 3) >> 3;
181 op[2] = (c2 + 3) >> 3;
182 op[3] = (d2 + 3) >> 3;
184 ip += 4;
185 op += 4;
186 }
188 for(i = 0; i < 16; i++)
189 {
190 mb_dqcoeff[i * 16] = output[i];
191 }
192 }
194 void vp8_short_inv_walsh4x4_1_c(short *input, short *mb_dqcoeff)
195 {
196 int i;
197 int a1;
199 a1 = ((input[0] + 3) >> 3);
200 for(i = 0; i < 16; i++)
201 {
202 mb_dqcoeff[i * 16] = a1;
203 }
204 }
