media/libvpx/vp8/encoder/treewriter.h@ac0c01689b40
media/libvpx/vp8/encoder/treewriter.h
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 #ifndef __INC_TREEWRITER_H
13 #define __INC_TREEWRITER_H
15 /* Trees map alphabets into huffman-like codes suitable for an arithmetic
16 bit coder. Timothy S Murphy 11 October 2004 */
18 #include "vp8/common/treecoder.h"
20 #include "boolhuff.h" /* for now */
22 typedef BOOL_CODER vp8_writer;
24 #define vp8_write vp8_encode_bool
25 #define vp8_write_literal vp8_encode_value
26 #define vp8_write_bit( W, V) vp8_write( W, V, vp8_prob_half)
28 #define vp8bc_write vp8bc_write_bool
29 #define vp8bc_write_literal vp8bc_write_bits
30 #define vp8bc_write_bit( W, V) vp8bc_write_bits( W, V, 1)
33 /* Approximate length of an encoded bool in 256ths of a bit at given prob */
35 #define vp8_cost_zero( x) ( vp8_prob_cost[x])
36 #define vp8_cost_one( x) vp8_cost_zero( vp8_complement(x))
38 #define vp8_cost_bit( x, b) vp8_cost_zero( (b)? vp8_complement(x) : (x) )
40 /* VP8BC version is scaled by 2^20 rather than 2^8; see bool_coder.h */
43 /* Both of these return bits, not scaled bits. */
45 static unsigned int vp8_cost_branch(const unsigned int ct[2], vp8_prob p)
46 {
47 /* Imitate existing calculation */
49 return ((ct[0] * vp8_cost_zero(p))
50 + (ct[1] * vp8_cost_one(p))) >> 8;
51 }
53 /* Small functions to write explicit values and tokens, as well as
54 estimate their lengths. */
56 static void vp8_treed_write
57 (
58 vp8_writer *const w,
59 vp8_tree t,
60 const vp8_prob *const p,
61 int v,
62 int n /* number of bits in v, assumed nonzero */
63 )
64 {
65 vp8_tree_index i = 0;
67 do
68 {
69 const int b = (v >> --n) & 1;
70 vp8_write(w, b, p[i>>1]);
71 i = t[i+b];
72 }
73 while (n);
74 }
75 static void vp8_write_token
76 (
77 vp8_writer *const w,
78 vp8_tree t,
79 const vp8_prob *const p,
80 vp8_token *const x
81 )
82 {
83 vp8_treed_write(w, t, p, x->value, x->Len);
84 }
86 static int vp8_treed_cost(
87 vp8_tree t,
88 const vp8_prob *const p,
89 int v,
90 int n /* number of bits in v, assumed nonzero */
91 )
92 {
93 int c = 0;
94 vp8_tree_index i = 0;
96 do
97 {
98 const int b = (v >> --n) & 1;
99 c += vp8_cost_bit(p[i>>1], b);
100 i = t[i+b];
101 }
102 while (n);
104 return c;
105 }
106 static int vp8_cost_token
107 (
108 vp8_tree t,
109 const vp8_prob *const p,
110 vp8_token *const x
111 )
112 {
113 return vp8_treed_cost(t, p, x->value, x->Len);
114 }
116 /* Fill array of costs for all possible token values. */
118 void vp8_cost_tokens(
119 int *Costs, const vp8_prob *, vp8_tree
120 );
122 void vp8_cost_tokens2(
123 int *Costs, const vp8_prob *, vp8_tree, int
124 );
126 #endif
