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 */
10
11 #ifndef VP8_ENCODER_TREEWRITER_H_
12 #define VP8_ENCODER_TREEWRITER_H_
13
14 /* Trees map alphabets into huffman-like codes suitable for an arithmetic
15 bit coder. Timothy S Murphy 11 October 2004 */
16
17 #include "./vpx_config.h"
18 #include "vp8/common/treecoder.h"
19
20 #include "boolhuff.h" /* for now */
21
22 #ifdef __cplusplus
23 extern "C" {
24 #endif
25
26 typedef BOOL_CODER vp8_writer;
27
28 #define vp8_write vp8_encode_bool
29 #define vp8_write_literal vp8_encode_value
30 #define vp8_write_bit(W, V) vp8_write(W, V, vp8_prob_half)
31
32 #define vp8bc_write vp8bc_write_bool
33 #define vp8bc_write_literal vp8bc_write_bits
34 #define vp8bc_write_bit(W, V) vp8bc_write_bits(W, V, 1)
35
36 /* Approximate length of an encoded bool in 256ths of a bit at given prob */
37
38 #define vp8_cost_zero(x) (vp8_prob_cost[x])
39 #define vp8_cost_one(x) vp8_cost_zero(vp8_complement(x))
40
41 #define vp8_cost_bit(x, b) vp8_cost_zero((b) ? vp8_complement(x) : (x))
42
43 /* VP8BC version is scaled by 2^20 rather than 2^8; see bool_coder.h */
44
45 /* Both of these return bits, not scaled bits. */
46
vp8_cost_branch(const unsigned int ct[2],vp8_prob p)47 static INLINE unsigned int vp8_cost_branch(const unsigned int ct[2],
48 vp8_prob p) {
49 /* Imitate existing calculation */
50
51 return ((ct[0] * vp8_cost_zero(p)) + (ct[1] * vp8_cost_one(p))) >> 8;
52 }
53
54 /* Small functions to write explicit values and tokens, as well as
55 estimate their lengths. */
56
vp8_treed_write(vp8_writer * const w,vp8_tree t,const vp8_prob * const p,int v,int n)57 static void vp8_treed_write(vp8_writer *const w, vp8_tree t,
58 const vp8_prob *const p, int v,
59 int n /* number of bits in v, assumed nonzero */
60 ) {
61 vp8_tree_index i = 0;
62
63 do {
64 const int b = (v >> --n) & 1;
65 vp8_write(w, b, p[i >> 1]);
66 i = t[i + b];
67 } while (n);
68 }
vp8_write_token(vp8_writer * const w,vp8_tree t,const vp8_prob * const p,vp8_token * const x)69 static INLINE void vp8_write_token(vp8_writer *const w, vp8_tree t,
70 const vp8_prob *const p,
71 vp8_token *const x) {
72 vp8_treed_write(w, t, p, x->value, x->Len);
73 }
74
vp8_treed_cost(vp8_tree t,const vp8_prob * const p,int v,int n)75 static int vp8_treed_cost(vp8_tree t, const vp8_prob *const p, int v,
76 int n /* number of bits in v, assumed nonzero */
77 ) {
78 int c = 0;
79 vp8_tree_index i = 0;
80
81 do {
82 const int b = (v >> --n) & 1;
83 c += vp8_cost_bit(p[i >> 1], b);
84 i = t[i + b];
85 } while (n);
86
87 return c;
88 }
vp8_cost_token(vp8_tree t,const vp8_prob * const p,vp8_token * const x)89 static INLINE int vp8_cost_token(vp8_tree t, const vp8_prob *const p,
90 vp8_token *const x) {
91 return vp8_treed_cost(t, p, x->value, x->Len);
92 }
93
94 /* Fill array of costs for all possible token values. */
95
96 void vp8_cost_tokens(int *Costs, const vp8_prob *, vp8_tree);
97
98 void vp8_cost_tokens2(int *Costs, const vp8_prob *, vp8_tree, int);
99
100 #ifdef __cplusplus
101 } // extern "C"
102 #endif
103
104 #endif // VP8_ENCODER_TREEWRITER_H_
105