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 VPX_VP8_ENCODER_TREEWRITER_H_
12 #define VPX_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 vp8_tree_index i = 0;
61
62 do {
63 const int b = (v >> --n) & 1;
64 vp8_write(w, b, p[i >> 1]);
65 i = t[i + b];
66 } while (n);
67 }
vp8_write_token(vp8_writer * const w,vp8_tree t,const vp8_prob * const p,vp8_token * const x)68 static INLINE void vp8_write_token(vp8_writer *const w, vp8_tree t,
69 const vp8_prob *const p,
70 vp8_token *const x) {
71 vp8_treed_write(w, t, p, x->value, x->Len);
72 }
73
vp8_treed_cost(vp8_tree t,const vp8_prob * const p,int v,int n)74 static int vp8_treed_cost(vp8_tree t, const vp8_prob *const p, int v,
75 int n) { /* number of bits in v, assumed nonzero */
76 int c = 0;
77 vp8_tree_index i = 0;
78
79 do {
80 const int b = (v >> --n) & 1;
81 c += vp8_cost_bit(p[i >> 1], b);
82 i = t[i + b];
83 } while (n);
84
85 return c;
86 }
vp8_cost_token(vp8_tree t,const vp8_prob * const p,vp8_token * const x)87 static INLINE int vp8_cost_token(vp8_tree t, const vp8_prob *const p,
88 vp8_token *const x) {
89 return vp8_treed_cost(t, p, x->value, x->Len);
90 }
91
92 /* Fill array of costs for all possible token values. */
93
94 void vp8_cost_tokens(int *c, const vp8_prob *, vp8_tree);
95
96 void vp8_cost_tokens2(int *c, const vp8_prob *, vp8_tree, int);
97
98 #ifdef __cplusplus
99 } // extern "C"
100 #endif
101
102 #endif // VPX_VP8_ENCODER_TREEWRITER_H_
103