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 12#ifndef VP8_ENCODER_TREEWRITER_H_ 13#define VP8_ENCODER_TREEWRITER_H_ 14 15/* Trees map alphabets into huffman-like codes suitable for an arithmetic 16 bit coder. Timothy S Murphy 11 October 2004 */ 17 18#include "vp8/common/treecoder.h" 19 20#include "boolhuff.h" /* for now */ 21 22#ifdef __cplusplus 23extern "C" { 24#endif 25 26typedef 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 37/* Approximate length of an encoded bool in 256ths of a bit at given prob */ 38 39#define vp8_cost_zero( x) ( vp8_prob_cost[x]) 40#define vp8_cost_one( x) vp8_cost_zero( vp8_complement(x)) 41 42#define vp8_cost_bit( x, b) vp8_cost_zero( (b)? vp8_complement(x) : (x) ) 43 44/* VP8BC version is scaled by 2^20 rather than 2^8; see bool_coder.h */ 45 46 47/* Both of these return bits, not scaled bits. */ 48 49static unsigned int vp8_cost_branch(const unsigned int ct[2], vp8_prob p) 50{ 51 /* Imitate existing calculation */ 52 53 return ((ct[0] * vp8_cost_zero(p)) 54 + (ct[1] * vp8_cost_one(p))) >> 8; 55} 56 57/* Small functions to write explicit values and tokens, as well as 58 estimate their lengths. */ 59 60static void vp8_treed_write 61( 62 vp8_writer *const w, 63 vp8_tree t, 64 const vp8_prob *const p, 65 int v, 66 int n /* number of bits in v, assumed nonzero */ 67) 68{ 69 vp8_tree_index i = 0; 70 71 do 72 { 73 const int b = (v >> --n) & 1; 74 vp8_write(w, b, p[i>>1]); 75 i = t[i+b]; 76 } 77 while (n); 78} 79static void vp8_write_token 80( 81 vp8_writer *const w, 82 vp8_tree t, 83 const vp8_prob *const p, 84 vp8_token *const x 85) 86{ 87 vp8_treed_write(w, t, p, x->value, x->Len); 88} 89 90static int vp8_treed_cost( 91 vp8_tree t, 92 const vp8_prob *const p, 93 int v, 94 int n /* number of bits in v, assumed nonzero */ 95) 96{ 97 int c = 0; 98 vp8_tree_index i = 0; 99 100 do 101 { 102 const int b = (v >> --n) & 1; 103 c += vp8_cost_bit(p[i>>1], b); 104 i = t[i+b]; 105 } 106 while (n); 107 108 return c; 109} 110static int vp8_cost_token 111( 112 vp8_tree t, 113 const vp8_prob *const p, 114 vp8_token *const x 115) 116{ 117 return vp8_treed_cost(t, p, x->value, x->Len); 118} 119 120/* Fill array of costs for all possible token values. */ 121 122void vp8_cost_tokens( 123 int *Costs, const vp8_prob *, vp8_tree 124); 125 126void vp8_cost_tokens2( 127 int *Costs, const vp8_prob *, vp8_tree, int 128); 129 130#ifdef __cplusplus 131} // extern "C" 132#endif 133 134#endif // VP8_ENCODER_TREEWRITER_H_ 135