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 __INC_TREEWRITER_H 13 #define __INC_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 typedef BOOL_CODER vp8_writer; 23 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) 27 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) 31 32 33 /* Approximate length of an encoded bool in 256ths of a bit at given prob */ 34 35 #define vp8_cost_zero( x) ( vp8_prob_cost[x]) 36 #define vp8_cost_one( x) vp8_cost_zero( vp8_complement(x)) 37 38 #define vp8_cost_bit( x, b) vp8_cost_zero( (b)? vp8_complement(x) : (x) ) 39 40 /* VP8BC version is scaled by 2^20 rather than 2^8; see bool_coder.h */ 41 42 43 /* Both of these return bits, not scaled bits. */ 44 vp8_cost_branch(const unsigned int ct[2],vp8_prob p)45 static __inline unsigned int vp8_cost_branch(const unsigned int ct[2], vp8_prob p) 46 { 47 /* Imitate existing calculation */ 48 49 return ((ct[0] * vp8_cost_zero(p)) 50 + (ct[1] * vp8_cost_one(p))) >> 8; 51 } 52 53 /* Small functions to write explicit values and tokens, as well as 54 estimate their lengths. */ 55 vp8_treed_write(vp8_writer * const w,vp8_tree t,const vp8_prob * const p,int v,int n)56 static __inline 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; 66 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 } vp8_write_token(vp8_writer * const w,vp8_tree t,const vp8_prob * const p,vp8_token * const x)75 static __inline 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 } 85 vp8_treed_cost(vp8_tree t,const vp8_prob * const p,int v,int n)86 static __inline 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; 95 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); 103 104 return c; 105 } vp8_cost_token(vp8_tree t,const vp8_prob * const p,vp8_token * const x)106 static __inline 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 } 115 116 /* Fill array of costs for all possible token values. */ 117 118 void vp8_cost_tokens( 119 int *Costs, const vp8_prob *, vp8_tree 120 ); 121 122 #endif 123