Line data    Source code

       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             : 
      47           0 : static INLINE unsigned int vp8_cost_branch(const unsigned int ct[2],
      48             :                                            vp8_prob p) {
      49             :   /* Imitate existing calculation */
      50             : 
      51           0 :   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             : 
      57           0 : 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           0 :   vp8_tree_index i = 0;
      62             : 
      63             :   do {
      64           0 :     const int b = (v >> --n) & 1;
      65           0 :     vp8_write(w, b, p[i >> 1]);
      66           0 :     i = t[i + b];
      67           0 :   } while (n);
      68           0 : }
      69           0 : 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           0 :   vp8_treed_write(w, t, p, x->value, x->Len);
      73           0 : }
      74             : 
      75           0 : 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           0 :   int c = 0;
      79           0 :   vp8_tree_index i = 0;
      80             : 
      81             :   do {
      82           0 :     const int b = (v >> --n) & 1;
      83           0 :     c += vp8_cost_bit(p[i >> 1], b);
      84           0 :     i = t[i + b];
      85           0 :   } while (n);
      86             : 
      87           0 :   return c;
      88             : }
      89           0 : static INLINE int vp8_cost_token(vp8_tree t, const vp8_prob *const p,
      90             :                                  vp8_token *const x) {
      91           0 :   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_