vp9_treewriter.h 3.12 KB
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/*
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 *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
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 *
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 *  Use of this source code is governed by a BSD-style license
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 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
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 *  in the file PATENTS.  All contributing project authors may
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 *  be found in the AUTHORS file in the root of the source tree.
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 */


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#ifndef VP9_ENCODER_VP9_TREEWRITER_H_
#define VP9_ENCODER_VP9_TREEWRITER_H_
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/* Trees map alphabets into huffman-like codes suitable for an arithmetic
   bit coder.  Timothy S Murphy  11 October 2004 */

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#include "vp9/common/vp9_treecoder.h"
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#include "vp9/encoder/vp9_boolhuff.h"       /* for now */
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typedef BOOL_CODER vp9_writer;
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#define vp9_write encode_bool
#define vp9_write_literal vp9_encode_value
#define vp9_write_bit(W, V) vp9_write(W, V, vp9_prob_half)
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/* Approximate length of an encoded bool in 256ths of a bit at given prob */

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#define vp9_cost_zero(x) (vp9_prob_cost[x])
#define vp9_cost_one(x) vp9_cost_zero(vp9_complement(x))
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#define vp9_cost_bit(x, b) vp9_cost_zero((b) ? vp9_complement(x) : (x))
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/* VP8BC version is scaled by 2^20 rather than 2^8; see bool_coder.h */


/* Both of these return bits, not scaled bits. */
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static INLINE unsigned int cost_branch256(const unsigned int ct[2],
                                          vp9_prob p) {
  /* Imitate existing calculation */
  return ct[0] * vp9_cost_zero(p) + ct[1] * vp9_cost_one(p);
}
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static INLINE unsigned int cost_branch(const unsigned int ct[2],
                                       vp9_prob p) {
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  /* Imitate existing calculation */
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  return cost_branch256(ct, p) >> 8;
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}

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/* Small functions to write explicit values and tokens, as well as
   estimate their lengths. */

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static INLINE void treed_write(vp9_writer *const w,
                               vp9_tree t,
                               const vp9_prob *const p,
                               int v,
                               /* number of bits in v, assumed nonzero */
                               int n) {
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  vp9_tree_index i = 0;
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  do {
    const int b = (v >> --n) & 1;
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    vp9_write(w, b, p[i >> 1]);
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    i = t[i + b];
  } while (n);
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}
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static INLINE void write_token(vp9_writer *w, vp9_tree t, const vp9_prob *p,
                               const struct vp9_token *x) {
  treed_write(w, t, p, x->value, x->len);
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}

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static INLINE int treed_cost(vp9_tree t,
                             const vp9_prob *const p,
                             int v,
                             /* number of bits in v, assumed nonzero */
                             int n) {
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  int c = 0;
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  vp9_tree_index i = 0;
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  do {
    const int b = (v >> --n) & 1;
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    c += vp9_cost_bit(p[i >> 1], b);
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    i = t[i + b];
  } while (n);

  return c;
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}
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static INLINE int cost_token(vp9_tree t, const vp9_prob *p,
                             const struct vp9_token *x) {
  return treed_cost(t, p, x->value, x->len);
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}

/* Fill array of costs for all possible token values. */

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void vp9_cost_tokens(int *Costs, const vp9_prob *, vp9_tree);
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void vp9_cost_tokens_skip(int *c, const vp9_prob *p, vp9_tree t);
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#endif  // VP9_ENCODER_VP9_TREEWRITER_H_