ref: 742dbe2a6ae83d01deafa2eea0e838418a8c6d37
dir: /vp8/encoder/treewriter.h/
/*
* Copyright (c) 2010 The WebM project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#ifndef VPX_VP8_ENCODER_TREEWRITER_H_
#define VPX_VP8_ENCODER_TREEWRITER_H_
/* Trees map alphabets into huffman-like codes suitable for an arithmetic
bit coder. Timothy S Murphy 11 October 2004 */
#include "./vpx_config.h"
#include "vp8/common/treecoder.h"
#include "boolhuff.h" /* for now */
#ifdef __cplusplus
extern "C" {
#endif
typedef BOOL_CODER vp8_writer;
#define vp8_write vp8_encode_bool
#define vp8_write_literal vp8_encode_value
#define vp8_write_bit(W, V) vp8_write(W, V, vp8_prob_half)
#define vp8bc_write vp8bc_write_bool
#define vp8bc_write_literal vp8bc_write_bits
#define vp8bc_write_bit(W, V) vp8bc_write_bits(W, V, 1)
/* Approximate length of an encoded bool in 256ths of a bit at given prob */
#define vp8_cost_zero(x) (vp8_prob_cost[x])
#define vp8_cost_one(x) vp8_cost_zero(vp8_complement(x))
#define vp8_cost_bit(x, b) vp8_cost_zero((b) ? vp8_complement(x) : (x))
/* VP8BC version is scaled by 2^20 rather than 2^8; see bool_coder.h */
/* Both of these return bits, not scaled bits. */
static INLINE unsigned int vp8_cost_branch(const unsigned int ct[2],
vp8_prob p) {
/* Imitate existing calculation */
return ((ct[0] * vp8_cost_zero(p)) + (ct[1] * vp8_cost_one(p))) >> 8;
}
/* Small functions to write explicit values and tokens, as well as
estimate their lengths. */
static void vp8_treed_write(vp8_writer *const w, vp8_tree t,
const vp8_prob *const p, int v,
int n) { /* number of bits in v, assumed nonzero */
vp8_tree_index i = 0;
do {
const int b = (v >> --n) & 1;
vp8_write(w, b, p[i >> 1]);
i = t[i + b];
} while (n);
}
static INLINE void vp8_write_token(vp8_writer *const w, vp8_tree t,
const vp8_prob *const p,
vp8_token *const x) {
vp8_treed_write(w, t, p, x->value, x->Len);
}
static int vp8_treed_cost(vp8_tree t, const vp8_prob *const p, int v,
int n) { /* number of bits in v, assumed nonzero */
int c = 0;
vp8_tree_index i = 0;
do {
const int b = (v >> --n) & 1;
c += vp8_cost_bit(p[i >> 1], b);
i = t[i + b];
} while (n);
return c;
}
static INLINE int vp8_cost_token(vp8_tree t, const vp8_prob *const p,
vp8_token *const x) {
return vp8_treed_cost(t, p, x->value, x->Len);
}
/* Fill array of costs for all possible token values. */
void vp8_cost_tokens(int *c, const vp8_prob *, vp8_tree);
void vp8_cost_tokens2(int *c, const vp8_prob *, vp8_tree, int);
#ifdef __cplusplus
} // extern "C"
#endif
#endif // VPX_VP8_ENCODER_TREEWRITER_H_