ref: b5707b6f14ea1e368ad739d2ae9748086b488a45
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_