ref: 73a4824c346e23939ce8c22c35aa373c66f452cf
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 __INC_TREEWRITER_H #define __INC_TREEWRITER_H /* Trees map alphabets into huffman-like codes suitable for an arithmetic bit coder. Timothy S Murphy 11 October 2004 */ #include "vp8/common/treecoder.h" #include "boolhuff.h" /* for now */ 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 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 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 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 *Costs, const vp8_prob *, vp8_tree ); void vp8_cost_tokens2( int *Costs, const vp8_prob *, vp8_tree, int ); #endif