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