ref: f1781e86b76d5fd9e2605655d78679f3153c292d
dir: /vp8/common/treecoder.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_TREECODER_H #define __INC_TREECODER_H typedef unsigned char vp8bc_index_t; /* probability index */ typedef unsigned char vp8_prob; #define vp8_prob_half ( (vp8_prob) 128) typedef signed char vp8_tree_index; struct bool_coder_spec; typedef struct bool_coder_spec bool_coder_spec; typedef struct bool_writer bool_writer; typedef struct bool_reader bool_reader; typedef const bool_coder_spec c_bool_coder_spec; typedef const bool_writer c_bool_writer; typedef const bool_reader c_bool_reader; # define vp8_complement( x) (255 - x) /* We build coding trees compactly in arrays. Each node of the tree is a pair of vp8_tree_indices. Array index often references a corresponding probability table. Index <= 0 means done encoding/decoding and value = -Index, Index > 0 means need another bit, specification at index. Nonnegative indices are always even; processing begins at node 0. */ typedef const vp8_tree_index vp8_tree[], *vp8_tree_p; typedef const struct vp8_token_struct { int value; int Len; } vp8_token; /* Construct encoding array from tree. */ void vp8_tokens_from_tree(struct vp8_token_struct *, vp8_tree); void vp8_tokens_from_tree_offset(struct vp8_token_struct *, vp8_tree, int offset); /* Convert array of token occurrence counts into a table of probabilities for the associated binary encoding tree. Also writes count of branches taken for each node on the tree; this facilitiates decisions as to probability updates. */ void vp8_tree_probs_from_distribution( int n, /* n = size of alphabet */ vp8_token tok [ /* n */ ], vp8_tree tree, vp8_prob probs [ /* n-1 */ ], unsigned int branch_ct [ /* n-1 */ ] [2], const unsigned int num_events[ /* n */ ], unsigned int Pfactor, int Round ); /* Variant of above using coder spec rather than hardwired 8-bit probs. */ void vp8bc_tree_probs_from_distribution( int n, /* n = size of alphabet */ vp8_token tok [ /* n */ ], vp8_tree tree, vp8_prob probs [ /* n-1 */ ], unsigned int branch_ct [ /* n-1 */ ] [2], const unsigned int num_events[ /* n */ ], c_bool_coder_spec *s ); #endif