ref: 29056561594eb3956e8942ca981d152b7e9df058
dir: /vp8/decoder/treereader.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 tree_reader_h #define tree_reader_h 1 #include "treecoder.h" #include "dboolhuff.h" typedef BOOL_DECODER vp8_reader; #define vp8_read vp8dx_decode_bool #define vp8_read_literal vp8_decode_value #define vp8_read_bit( R) vp8_read( R, vp8_prob_half) /* Intent of tree data structure is to make decoding trivial. */ static int vp8_treed_read( vp8_reader *const r, /* !!! must return a 0 or 1 !!! */ vp8_tree t, const vp8_prob *const p ) { register vp8_tree_index i = 0; while ((i = t[ i + vp8_read(r, p[i>>1])]) > 0) ; return -i; } /* Variant reads a binary number given distributions on each bit. Note that tree is arbitrary; probability of decoding a zero may or may not depend on previously decoded bits. */ static int vp8_treed_read_num( vp8_reader *const r, /* !!! must return a 0 or 1 !!! */ vp8_tree t, const vp8_prob *const p ) { vp8_tree_index i = 0; int v = 0, b; do { b = vp8_read(r, p[i>>1]); v = (v << 1) + b; } while ((i = t[i+b]) > 0); return v; } #endif /* tree_reader_h */