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: #ifndef VP9_DECODER_VP9_DBOOLHUFF_H_
michael@0: #define VP9_DECODER_VP9_DBOOLHUFF_H_
michael@0: 
michael@0: #include <stddef.h>
michael@0: #include <limits.h>
michael@0: 
michael@0: #include "./vpx_config.h"
michael@0: #include "vpx_ports/mem.h"
michael@0: #include "vpx/vpx_integer.h"
michael@0: 
michael@0: typedef size_t VP9_BD_VALUE;
michael@0: 
michael@0: #define BD_VALUE_SIZE ((int)sizeof(VP9_BD_VALUE)*CHAR_BIT)
michael@0: 
michael@0: typedef struct {
michael@0:   const uint8_t *buffer_end;
michael@0:   const uint8_t *buffer;
michael@0:   VP9_BD_VALUE value;
michael@0:   int count;
michael@0:   unsigned int range;
michael@0: } vp9_reader;
michael@0: 
michael@0: DECLARE_ALIGNED(16, extern const uint8_t, vp9_norm[256]);
michael@0: 
michael@0: int vp9_reader_init(vp9_reader *r, const uint8_t *buffer, size_t size);
michael@0: 
michael@0: void vp9_reader_fill(vp9_reader *r);
michael@0: 
michael@0: const uint8_t *vp9_reader_find_end(vp9_reader *r);
michael@0: 
michael@0: static int vp9_read(vp9_reader *br, int probability) {
michael@0:   unsigned int bit = 0;
michael@0:   VP9_BD_VALUE value;
michael@0:   VP9_BD_VALUE bigsplit;
michael@0:   int count;
michael@0:   unsigned int range;
michael@0:   unsigned int split = ((br->range * probability) + (256 - probability)) >> 8;
michael@0: 
michael@0:   if (br->count < 0)
michael@0:     vp9_reader_fill(br);
michael@0: 
michael@0:   value = br->value;
michael@0:   count = br->count;
michael@0: 
michael@0:   bigsplit = (VP9_BD_VALUE)split << (BD_VALUE_SIZE - 8);
michael@0: 
michael@0:   range = split;
michael@0: 
michael@0:   if (value >= bigsplit) {
michael@0:     range = br->range - split;
michael@0:     value = value - bigsplit;
michael@0:     bit = 1;
michael@0:   }
michael@0: 
michael@0:   {
michael@0:     register unsigned int shift = vp9_norm[range];
michael@0:     range <<= shift;
michael@0:     value <<= shift;
michael@0:     count -= shift;
michael@0:   }
michael@0:   br->value = value;
michael@0:   br->count = count;
michael@0:   br->range = range;
michael@0: 
michael@0:   return bit;
michael@0: }
michael@0: 
michael@0: static int vp9_read_bit(vp9_reader *r) {
michael@0:   return vp9_read(r, 128);  // vp9_prob_half
michael@0: }
michael@0: 
michael@0: static int vp9_read_literal(vp9_reader *br, int bits) {
michael@0:   int z = 0, bit;
michael@0: 
michael@0:   for (bit = bits - 1; bit >= 0; bit--)
michael@0:     z |= vp9_read_bit(br) << bit;
michael@0: 
michael@0:   return z;
michael@0: }
michael@0: 
michael@0: int vp9_reader_has_error(vp9_reader *r);
michael@0: 
michael@0: #endif  // VP9_DECODER_VP9_DBOOLHUFF_H_