1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
|
/*
* 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 TREEREADER_H
#define TREEREADER_H
#include "treereader_common.h"
#include "vp8_mem.h"
typedef size_t VP8_BD_VALUE;
typedef struct
{
const unsigned char *user_buffer_end;
const unsigned char *user_buffer;
VP8_BD_VALUE value;
int count;
unsigned int range;
} BOOL_DECODER;
/**
* This is meant to be a large, positive constant that can still be efficiently
* loaded as an immediate (on platforms like ARM, for example).
* Even relatively modest values like 100 would work fine.
*/
#define VP8_LOTS_OF_BITS (0x40000000)
#define VP8_BD_VALUE_SIZE ((int)sizeof(VP8_BD_VALUE)*CHAR_BIT)
#define vp8_read vp8dx_decode_bool
#define vp8_read_literal vp8_decode_value
#define vp8_read_bit( R) vp8_read( R, vp8_prob_half)
DECLARE_ALIGNED(16, extern const unsigned char, vp8_norm[256]);
int vp8dx_start_decode(BOOL_DECODER *bd, const unsigned char *data,
const unsigned int data_size);
void vp8dx_bool_decoder_fill(BOOL_DECODER *bd);
int vp8dx_bool_error(BOOL_DECODER *bd);
int vp8dx_decode_bool(BOOL_DECODER *bd, int probability);
int vp8_decode_value(BOOL_DECODER *bd, int bits);
int vp8_treed_read(BOOL_DECODER *const bd, vp8_tree t, const vp8_prob *const p);
/**
* The refill loop is used in several places, so define it in a macro to make
* sure they're all consistent.
* An inline function would be cleaner, but has a significant penalty, because
* multiple BOOL_DECODER fields must be modified, and the compiler is not smart
* enough to eliminate the stores to those fields and the subsequent reloads
* from them when inlining the function.
*/
#define VP8DX_BOOL_DECODER_FILL(_count, _value, _bufptr, _bufend) \
do \
{ \
size_t bits_left = ((_bufend)-(_bufptr))*CHAR_BIT; \
int shift = VP8_BD_VALUE_SIZE - 8 - ((_count) + 8); \
int loop_end = 0; \
int x = shift + CHAR_BIT - bits_left; \
\
if (x >= 0) \
{ \
(_count) += VP8_LOTS_OF_BITS; \
loop_end = x; \
if (!bits_left) break; \
} \
while (shift >= loop_end) \
{ \
(_count) += CHAR_BIT; \
(_value) |= (VP8_BD_VALUE)*(_bufptr)++ << shift; \
shift -= CHAR_BIT; \
} \
} \
while(0)
#endif /* TREEREADER_H */
|
