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
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
|
// Copyright 2011 Google Inc. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the COPYING 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.
// -----------------------------------------------------------------------------
//
// Bit writing and boolean coder
//
// Author: Skal (pascal.massimino@gmail.com)
#ifndef WEBP_UTILS_BIT_WRITER_H_
#define WEBP_UTILS_BIT_WRITER_H_
#include "../webp/types.h"
#ifdef __cplusplus
extern "C" {
#endif
//------------------------------------------------------------------------------
// Bit-writing
typedef struct VP8BitWriter VP8BitWriter;
struct VP8BitWriter {
int32_t range_; // range-1
int32_t value_;
int run_; // number of outstanding bits
int nb_bits_; // number of pending bits
uint8_t* buf_; // internal buffer. Re-allocated regularly. Not owned.
size_t pos_;
size_t max_pos_;
int error_; // true in case of error
};
// Initialize the object. Allocates some initial memory based on expected_size.
int VP8BitWriterInit(VP8BitWriter* const bw, size_t expected_size);
// Finalize the bitstream coding. Returns a pointer to the internal buffer.
uint8_t* VP8BitWriterFinish(VP8BitWriter* const bw);
// Release any pending memory and zeroes the object. Not a mandatory call.
// Only useful in case of error, when the internal buffer hasn't been grabbed!
void VP8BitWriterWipeOut(VP8BitWriter* const bw);
int VP8PutBit(VP8BitWriter* const bw, int bit, int prob);
int VP8PutBitUniform(VP8BitWriter* const bw, int bit);
void VP8PutBits(VP8BitWriter* const bw, uint32_t value, int nb_bits);
void VP8PutSignedBits(VP8BitWriter* const bw, int value, int nb_bits);
// Appends some bytes to the internal buffer. Data is copied.
int VP8BitWriterAppend(VP8BitWriter* const bw,
const uint8_t* data, size_t size);
// return approximate write position (in bits)
static WEBP_INLINE uint64_t VP8BitWriterPos(const VP8BitWriter* const bw) {
const uint64_t nb_bits = 8 + bw->nb_bits_; // bw->nb_bits_ is <= 0, note
return (bw->pos_ + bw->run_) * 8 + nb_bits;
}
// Returns a pointer to the internal buffer.
static WEBP_INLINE uint8_t* VP8BitWriterBuf(const VP8BitWriter* const bw) {
return bw->buf_;
}
// Returns the size of the internal buffer.
static WEBP_INLINE size_t VP8BitWriterSize(const VP8BitWriter* const bw) {
return bw->pos_;
}
//------------------------------------------------------------------------------
// VP8LBitWriter
#if defined(__x86_64__) || defined(_M_X64) // 64bit
typedef uint64_t vp8l_atype_t; // accumulator type
typedef uint32_t vp8l_wtype_t; // writing type
#define WSWAP HToLE32
#define VP8L_WRITER_BYTES 4 // sizeof(vp8l_wtype_t)
#define VP8L_WRITER_BITS 32 // 8 * sizeof(vp8l_wtype_t)
#define VP8L_WRITER_MAX_BITS 64 // 8 * sizeof(vp8l_atype_t)
#else
typedef uint32_t vp8l_atype_t;
typedef uint16_t vp8l_wtype_t;
#define WSWAP HToLE16
#define VP8L_WRITER_BYTES 2
#define VP8L_WRITER_BITS 16
#define VP8L_WRITER_MAX_BITS 32
#endif
typedef struct {
vp8l_atype_t bits_; // bit accumulator
int used_; // number of bits used in accumulator
uint8_t* buf_; // start of buffer
uint8_t* cur_; // current write position
uint8_t* end_; // end of buffer
// After all bits are written (VP8LBitWriterFinish()), the caller must observe
// the state of error_. A value of 1 indicates that a memory allocation
// failure has happened during bit writing. A value of 0 indicates successful
// writing of bits.
int error_;
} VP8LBitWriter;
static WEBP_INLINE size_t VP8LBitWriterNumBytes(VP8LBitWriter* const bw) {
return (bw->cur_ - bw->buf_) + ((bw->used_ + 7) >> 3);
}
// Returns false in case of memory allocation error.
int VP8LBitWriterInit(VP8LBitWriter* const bw, size_t expected_size);
// Finalize the bitstream coding. Returns a pointer to the internal buffer.
uint8_t* VP8LBitWriterFinish(VP8LBitWriter* const bw);
// Release any pending memory and zeroes the object.
void VP8LBitWriterWipeOut(VP8LBitWriter* const bw);
// Internal function for VP8LPutBits flushing 32 bits from the written state.
void VP8LPutBitsFlushBits(VP8LBitWriter* const bw);
// PutBits internal function used in the 16 bit vp8l_wtype_t case.
void VP8LPutBitsInternal(VP8LBitWriter* const bw, uint32_t bits, int n_bits);
// This function writes bits into bytes in increasing addresses (little endian),
// and within a byte least-significant-bit first.
// This function can write up to 32 bits in one go, but VP8LBitReader can only
// read 24 bits max (VP8L_MAX_NUM_BIT_READ).
// VP8LBitWriter's error_ flag is set in case of memory allocation error.
static WEBP_INLINE void VP8LPutBits(VP8LBitWriter* const bw,
uint32_t bits, int n_bits) {
if (sizeof(vp8l_wtype_t) == 4) {
if (n_bits > 0) {
if (bw->used_ >= 32) {
VP8LPutBitsFlushBits(bw);
}
bw->bits_ |= (vp8l_atype_t)bits << bw->used_;
bw->used_ += n_bits;
}
} else {
VP8LPutBitsInternal(bw, bits, n_bits);
}
}
//------------------------------------------------------------------------------
#ifdef __cplusplus
} // extern "C"
#endif
#endif /* WEBP_UTILS_BIT_WRITER_H_ */
|
