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
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
|
///////////////////////////////////////////////////////////////////////////////
//
/// \file range_encoder.h
/// \brief Range Encoder
///
// Authors: Igor Pavlov
// Lasse Collin
//
// This file has been put into the public domain.
// You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////
#ifndef LZMA_RANGE_ENCODER_H
#define LZMA_RANGE_ENCODER_H
#include "range_common.h"
#include "price.h"
/// Maximum number of symbols that can be put pending into lzma_range_encoder
/// structure between calls to lzma_rc_encode(). For LZMA, 52+5 is enough
/// (match with big distance and length followed by range encoder flush).
#define RC_SYMBOLS_MAX 58
typedef struct {
uint64_t low;
uint64_t cache_size;
uint32_t range;
uint8_t cache;
/// Number of symbols in the tables
size_t count;
/// rc_encode()'s position in the tables
size_t pos;
/// Symbols to encode
enum {
RC_BIT_0,
RC_BIT_1,
RC_DIRECT_0,
RC_DIRECT_1,
RC_FLUSH,
} symbols[RC_SYMBOLS_MAX];
/// Probabilities associated with RC_BIT_0 or RC_BIT_1
probability *probs[RC_SYMBOLS_MAX];
} lzma_range_encoder;
static inline void
rc_reset(lzma_range_encoder *rc)
{
rc->low = 0;
rc->cache_size = 1;
rc->range = UINT32_MAX;
rc->cache = 0;
rc->count = 0;
rc->pos = 0;
}
static inline void
rc_bit(lzma_range_encoder *rc, probability *prob, uint32_t bit)
{
rc->symbols[rc->count] = bit;
rc->probs[rc->count] = prob;
++rc->count;
}
static inline void
rc_bittree(lzma_range_encoder *rc, probability *probs,
uint32_t bit_count, uint32_t symbol)
{
uint32_t model_index = 1;
do {
const uint32_t bit = (symbol >> --bit_count) & 1;
rc_bit(rc, &probs[model_index], bit);
model_index = (model_index << 1) + bit;
} while (bit_count != 0);
}
static inline void
rc_bittree_reverse(lzma_range_encoder *rc, probability *probs,
uint32_t bit_count, uint32_t symbol)
{
uint32_t model_index = 1;
do {
const uint32_t bit = symbol & 1;
symbol >>= 1;
rc_bit(rc, &probs[model_index], bit);
model_index = (model_index << 1) + bit;
} while (--bit_count != 0);
}
static inline void
rc_direct(lzma_range_encoder *rc,
uint32_t value, uint32_t bit_count)
{
do {
rc->symbols[rc->count++]
= RC_DIRECT_0 + ((value >> --bit_count) & 1);
} while (bit_count != 0);
}
static inline void
rc_flush(lzma_range_encoder *rc)
{
for (size_t i = 0; i < 5; ++i)
rc->symbols[rc->count++] = RC_FLUSH;
}
static inline bool
rc_shift_low(lzma_range_encoder *rc,
uint8_t *out, size_t *out_pos, size_t out_size)
{
if ((uint32_t)(rc->low) < (uint32_t)(0xFF000000)
|| (uint32_t)(rc->low >> 32) != 0) {
do {
if (*out_pos == out_size)
return true;
out[*out_pos] = rc->cache + (uint8_t)(rc->low >> 32);
++*out_pos;
rc->cache = 0xFF;
} while (--rc->cache_size != 0);
rc->cache = (rc->low >> 24) & 0xFF;
}
++rc->cache_size;
rc->low = (rc->low & 0x00FFFFFF) << RC_SHIFT_BITS;
return false;
}
static inline bool
rc_encode(lzma_range_encoder *rc,
uint8_t *out, size_t *out_pos, size_t out_size)
{
assert(rc->count <= RC_SYMBOLS_MAX);
while (rc->pos < rc->count) {
// Normalize
if (rc->range < RC_TOP_VALUE) {
if (rc_shift_low(rc, out, out_pos, out_size))
return true;
rc->range <<= RC_SHIFT_BITS;
}
// Encode a bit
switch (rc->symbols[rc->pos]) {
case RC_BIT_0: {
probability prob = *rc->probs[rc->pos];
rc->range = (rc->range >> RC_BIT_MODEL_TOTAL_BITS)
* prob;
prob += (RC_BIT_MODEL_TOTAL - prob) >> RC_MOVE_BITS;
*rc->probs[rc->pos] = prob;
break;
}
case RC_BIT_1: {
probability prob = *rc->probs[rc->pos];
const uint32_t bound = prob * (rc->range
>> RC_BIT_MODEL_TOTAL_BITS);
rc->low += bound;
rc->range -= bound;
prob -= prob >> RC_MOVE_BITS;
*rc->probs[rc->pos] = prob;
break;
}
case RC_DIRECT_0:
rc->range >>= 1;
break;
case RC_DIRECT_1:
rc->range >>= 1;
rc->low += rc->range;
break;
case RC_FLUSH:
// Prevent further normalizations.
rc->range = UINT32_MAX;
// Flush the last five bytes (see rc_flush()).
do {
if (rc_shift_low(rc, out, out_pos, out_size))
return true;
} while (++rc->pos < rc->count);
// Reset the range encoder so we are ready to continue
// encoding if we weren't finishing the stream.
rc_reset(rc);
return false;
default:
assert(0);
break;
}
++rc->pos;
}
rc->count = 0;
rc->pos = 0;
return false;
}
static inline uint64_t
rc_pending(const lzma_range_encoder *rc)
{
return rc->cache_size + 5 - 1;
}
#endif
|
