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
|
// Copyright (C) 2004 Davis E. King (davis@dlib.net)
// License: Boost Software License See LICENSE.txt for the full license.
#ifndef DLIB_ENTROPY_DECODER_MODEL_KERNEl_1_
#define DLIB_ENTROPY_DECODER_MODEL_KERNEl_1_
#include "../algs.h"
#include "entropy_decoder_model_kernel_abstract.h"
#include "../assert.h"
namespace dlib
{
template <
unsigned long alphabet_size,
typename entropy_decoder,
typename cc
>
class entropy_decoder_model_kernel_1
{
/*!
REQUIREMENTS ON cc
cc is an implementation of conditioning_class/conditioning_class_kernel_abstract.h
cc::get_alphabet_size() == alphabet_size+1
INITIAL VALUE
Initially this object's finite context model is empty
CONVENTION
&get_entropy_decoder() == coder
&order_0.get_global_state() == &gs
This is an order-0 model. The last symbol in the order-0 context is
an escape into the order minus 1 context.
!*/
public:
typedef entropy_decoder entropy_decoder_type;
entropy_decoder_model_kernel_1 (
entropy_decoder& coder
);
virtual ~entropy_decoder_model_kernel_1 (
);
inline void clear(
);
inline void decode (
unsigned long& symbol
);
entropy_decoder& get_entropy_decoder (
) { return coder; }
static unsigned long get_alphabet_size (
) { return alphabet_size; }
private:
entropy_decoder& coder;
typename cc::global_state_type gs;
cc order_0;
// restricted functions
entropy_decoder_model_kernel_1(entropy_decoder_model_kernel_1<alphabet_size,entropy_decoder,cc>&); // copy constructor
entropy_decoder_model_kernel_1<alphabet_size,entropy_decoder,cc>& operator=(entropy_decoder_model_kernel_1<alphabet_size,entropy_decoder,cc>&); // assignment operator
};
// ----------------------------------------------------------------------------------------
// ----------------------------------------------------------------------------------------
// member function definitions
// ----------------------------------------------------------------------------------------
// ----------------------------------------------------------------------------------------
template <
unsigned long alphabet_size,
typename entropy_decoder,
typename cc
>
entropy_decoder_model_kernel_1<alphabet_size,entropy_decoder,cc>::
entropy_decoder_model_kernel_1 (
entropy_decoder& coder_
) :
coder(coder_),
order_0(gs)
{
COMPILE_TIME_ASSERT( 1 < alphabet_size && alphabet_size < 65535 );
}
// ----------------------------------------------------------------------------------------
template <
unsigned long alphabet_size,
typename entropy_decoder,
typename cc
>
entropy_decoder_model_kernel_1<alphabet_size,entropy_decoder,cc>::
~entropy_decoder_model_kernel_1 (
)
{
}
// ----------------------------------------------------------------------------------------
template <
unsigned long alphabet_size,
typename entropy_decoder,
typename cc
>
void entropy_decoder_model_kernel_1<alphabet_size,entropy_decoder,cc>::
clear(
)
{
order_0.clear();
}
// ----------------------------------------------------------------------------------------
template <
unsigned long alphabet_size,
typename entropy_decoder,
typename cc
>
void entropy_decoder_model_kernel_1<alphabet_size,entropy_decoder,cc>::
decode (
unsigned long& symbol
)
{
unsigned long current_symbol, low_count, high_count, target;
// look in the order-0 context
target = coder.get_target(order_0.get_total());
order_0.get_symbol(target,current_symbol,low_count,high_count);
// have coder decode the next symbol
coder.decode(low_count,high_count);
// if current_symbol is not an escape from the order-0 context
if (current_symbol != alphabet_size)
{
// update the count for this symbol
order_0.increment_count(current_symbol,2);
symbol = current_symbol;
return;
}
// update the count for the escape symbol
order_0.increment_count(alphabet_size);
// go into the order minus one context
target = coder.get_target(alphabet_size);
coder.decode(target,target+1);
// update the count for this symbol in the order-0 context
order_0.increment_count(target,2);
symbol = target;
}
// ----------------------------------------------------------------------------------------
}
#endif // DLIB_ENTROPY_DECODER_MODEL_KERNEl_1_
|
