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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335
|
// 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_3_
#define DLIB_ENTROPY_DECODER_MODEL_KERNEl_3_
#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,
typename cc_high
>
class entropy_decoder_model_kernel_3
{
/*!
REQUIREMENTS ON cc
cc is an implementation of conditioning_class/conditioning_class_kernel_abstract.h
cc::get_alphabet_size() == alphabet_size+1
REQUIREMENTS ON cc_high
cc_high is an implementation of conditioning_class/conditioning_class_kernel_abstract.h
cc_high::get_alphabet_size() == alphabet_size+1
INITIAL VALUE
- Initially this object's finite context model is empty
- previous_symbol == 0
- previous_symbol2 == 0
- order_1 == pointer to an array of alphabet_size elements
- order_2 == pointer to an array of alphabet_size*alphabet_size elements
- for all values of i: order_2[i] == 0
CONVENTION
&get_entropy_encoder() == coder
&order_0.get_global_state() == &gs
&order_1[i]->get_global_state() == &gs
if (order_2[i] != 0) then
&order_2[i]->get_global_state() == &gs_high
This is an order-2-1-0 model. The last symbol in the order-2, order-1 and
order-0 contexts is an escape into the lower context.
previous_symbol == the last symbol seen
previous_symbol2 == the symbol we saw before previous_symbol
!*/
public:
typedef entropy_decoder entropy_decoder_type;
entropy_decoder_model_kernel_3 (
entropy_decoder& coder
);
virtual ~entropy_decoder_model_kernel_3 (
);
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;
typename cc_high::global_state_type gs_high;
cc order_0;
cc** order_1;
unsigned long previous_symbol;
cc_high** order_2;
unsigned long previous_symbol2;
// restricted functions
entropy_decoder_model_kernel_3(entropy_decoder_model_kernel_3&); // copy constructor
entropy_decoder_model_kernel_3& operator=(entropy_decoder_model_kernel_3&); // assignment operator
};
// ----------------------------------------------------------------------------------------
// ----------------------------------------------------------------------------------------
// member function definitions
// ----------------------------------------------------------------------------------------
// ----------------------------------------------------------------------------------------
template <
unsigned long alphabet_size,
typename entropy_decoder,
typename cc,
typename cc_high
>
entropy_decoder_model_kernel_3<alphabet_size,entropy_decoder,cc,cc_high>::
entropy_decoder_model_kernel_3 (
entropy_decoder& coder_
) :
coder(coder_),
order_0(gs),
order_1(0),
previous_symbol(0),
order_2(0),
previous_symbol2(0)
{
COMPILE_TIME_ASSERT( 1 < alphabet_size && alphabet_size < 65535);
try
{
order_1 = new cc*[alphabet_size];
order_2 = new cc_high*[alphabet_size*alphabet_size];
}
catch (...)
{
if (order_1) delete [] order_1;
if (order_2) delete [] order_2;
throw;
}
unsigned long i;
for (i = 0; i < alphabet_size*alphabet_size; ++i)
{
order_2[i] = 0;
}
try
{
for (i = 0; i < alphabet_size; ++i)
{
order_1[i] = new cc(gs);
}
}
catch (...)
{
for (unsigned long j = 0; j < i; ++j)
{
delete order_1[j];
}
throw;
}
}
// ----------------------------------------------------------------------------------------
template <
unsigned long alphabet_size,
typename entropy_decoder,
typename cc,
typename cc_high
>
entropy_decoder_model_kernel_3<alphabet_size,entropy_decoder,cc,cc_high>::
~entropy_decoder_model_kernel_3 (
)
{
for (unsigned long i = 0; i < alphabet_size; ++i)
{
delete order_1[i];
}
for (unsigned long i = 0; i < alphabet_size*alphabet_size; ++i)
{
if (order_2[i] != 0)
delete order_2[i];
}
delete [] order_1;
delete [] order_2;
}
// ----------------------------------------------------------------------------------------
template <
unsigned long alphabet_size,
typename entropy_decoder,
typename cc,
typename cc_high
>
void entropy_decoder_model_kernel_3<alphabet_size,entropy_decoder,cc,cc_high>::
clear(
)
{
previous_symbol = 0;
previous_symbol2 = 0;
order_0.clear();
for (unsigned long i = 0; i < alphabet_size; ++i)
{
order_1[i]->clear();
}
for (unsigned long i = 0; i < alphabet_size*alphabet_size; ++i)
{
if (order_2[i] != 0)
{
delete order_2[i];
order_2[i] = 0;
}
}
}
// ----------------------------------------------------------------------------------------
template <
unsigned long alphabet_size,
typename entropy_decoder,
typename cc,
typename cc_high
>
void entropy_decoder_model_kernel_3<alphabet_size,entropy_decoder,cc,cc_high>::
decode (
unsigned long& symbol
)
{
unsigned long current_symbol, low_count, high_count, target;
// look in the order-2 context
unsigned long temp = previous_symbol + (previous_symbol2 * alphabet_size);
if (order_2[temp] != 0)
{
target = coder.get_target(order_2[temp]->get_total());
order_2[temp]->get_symbol(target,current_symbol,low_count,high_count);
// have the coder decode the next symbol
coder.decode(low_count,high_count);
// if the current_symbol is not an escape from the order-2 context
if (current_symbol != alphabet_size)
{
symbol = current_symbol;
order_2[temp]->increment_count(current_symbol,2);
previous_symbol2 = previous_symbol;
previous_symbol = current_symbol;
return;
}
// since this is an escape to order-1 we should increment
// the escape symbol
order_2[temp]->increment_count(alphabet_size);
}
else
{
order_2[temp] = new cc_high(gs_high);
}
// look in the order-1 context
target = coder.get_target(order_1[previous_symbol]->get_total());
order_1[previous_symbol]->get_symbol(target,current_symbol,low_count,high_count);
// have the coder decode the next symbol
coder.decode(low_count,high_count);
// if the current_symbol is not an escape from the order-1 context
if (current_symbol != alphabet_size)
{
symbol = current_symbol;
order_2[temp]->increment_count(current_symbol,2);
order_1[previous_symbol]->increment_count(current_symbol,2);
previous_symbol2 = previous_symbol;
previous_symbol = current_symbol;
return;
}
// since this is an escape to order-0 we should increment
// the escape symbol
order_1[previous_symbol]->increment_count(alphabet_size);
// 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_2[temp]->increment_count(current_symbol,2);
order_1[previous_symbol]->increment_count(current_symbol,2);
order_0.increment_count(current_symbol,2);
symbol = current_symbol;
previous_symbol2 = previous_symbol;
previous_symbol = current_symbol;
return;
}
// update the count for the escape symbol
order_0.increment_count(current_symbol);
// go into the order minus one context
target = coder.get_target(alphabet_size);
coder.decode(target,target+1);
// update the count for this symbol
order_2[temp]->increment_count(target,2);
order_1[previous_symbol]->increment_count(target,2);
order_0.increment_count(target,2);
symbol = target;
previous_symbol2 = previous_symbol;
previous_symbol = target;
}
// ----------------------------------------------------------------------------------------
}
#endif // DLIB_ENTROPY_DECODER_MODEL_KERNEl_3_
|