File size: 7,267 Bytes
9375c9a |
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 |
// Copyright (C) 2003 Davis E. King ([email protected])
// License: Boost Software License See LICENSE.txt for the full license.
#ifndef DLIB_COMPRESS_STREAM_KERNEl_1_
#define DLIB_COMPRESS_STREAM_KERNEl_1_
#include "../algs.h"
#include <iostream>
#include <streambuf>
#include <cstdio>
#include "compress_stream_kernel_abstract.h"
namespace dlib
{
template <
typename fce,
typename fcd,
typename crc32
>
class compress_stream_kernel_1
{
/*!
REQUIREMENTS ON fce
is an implementation of entropy_encoder_model/entropy_encoder_model_kernel_abstract.h
the alphabet_size of fce must be 257.
fce and fcd share the same kernel number.
REQUIREMENTS ON fcd
is an implementation of entropy_decoder_model/entropy_decoder_model_kernel_abstract.h
the alphabet_size of fcd must be 257.
fce and fcd share the same kernel number.
REQUIREMENTS ON crc32
is an implementation of crc32/crc32_kernel_abstract.h
INITIAL VALUE
this object has no state
CONVENTION
this object has no state
!*/
const static unsigned long eof_symbol = 256;
public:
class decompression_error : public dlib::error
{
public:
decompression_error(
const char* i
) :
dlib::error(std::string(i))
{}
decompression_error(
const std::string& i
) :
dlib::error(i)
{}
};
compress_stream_kernel_1 (
)
{}
~compress_stream_kernel_1 (
)
{}
void compress (
std::istream& in,
std::ostream& out
) const;
void decompress (
std::istream& in,
std::ostream& out
) const;
private:
// restricted functions
compress_stream_kernel_1(compress_stream_kernel_1&); // copy constructor
compress_stream_kernel_1& operator=(compress_stream_kernel_1&); // assignment operator
};
// ----------------------------------------------------------------------------------------
// ----------------------------------------------------------------------------------------
// member function definitions
// ----------------------------------------------------------------------------------------
// ----------------------------------------------------------------------------------------
template <
typename fce,
typename fcd,
typename crc32
>
void compress_stream_kernel_1<fce,fcd,crc32>::
compress (
std::istream& in_,
std::ostream& out_
) const
{
std::streambuf::int_type temp;
std::streambuf& in = *in_.rdbuf();
typename fce::entropy_encoder_type coder;
coder.set_stream(out_);
fce model(coder);
crc32 crc;
unsigned long count = 0;
while (true)
{
// write out a known value every 20000 symbols
if (count == 20000)
{
count = 0;
coder.encode(1500,1501,8000);
}
++count;
// get the next character
temp = in.sbumpc();
// if we have hit EOF then encode the marker symbol
if (temp != EOF)
{
// encode the symbol
model.encode(static_cast<unsigned long>(temp));
crc.add(static_cast<unsigned char>(temp));
continue;
}
else
{
model.encode(eof_symbol);
// now write the checksum
unsigned long checksum = crc.get_checksum();
unsigned char byte1 = static_cast<unsigned char>((checksum>>24)&0xFF);
unsigned char byte2 = static_cast<unsigned char>((checksum>>16)&0xFF);
unsigned char byte3 = static_cast<unsigned char>((checksum>>8)&0xFF);
unsigned char byte4 = static_cast<unsigned char>((checksum)&0xFF);
model.encode(byte1);
model.encode(byte2);
model.encode(byte3);
model.encode(byte4);
break;
}
}
}
// ----------------------------------------------------------------------------------------
template <
typename fce,
typename fcd,
typename crc32
>
void compress_stream_kernel_1<fce,fcd,crc32>::
decompress (
std::istream& in_,
std::ostream& out_
) const
{
std::streambuf& out = *out_.rdbuf();
typename fcd::entropy_decoder_type coder;
coder.set_stream(in_);
fcd model(coder);
unsigned long symbol;
unsigned long count = 0;
crc32 crc;
// decode until we hit the marker symbol
while (true)
{
// make sure this is the value we expect
if (count == 20000)
{
if (coder.get_target(8000) != 1500)
{
throw decompression_error("Error detected in compressed data stream.");
}
count = 0;
coder.decode(1500,1501);
}
++count;
// decode the next symbol
model.decode(symbol);
if (symbol != eof_symbol)
{
crc.add(static_cast<unsigned char>(symbol));
// write this symbol to out
if (out.sputc(static_cast<char>(symbol)) != static_cast<int>(symbol))
{
throw std::ios::failure("error occurred in compress_stream_kernel_1::decompress");
}
continue;
}
else
{
// we read eof from the encoded data. now we just have to check the checksum and we are done.
unsigned char byte1;
unsigned char byte2;
unsigned char byte3;
unsigned char byte4;
model.decode(symbol); byte1 = static_cast<unsigned char>(symbol);
model.decode(symbol); byte2 = static_cast<unsigned char>(symbol);
model.decode(symbol); byte3 = static_cast<unsigned char>(symbol);
model.decode(symbol); byte4 = static_cast<unsigned char>(symbol);
unsigned long checksum = byte1;
checksum <<= 8;
checksum |= byte2;
checksum <<= 8;
checksum |= byte3;
checksum <<= 8;
checksum |= byte4;
if (checksum != crc.get_checksum())
throw decompression_error("Error detected in compressed data stream.");
break;
}
} // while (true)
}
// ----------------------------------------------------------------------------------------
}
#endif // DLIB_COMPRESS_STREAM_KERNEl_1_
|