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| #include <iostream.h>
#include <stdio.h>
//#include <stdlib.h>
#include <string.h>
#include <conio.h>
#define BITS 12
#define HASHING_SHIFT BITS-8
#define MAX_VALUE (1 << BITS) - 1
#define MAX_CODE MAX_VALUE - 1
#if BITS == 14
#define TABLE_SIZE 18041
#endif
#if BITS == 13
#define TABLE_SIZE 9029
#endif
#if BITS <= 12
#define TABLE_SIZE 5021
#endif
void compress(FILE *input,FILE *output);
void expand(FILE *input,FILE *output);
char *decode_string(unsigned char *buffer, unsigned int code);
int find_match(int hash_prefix,unsigned int hash_character);
void output_code(FILE *output,unsigned int code);
int input_code(FILE *input);
int *mas_code;
unsigned int *prefix_code;
unsigned char *append_character;
unsigned char decode_stack[4000];
int main(int argc, char *argv[])
{
FILE *input_file;
FILE *output_file;
FILE *lzw_file;
char input_file_name[81];
char menu;
mas_code = (int*)malloc(TABLE_SIZE*sizeof(int));
prefix_code = (unsigned int*)malloc(TABLE_SIZE*sizeof(unsigned int));
append_character = (unsigned char*)malloc(TABLE_SIZE*sizeof(unsigned char));
if (mas_code == NULL || prefix_code == NULL || append_character == NULL) {
cout << "Owibka videleniya tablici\n";
exit(1);
}
if (argc > 1)
strcpy(input_file_name, argv[1]);
else {
cout << "Enter name of start-file ";
cin.getline(input_file_name, 81);
}
input_file = fopen(input_file_name, "rb");
lzw_file = fopen("metod_lzw.lzw", "wb");
if (input_file == NULL || lzw_file == NULL)
{
cout << "Error open file\n";
exit(1);
}
compress(input_file, lzw_file);
fclose(input_file);
fclose(lzw_file);
free(mas_code);
lzw_file = fopen("metod_lzw.lzw", "rb");
output_file = fopen("unpack_file.out", "wb");
if (lzw_file == NULL || output_file == NULL)
{
cout << "Error open file\n";
exit(1);
}
expand(lzw_file, output_file);
fclose(lzw_file);
fclose(output_file);
getch();
free(prefix_code);
free(append_character);
return 1;
}
void compress(FILE *input, FILE *output) {
unsigned int next_code;
unsigned int character;
unsigned int string_code;
unsigned int index;
int i;
next_code = 256;
for (i = 0; i < TABLE_SIZE; i++)
mas_code[i] = -1;
i = 0;
cout << "Compressing...";
string_code = getc(input);
while ((character=getc(input))!= EOF)
{
index = find_match(string_code, character);
if (mas_code[index] != -1)
{
string_code = mas_code[index];
}
else
{
if (next_code != MAX_CODE) {
mas_code[index] = next_code++;
prefix_code[index] = string_code;
append_character[index] = character;
}
output_code(output, string_code);
string_code=character;
cout <<"="<<mas_code[index]<<"\n"; /**/
}
}
output_code(output, string_code);
output_code(output, MAX_VALUE);
output_code(output, 0);
cout << "Compress\n";
}
int find_match(int hash_prefix, unsigned int hash_character)
{
int index;
int offset;
index = (hash_character << HASHING_SHIFT) ^ hash_prefix;
if (index == 0)
offset = 1;
else
offset = TABLE_SIZE - index;
while (true)
{
if (mas_code[index] == -1)
return(index);
if (prefix_code[index] == hash_prefix && append_character[index] == hash_character)
return(index);
index -= offset;
if (index < 0)
index += TABLE_SIZE;
}
}
void expand(FILE *input, FILE *output)
{
unsigned int next_code;
unsigned int new_code;
unsigned int old_code;
int character;
int counter;
unsigned char *string;
next_code = 256;
counter = 0;
cout << "Decompress...";
old_code = input_code(input);
character = old_code;
putc(old_code, output);
while ((new_code = input_code(input)) != (MAX_VALUE)) {
if (new_code >= next_code) {
*decode_stack = character;
string = (unsigned char*)decode_string(decode_stack+1, old_code);
}
else
string = (unsigned char*)decode_string(decode_stack, new_code);
character = *string;
while (string >= decode_stack)
putc(*string--, output);
if (next_code <= MAX_CODE) {
prefix_code[next_code] = old_code;
append_character[next_code] = character;
next_code++;
}
old_code = new_code;
}
cout << " decompress.\n";
}
char *decode_string(unsigned char *buffer,unsigned int code) {
int i;
i = 0;
while (code > 255) {
*buffer++ = append_character[code];
code = prefix_code[code];
if (i++ >= 4094) {
cout << "Error memory\n";
exit(1);
}
}
*buffer = code;
return((char*)buffer);
getch();
}
int input_code(FILE *input) {
unsigned int return_value;
static int input_bit_count = 0;
static unsigned long input_bit_buffer = 0L;
while (input_bit_count <= 24) {
input_bit_buffer |= (unsigned long) getc(input) << (24-input_bit_count);
input_bit_count += 8;
}
return_value = input_bit_buffer >> (32 - BITS);
input_bit_buffer <<= BITS;
input_bit_count -= BITS;
return(return_value);
}
void output_code(FILE *output, unsigned int code) {
static int output_bit_count = 0;
static unsigned long output_bit_buffer = 0L;
output_bit_buffer |= (unsigned long) code << (32 - BITS - output_bit_count);
output_bit_count += BITS;
while (output_bit_count >= 8) {
putc(output_bit_buffer >> 24,output);
output_bit_buffer <<= 8;
output_bit_count -= 8;
}
/* cout << " Vvedite deictvie: c - compress, d - decompress : "; cin >> menu;
switch (menu)
{
case 'c': compress(input_file, lzw_file); break;
case 'd': expand(lzw_file, output_file); break;
default;
}
*/
} |
(
И еще смущает вопрос - верно ли реализован данный алгоритм? 
