109 lines
2.6 KiB
C
109 lines
2.6 KiB
C
#include "compressor.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stddef.h>
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// Trie (prefix tree) structure for LZ78 compression
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struct dict {
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int index;
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struct dict* characters[LZ78_DICT_SIZE];
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};
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// Free the dictionary trie
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void delete_dict(struct dict* tree) {
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if (!tree) {
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return;
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}
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for (int i = 0; i < LZ78_DICT_SIZE; i++) {
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delete_dict(tree->characters[i]);
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}
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free(tree);
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}
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// LZ78 Compression
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void lz78_compress(FILE* in, FILE* out) {
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struct dict* root = calloc(1, sizeof(struct dict));
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struct dict* current = root;
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int index = 1;
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int c;
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while ((c = fgetc(in)) != EOF) {
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if (current->characters[c]) {
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current = current->characters[c];
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} else {
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current->characters[c] = calloc(1, sizeof(struct dict));
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current->characters[c]->index = index++;
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fprintf(out, "%d-%c\n", current->index, c);
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current = root;
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}
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}
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delete_dict(root);
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}
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// LZ78 Decompression
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void lz78_decompress(FILE* in, FILE* out) {
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char buffer[LZ78_DICT_SIZE][BUFFER_SIZE] = {""};
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int index, dict_index = 1;
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char c;
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while (fscanf(in, "%d-%c\n", &index, &c) == 2) {
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if (index > 0) {
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fprintf(out, "%s", buffer[index]);
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}
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fputc(c, out);
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snprintf(buffer[dict_index], BUFFER_SIZE, "%s%c", buffer[index], c);
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dict_index++;
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}
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}
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// Compress function
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int compress(const char* input_file_name, const char* output_file_name) {
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FILE* input_file = fopen(input_file_name, "rb");
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if (!input_file) {
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perror("Error opening input file");
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return -1;
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}
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FILE* output_file = fopen(output_file_name, "wb");
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if (!output_file) {
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perror("Error opening output file");
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fclose(input_file);
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return -1;
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}
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lz78_compress(input_file, output_file);
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fclose(input_file);
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fclose(output_file);
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printf("File compressed successfully.\n");
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return 0;
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}
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// Decompress function
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int decompress(const char* input_file_name, const char* output_file_name) {
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FILE* input_file = fopen(input_file_name, "rb");
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if (!input_file) {
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perror("Error opening input file");
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return -1;
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}
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FILE* output_file = fopen(output_file_name, "wb");
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if (!output_file) {
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perror("Error opening output file");
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fclose(input_file);
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return -1;
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}
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lz78_decompress(input_file, output_file);
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fclose(input_file);
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fclose(output_file);
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printf("File decompressed successfully.\n");
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return 0;
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}
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