From cac4809a6428a9689a3ba1ca772973bd65400ee2 Mon Sep 17 00:00:00 2001
From: Kozar <anton.kozar@student.tuke.sk>
Date: Sat, 14 Dec 2024 13:20:39 +0000
Subject: [PATCH] Update sk1/compressor.c

---
 sk1/compressor.c | 136 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 136 insertions(+)

diff --git a/sk1/compressor.c b/sk1/compressor.c
index e69de29..408ad14 100644
--- a/sk1/compressor.c
+++ b/sk1/compressor.c
@@ -0,0 +1,136 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+
+#define BUFFER_SIZE 1024
+#define LZ78_DICT_SIZE 256
+
+// Function prototypes
+int compress(const char* input_file_name, const char* output_file_name);
+int decompress(const char* input_file_name, const char* output_file_name);
+void lz78_compress(FILE* in, FILE* out);
+void lz78_decompress(FILE* in, FILE* out);
+
+void print_usage() {
+    printf("Usage:\n");
+    printf("  ./compressor -c infile outfile   Compress infile into outfile\n");
+    printf("  ./compressor -d compressed uncompressed   Decompress compressed into uncompressed\n");
+}
+
+int main(int argc, char* argv[]) {
+    if (argc != 4) {
+        print_usage();
+        return 1;
+    }
+
+    const char* mode = argv[1];
+    const char* infile = argv[2];
+    const char* outfile = argv[3];
+
+    if (strcmp(mode, "-c") == 0) {
+        return compress(infile, outfile);
+    } else if (strcmp(mode, "-d") == 0) {
+        return decompress(infile, outfile);
+    } else {
+        print_usage();
+        return 1;
+    }
+}
+
+int compress(const char* input_file_name, const char* output_file_name) {
+    FILE* input_file = fopen(input_file_name, "rb");
+    if (!input_file) {
+        perror("Error opening input file");
+        return -1;
+    }
+
+    FILE* output_file = fopen(output_file_name, "wb");
+    if (!output_file) {
+        perror("Error opening output file");
+        fclose(input_file);
+        return -1;
+    }
+
+    lz78_compress(input_file, output_file);
+
+    fclose(input_file);
+    fclose(output_file);
+
+    printf("File compressed successfully.\n");
+    return 0;
+}
+
+int decompress(const char* input_file_name, const char* output_file_name) {
+    FILE* input_file = fopen(input_file_name, "rb");
+    if (!input_file) {
+        perror("Error opening input file");
+        return -1;
+    }
+
+    FILE* output_file = fopen(output_file_name, "wb");
+    if (!output_file) {
+        perror("Error opening output file");
+        fclose(input_file);
+        return -1;
+    }
+
+    lz78_decompress(input_file, output_file);
+
+    fclose(input_file);
+    fclose(output_file);
+
+    printf("File decompressed successfully.\n");
+    return 0;
+}
+
+// LZ78 compression
+struct dict {
+    int index;
+    struct dict* characters[LZ78_DICT_SIZE];
+};
+
+void delete_dict(struct dict* tree) {
+    if (!tree) {
+        return;
+    }
+    for (int i = 0; i < LZ78_DICT_SIZE; i++) {
+        delete_dict(tree->characters[i]);
+    }
+    free(tree);
+}
+
+void lz78_compress(FILE* in, FILE* out) {
+    struct dict* root = calloc(1, sizeof(struct dict));
+    struct dict* current = root;
+    int index = 1;
+    int c;
+
+    while ((c = fgetc(in)) != EOF) {
+        if (current->characters[c]) {
+            current = current->characters[c];
+        } else {
+            current->characters[c] = calloc(1, sizeof(struct dict));
+            current->characters[c]->index = index++;
+            fprintf(out, "%d-%c\n", current->index, c);
+            current = root;
+        }
+    }
+
+    delete_dict(root);
+}
+
+// LZ78 decompression
+void lz78_decompress(FILE* in, FILE* out) {
+    char buffer[LZ78_DICT_SIZE][BUFFER_SIZE] = {""};
+    int index;
+    char c;
+
+    while (fscanf(in, "%d-%c\n", &index, &c) == 2) {
+        if (index > 0) {
+            fprintf(out, "%s", buffer[index]);
+        }
+        fputc(c, out);
+        snprintf(buffer[index], BUFFER_SIZE, "%s%c", buffer[index], c);
+    }
+}