From 790aa2149cf642c1fbc58c7e05d0a214f347e1a0 Mon Sep 17 00:00:00 2001
From: VIliam <viliam.dzubara@student.tuke.sk>
Date: Sun, 19 Jan 2025 21:45:12 +0100
Subject: [PATCH] skuska

---
 sk1/compressor.c | 110 +++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 98 insertions(+), 12 deletions(-)

diff --git a/sk1/compressor.c b/sk1/compressor.c
index 0c0c18d..9a9b9d3 100644
--- a/sk1/compressor.c
+++ b/sk1/compressor.c
@@ -266,21 +266,107 @@ int compress_2(const char* input_file_name, const char* output_file_name) {
     unsigned char* data = read_file(input_file_name, &size);
     if (!data) return -1;
 
-    printf("Compressing using Algorithm 2 (LZ77)...\n");
-   
-    int result = write_file(output_file_name, data, size);
+    FILE* output_file = fopen(output_file_name, "wb");
+    if (!output_file) {
+        perror("Error opening output file");
+        free(data);
+        return -1;
+    }
+
+    size_t search_buffer_size = 1024; // Veľkosť search bufferu
+    size_t lookahead_buffer_size = 16; // Veľkosť lookahead bufferu
+
+    size_t pos = 0;
+    while (pos < size) {
+        size_t best_match_offset = 0;
+        size_t best_match_length = 0;
+
+        // Vyhľadaj najlepšiu zhodu v search bufferi
+        for (size_t i = (pos > search_buffer_size ? pos - search_buffer_size : 0); i < pos; i++) {
+            size_t match_length = 0;
+            while (match_length < lookahead_buffer_size &&
+                   pos + match_length < size &&
+                   data[i + match_length] == data[pos + match_length]) {
+                match_length++;
+            }
+            if (match_length > best_match_length) {
+                best_match_length = match_length;
+                best_match_offset = pos - i;
+            }
+        }
+
+        // Ulož trojicu (offset, length, next_symbol)
+        unsigned char offset_high = (best_match_offset >> 8) & 0xFF;
+        unsigned char offset_low = best_match_offset & 0xFF;
+        unsigned char length = best_match_length;
+        unsigned char next_symbol = (pos + best_match_length < size) ? data[pos + best_match_length] : 0;
+
+        fputc(offset_high, output_file);
+        fputc(offset_low, output_file);
+        fputc(length, output_file);
+        fputc(next_symbol, output_file);
+
+        // Posuň pozíciu v dátach
+        pos += best_match_length + 1;
+    }
+
+    fclose(output_file);
     free(data);
-    return result;
+
+    printf("Compression using LZ77 completed successfully.\n");
+    return 0;
 }
 
+
 int decompress_2(const char* input_file_name, const char* output_file_name) {
-    size_t size;
-    unsigned char* data = read_file(input_file_name, &size);
-    if (!data) return -1;
+    FILE* input_file = fopen(input_file_name, "rb");
+    if (!input_file) {
+        perror("Error opening input file");
+        return -1;
+    }
 
-    printf("Decompressing using Algorithm 2 (LZ77)...\n");
+    FILE* output_file = fopen(output_file_name, "wb");
+    if (!output_file) {
+        perror("Error opening output file");
+        fclose(input_file);
+        return -1;
+    }
 
-    int result = write_file(output_file_name, data, size);
-    free(data);
-    return result;
-}
\ No newline at end of file
+    unsigned char* output_buffer = (unsigned char*)malloc(10 * 1024 * 1024); // Pre alokáciu 10 MB
+    if (!output_buffer) {
+        perror("Memory allocation error");
+        fclose(input_file);
+        fclose(output_file);
+        return -1;
+    }
+
+    size_t pos = 0;
+    while (1) {
+        int offset_high = fgetc(input_file);
+        int offset_low = fgetc(input_file);
+        int length = fgetc(input_file);
+        int next_symbol = fgetc(input_file);
+
+        if (offset_high == EOF || offset_low == EOF || length == EOF || next_symbol == EOF) break;
+
+        size_t offset = (offset_high << 8) | offset_low;
+
+        // Skopíruj zhodu z histórie
+        for (size_t i = 0; i < length; i++) {
+            output_buffer[pos] = output_buffer[pos - offset];
+            pos++;
+        }
+
+        // Pridaj ďalší symbol
+        output_buffer[pos++] = next_symbol;
+    }
+
+    fwrite(output_buffer, 1, pos, output_file);
+
+    free(output_buffer);
+    fclose(input_file);
+    fclose(output_file);
+
+    printf("Decompression using LZ77 completed successfully.\n");
+    return 0;
+}