usaa21/sk2a/compressor.c

#define _GNU_SOURCE
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "compressor.h"
#define BUFSIZE 2000000 
#define BSIZE 9


int mycompress(char* buff,int size,char* outbuf){
    //memcpy(outbuf,buff,size);
	int k = 0;
	int head = 0;
	while(head < size && buff[head] > 0 ){
		// 
		//
		//	Kod inspirovany riesenim 
		//	pana Ing. Daniela Hladeka
		//  2019 Technical University of Kosice	
		//
		//
		int bufferSize = BSIZE;
		if (head < bufferSize){
			bufferSize = head;
		}

		char* searchBuffer = buff + head - bufferSize;

		char* window = buff + head;

		int lookAheadSize = BSIZE;
		if((size - head) < lookAheadSize){
			lookAheadSize = BSIZE - head;
		}
		int wsz = BSIZE;
		int msz = wsz;
        if (bufferSize < wsz){
       		msz = bufferSize;
        }
		int offset = -1;

		int size = -1;

		for(int i = 1; i<msz; i++){
			char* r = memmem(searchBuffer, bufferSize, window, i);
			if(r > 0){
				offset = bufferSize - ( r - searchBuffer );
				size = i+1;
			}else {
				break;
			}
		}
		

		if(size > 0){
			sprintf(&outbuf[k],"%d%d%c",offset,size-1,buff[head+size-1]);
			k+=3;
			head+=size;
			
		}else {
			sprintf(&outbuf[k],"00%c",buff[head]);
			k+=3;
			head+=1;
		}
	
	}

	
    return k;
}


void compress(FILE* infile,FILE* outfile){
    char buffer[BUFSIZE];
    memset(buffer,0,BUFSIZE);
    while(1){
        int insize = fread(buffer,sizeof(char),BUFSIZE,infile);
        if (insize == 0){
            if (feof(infile)){
                // end of file
                break;
            }
            assert(!ferror(infile));
        }
        char outbuf[BUFSIZE*2];
        // Doplnte implementaciu kompresie. 
        int outsize = mycompress(buffer,insize,outbuf);
        if (outsize   > 0){
            fwrite(outbuf,sizeof(char),outsize,outfile);
        }
    }
}



void decompress(FILE* infile,FILE* outfile){
   	char code[3];
    char buffer[BUFSIZE];
	int size = 0;
	int k = 0;
	fseek(infile, 0, SEEK_END);
	long fileSize = ftell(infile);
	fseek(infile, 0, SEEK_SET);
	printf("size: %ld\n", fileSize);
	char letter;
while(!feof(infile)){
	size = 0;
	memset(buffer,0,BUFSIZE);
	for(int j = 0; j < 4096; j++){
	fread(code, sizeof(char), 3, infile);
	int offset = atoi(code);
	int length = atoi(&code[1]);
	letter = code[2];
	offset=(offset-length)/10;
	if(offset == 0){
		buffer[size] = letter;
		size++;
	}else {
		for(int i = 0; i < length; i++){
			buffer[size] = buffer[size-offset];
			size++;
		} 
		buffer[size] = letter;
		size++;
	}
	printf("%d\n",k);
	k+=3;
}

fwrite(buffer, sizeof(char), size-1, outfile);
}


}