asd

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/syslimits.h>
#include <dirent.h>
#include <sys/dir.h>
#include <sys/stat.h>
#include <time.h>
#include <pwd.h>
#include <grp.h>
#include <fcntl.h>

int main (int argc, char* argv[]) {
	if (argc != 3) {
		printf("usage: %s [source file] [destination path]\n", argv[0]);
		return -1;
	}

	int fd_src, fd_dst;
	if ((fd_src = open(argv[1], O_RDONLY)) < 0) {
		perror(argv[0]);
		return -1;
	}

	if ((fd_dst = open(argv[2], O_WRONLY | O_CREAT | O_TRUNC, 0666)) < 0) {
		perror(argv[0]);
		return -1;
	}

	int bytes, i;
	unsigned char buff[1];
	unsigned char aux;
	while ((bytes = read(fd_src, buff, sizeof(char))) > 0) {
	    unsigned char c = buff[0];
		aux = 0;
		for (i = 0; i < 4; i++) {
			if (c & (1<<i)) {
				aux |= (1 << (i+4));
			}
		}
		for (i = 4; i < 8; i++) {
			if (c & (1<<i)) {
				aux |= (1 << (i-4));
			}
		}
		buff[0] = aux;
		write(fd_dst, buff, bytes);
	}
	close(fd_src); close(fd_dst);
	return 0;
}