#include <stdio.h>

int main(int argc, char** argv)
{
	FILE* fin, *fout;
	char buffer[4];
	char  temp;
	size_t byteswritten;
	
	if (argc != 3) {
		printf("Usage: %s filein fileout\n\n", argv[0]);
		return 1;
	}
	
	fin  = fopen(argv[1], "rb");
	fout = fopen(argv[2], "wb");

	while (fread(buffer, 1, 4, fin) == 4) {
		/* swap bytes */
		temp = buffer[0];
		buffer[0] = buffer[3];
		buffer[3] = temp;
		temp = buffer[1];
		buffer[1] = buffer[2];
		buffer[2] = temp;
		/* write them out */
		byteswritten = fwrite(buffer, 1, 4, fout);
		if (byteswritten != 4) {
			printf("Write error!\n\n");
			return 1;
		}
	}
	
	fclose(fin);
	fclose(fout);
	
	return 0;
}