Calculate checksum

makeimg.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>


int main(int argc, char* argv[])
{
    char *szFilename = 0;
	FILE *fp;
	unsigned long data;
	unsigned long checksum = 0;
	int size = 0;

    if (argc == 1)
        printf("need input file name\n");

	szFilename = argv[1];

	fp = fopen(szFilename, "rb");
	while(fread(&data, 4, 1, fp))
	{
		size += 4;
		checksum ^= data;
	}
	fclose(fp);

	printf("size=%d, checksum=%08X\n", size, checksum);

	fp = fopen(szFilename, "ab");
	fwrite(&checksum, 4, 1, fp);
	fclose(fp);

	return 0;
}