/* img_ship_diff -U<unpolished_prediction.img> -S<polished_standard.img> -O<diff_at_ship_points.img> > pointdiff.dat
*/

#include "img_predict.h"

int main (int argc, char **argv) {

	short int *x, y;
	int	i, nx, ny, n, ax, goes_out;
	char	*ufile = NULL, *sfile = NULL, *ofile = NULL;
	FILE *fp;
	
	n = 0;
	for (i = 1; i < argc; i++) {
		if (argv[i][0] == '-') {
			switch (argv[i][1]) {
				case 'U':
					ufile = &argv[i][2];
					break;
				case 'S':
					sfile = &argv[i][2];
					break;
				case 'O':
					ofile = &argv[i][2];
					break;
				default:
					n++;
			}
		}
		else {
			n++;
		}
	}
	
	if (n || (ufile == NULL) || (sfile == NULL) || (ofile == NULL)  ) {
		fprintf (stderr, "usage: img_ship_diff -U<unpolished_prediction.img> -S<polished_standard.img> -O<diff_at_ship_points.img> > pointdiff.dat\n");
		exit (-1);
	}
	
	if (check_imgfile_size (sfile, &nx, &ny) ) {
		fprintf (stderr, "img_ship_diff:  FATAL ERROR.  Cannot understand size of %s\n", sfile);
		exit (EXIT_FAILURE);
	}
	
	n = nx * ny;
	if ( (x = (short int *) malloc ( (size_t) (2 * n) ) ) == NULL) {
		fprintf (stderr, "img_ship_diff:  FATAL ERROR.  Cannot malloc %d bytes\n", 2*n);
		exit (EXIT_FAILURE);
	}

	if ( (fp = fopen(sfile, "r") ) == NULL) {
		fprintf (stderr, "img_ship_diff:  FATAL ERROR.  Cannot open r %s\n", sfile);
		exit (-1);
	}
	if ( (fread ( (void *)x, (size_t)2, (size_t)n, fp) ) != n) {
		fprintf (stderr, "img_ship_diff:  FATAL ERROR reading %s\n", sfile);
		exit (-1);
	}
	fclose (fp);
	
	if ( (fp = fopen(ufile, "r") ) == NULL) {
		fprintf (stderr, "img_ship_diff:  FATAL ERROR.  Cannot open r %s\n", ufile);
		exit (-1);
	}
	for (i = 0; i < n; i++) {
		if ( (fread ( (void *)&y, (size_t)2, (size_t)1, fp) ) != 1) {
			fprintf (stderr, "img_ship_diff:  FATAL ERROR reading i = %d from %s\n", i, ufile);
			exit (-1);
		}
		goes_out = 0;
		if (x[i] < 0) {
			ax = abs((int)x[i]);
			if (ax%2 == 1) {
				x[i] -= y;
				goes_out = 1;
			}
			else {
				x[i] = 0;
			}
		}
		else {
			x[i] = 0;
		}
		if (goes_out) printf ("%d\n", (int)x[i]);
	}
	fclose (fp);
	
	if ( (fp = fopen(ofile, "w") ) == NULL) {
		fprintf (stderr, "img_ship_diff:  FATAL ERROR.  Cannot open w %s\n", ofile);
		exit (-1);
	}
	
	if ( (fwrite( (void *)x, (size_t)2, (size_t)n, fp) ) != n) {
		fprintf (stderr, "img_ship_diff:  FATAL ERROR writing diff to stdout\n");
		exit (-1);
	}
	fclose (fp);
	
	free ((void *)x);

	exit (EXIT_SUCCESS);
}