/* imgbm_check_sea.c sealevel.bitmask < binary input > binary output 
 * 
 * Program to filter out ocean data within the land mask and eliminate
 * positive depths.
 *
 * Read and write 8-byte binary records consisting of two 4-byte ints;
 * the first is the index to the img pixel, and the second is the data value.
 * checks index against sea level mask and removes data in "ocean areas"
 *
 */

#include <stdio.h>
#include <math.h>

#define NX 10800
#define NY 6336
#define NMASK 8553600   /* NX * NY / 8  for bitmask  */

struct IMGPAIR {
	int	index;
	int	depth;
};

	unsigned char mask[NMASK];
	static unsigned char maskset[8] = {128, 64, 32, 16, 8, 4, 2, 1};

main(argc, argv)
int	argc;
char	**argv;
{
	int	i, j,  n_in, n_out, n_edit;
	struct IMGPAIR imgpair;
	FILE    *fp;

	if (argc <= 1) {
		fprintf(stderr,"usage:  imgbm_check_sea sealevel.bitmask < <binary input> > <binary output>\n\n");
		exit(-1);
	}

	if ( (fp = fopen(argv[1], "r")) == NULL) return(-1);
	if ( (fread(mask, 1, NMASK, fp)) != NMASK) return(-1);
	fclose(fp);

        n_in = 0;
	n_out = 0;
        n_edit = 0;

	while ( (fread((char *)&imgpair, sizeof(struct IMGPAIR), 1, stdin)) == 1) {
		n_in++;
                if (imgpair.index < 0 || imgpair.index >= 8*NMASK) {
			fprintf(stderr,"imgbm_check:  bad index %d \n", imgpair.index);
			n_edit++;
                        continue;
                }
                i = imgpair.index;
		if(!(mask[i/8] & maskset[i%8]) || imgpair.depth > -2 ){
			if ( (fwrite((void *)&imgpair, sizeof(struct IMGPAIR), 1, stdout)) != 1) {
				fprintf(stderr,"imgbm_check:  Write error.\n");
				exit(-1);
			}
			n_out++;
		}
		else {
/*  			fprintf(stderr," land area %d %d \n", imgpair.index, imgpair.depth); */
			n_edit++;
		}
	}
	fprintf(stderr,"imgbm_check , read, wrote, edited %d %d %d\n", n_in,n_out,n_edit);
	exit(0);
}