#include <stdio.h>
#include <string.h>
#include <sys/fcntl.h>
#define	MAXWLEN	20
#define	CLSIZE	1024
#define	EPERCLUST 42	/* pack 42 elements per cluster */

struct element {	/* each element is a word and count or a word index */
	int	count;	/* dual use field - cluster index or word count */
	char	word[MAXWLEN];
};

struct cluster {	/* use the same cluster struct for index or words */
	int isindexcluster;	/* set to 1 for index clust, 0 for words */
	struct element elem[EPERCLUST];
} clust;

char *file_name = "isamfile";

main(int argc, char *argv[]) {
	int i, j, n, fd;
	fd = open(file_name, O_RDONLY);	/* open the file for reading */
	if(fd < 0) {
		fprintf(stderr, "Could not open %s\n", file_name);
		exit(1);
	}
	for(i = 0; ; i++) {
		lseek(fd, i*CLSIZE, 0);
		n = read(fd, &clust, sizeof(struct cluster));
		if(n <= 0)
			break;
		printf("-----------  cluster %d is %s cluster --------\n", i,
			clust.isindexcluster ? "an index" : "a word count");
		for(j = 0; j < EPERCLUST; j++) {
			printf("%d.%d <%s> %d\n", i, j,
				clust.elem[j].word, clust.elem[j].count);
			if(clust.elem[j].word[0] == 0)
				break;
		}
	}
	printf("read %d clusters\n", i);
}