/* click.c   by Michael Thorpe   2008-04-05 */

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

#define SAMPLE_RATE 44100
#define BEAT_LEN (SAMPLE_RATE/10) /* 1/10th second */

int main(int argc,char **argv) {
	signed short *buf;
	char *tmp;
	unsigned long bufsize,i;
	unsigned long bpm;
	unsigned long numtimes=0;

	if(argc<2 || 3<argc || !isdigit(argv[1][0])) {
		fprintf(stderr,"usage: %s <beats_per_minute> [<num_beats>]\n",argv[0]);
		return(1);
	}
	bpm=strtoul(argv[1],&tmp,0);
	if(*tmp) {
		fprintf(stderr,"invalid BPM: %s\n",argv[1]);
		return(2);
	}
	if(argc>2) {
		numtimes=strtoul(argv[2],&tmp,0);
		if(*tmp) {
			fprintf(stderr,"invalid number of beats: %s\n",argv[2]);
			return(3);
		}
	}
	bufsize=SAMPLE_RATE*60/bpm;
	if(bufsize<=BEAT_LEN) {
		fprintf(stderr,"tempo too fast\n");
		return(4);
	}
	buf=(signed short *)calloc(bufsize,2);
	if(!buf) {
		perror("calloc");
		return(5);
	}
	for(i=0;i<BEAT_LEN;i++) {
		buf[i]=0x8000*(BEAT_LEN-i)/BEAT_LEN;
	}
	while(1) {
		fwrite(buf,bufsize,2,stdout);
		if(numtimes && !--numtimes)
			break;
	}
	return(0);
}