Here is the sourcecode:
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <tgmath.h>
#include <sys/soundcard.h>
char *SoundDev = "/dev/dsp"; /* device name for soundcard */
#define FSAMP 8000 /* sample rate */
#define AMPLI 30000 /* output amplitude */
#define TONE1 440 /* tone 1 freq */
#define DURA1 ((int)(0.1*FSAMP)) /* duration = 100 ms */
#define TONE2 440 /* tone 2 freq */
#define DURA2 ((int)(0.1*FSAMP)) /* duration = 100 ms */
#define STAR2 ((int)(0.25*FSAMP)) /* start tone2 = 250 ms */
#define RAMP ((int)(0.01*FSAMP)) /* ramp-up/down = 10 ms */
#define PAUSE ((int)(1.75*FSAMP)) /* pause = 1750 ms */
#define CYCLE (STAR2+DURA2+PAUSE) /* total cycle time */
short int sample[CYCLE];
int
main (argc,argv)
int argc;
char *argv;
{
int soundfd;
int blksize;
int n;
int ampli;
double rate;
if ((soundfd = open(SoundDev,O_WRONLY)) < 0) {
perror(SoundDev);
exit(1);
}
n = APF_NETWORK; /* underruns occur */
ioctl(soundfd,SNDCTL_DSP_PROFILE,&n);
if (ioctl(soundfd,SNDCTL_DSP_GETBLKSIZE,&blksize) < 0 ||
blksize < 1 || blksize > 65536) {
perror(SoundDev);
exit(1);
}
if (argc > 1) {
printf("%s: blocksize %d bytes\n",SoundDev,n);
printf("sample rate: %d length: %d\n",FSAMP,sizeof(sample));
printf("tone1: %dms %dHz %dms
ramp\n",1000*DURA1/FSAMP,TONE1,1000*RAMP/FSAMP);
printf("tone2: %dms %dHz %dms
ramp\n",1000*DURA2/FSAMP,TONE2,1000*RAMP/FSAMP);
printf("pause: %dms\n",1000*PAUSE/FSAMP);
}
n = 0; /* select MONO */
if (ioctl(soundfd,SNDCTL_DSP_STEREO,&n) < 0) {
perror(SoundDev);
exit(1);
}
n = AFMT_S16_LE; /* Little-endian signed 16bit */
if (ioctl(soundfd,SNDCTL_DSP_SETFMT,&n) < 0) {
perror(SoundDev);
exit(1);
}
n = FSAMP; /* sample rate */
if (ioctl(soundfd,SNDCTL_DSP_SPEED,&n) < 0) {
perror(SoundDev);
exit(1);
}
/* silence in buffer */
memset(sample,0,sizeof(sample));
/* tone1 */
rate = ((double)TONE1 * 2 * M_PI) / (double)FSAMP;
for (n = 0; n < DURA1; n++) {
if (n < RAMP)
ampli = n * AMPLI / RAMP;
else
if (n > (DURA1 - RAMP))
ampli = (DURA1 - n) * AMPLI / RAMP;
else
ampli = AMPLI;
sample[n] = ampli * sin((double)n * rate);
if (argc > 2) {
printf("n=%d ampli=%d sample=%d\n",n,ampli,sample[n]);
}
}
/* tone2 */
rate = ((double)TONE2 * 2 * M_PI) / (double)FSAMP;
for (n = 0; n < DURA2; n++) {
if (n < RAMP)
ampli = n * AMPLI / RAMP;
else
if (n > (DURA2 - RAMP))
ampli = (DURA2 - n) * AMPLI / RAMP;
else
ampli = AMPLI;
sample[STAR2+n] = ampli * sin((double)n * rate);
if (argc > 2) {
printf("n=%d ampli=%d sample=%d\n",STAR2+n,ampli,sample[STAR2+n]);
}
}
/* send the prepared buffer in an endless loop */
for (;;) {
if (write(soundfd,sample,sizeof(sample)) != sizeof(sample)) {
perror(SoundDev);
exit(1);
}
}
exit(0);
}
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