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soundcurses.c
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soundcurses.c
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/**************************************************************************
* soundcurses.c - Send sound to the device when a button is pressed.
*/
#include "wav.h"
#include "binfile.h"
#include <math.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <stdio.h>
#include <linux/soundcard.h>
#include <ncurses.h>
#define LENGTH 3 /* how many seconds of speech to store */
#define RATE 8000 /* the sampling rate */
#define SIZE 16 /* sample size: 8 or 16 bits */
#define CHANNELS 1 /* 1 = mono 2 = stereo */
/* Generate a pure tone by sampling a sine wave with the given
frequency at the time indicated. */
float pure_tone(float time, float freq_hz) {
return sin(time * freq_hz * 2 * M_PI);
}
int main(int argc, char** argv) {
const int sample_rate = RATE;
const float dt = 1.0 / sample_rate;
const float freq_hz = 440; /* A above middle C */
float time;
int fd; /* sound device file descriptor */
int arg; /* argument for ioctl calls */
int status; /* return status of system calls */
/* open sound device */
fd = open("/dev/dsp", O_RDWR);
if (fd < 0) {
perror("open of /dev/dsp failed");
exit(1);
}
arg = SIZE; /* sample size */
status = ioctl(fd, SOUND_PCM_WRITE_BITS, &arg);
if (status == -1)
perror("SOUND_PCM_WRITE_BITS ioctl failed");
if (arg != SIZE)
perror("unable to set sample size");
arg = CHANNELS; /* mono or stereo */
status = ioctl(fd, SOUND_PCM_WRITE_CHANNELS, &arg);
if (status == -1)
perror("SOUND_PCM_WRITE_CHANNELS ioctl failed");
if (arg != CHANNELS)
perror("unable to set number of channels");
arg = RATE; /* sampling rate */
status = ioctl(fd, SOUND_PCM_WRITE_RATE, &arg);
if (status == -1)
perror("SOUND_PCM_WRITE_WRITE ioctl failed");
for (time=0; time<LENGTH; time+=dt) { //Generate sound and write it to dsp
float fsample = pure_tone(time, freq_hz);
int sample = (int)(fsample * 1e16);
status = write(fd, sample, sizeof(sample)); //This line is giving problems.
if (status != sizeof(sample))
perror("wrote wrong number of bytes");
status = ioctl(fd, SOUND_PCM_SYNC, 0);
if (status == -1)
perror("SOUND_PCM_SYNC ioctl failed");
}
return 0;
}