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#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <math.h>
#include <errno.h>
#include <getopt.h>
#include <time.h>
#include <sys/time.h>
#include <alsa/asoundlib.h>
#define SAMPLE_RATE 8000
#define BUFFER_SIZE 512
/* 2 bytes per sample; 0.1 seconds long */
#define TONE_SIZE (2*SAMPLE_RATE/10)
#define TONE1_FREQ 800
#define TONE2_FREQ 440
static uint8_t tone1[TONE_SIZE];
static uint8_t tone2[TONE_SIZE];
static const uint8_t silence[BUFFER_SIZE];
static int bpm = 120;
static const char *pattern = "1222";
static int set_alsa_params(snd_pcm_t *pcm_handle)
{
snd_pcm_hw_params_t *hwparams;
unsigned int rate = SAMPLE_RATE;
snd_pcm_uframes_t bufsize = BUFFER_SIZE;
snd_pcm_hw_params_alloca(&hwparams);
if (snd_pcm_hw_params_any(pcm_handle, hwparams) < 0) {
printf("Failed configuring device\n");
return -1;
}
if (snd_pcm_hw_params_set_access(pcm_handle, hwparams, SND_PCM_ACCESS_RW_INTERLEAVED) < 0) {
printf("Failed setting access mode\n");
return -1;
}
if (snd_pcm_hw_params_set_format(pcm_handle, hwparams, SND_PCM_FORMAT_S16_LE) < 0) {
printf("Failed setting format\n");
return -1;
}
if (snd_pcm_hw_params_set_rate_near(pcm_handle, hwparams, &rate, 0) < 0) {
printf("Failed setting sample rate\n");
return -1;
}
if (snd_pcm_hw_params_set_buffer_size_near(pcm_handle, hwparams, &bufsize) < 0) {
printf("Failed setting sample rate\n");
return -1;
}
if (snd_pcm_hw_params_set_channels(pcm_handle, hwparams, 1) < 0) {
printf("Failed setting channel number\n");
return -1;
}
if (snd_pcm_hw_params(pcm_handle, hwparams) < 0) {
printf("Failed applying hardware parameters\n");
return -1;
}
return 0;
}
static void prepare_tones()
{
int i, amplitude = 20;
uint16_t sample;
for(i=0; i<TONE_SIZE-1; i++) {
sample = amplitude * sin(2*M_PI*TONE1_FREQ*i/SAMPLE_RATE);
tone1[i] = sample % 256;
tone1[i+1] = sample >> 8;
sample = amplitude * sin(2*M_PI*TONE2_FREQ*i/SAMPLE_RATE);
tone2[i] = sample % 256;
tone2[i+1] = sample >> 8;
}
}
static long timediff_us(struct timespec *ts1, struct timespec *ts2)
{
struct timeval tv1, tv2, diff;
TIMESPEC_TO_TIMEVAL(&tv1, ts1);
TIMESPEC_TO_TIMEVAL(&tv2, ts2);
timersub(&tv1, &tv2, &diff);
return diff.tv_sec * 1000000 + diff.tv_usec;
}
static void play_tone(snd_pcm_t *pcm_handle, char tone)
{
const uint8_t *tonebuf;
int tonebuf_size;
switch(tone) {
case '1':
tonebuf = tone1;
tonebuf_size = sizeof(tone1);
break;
case '2':
tonebuf = tone2;
tonebuf_size = sizeof(tone2);
break;
case 's':
default:
tonebuf = silence;
tonebuf_size = sizeof(silence);
break;
}
while (snd_pcm_writei(pcm_handle, tonebuf, tonebuf_size / 2) < 0) {
snd_pcm_prepare(pcm_handle);
printf("underrun\n");
}
}
static int play(snd_pcm_t *pcm_handle, const char *pattern, int bpm)
{
int i = 0;
double period_us;
struct timespec cur_t, old_t = {};
period_us = 1000000 * 60.0 / bpm;
/* fill buffer with silence */
snd_pcm_prepare(pcm_handle);
play_tone(pcm_handle, 's');
while(1) {
if (clock_gettime(CLOCK_MONOTONIC, &cur_t) == -1) {
printf("Failed getting time: %s\n", strerror(errno));
return -1;
}
if (timediff_us(&cur_t, &old_t) >= period_us) {
memcpy(&old_t, &cur_t, sizeof(struct timespec));
play_tone(pcm_handle, pattern[i++ % strlen(pattern)]);
} else {
play_tone(pcm_handle, 's');
}
}
}
static void usage(const char *name)
{
printf("Usage: %s [OPTION]\n", name);
printf(" -b, --bpm=N Set beats per minute\n");
printf(" -p, --pattern=PATTERN Set beeping pattern (e.g. 1222)\n");
}
static int parse_cmdline(int argc, char *argv[])
{
int opt;
struct option options[] = {
{"help", no_argument, 0, 'h'},
{"bpm", required_argument, 0, 'b'},
{"pattern", required_argument, 0, 'p'},
{0, 0, 0, 0},
};
while ((opt = getopt_long(argc, argv, "hb:p:", options, NULL)) != -1) {
switch(opt) {
case 'b':
if (sscanf(optarg, "%d", &bpm) != 1) {
return -1;
}
break;
case 'p':
pattern = strdup(optarg);
break;
case 'h':
default:
return -1;
}
}
return 0;
}
int main(int argc, char *argv[])
{
snd_pcm_t *pcm_handle;
if (parse_cmdline(argc, argv) < 0) {
usage(argv[0]);
return 1;
}
if (snd_pcm_open(&pcm_handle, "default", SND_PCM_STREAM_PLAYBACK, 0) < 0) {
printf("Failed opening device\n");
return 1;
}
if (set_alsa_params(pcm_handle) < 0) {
return 1;
}
prepare_tones();
play(pcm_handle, pattern, bpm);
snd_pcm_close(pcm_handle);
return 0;
}
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