/*
 *  This extra small demo sends silence to your speakers and tests the precision of the reported position.
 */

#include <asoundlib.h>

#include <stdio.h>
#include <stdlib.h>

const char* device;
const int channels = 2;
const snd_pcm_sframes_t period_size = 960;
const int periods = 4;
const int rate = 48000;


int main(int argc, char* argv[])
{
        int err;
	int failed = 0;
        unsigned int j, j_old;
	short *silence;
	snd_pcm_sframes_t avail = -1, delay = -1;
	snd_pcm_uframes_t min_period_size;
	snd_pcm_uframes_t boundary;
	int dir;
	struct timeval tv_old;

	if (argc != 2) {
		fprintf(stderr, "Usage: %s pcm_name\n", argv[0]);
		exit(EXIT_FAILURE);
	}

	device = argv[1];
	printf("======= testing %s =======\n", device);


        snd_pcm_t *handle;
	snd_output_t *out = NULL;

	snd_pcm_hw_params_t *params;
	snd_pcm_sw_params_t *swparams;

	snd_pcm_hw_params_alloca(&params);
	snd_pcm_sw_params_alloca(&swparams);

	snd_output_stdio_attach(&out, stdout, 0);
	silence = calloc(period_size * periods, sizeof(short) * channels);

	if ((err = snd_pcm_open(&handle, device, SND_PCM_STREAM_PLAYBACK, 0)) < 0) {
		fprintf(stderr, "Playback open error: %s\n", snd_strerror(err));
		exit(EXIT_FAILURE);
	}

	failed =           (err = snd_pcm_hw_params_any(handle, params)) < 0;
	failed = failed || (err = snd_pcm_hw_params_set_rate_resample(handle, params, 1)) < 0;
	failed = failed || (err = snd_pcm_hw_params_set_access(handle, params, SND_PCM_ACCESS_RW_INTERLEAVED)) < 0;
	failed = failed || (err = snd_pcm_hw_params_set_format(handle, params, SND_PCM_FORMAT_S16)) < 0;
	failed = failed || (err = snd_pcm_hw_params_set_channels(handle, params, channels)) < 0;
	failed = failed || (err = snd_pcm_hw_params_set_rate(handle, params, rate, 0)) < 0;

	if (failed) {
		fprintf(stderr, "Playback hwparams (access & format) error: %s\n", snd_strerror(err));
		exit(EXIT_FAILURE);
	}

	err = snd_pcm_hw_params_get_period_size_min(params, &min_period_size, &dir);
	if (err < 0) {
		fprintf(stderr, "Cannot get minimum period size: %s\n", snd_strerror(err));
	}

	printf("min_period_size: %d frames, dir: %d\n", (int)min_period_size, dir);

	failed =           (err = snd_pcm_hw_params_set_period_size(handle, params, period_size, 0)) < 0;
	failed = failed || (err = snd_pcm_hw_params_set_periods(handle, params, periods, 0)) < 0;
	failed = failed || (err = snd_pcm_hw_params(handle, params)) < 0;
	if (failed) {
		fprintf(stderr, "Playback hwparams (period size & periods) error: %s\n", snd_strerror(err));
		exit(EXIT_FAILURE);
	}

	err = snd_pcm_hw_params_get_fifo_size(params);
	if (err < 0) {
		fprintf(stderr, "Playback hwparams: can't get FIFO size, error: %s\n", snd_strerror(err));
	} else {
		printf("FIFO size is %d\n", err);
	}

	failed =           (err = snd_pcm_sw_params_current(handle, swparams)) < 0;
	failed = failed || (err = snd_pcm_sw_params_set_start_threshold(handle, swparams, period_size)) < 0;
	failed = failed || (err = snd_pcm_sw_params_set_avail_min(handle, swparams, period_size)) < 0;
	failed = failed || (err = snd_pcm_sw_params(handle, swparams)) < 0;
	if (failed) {
		fprintf(stderr, "Playback swparams error: %s\n", snd_strerror(err));
		exit(EXIT_FAILURE);
	}

	snd_pcm_dump(handle, out);
	printf("Playing silence\n");
	fflush(stdout);
	memset(silence, 0, period_size * periods * sizeof(short) * channels);
	err = snd_pcm_writei(handle, silence, period_size * periods);
	if (err < 0) {
		fprintf(stderr, "Playback error: %s\n", snd_strerror(err));
		exit(EXIT_FAILURE);
	}

	j = 0;
	j_old = 0;
	gettimeofday(&tv_old, NULL);
	while (1) {
		snd_pcm_sframes_t avail1;
		snd_pcm_sframes_t delay1;
		err = snd_pcm_avail_delay(handle, &avail1, &delay1);
		if (err < 0 || avail1 < 0)
			break;
		if (avail != avail1 || delay != delay1) {
			struct timeval tv;
			gettimeofday(&tv, NULL);
			printf("Available: %d, delay: %d, loop iteration: %d, diff: %d, timestamp diff: %d usec\n", (int)avail1, (int)delay1, j, j - j_old,
				(int)((tv.tv_sec - tv_old.tv_sec) * 1000000 + (tv.tv_usec - tv_old.tv_usec)));
			tv_old = tv;
			j_old = j;
		}
		avail = avail1;
		delay = delay1;
		j++;
	}
	snd_pcm_drop(handle);
	snd_pcm_close(handle);

	free(silence);
	return 0;
}