#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif

#include <stdio.h>
#include <alsa/asoundlib.h>

#define BUFFER_TIME_MIN		(100000)
#define BUFFER_TIME_MAX		(1000000)
#define BUFFER_TIME_STEP	(5000)

int try_alsa_setup(snd_pcm_t *pcm, unsigned int rate, unsigned int *buffer_time,
		   unsigned int *periods)
{
	int r;
	snd_pcm_hw_params_t *hwparams;

	snd_pcm_hw_params_alloca (&hwparams);

	r = snd_pcm_hw_params_any(pcm, hwparams);
	if (r < 0)
		return r;

	r = snd_pcm_hw_params_set_rate_resample(pcm, hwparams, 0);
	if (r < 0)
		return r;

	r = snd_pcm_hw_params_set_access(pcm, hwparams,
	                                  SND_PCM_ACCESS_RW_INTERLEAVED);
	if (r < 0)
		return r;

	r = snd_pcm_hw_params_set_format(pcm, hwparams,SND_PCM_FORMAT_S16_LE);
	if (r < 0)
		return r;

	r = snd_pcm_hw_params_set_rate_near(pcm, hwparams, &rate, NULL);
	if (r < 0)
		return r;

	r = snd_pcm_hw_params_set_channels(pcm, hwparams, 2);
	if (r < 0)
		return r;

	r = snd_pcm_hw_params_set_buffer_time_near(pcm, hwparams, buffer_time,
	                NULL);
	if (r < 0)
		return r;

	r = snd_pcm_hw_params_set_periods_near(pcm, hwparams, periods, NULL);
	if (r < 0)
		return r;

	r = snd_pcm_hw_params(pcm, hwparams);
	if (r < 0)
		return r;

	r = snd_pcm_hw_params_current(pcm, hwparams);
	if (r < 0)
		return r;

	return 0;
}

int main(int argc, char *argv[])
{
	const char *dev;
	snd_pcm_t *pcm;
	unsigned int rates[] = {44100, 88200, 48000, 96000, 0 };
	unsigned int periods = 10;
	unsigned int i;
	int r;

	dev = argc > 1 ? argv[1] : "hw:0,0";

	printf("Opening %s\n\n", dev);
	for (i = 0; rates[i]; i++) {
		unsigned int time = BUFFER_TIME_MIN;
		do {
			unsigned int buffer_time = time;
			r = snd_pcm_open(&pcm, dev, SND_PCM_STREAM_PLAYBACK, 0);
			if (r < 0) {
				printf("Failed to open %s\n", dev);
				return -1;
			}

			printf("Try of %dHz, %u us buffer: ", rates[i],
			       buffer_time);

			r = try_alsa_setup(pcm, rates[i], &buffer_time,
					   &periods);

			if (r < 0)
				printf("FAILED\n");
			else
				printf("OK (got %u us)\n", buffer_time);

			r = snd_pcm_close(pcm);
			if (r < 0) {
				printf("snd_pcm_close() failed %d\n", r);
				return r;
			}
			time += BUFFER_TIME_STEP;
		} while (time <= BUFFER_TIME_MAX);
	}

	printf("Done with %s\n\n", dev);
	return 0;
}