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/*

 *  This small demo sends a simple sinusoidal wave to your speakers.

 */

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <sched.h>

#include <errno.h>

#include <getopt.h>

#include <alsa/asoundlib.h>

#include <sys/time.h>

#include <math.h>

static char *device = "plughw:0,0";			/* playback device */

static snd_pcm_format_t format = SND_PCM_FORMAT_S16;	/* sample format */

static unsigned int rate = 44100;			/* stream rate */

static unsigned int channels = 1;			/* count of channels */

static unsigned int buffer_time = 500000;		/* ring buffer length in us */

static unsigned int period_time = 100000;		/* period time in us */

static double freq = 440;				/* sinusoidal wave frequency in Hz */

static int verbose = 0;					/* verbose flag */

static int resample = 1;				/* enable alsa-lib resampling */

static int period_event = 0;				/* produce poll event after each period */

static snd_pcm_sframes_t buffer_size;

static snd_pcm_sframes_t period_size;

static snd_output_t *output = NULL;

static void generate_sine(const snd_pcm_channel_area_t *areas, 

			  snd_pcm_uframes_t offset,

			  int count, double *_phase)

{

	static double max_phase = 2. * M_PI;

	double phase = *_phase;

	double step = max_phase*freq/(double)rate;

	unsigned char *samples[channels];

	int steps[channels];

	unsigned int chn;

	int format_bits = snd_pcm_format_width(format);

	unsigned int maxval = (1 << (format_bits - 1)) - 1;

	int bps = format_bits / 8;  /* bytes per sample */

	int phys_bps = snd_pcm_format_physical_width(format) / 8;

	int big_endian = snd_pcm_format_big_endian(format) == 1;

	int to_unsigned = snd_pcm_format_unsigned(format) == 1;

	int is_float = (format == SND_PCM_FORMAT_FLOAT_LE ||

			format == SND_PCM_FORMAT_FLOAT_BE);

	/* verify and prepare the contents of areas */

	for (chn = 0; chn < channels; chn++) {

		if ((areas[chn].first % 8) != 0) {

			printf("areas[%i].first == %i, aborting...\n", chn, areas[chn].first);

			exit(EXIT_FAILURE);

		}

		samples[chn] = /*(signed short *)*/(((unsigned char *)areas[chn].addr) + (areas[chn].first / 8));

		if ((areas[chn].step % 16) != 0) {

			printf("areas[%i].step == %i, aborting...\n", chn, areas[chn].step);

			exit(EXIT_FAILURE);

		}

		steps[chn] = areas[chn].step / 8;

		samples[chn] += offset * steps[chn];

	}

	/* fill the channel areas */

	while (count-- > 0) {

		union {

			float f;

			int i;

		} fval;

		int res, i;

		if (is_float) {

			fval.f = sin(phase) * maxval;

			res = fval.i;

		} else

			res = sin(phase) * maxval;

		if (to_unsigned)

			res ^= 1U << (format_bits - 1);

		for (chn = 0; chn < channels; chn++) {

			/* Generate data in native endian format */

			if (big_endian) {

				for (i = 0; i < bps; i++)

					*(samples[chn] + phys_bps - 1 - i) = (res >> i * 8) & 0xff;

			} else {

				for (i = 0; i < bps; i++)

					*(samples[chn] + i) = (res >>  i * 8) & 0xff;

			}

			samples[chn] += steps[chn];

		}

		phase += step;

		if (phase >= max_phase)

			phase -= max_phase;

	}

	*_phase = phase;

}

static int set_hwparams(snd_pcm_t *handle,

			snd_pcm_hw_params_t *params,

			snd_pcm_access_t access)

{

	unsigned int rrate;

	snd_pcm_uframes_t size;

	int err, dir;

	/* choose all parameters */

	err = snd_pcm_hw_params_any(handle, params);

	if (err < 0) {

		printf("Broken configuration for playback: no configurations available: %s\n", snd_strerror(err));

		return err;

	}

	/* set hardware resampling */

	err = snd_pcm_hw_params_set_rate_resample(handle, params, resample);

	if (err < 0) {

		printf("Resampling setup failed for playback: %s\n", snd_strerror(err));

		return err;

	}

	/* set the interleaved read/write format */

	err = snd_pcm_hw_params_set_access(handle, params, access);

	if (err < 0) {

		printf("Access type not available for playback: %s\n", snd_strerror(err));

		return err;

	}

	/* set the sample format */

	err = snd_pcm_hw_params_set_format(handle, params, format);

	if (err < 0) {

		printf("Sample format not available for playback: %s\n", snd_strerror(err));

		return err;

	}

	/* set the count of channels */

	err = snd_pcm_hw_params_set_channels(handle, params, channels);

	if (err < 0) {

		printf("Channels count (%i) not available for playbacks: %s\n", channels, snd_strerror(err));

		return err;

	}

	/* set the stream rate */

	rrate = rate;

	err = snd_pcm_hw_params_set_rate_near(handle, params, &rrate, 0);

	if (err < 0) {

		printf("Rate %iHz not available for playback: %s\n", rate, snd_strerror(err));

		return err;

	}

	if (rrate != rate) {

		printf("Rate doesn't match (requested %iHz, get %iHz)\n", rate, err);

		return -EINVAL;

	}

	/* set the buffer time */

	err = snd_pcm_hw_params_set_buffer_time_near(handle, params, &buffer_time, &dir);

	if (err < 0) {

		printf("Unable to set buffer time %i for playback: %s\n", buffer_time, snd_strerror(err));

		return err;

	}

	err = snd_pcm_hw_params_get_buffer_size(params, &size);

	if (err < 0) {

		printf("Unable to get buffer size for playback: %s\n", snd_strerror(err));

		return err;

	}

	buffer_size = size;

	/* set the period time */

	err = snd_pcm_hw_params_set_period_time_near(handle, params, &period_time, &dir);

	if (err < 0) {

		printf("Unable to set period time %i for playback: %s\n", period_time, snd_strerror(err));

		return err;

	}

	err = snd_pcm_hw_params_get_period_size(params, &size, &dir);

	if (err < 0) {

		printf("Unable to get period size for playback: %s\n", snd_strerror(err));

		return err;

	}

	period_size = size;

	/* write the parameters to device */

	err = snd_pcm_hw_params(handle, params);

	if (err < 0) {

		printf("Unable to set hw params for playback: %s\n", snd_strerror(err));

		return err;

	}

	return 0;

}

static int set_swparams(snd_pcm_t *handle, snd_pcm_sw_params_t *swparams)

{

	int err;

	/* get the current swparams */

	err = snd_pcm_sw_params_current(handle, swparams);

	if (err < 0) {

		printf("Unable to determine current swparams for playback: %s\n", snd_strerror(err));

		return err;

	}

	/* start the transfer when the buffer is almost full: */

	/* (buffer_size / avail_min) * avail_min */

	err = snd_pcm_sw_params_set_start_threshold(handle, swparams, (buffer_size / period_size) * period_size);

	if (err < 0) {

		printf("Unable to set start threshold mode for playback: %s\n", snd_strerror(err));

		return err;

	}

	/* allow the transfer when at least period_size samples can be processed */

	/* or disable this mechanism when period event is enabled (aka interrupt like style processing) */

	err = snd_pcm_sw_params_set_avail_min(handle, swparams, period_event ? buffer_size : period_size);

	if (err < 0) {

		printf("Unable to set avail min for playback: %s\n", snd_strerror(err));

		return err;

	}

	/* enable period events when requested */

	if (period_event) {

		err = snd_pcm_sw_params_set_period_event(handle, swparams, 1);

		if (err < 0) {

			printf("Unable to set period event: %s\n", snd_strerror(err));

			return err;

		}

	}

	/* write the parameters to the playback device */

	err = snd_pcm_sw_params(handle, swparams);

	if (err < 0) {

		printf("Unable to set sw params for playback: %s\n", snd_strerror(err));

		return err;

	}

	return 0;

}

/*

 *   Underrun and suspend recovery

 */

static int xrun_recovery(snd_pcm_t *handle, int err)

{

	if (verbose)

		printf("stream recovery\n");

	if (err == -EPIPE) {	/* under-run */

		err = snd_pcm_prepare(handle);

		if (err < 0)

			printf("Can't recovery from underrun, prepare failed: %s\n", snd_strerror(err));

		return 0;

	} else if (err == -ESTRPIPE) {

		while ((err = snd_pcm_resume(handle)) == -EAGAIN)

			sleep(1);	/* wait until the suspend flag is released */

		if (err < 0) {

			err = snd_pcm_prepare(handle);

			if (err < 0)

				printf("Can't recovery from suspend, prepare failed: %s\n", snd_strerror(err));

		}

		return 0;

	}

	return err;

}

/*

 *   Transfer method - write only

 */

static int write_loop(snd_pcm_t *handle,

		      signed short *samples,

		      snd_pcm_channel_area_t *areas)

{

	double phase = 0;

	signed short *ptr;

	int err, cptr;

	while (1) {

		generate_sine(areas, 0, period_size, &phase);

		ptr = samples;

		cptr = period_size;

		while (cptr > 0) {

			err = snd_pcm_writei(handle, ptr, cptr);

			if (err == -EAGAIN)

				continue;

			if (err < 0) {

				if (xrun_recovery(handle, err) < 0) {

					printf("Write error: %s\n", snd_strerror(err));

					exit(EXIT_FAILURE);

				}

				break;	/* skip one period */

			}

			ptr += err * channels;

			cptr -= err;

		}

	}

}

/*

 *   Transfer method - write and wait for room in buffer using poll

 */

static int wait_for_poll(snd_pcm_t *handle, struct pollfd *ufds, unsigned int count)

{

	unsigned short revents;

	while (1) {

		poll(ufds, count, -1);

		snd_pcm_poll_descriptors_revents(handle, ufds, count, &revents);

		if (revents & POLLERR)

			return -EIO;

		if (revents & POLLOUT)

			return 0;

	}

}

static int write_and_poll_loop(snd_pcm_t *handle,

			       signed short *samples,

			       snd_pcm_channel_area_t *areas)

{

	struct pollfd *ufds;

	double phase = 0;

	signed short *ptr;

	int err, count, cptr, init;

	count = snd_pcm_poll_descriptors_count (handle);

	if (count <= 0) {

		printf("Invalid poll descriptors count\n");

		return count;

	}

	ufds = malloc(sizeof(struct pollfd) * count);

	if (ufds == NULL) {

		printf("No enough memory\n");

		return -ENOMEM;

	}

	if ((err = snd_pcm_poll_descriptors(handle, ufds, count)) < 0) {

		printf("Unable to obtain poll descriptors for playback: %s\n", snd_strerror(err));

		return err;

	}

	init = 1;

	while (1) {

		if (!init) {

			err = wait_for_poll(handle, ufds, count);

			if (err < 0) {

				if (snd_pcm_state(handle) == SND_PCM_STATE_XRUN ||

				    snd_pcm_state(handle) == SND_PCM_STATE_SUSPENDED) {

					err = snd_pcm_state(handle) == SND_PCM_STATE_XRUN ? -EPIPE : -ESTRPIPE;

					if (xrun_recovery(handle, err) < 0) {

						printf("Write error: %s\n", snd_strerror(err));

						exit(EXIT_FAILURE);

					}

					init = 1;

				} else {

					printf("Wait for poll failed\n");

					return err;

				}

			}

		}

		generate_sine(areas, 0, period_size, &phase);

		ptr = samples;

		cptr = period_size;

		while (cptr > 0) {

			err = snd_pcm_writei(handle, ptr, cptr);

			if (err < 0) {

				if (xrun_recovery(handle, err) < 0) {

					printf("Write error: %s\n", snd_strerror(err));

					exit(EXIT_FAILURE);

				}

				init = 1;

				break;	/* skip one period */

			}

			if (snd_pcm_state(handle) == SND_PCM_STATE_RUNNING)

				init = 0;

			ptr += err * channels;

			cptr -= err;

			if (cptr == 0)

				break;

			/* it is possible, that the initial buffer cannot store */

			/* all data from the last period, so wait awhile */

			err = wait_for_poll(handle, ufds, count);

			if (err < 0) {

				if (snd_pcm_state(handle) == SND_PCM_STATE_XRUN ||

				    snd_pcm_state(handle) == SND_PCM_STATE_SUSPENDED) {

					err = snd_pcm_state(handle) == SND_PCM_STATE_XRUN ? -EPIPE : -ESTRPIPE;

					if (xrun_recovery(handle, err) < 0) {

						printf("Write error: %s\n", snd_strerror(err));

						exit(EXIT_FAILURE);

					}

					init = 1;

				} else {

					printf("Wait for poll failed\n");

					return err;

				}

			}

		}

	}

}

/*

 *   Transfer method - asynchronous notification

 */

struct async_private_data {

	signed short *samples;

	snd_pcm_channel_area_t *areas;

	double phase;

};

static void async_callback(snd_async_handler_t *ahandler)

{

	snd_pcm_t *handle = snd_async_handler_get_pcm(ahandler);

	struct async_private_data *data = snd_async_handler_get_callback_private(ahandler);

	signed short *samples = data->samples;

	snd_pcm_channel_area_t *areas = data->areas;

	snd_pcm_sframes_t avail;

	int err;

	avail = snd_pcm_avail_update(handle);

	while (avail >= period_size) {

		generate_sine(areas, 0, period_size, &data->phase);

		err = snd_pcm_writei(handle, samples, period_size);

		if (err < 0) {

			printf("Write error: %s\n", snd_strerror(err));

			exit(EXIT_FAILURE);

		}

		if (err != period_size) {

			printf("Write error: written %i expected %li\n", err, period_size);

			exit(EXIT_FAILURE);

		}

		avail = snd_pcm_avail_update(handle);

	}

}

static int async_loop(snd_pcm_t *handle,

		      signed short *samples,

		      snd_pcm_channel_area_t *areas)

{

	struct async_private_data data;

	snd_async_handler_t *ahandler;

	int err, count;

	data.samples = samples;

	data.areas = areas;

	data.phase = 0;

	err = snd_async_add_pcm_handler(&ahandler, handle, async_callback, &data);

	if (err < 0) {

		printf("Unable to register async handler\n");

		exit(EXIT_FAILURE);

	}

	for (count = 0; count < 2; count++) {

		generate_sine(areas, 0, period_size, &data.phase);

		err = snd_pcm_writei(handle, samples, period_size);

		if (err < 0) {

			printf("Initial write error: %s\n", snd_strerror(err));

			exit(EXIT_FAILURE);

		}

		if (err != period_size) {

			printf("Initial write error: written %i expected %li\n", err, period_size);

			exit(EXIT_FAILURE);

		}

	}

	if (snd_pcm_state(handle) == SND_PCM_STATE_PREPARED) {

		err = snd_pcm_start(handle);

		if (err < 0) {

			printf("Start error: %s\n", snd_strerror(err));

			exit(EXIT_FAILURE);

		}

	}

	/* because all other work is done in the signal handler,

	   suspend the process */

	while (1) {

		sleep(1);

	}

}

/*

 *   Transfer method - asynchronous notification + direct write

 */

static void async_direct_callback(snd_async_handler_t *ahandler)

{

	snd_pcm_t *handle = snd_async_handler_get_pcm(ahandler);

	struct async_private_data *data = snd_async_handler_get_callback_private(ahandler);

	const snd_pcm_channel_area_t *my_areas;

	snd_pcm_uframes_t offset, frames, size;

	snd_pcm_sframes_t avail, commitres;

	snd_pcm_state_t state;

	int first = 0, err;

	while (1) {

		state = snd_pcm_state(handle);

		if (state == SND_PCM_STATE_XRUN) {

			err = xrun_recovery(handle, -EPIPE);

			if (err < 0) {

				printf("XRUN recovery failed: %s\n", snd_strerror(err));

				exit(EXIT_FAILURE);

			}

			first = 1;

		} else if (state == SND_PCM_STATE_SUSPENDED) {

			err = xrun_recovery(handle, -ESTRPIPE);

			if (err < 0) {

				printf("SUSPEND recovery failed: %s\n", snd_strerror(err));

				exit(EXIT_FAILURE);

			}

		}

		avail = snd_pcm_avail_update(handle);

		if (avail < 0) {

			err = xrun_recovery(handle, avail);

			if (err < 0) {

				printf("avail update failed: %s\n", snd_strerror(err));

				exit(EXIT_FAILURE);

			}

			first = 1;

			continue;

		}

		if (avail < period_size) {

			if (first) {

				first = 0;

				err = snd_pcm_start(handle);

				if (err < 0) {

					printf("Start error: %s\n", snd_strerror(err));

					exit(EXIT_FAILURE);

				}

			} else {

				break;

			}

			continue;

		}

		size = period_size;

		while (size > 0) {

			frames = size;

			err = snd_pcm_mmap_begin(handle, &my_areas, &offset, &frames);

			if (err < 0) {

				if ((err = xrun_recovery(handle, err)) < 0) {

					printf("MMAP begin avail error: %s\n", snd_strerror(err));

					exit(EXIT_FAILURE);

				}

				first = 1;

			}

			generate_sine(my_areas, offset, frames, &data->phase);

			commitres = snd_pcm_mmap_commit(handle, offset, frames);

			if (commitres < 0 || (snd_pcm_uframes_t)commitres != frames) {

				if ((err = xrun_recovery(handle, commitres >= 0 ? -EPIPE : commitres)) < 0) {

					printf("MMAP commit error: %s\n", snd_strerror(err));

					exit(EXIT_FAILURE);

				}

				first = 1;

			}

			size -= frames;

		}

	}

}

static int async_direct_loop(snd_pcm_t *handle,

			     signed short *samples ATTRIBUTE_UNUSED,

			     snd_pcm_channel_area_t *areas ATTRIBUTE_UNUSED)

{

	struct async_private_data data;

	snd_async_handler_t *ahandler;

	const snd_pcm_channel_area_t *my_areas;

	snd_pcm_uframes_t offset, frames, size;

	snd_pcm_sframes_t commitres;

	int err, count;

	data.samples = NULL;	/* we do not require the global sample area for direct write */

	data.areas = NULL;	/* we do not require the global areas for direct write */

	data.phase = 0;

	err = snd_async_add_pcm_handler(&ahandler, handle, async_direct_callback, &data);

	if (err < 0) {

		printf("Unable to register async handler\n");

		exit(EXIT_FAILURE);

	}

	for (count = 0; count < 2; count++) {

		size = period_size;

		while (size > 0) {

			frames = size;

			err = snd_pcm_mmap_begin(handle, &my_areas, &offset, &frames);

			if (err < 0) {

				if ((err = xrun_recovery(handle, err)) < 0) {

					printf("MMAP begin avail error: %s\n", snd_strerror(err));

					exit(EXIT_FAILURE);

				}

			}

			generate_sine(my_areas, offset, frames, &data.phase);

			commitres = snd_pcm_mmap_commit(handle, offset, frames);

			if (commitres < 0 || (snd_pcm_uframes_t)commitres != frames) {

				if ((err = xrun_recovery(handle, commitres >= 0 ? -EPIPE : commitres)) < 0) {

					printf("MMAP commit error: %s\n", snd_strerror(err));

					exit(EXIT_FAILURE);

				}

			}

			size -= frames;

		}

	}

	err = snd_pcm_start(handle);

	if (err < 0) {

		printf("Start error: %s\n", snd_strerror(err));

		exit(EXIT_FAILURE);

	}

	/* because all other work is done in the signal handler,

	   suspend the process */

	while (1) {

		sleep(1);

	}

}

/*

 *   Transfer method - direct write only

 */

static int direct_loop(snd_pcm_t *handle,

		       signed short *samples ATTRIBUTE_UNUSED,

		       snd_pcm_channel_area_t *areas ATTRIBUTE_UNUSED)

{

	double phase = 0;

	const snd_pcm_channel_area_t *my_areas;

	snd_pcm_uframes_t offset, frames, size;

	snd_pcm_sframes_t avail, commitres;

	snd_pcm_state_t state;

	int err, first = 1;

	while (1) {

		state = snd_pcm_state(handle);

		if (state == SND_PCM_STATE_XRUN) {

			err = xrun_recovery(handle, -EPIPE);

			if (err < 0) {

				printf("XRUN recovery failed: %s\n", snd_strerror(err));

				return err;

			}

			first = 1;

		} else if (state == SND_PCM_STATE_SUSPENDED) {

			err = xrun_recovery(handle, -ESTRPIPE);

			if (err < 0) {

				printf("SUSPEND recovery failed: %s\n", snd_strerror(err));

				return err;

			}

		}

		avail = snd_pcm_avail_update(handle);

		if (avail < 0) {

			err = xrun_recovery(handle, avail);

			if (err < 0) {

				printf("avail update failed: %s\n", snd_strerror(err));

				return err;

			}

			first = 1;

			continue;

		}

		if (avail < period_size) {

			if (first) {

				first = 0;

				err = snd_pcm_start(handle);

				if (err < 0) {

					printf("Start error: %s\n", snd_strerror(err));

					exit(EXIT_FAILURE);

				}

			} else {

				err = snd_pcm_wait(handle, -1);

				if (err < 0) {

					if ((err = xrun_recovery(handle, err)) < 0) {

						printf("snd_pcm_wait error: %s\n", snd_strerror(err));

						exit(EXIT_FAILURE);

					}

					first = 1;

				}

			}

			continue;

		}

		size = period_size;

		while (size > 0) {

			frames = size;

			err = snd_pcm_mmap_begin(handle, &my_areas, &offset, &frames);

			if (err < 0) {

				if ((err = xrun_recovery(handle, err)) < 0) {

					printf("MMAP begin avail error: %s\n", snd_strerror(err));

					exit(EXIT_FAILURE);

				}

				first = 1;

			}

			generate_sine(my_areas, offset, frames, &phase);

			commitres = snd_pcm_mmap_commit(handle, offset, frames);

			if (commitres < 0 || (snd_pcm_uframes_t)commitres != frames) {

				if ((err = xrun_recovery(handle, commitres >= 0 ? -EPIPE : commitres)) < 0) {

					printf("MMAP commit error: %s\n", snd_strerror(err));

					exit(EXIT_FAILURE);

				}

				first = 1;

			}

			size -= frames;

		}

	}

}

/*

 *   Transfer method - direct write only using mmap_write functions

 */

static int direct_write_loop(snd_pcm_t *handle,

			     signed short *samples,

			     snd_pcm_channel_area_t *areas)

{

	double phase = 0;

	signed short *ptr;

	int err, cptr;

	while (1) {

		generate_sine(areas, 0, period_size, &phase);

		ptr = samples;

		cptr = period_size;

		while (cptr > 0) {

			err = snd_pcm_mmap_writei(handle, ptr, cptr);

			if (err == -EAGAIN)

				continue;

			if (err < 0) {

				if (xrun_recovery(handle, err) < 0) {

					printf("Write error: %s\n", snd_strerror(err));

					exit(EXIT_FAILURE);

				}

				break;	/* skip one period */

			}

			ptr += err * channels;

			cptr -= err;

		}

	}

}

/*

 *

 */

struct transfer_method {

	const char *name;

	snd_pcm_access_t access;

	int (*transfer_loop)(snd_pcm_t *handle,

			     signed short *samples,

			     snd_pcm_channel_area_t *areas);

};

static struct transfer_method transfer_methods[] = {

	{ "write", SND_PCM_ACCESS_RW_INTERLEAVED, write_loop },

	{ "write_and_poll", SND_PCM_ACCESS_RW_INTERLEAVED, write_and_poll_loop },

	{ "async", SND_PCM_ACCESS_RW_INTERLEAVED, async_loop },

	{ "async_direct", SND_PCM_ACCESS_MMAP_INTERLEAVED, async_direct_loop },

	{ "direct_interleaved", SND_PCM_ACCESS_MMAP_INTERLEAVED, direct_loop },

	{ "direct_noninterleaved", SND_PCM_ACCESS_MMAP_NONINTERLEAVED, direct_loop },

	{ "direct_write", SND_PCM_ACCESS_MMAP_INTERLEAVED, direct_write_loop },

	{ NULL, SND_PCM_ACCESS_RW_INTERLEAVED, NULL }

};

static void help(void)

{

	int k;

	printf(

"Usage: pcm [OPTION]... [FILE]...\n"

"-h,--help	help\n"

"-D,--device	playback device\n"

"-r,--rate	stream rate in Hz\n"

"-c,--channels	count of channels in stream\n"

"-f,--frequency	sine wave frequency in Hz\n"

"-b,--buffer	ring buffer size in us\n"

"-p,--period	period size in us\n"

"-m,--method	transfer method\n"

"-o,--format	sample format\n"

"-v,--verbose   show the PCM setup parameters\n"

"-n,--noresample  do not resample\n"

"-e,--pevent    enable poll event after each period\n"

"\n");

        printf("Recognized sample formats are:");

        for (k = 0; k < SND_PCM_FORMAT_LAST; ++k) {

                const char *s = snd_pcm_format_name(k);

                if (s)

                        printf(" %s", s);

        }

        printf("\n");

        printf("Recognized transfer methods are:");

        for (k = 0; transfer_methods[k].name; k++)

        	printf(" %s", transfer_methods[k].name);

	printf("\n");

}

int main(int argc, char *argv[])

{

	struct option long_option[] =

	{

		{"help", 0, NULL, 'h'},

		{"device", 1, NULL, 'D'},

		{"rate", 1, NULL, 'r'},

		{"channels", 1, NULL, 'c'},

		{"frequency", 1, NULL, 'f'},

		{"buffer", 1, NULL, 'b'},

		{"period", 1, NULL, 'p'},

		{"method", 1, NULL, 'm'},

		{"format", 1, NULL, 'o'},

		{"verbose", 1, NULL, 'v'},

		{"noresample", 1, NULL, 'n'},

		{"pevent", 1, NULL, 'e'},

		{NULL, 0, NULL, 0},

	};

	snd_pcm_t *handle;

	int err, morehelp;

	snd_pcm_hw_params_t *hwparams;

	snd_pcm_sw_params_t *swparams;

	int method = 0;

	signed short *samples;

	unsigned int chn;

	snd_pcm_channel_area_t *areas;

	snd_pcm_hw_params_alloca(&hwparams);

	snd_pcm_sw_params_alloca(&swparams);

	morehelp = 0;

	while (1) {

		int c;

		if ((c = getopt_long(argc, argv, "hD:r:c:f:b:p:m:o:vne", long_option, NULL)) < 0)

			break;

		switch (c) {

		case 'h':

			morehelp++;

			break;

		case 'D':

			device = strdup(optarg);

			break;

		case 'r':

			rate = atoi(optarg);

			rate = rate < 4000 ? 4000 : rate;

			rate = rate > 196000 ? 196000 : rate;

			break;

		case 'c':

			channels = atoi(optarg);

			channels = channels < 1 ? 1 : channels;

			channels = channels > 1024 ? 1024 : channels;

			break;

		case 'f':

			freq = atoi(optarg);

			freq = freq < 50 ? 50 : freq;

			freq = freq > 5000 ? 5000 : freq;

			break;

		case 'b':

			buffer_time = atoi(optarg);

			buffer_time = buffer_time < 1000 ? 1000 : buffer_time;

			buffer_time = buffer_time > 1000000 ? 1000000 : buffer_time;

			break;

		case 'p':

			period_time = atoi(optarg);

			period_time = period_time < 1000 ? 1000 : period_time;

			period_time = period_time > 1000000 ? 1000000 : period_time;

			break;

		case 'm':

			for (method = 0; transfer_methods[method].name; method++)

					if (!strcasecmp(transfer_methods[method].name, optarg))

					break;

			if (transfer_methods[method].name == NULL)

				method = 0;

			break;

		case 'o':

			for (format = 0; format < SND_PCM_FORMAT_LAST; format++) {

				const char *format_name = snd_pcm_format_name(format);

				if (format_name)

					if (!strcasecmp(format_name, optarg))

					break;

			}

			if (format == SND_PCM_FORMAT_LAST)

				format = SND_PCM_FORMAT_S16;

			if (!snd_pcm_format_linear(format) &&

			    !(format == SND_PCM_FORMAT_FLOAT_LE ||

			      format == SND_PCM_FORMAT_FLOAT_BE)) {

				printf("Invalid (non-linear/float) format %s\n",

				       optarg);

				return 1;

			}

			break;

		case 'v':

			verbose = 1;

			break;

		case 'n':

			resample = 0;

			break;

		case 'e':

			period_event = 1;

			break;

		}

	}

	if (morehelp) {

		help();

		return 0;

	}

	err = snd_output_stdio_attach(&output, stdout, 0);

	if (err < 0) {

		printf("Output failed: %s\n", snd_strerror(err));

		return 0;

	}

	printf("Playback device is %s\n", device);

	printf("Stream parameters are %iHz, %s, %i channels\n", rate, snd_pcm_format_name(format), channels);

	printf("Sine wave rate is %.4fHz\n", freq);

	printf("Using transfer method: %s\n", transfer_methods[method].name);

	if ((err = snd_pcm_open(&handle, device, SND_PCM_STREAM_PLAYBACK, 0)) < 0) {

		printf("Playback open error: %s\n", snd_strerror(err));

		return 0;

	}

	if ((err = set_hwparams(handle, hwparams, transfer_methods[method].access)) < 0) {

		printf("Setting of hwparams failed: %s\n", snd_strerror(err));

		exit(EXIT_FAILURE);

	}

	if ((err = set_swparams(handle, swparams)) < 0) {

		printf("Setting of swparams failed: %s\n", snd_strerror(err));

		exit(EXIT_FAILURE);

	}

	if (verbose > 0)

		snd_pcm_dump(handle, output);

	samples = malloc((period_size * channels * snd_pcm_format_physical_width(format)) / 8);

	if (samples == NULL) {

		printf("No enough memory\n");

		exit(EXIT_FAILURE);

	}

	areas = calloc(channels, sizeof(snd_pcm_channel_area_t));

	if (areas == NULL) {

		printf("No enough memory\n");

		exit(EXIT_FAILURE);

	}

	for (chn = 0; chn < channels; chn++) {

		areas[chn].addr = samples;

		areas[chn].first = chn * snd_pcm_format_physical_width(format);

		areas[chn].step = channels * snd_pcm_format_physical_width(format);

	}

	err = transfer_methods[method].transfer_loop(handle, samples, areas);

	if (err < 0)

		printf("Transfer failed: %s\n", snd_strerror(err));

	free(areas);

	free(samples);

	snd_pcm_close(handle);

	return 0;

}