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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 */

int period=0;

short sample[1000000];

static snd_pcm_sframes_t buffer_size;	// size of buffer at sound card

static snd_pcm_sframes_t period_size;	//samples per frame

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;

	double res;

	unsigned char *samples[channels], *tmp;

	int steps[channels];

	unsigned int chn, byte;

	union {

		int i;

		unsigned char c[4];

	} ires;

	unsigned int maxval = (1 << (snd_pcm_format_width(format) - 1)) - 1;

	int bps = snd_pcm_format_width(format) / 8;  /* bytes per sample */

	/* 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) {

		res = sin(phase) * maxval;

		ires.i = res;

		tmp = ires.c;

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

			for (byte = 0; byte < (unsigned int)bps; byte++)

				*(samples[chn] + byte) = tmp[byte];

			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;

}

struct async_private_data {

	signed short *samples;

	snd_pcm_channel_area_t *areas;

	unsigned int period;

};

/*int linear_chirp(int *pole, int delka_pole){  // vygeneruje linearni chirp a vzorky ulozi do pole

static const float f0 = 0.0001;

static const float k = 0.00001;

int t;

//  if((spozdeni+delka) < delka_pole)

    for(t=0;t < delka_pole;t++) pole[t] = round ( 10000*sin(2*M_PI*(t+faze)*(f0+(k/2)*(t+faze))) );

    faze +=t;

//  else return 0;

}

int linear_windowed_chirp(int *pole, int delka_pole){  // vygeneruje linearni chirp a vzorky ulozi do pole

static const float f0 = 0.0001;

static const float k = 0.00001;

int t;

// (0.35875 - 0.48829 cos(t) + 0.14128 cos(2t) - 0.01168 cos(3t))

    for(t=0;t < delka_pole;t++) pole[t] = (short) round ( (0.35875 - 0.48829*cos((t+faze)*0.0001) + 0.14128*cos(.0002*(t+faze)) - 0.01168*cos(.0003*(t+faze)))*30000*sin(2*M_PI*(t+faze)*(f0+(k/2)*(t+faze))) );

    faze +=t;

}*/

int sine(int *pole, int delka_pole)

{

int t;

  for(t=0;t < delka_pole;t++) pole[t] = (short) round(10000*sin( (double)(t)/10.0));

}

static void async_playback_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);

//	linear_windowed_chirp(signal,period_size);

		err = snd_pcm_writei(handle, sample, 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);

	}

}

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

{

	snd_pcm_t *playback_handle, *capture_handle;

	int err;

	snd_pcm_hw_params_t *hwparams;

	snd_pcm_sw_params_t *swparams;

	signed short *frame;  // pointer to array of samples

	unsigned int chn;

	snd_pcm_channel_area_t *areas;

	struct async_private_data data;

	snd_async_handler_t *ahandler;

	int count;

	unsigned int i;

	snd_pcm_hw_params_alloca(&hwparams);

	snd_pcm_sw_params_alloca(&swparams);

//open adn set playback device

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

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

		return 0;

	}

	if ((err = set_hwparams(playback_handle, hwparams, SND_PCM_ACCESS_RW_INTERLEAVED)) < 0) {

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

		exit(EXIT_FAILURE);

	}

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

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

		exit(EXIT_FAILURE);

	}

//open and set capture device

	if ((err = snd_pcm_open(&capture_handle, device, SND_PCM_STREAM_CAPTURE, 0)) < 0) {

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

		return 0;

	}

	if ((err = set_hwparams(capture_handle, hwparams, SND_PCM_ACCESS_RW_INTERLEAVED)) < 0) {

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

		exit(EXIT_FAILURE);

	}

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

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

		exit(EXIT_FAILURE);

	}

// allocate memory for frame (package of samples)

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

	if (frame == NULL) {

		printf("No enough memory\n");

		exit(EXIT_FAILURE);

	}

//allocate memory for frame structure definition	

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

	if (areas == NULL) {

		printf("No enough memory\n");

		exit(EXIT_FAILURE);

	}

//fill areas by definition of frame structure

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

		areas[chn].addr = frame; 	// frame start adress

		areas[chn].first = chn * snd_pcm_format_physical_width(format); // ofset to first sample (in bits)

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

	}

        sine(sample,100000);

	data.samples = frame;

	data.areas = areas;

	data.period = 1;

// register playback callback

	err = snd_async_add_pcm_handler(&ahandler, playback_handle, async_playback_callback, &data);

	if (err < 0) {

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

		exit(EXIT_FAILURE);

	}

	for (data.period = 0; data.period < 2; data.period++) {

		err = snd_pcm_writei(playback_handle, sample, 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);

		}

	}

//start playback

	if (snd_pcm_state(playback_handle) == SND_PCM_STATE_PREPARED) {

		err = snd_pcm_start(playback_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 */

	for(i=0; i<=10;i++) {

		sleep(1);

	}

	free(areas);

	free(frame);

	snd_pcm_close(playback_handle);

	snd_pcm_close(capture_handle);

	return 0;

}