/*
  An LV2 plugin to generate a non-bandlimited square waveform with gate for
  trigger and sync.
  Copyright 2011 David Robillard
  Copyright 2002 Mike Rawes

  This is free software: you can redistribute it and/or modify it
  under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  This software is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this software.  If not, see <http://www.gnu.org/licenses/>.
*/

#include <stdlib.h>
#include "lv2/lv2plug.in/ns/lv2core/lv2.h"

#define SYNCSQUARE_FREQUENCY 0
#define SYNCSQUARE_GATE      1
#define SYNCSQUARE_OUTPUT    2

typedef struct {
	float* frequency;
	float* gate;
	float* output;
	float  srate;
	float  nyquist;
	float  phase;
} SyncSquare;

static void
cleanup(LV2_Handle instance)
{
	free(instance);
}

static void
connect_port(LV2_Handle instance,
             uint32_t   port,
             void*      data)
{
	SyncSquare* plugin = (SyncSquare*)instance;

	switch (port) {
	case SYNCSQUARE_FREQUENCY:
		plugin->frequency = data;
		break;
	case SYNCSQUARE_GATE:
		plugin->gate = data;
		break;
	case SYNCSQUARE_OUTPUT:
		plugin->output = data;
		break;
	}
}

static LV2_Handle
instantiate(const LV2_Descriptor*     descriptor,
            double                    sample_rate,
            const char*               bundle_path,
            const LV2_Feature* const* features)
{
	SyncSquare* plugin = (SyncSquare*)malloc(sizeof(SyncSquare));

	plugin->srate   = (float)sample_rate;
	plugin->nyquist = (float)(sample_rate / 2);

	return (LV2_Handle)plugin;
}

static void
activate(LV2_Handle instance)
{
	SyncSquare* plugin = (SyncSquare*)instance;

	plugin->phase = 0.0f;
}

static void
runSyncSquare_faga_oa(LV2_Handle instance,
                      uint32_t   sample_count)
{
	SyncSquare* plugin = (SyncSquare*)instance;

	/* Frequency (array of float of length sample_count) */
	const float* frequency = plugin->frequency;

	/* Gate (array of float of length sample_count) */
	const float* gate = plugin->gate;

	/* Output (pointer to float value) */
	float* output = plugin->output;

	/* Instance data */
	float phase   = plugin->phase;
	float srate   = plugin->srate;
	float nyquist = plugin->nyquist;

	float freq;

	for (uint32_t s = 0; s < sample_count; ++s) {
		if (gate[s] > 0.0f) {
			freq = frequency[s];

			if (phase < nyquist) {
				output[s] = 1.0f;
			} else {
				output[s] = -1.0f;
			}

			phase += freq;
			if (phase < 0.0f) {
				phase += srate;
			} else if (phase > srate) {
				phase -= srate;
			}
		} else {
			output[s] = 0.0f;
			phase     = 0.0f;
		}
	}

	plugin->phase = phase;
}

static void
runSyncSquare_fcga_oa(LV2_Handle instance,
                      uint32_t   sample_count)
{
	SyncSquare* plugin = (SyncSquare*)instance;

	/* Frequency (float value) */
	const float frequency = *(plugin->frequency);

	/* Gate (array of float of length sample_count) */
	const float* gate = plugin->gate;

	/* Output (pointer to float value) */
	float* output = plugin->output;

	/* Instance Data */
	float phase   = plugin->phase;
	float srate   = plugin->srate;
	float nyquist = plugin->nyquist;

	for (uint32_t s = 0; s < sample_count; ++s) {
		if (gate[s] > 0.0f) {
			if (phase < nyquist) {
				output[s] = 1.0f;
			} else {
				output[s] = -1.0f;
			}

			phase += frequency;
			if (phase < 0.0f) {
				phase += srate;
			} else if (phase > srate) {
				phase -= srate;
			}
		} else {
			output[s] = 0.0f;
			phase     = 0.0f;
		}
	}

	plugin->phase = phase;
}

static const LV2_Descriptor descriptor = {
	"http://drobilla.net/plugins/blip/sync_square",
	instantiate,
	connect_port,
	activate,
	runSyncSquare_fcga_oa,
	NULL,
	cleanup,
	NULL,
};

LV2_SYMBOL_EXPORT const LV2_Descriptor*
lv2_descriptor(uint32_t index)
{
	switch (index) {
	case 0:  return &descriptor;
	default: return NULL;
	}
}