/*
  An LV2 plugin to generate a bandlimited slope-variable triangle waveform.
  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"
#include "wavedata.h"

#define TRIANGLE_FREQUENCY 0
#define TRIANGLE_SLOPE     1
#define TRIANGLE_OUTPUT    2

typedef struct {
	float*   frequency;
	float*   slope;
	float*   output;
	float    phase;
	float    min_slope;
	float    max_slope;
	Wavedata wdat;
} Triangle;

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

	switch (port) {
	case TRIANGLE_FREQUENCY:
		plugin->frequency = data;
		break;
	case TRIANGLE_SLOPE:
		plugin->slope = data;
		break;
	case TRIANGLE_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)
{
	Triangle* plugin = (Triangle*)malloc(sizeof(Triangle));

	if (wavedata_load(&plugin->wdat, BLOP_DLSYM_PARABOLA, sample_rate)) {
		free(plugin);
		return 0;
	}

	plugin->min_slope = 2.0f / plugin->wdat.sample_rate;
	plugin->max_slope = 1.0f - plugin->min_slope;

	return (LV2_Handle)plugin;
}

static void
cleanup(LV2_Handle instance)
{
	Triangle* plugin = (Triangle*)instance;

	wavedata_unload(&plugin->wdat);
	free(instance);
}

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

	plugin->phase = 0.0f;
}

static void
runTriangle_fasa_oa(LV2_Handle instance,
                    uint32_t   sample_count)
{
	Triangle* plugin = (Triangle*)instance;

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

	/* Slope (array of float of length sample_count) */
	float* slope = plugin->slope;

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

	/* Instance data */
	Wavedata* wdat      = &plugin->wdat;
	float     phase     = plugin->phase;
	float     min_slope = plugin->min_slope;
	float     max_slope = plugin->max_slope;

	float freq;
	float slp;
	float phase_shift;

	for (uint32_t s = 0; s < sample_count; ++s) {
		freq        = frequency[s];
		slp         = f_clip(slope[s], min_slope, max_slope);
		phase_shift = slp * wdat->sample_rate;

		/* Lookup which table to use from frequency */
		wavedata_get_table(wdat, freq);

		/* Get samples from parabola and phase shifted inverted parabola,
		   and scale to compensate */
		output[s] = (wavedata_get_sample(wdat, phase)
		             - wavedata_get_sample(wdat, phase + phase_shift))
		    / (8.0f * (slp - (slp * slp)));

		/* Update phase, wrapping if necessary */
		phase += wdat->frequency;
		if (phase < 0.0f) {
			phase += wdat->sample_rate;
		} else if (phase > wdat->sample_rate) {
			phase -= wdat->sample_rate;
		}
	}
	plugin->phase = phase;
}

static void
runTriangle_fasc_oa(LV2_Handle instance,
                    uint32_t   sample_count)
{
	Triangle* plugin = (Triangle*)instance;

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

	/* Slope (float value) */
	float slope = *(plugin->slope);

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

	/* Instance data */
	Wavedata* wdat      = &plugin->wdat;
	float     phase     = plugin->phase;
	float     min_slope = plugin->min_slope;
	float     max_slope = plugin->max_slope;

	float freq;
	float phase_shift;
	float scale;

	slope       = f_clip(slope, min_slope, max_slope);
	scale       = 1.0f / (8.0f * (slope - (slope * slope)));
	phase_shift = slope * wdat->sample_rate;

	for (uint32_t s = 0; s < sample_count; ++s) {
		freq = frequency[s];

		/* Lookup which table to use from frequency */
		wavedata_get_table(wdat, freq);

		/* Get samples from parabola and phase shifted inverted parabola,
		   and scale to compensate */
		output[s] = (wavedata_get_sample(wdat, phase)
		             - wavedata_get_sample(wdat, phase + phase_shift)) * scale;

		/* Update phase, wrapping if necessary */
		phase += wdat->frequency;
		if (phase < 0.0f) {
			phase += wdat->sample_rate;
		} else if (phase > wdat->sample_rate) {
			phase -= wdat->sample_rate;
		}
	}
	plugin->phase = phase;
}

static void
runTriangle_fcsa_oa(LV2_Handle instance,
                    uint32_t   sample_count)
{
	Triangle* plugin = (Triangle*)instance;

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

	/* Slope (array of float of length sample_count) */
	float* slope = plugin->slope;

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

	/* Instance data */
	Wavedata* wdat      = &plugin->wdat;
	float     phase     = plugin->phase;
	float     min_slope = plugin->min_slope;
	float     max_slope = plugin->max_slope;

	float slp;
	float phase_shift;

	wavedata_get_table(wdat, frequency);

	for (uint32_t s = 0; s < sample_count; ++s) {
		slp         = f_clip(slope[s], min_slope, max_slope);
		phase_shift = slp * wdat->sample_rate;

		/* Get samples from parabola and phase shifted inverted parabola,
		   and scale to compensate */
		output[s] = (wavedata_get_sample(wdat, phase)
		             - wavedata_get_sample(wdat, phase + phase_shift))
		    / (8.0f * (slp - (slp * slp)));

		/* Update phase, wrapping if necessary */
		phase += wdat->frequency;
		if (phase < 0.0f) {
			phase += wdat->sample_rate;
		} else if (phase > wdat->sample_rate) {
			phase -= wdat->sample_rate;
		}
	}
	plugin->phase = phase;
}

static void
runTriangle_fcsc_oa(LV2_Handle instance,
                    uint32_t   sample_count)
{
	Triangle* plugin = (Triangle*)instance;

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

	/* Slope (float value) */
	float slope = *(plugin->slope);

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

	/* Instance data */
	Wavedata* wdat      = &plugin->wdat;
	float     phase     = plugin->phase;
	float     min_slope = plugin->min_slope;
	float     max_slope = plugin->max_slope;

	float scale;
	float phase_shift;

	slope       = f_clip(slope, min_slope, max_slope);
	scale       = 1.0f / (8.0f * (slope - (slope * slope)));
	phase_shift = slope * wdat->sample_rate;

	wavedata_get_table(wdat, frequency);

	for (uint32_t s = 0; s < sample_count; ++s) {
		/* Get samples from parabola and phase shifted inverted parabola,
		   and scale to compensate */
		output[s] = (wavedata_get_sample(wdat, phase)
		             - wavedata_get_sample(wdat, phase + phase_shift)) * scale;

		/* Update phase, wrapping if necessary */
		phase += wdat->frequency;
		if (phase < 0.0f) {
			phase += wdat->sample_rate;
		} else if (phase > wdat->sample_rate) {
			phase -= wdat->sample_rate;
		}
	}
	plugin->phase = phase;
}

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

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