/*	wfmmod.c

This file is part of a program that implements a Software-Defined Radio.

Copyright (C) 2013, 2016, 2023 Warren Pratt, NR0V

This program 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 2
of the License, or (at your option) any later version.

This program 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 program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

The author can be reached by email at

warren@wpratt.com

*/

#include "comm.h"

// the modulated spectrum spans +/-(deviation + f_high); at the sample rates used for
// narrowband modes that exceeds Nyquist, so the bandpass degenerates to a passthrough.
static double bpfc_wfmmod (double samplerate, double deviation, double f_high)
{
	double fc = deviation + f_high;
	double max_fc = 0.45 * samplerate;
	if (fc > max_fc) fc = max_fc;
	return fc;
}

void calc_wfmmod (WFMMOD a)
{
	// pre-emphasis
	if (a->tau_pre > 0.0) a->pmult = exp(-1.0 / (a->samplerate * a->tau_pre));
	else				  a->pmult = 0.0;
	a->pnorm = 1.0 / (1.0 - a->pmult);
	a->pre_z = 0.0;
	// mod
	a->sphase = 0.0;
	a->sdelta = TWOPI * a->deviation / a->samplerate;
	// bandpass
	a->bp_fc = bpfc_wfmmod (a->samplerate, a->deviation, a->f_high);
}

WFMMOD create_wfmmod (int run, int size, double* in, double* out, int rate, double dev, double f_low, double f_high,
	int pre_run, double tau_pre, int bp_run, int nc, int mp)
{
	WFMMOD a = (WFMMOD) malloc0 (sizeof (wfmmod));
	double* impulse;
	a->run = run;
	a->size = size;
	a->in = in;
	a->out = out;
	a->samplerate = (double)rate;
	a->deviation = dev;
	a->f_low = f_low;
	a->f_high = f_high;
	a->pre_run = pre_run;
	a->tau_pre = tau_pre;
	a->bp_run = bp_run;
	a->nc = nc;
	a->mp = mp;
	calc_wfmmod (a);
	impulse = fir_bandpass(a->nc, -a->bp_fc, +a->bp_fc, a->samplerate, 0, 1, 1.0 / (2 * a->size));
	a->p = create_fircore (a->size, a->out, a->out, a->nc, a->mp, impulse);
	_aligned_free (impulse);
	return a;
}

void destroy_wfmmod (WFMMOD a)
{
	destroy_fircore (a->p);
	_aligned_free (a);
}

void flush_wfmmod (WFMMOD a)
{
	a->pre_z = 0.0;
	a->sphase = 0.0;
	flush_fircore (a->p);
}

void xwfmmod (WFMMOD a)
{
	int i;
	double aud, dp;
	if (a->run)
	{
		for (i = 0; i < a->size; i++)
		{
			aud = a->in[2 * i + 0];
			if (a->pre_run)
			{
				dp = a->pnorm * (aud - a->pmult * a->pre_z);
				a->pre_z = aud;
				aud = dp;
			}
			dp = aud * a->sdelta;
			a->sphase += dp;
			// at the wide deviation, |dp| exceeds TWOPI once samplerate < deviation,
			// so one subtraction is not enough to bring sphase back into range
			while (a->sphase >= TWOPI) a->sphase -= TWOPI;
			while (a->sphase <	 0.0 ) a->sphase += TWOPI;
			a->out[2 * i + 0] = 0.7071 * cos (a->sphase);
			a->out[2 * i + 1] = 0.7071 * sin (a->sphase);
		}
		if (a->bp_run)
			xfircore (a->p);
	}
	else if (a->in != a->out)
		memcpy (a->out, a->in, a->size * sizeof (complex));
}

void setBuffers_wfmmod (WFMMOD a, double* in, double* out)
{
	a->in = in;
	a->out = out;
	calc_wfmmod (a);
	setBuffers_fircore (a->p, a->out, a->out);
}

void setSamplerate_wfmmod (WFMMOD a, int rate)
{
	double* impulse;
	a->samplerate = rate;
	calc_wfmmod (a);
	impulse = fir_bandpass(a->nc, -a->bp_fc, +a->bp_fc, a->samplerate, 0, 1, 1.0 / (2 * a->size));
	setImpulse_fircore (a->p, impulse, 1);
	_aligned_free (impulse);
}

void setSize_wfmmod (WFMMOD a, int size)
{
	double* impulse;
	a->size = size;
	calc_wfmmod (a);
	setSize_fircore (a->p, a->size);
	impulse = fir_bandpass(a->nc, -a->bp_fc, +a->bp_fc, a->samplerate, 0, 1, 1.0 / (2 * a->size));
	setImpulse_fircore (a->p, impulse, 1);
	_aligned_free (impulse);
}

/********************************************************************************************************
*																										*
*											TXA Properties												*
*																										*
********************************************************************************************************/

PORT
void SetTXAWFMDeviation (int channel, double deviation)
{
	WFMMOD a = txa[channel].wfmmod.p;
	double bp_fc = bpfc_wfmmod (a->samplerate, deviation, a->f_high);
	double* impulse = fir_bandpass (a->nc, -bp_fc, +bp_fc, a->samplerate, 0, 1, 1.0 / (2 * a->size));
	setImpulse_fircore (a->p, impulse, 0);
	_aligned_free (impulse);
	EnterCriticalSection (&ch[channel].csDSP);
	a->deviation = deviation;
	// mod
	a->sphase = 0.0;
	a->sdelta = TWOPI * a->deviation / a->samplerate;
	// bandpass
	a->bp_fc = bp_fc;
	setUpdate_fircore (a->p);
	LeaveCriticalSection (&ch[channel].csDSP);
}

PORT
void SetTXAWFMNC (int channel, int nc)
{
	WFMMOD a;
	double* impulse;
	EnterCriticalSection (&ch[channel].csDSP);
	a = txa[channel].wfmmod.p;
	if (a->nc != nc)
	{
		a->nc = nc;
		impulse = fir_bandpass (a->nc, -a->bp_fc, +a->bp_fc, a->samplerate, 0, 1, 1.0 / (2 * a->size));
		setNc_fircore (a->p, a->nc, impulse);
		_aligned_free (impulse);
	}
	LeaveCriticalSection (&ch[channel].csDSP);
}

PORT
void SetTXAWFMMP (int channel, int mp)
{
	WFMMOD a;
	a = txa[channel].wfmmod.p;
	if (a->mp != mp)
	{
		a->mp = mp;
		setMp_fircore (a->p, a->mp);
	}
}

PORT
void SetTXAWFMAFFreqs (int channel, double low, double high)
{
	WFMMOD a;
	double* impulse;
	EnterCriticalSection (&ch[channel].csDSP);
	a = txa[channel].wfmmod.p;
	if (a->f_low != low || a->f_high != high)
	{
		a->f_low = low;
		a->f_high = high;
		a->bp_fc = bpfc_wfmmod (a->samplerate, a->deviation, a->f_high);
		impulse = fir_bandpass (a->nc, -a->bp_fc, +a->bp_fc, a->samplerate, 0, 1, 1.0 / (2 * a->size));
		setImpulse_fircore (a->p, impulse, 1);
		_aligned_free (impulse);
	}
	LeaveCriticalSection (&ch[channel].csDSP);
}

PORT
void SetTXAWFMPreEmphRun (int channel, int run)
{
	WFMMOD a = txa[channel].wfmmod.p;
	EnterCriticalSection (&ch[channel].csDSP);
	if (a->pre_run != run)
	{
		a->pre_run = run;
		a->pre_z = 0.0;
	}
	LeaveCriticalSection (&ch[channel].csDSP);
}

PORT
void SetTXAWFMPreEmphTau (int channel, double tau)
{
	WFMMOD a = txa[channel].wfmmod.p;
	EnterCriticalSection (&ch[channel].csDSP);
	if (a->tau_pre != tau && tau > 0.0)
	{
		a->tau_pre = tau;
		a->pmult = exp(-1.0 / (a->samplerate * a->tau_pre));
		a->pnorm = 1.0 / (1.0 - a->pmult);
		a->pre_z = 0.0;
	}
	LeaveCriticalSection (&ch[channel].csDSP);
}