/*******************************************************************************

"A Collection of Useful C++ Classes for Digital Signal Processing"
 By Vinnie Falco

Official project location:
https://github.com/vinniefalco/DSPFilters

See Documentation.cpp for contact information, notes, and bibliography.

--------------------------------------------------------------------------------

License: MIT License (http://www.opensource.org/licenses/mit-license.php)
Copyright (c) 2009 by Vinnie Falco

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

*******************************************************************************/

#include "Common.h"
#include "PoleFilter.h"

namespace Dsp
{

	//------------------------------------------------------------------------------

	complex_t LowPassTransform::transform(complex_t c) const
	{
		if (c == infinity()) { return complex_t(-1, 0); }

		// frequency transform
		c = f * c; 
  
		// bilinear low pass transform
		return (1. + c) / (1. - c);
	}

	LowPassTransform::LowPassTransform(double fc, LayoutBase& digital, LayoutBase const& analog)
	{
		digital.reset();

		// prewarp
		f = tan(doublePi * fc);

		const int numPoles = analog.getNumPoles();
		const int pairs    = numPoles / 2;
		for (int i = 0; i < pairs; ++i)
		{
			const PoleZeroPair& pair = analog[i];
			digital.addPoleZeroConjugatePairs(transform(pair.poles.first), transform(pair.zeros.first));
		}

		if (numPoles & 1)
		{
			const PoleZeroPair& pair = analog[pairs];
			digital.add(transform(pair.poles.first), transform(pair.zeros.first));
		}

		digital.setNormal(analog.getNormalW(), analog.getNormalGain());
	}

	//------------------------------------------------------------------------------

	complex_t HighPassTransform::transform(complex_t c) const
	{
		if (c == infinity()) { return complex_t(1, 0); }

		// frequency transform
		c = f * c; 

		// bilinear high pass transform
		return - (1. + c) / (1. - c);
	}

	HighPassTransform::HighPassTransform(double fc, LayoutBase& digital, LayoutBase const& analog)
	{
		digital.reset();

		// prewarp
		f = 1. / tan(doublePi * fc);

		const int numPoles = analog.getNumPoles();
		const int pairs    = numPoles / 2;
		for (int i = 0; i < pairs; ++i)
		{
			const PoleZeroPair& pair = analog[i];
			digital.addPoleZeroConjugatePairs(transform(pair.poles.first), transform(pair.zeros.first));
		}

		if (numPoles & 1)
		{
			const PoleZeroPair& pair = analog[pairs];
			digital.add(transform(pair.poles.first), transform(pair.zeros.first));
		}

		digital.setNormal(doublePi - analog.getNormalW(), analog.getNormalGain());
	}

	//------------------------------------------------------------------------------

	BandPassTransform::BandPassTransform(double fc, double fw, LayoutBase& digital, LayoutBase const& analog)
	{
		// handle degenerate cases efficiently
		// THIS DOESNT WORK because the cascade states won't match
#if 0
  const double fw_2 = fw / 2;
  if (fc - fw_2 < 0) { LowPassTransform::transform (fc + fw_2, digital, analog); }
  else if (fc + fw_2 >= 0.5) { HighPassTransform::transform (fc - fw_2, digital, analog); }
  else
#endif
		digital.reset();

		const double ww = 2 * doublePi * fw;

		// pre-calcs
		wc2 = 2 * doublePi * fc - (ww / 2);
		wc  = wc2 + ww;

		// what is this crap?
		if (wc2 < 1e-8) { wc2 = 1e-8; }
		if (wc > doublePi - 1e-8) { wc = doublePi - 1e-8; }

		a = cos((wc + wc2) * 0.5) /
			cos((wc - wc2) * 0.5);
		b    = 1 / tan((wc - wc2) * 0.5);
		a2   = a * a;
		b2   = b * b;
		ab   = a * b;
		ab_2 = 2 * ab;

		const int numPoles = analog.getNumPoles();
		const int pairs    = numPoles / 2;
		for (int i = 0; i < pairs; ++i)
		{
			const PoleZeroPair& pair = analog[i];
			ComplexPair p1           = transform(pair.poles.first);
			const ComplexPair z1     = transform(pair.zeros.first);

			//
			// Optimize out the calculations for conjugates for Release builds
			//
#ifndef NDEBUG
			ComplexPair p2 = transform(pair.poles.second);
			assert(p2.first == std::conj (p1.first));
			assert(p2.second == std::conj (p1.second));
#endif

			digital.addPoleZeroConjugatePairs(p1.first, z1.first);
			digital.addPoleZeroConjugatePairs(p1.second, z1.second);
		}

		if (numPoles & 1)
		{
			const ComplexPair poles = transform(analog[pairs].poles.first);
			const ComplexPair zeros = transform(analog[pairs].zeros.first);

			digital.add(poles, zeros);
		}

		const double wn = analog.getNormalW();
		digital.setNormal(2 * atan(sqrt(tan((wc + wn) * 0.5) * tan((wc2 + wn) * 0.5))), analog.getNormalGain());
	}

	ComplexPair BandPassTransform::transform(complex_t c) const
	{
		if (c == infinity()) { return ComplexPair(-1, 1); }

		c = (1. + c) / (1. - c); // bilinear

		complex_t v = 0;
		v           = addmul(v, 4 * (b2 * (a2 - 1) + 1), c);
		v += 8 * (b2 * (a2 - 1) - 1);
		v *= c;
		v += 4 * (b2 * (a2 - 1) + 1);
		v = std::sqrt(v);

		complex_t u = -v;
		u           = addmul(u, ab_2, c);
		u += ab_2;

		v = addmul(v, ab_2, c);
		v += ab_2;

		complex_t d = 0;
		d           = addmul(d, 2 * (b - 1), c) + 2 * (1 + b);

		return ComplexPair(u / d, v / d);
	}

	//------------------------------------------------------------------------------

	BandStopTransform::BandStopTransform(double fc, double fw, LayoutBase& digital, LayoutBase const& analog)
	{
		digital.reset();

		const double ww = 2 * doublePi * fw;

		wc2 = 2 * doublePi * fc - (ww / 2);
		wc  = wc2 + ww;

		// this is crap
		if (wc2 < 1e-8) { wc2 = 1e-8; }
		if (wc > doublePi - 1e-8) { wc = doublePi - 1e-8; }

		a = cos((wc + wc2) * .5) /
			cos((wc - wc2) * .5);
		b  = tan((wc - wc2) * .5);
		a2 = a * a;
		b2 = b * b;

		const int numPoles = analog.getNumPoles();
		const int pairs    = numPoles / 2;
		for (int i = 0; i < pairs; ++i)
		{
			const PoleZeroPair& pair = analog[i];
			const ComplexPair p      = transform(pair.poles.first);
			ComplexPair z            = transform(pair.zeros.first);

			//
			// Optimize out the calculations for conjugates for Release builds
			//
			// trick to get the conjugate
			if (z.second == z.first) { z.second = std::conj(z.first); }

			digital.addPoleZeroConjugatePairs(p.first, z.first);
			digital.addPoleZeroConjugatePairs(p.second, z.second);
		}

		if (numPoles & 1)
		{
			const ComplexPair poles = transform(analog[pairs].poles.first);
			const ComplexPair zeros = transform(analog[pairs].zeros.first);

			digital.add(poles, zeros);
		}

		if (fc < 0.25) { digital.setNormal(doublePi, analog.getNormalGain()); }
		else { digital.setNormal(0, analog.getNormalGain()); }
	}

	ComplexPair BandStopTransform::transform(complex_t c) const
	{
		if (c == infinity()) { c = -1; }
		else { c = (1. + c) / (1. - c); }// bilinear 

		complex_t u(0);
		u = addmul(u, 4 * (b2 + a2 - 1), c);
		u += 8 * (b2 - a2 + 1);
		u *= c;
		u += 4 * (a2 + b2 - 1);
		u = std::sqrt(u);

		complex_t v = u * -.5;
		v += a;
		v = addmul(v, -a, c);

		u *= .5;
		u += a;
		u = addmul(u, -a, c);

		complex_t d(b + 1);
		d = addmul(d, b - 1, c);

		return ComplexPair(u / d, v / d);
	}
} // namespace Dsp
