dl-fldigi/src/include/filters.h

// ----------------------------------------------------------------------------
//
// filters.h  --  Several Digital Filter classes used in fldigi
//
//    Copyright (C) 2006-2008
//			Dave Freese, W1HKJ
//
//    This file is part of fldigi.  These filters are based on the 
//    gmfsk design and the design notes given in 
//    "Digital Signal Processing", A Practical Guid for Engineers and Scientists
//	  by Steven W. Smith.
//
// Fldigi 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.
//
// Fldigi 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 fldigi.  If not, see <http://www.gnu.org/licenses/>.
// ----------------------------------------------------------------------------


#ifndef _FILTER_H
#define _FILTER_H

#include "complex.h"
#ifndef M_PI
#define M_PI (3.1415926535897932385)
#endif

//=====================================================================
// FIR filters
//=====================================================================

class C_FIR_filter {
#define FIRBufferLen 4096
private:
	int length;
	int decimateratio;

	double *ifilter;
	double *qfilter;

	double ffreq;
	
	double ibuffer[FIRBufferLen];
	double qbuffer[FIRBufferLen];

	int pointer;
	int counter;
	
	cmplx fu;

	inline double sinc(double x) {
		if (fabs(x) < 1e-10)
			return 1.0;
		else
			return sin(M_PI * x) / (M_PI * x);
	}
	inline double cosc(double x) {
		if (fabs(x) < 1e-10)
			return 0.0;
		else
			return (1.0 - cos(M_PI * x)) / (M_PI * x);
	}
	inline double hamming(double x) {
		return 0.54 - 0.46 * cos(2 * M_PI * x);
	}
	inline double mac(const double *a, const double *b, unsigned int size) {
		double sum = 0.0;
		double sum2 = 0.0;
		double sum3 = 0.0;
		double sum4 = 0.0;
		// Reduces read-after-write dependencies : Each subsum does not wait for the others.
		// The CPU can therefore schedule each line independently.
		for (; size > 3; size -= 4, a += 4, b+=4)
		{
			sum  += a[0] * b[0];
			sum2 += a[1] * b[1];
			sum3 += a[2] * b[2];
			sum4 += a[3] * b[3];
		}
		for (; size; --size)
			sum += (*a++) * (*b++);
		return sum + sum2 + sum3 + sum4 ;
	}

protected:
	
public:
	C_FIR_filter ();
	~C_FIR_filter ();
	void init (int len, int dec, double *ifil, double *qfil);
	void init_lowpass (int len, int dec, double freq );
	void init_bandpass (int len, int dec, double freq1, double freq2);
	void init_hilbert (int len, int dec);
	double *bp_FIR(int len, int hilbert, double f1, double f2);
	void dump();
	int run (const cmplx &in, cmplx &out);
	int Irun (const double &in, double &out);
	int Qrun (const double &in, double &out);
};

//=====================================================================
// Moving average filter
//=====================================================================

class Cmovavg {
#define MAXMOVAVG 2048
private:
	double	*in;
	double	out;
	int		len, pint;
	bool	empty;
public:
	Cmovavg(int filtlen);
	~Cmovavg();
	double run(double a);
	void setLength(int filtlen);
	void reset();
	double value() { return out / (len > 0 ? len : 1); }
};


//=====================================================================
// Sliding FFT
//=====================================================================

class sfft {
#define K1 0.99999999999L
private:
	int fftlen;
	int first;
	int last;
	int ptr;
	struct vrot_bins_pair ;
	vrot_bins_pair * __restrict__ vrot_bins ;
	cmplx * __restrict__ delay;
	double k2;
	int count;
public:
	sfft(int len, int first, int last);
	~sfft();
	bool is_stable();
	void reset();
	void run(const cmplx& input, cmplx * __restrict__ result, int stride );
};



//=============================================================================
// Goertzel DFT
//=============================================================================

class goertzel {
private:
	int N;
	int count;
	double Q0;
	double Q1;
	double Q2;
	double k1;
	double k2;
	double k3;
	bool isvalid;
public:
	goertzel(int n, double freq, double sr);
	~goertzel();
	void reset();
	void reset(int n, double freq, double sr);
	bool run(double v);
	double real();
	double imag();
	double mag();
};

#endif				/* _FILTER_H */