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49 lines
1.4 KiB
49 lines
1.4 KiB
/*
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* Copyright (C) 2009,2013 by Jonathan Naylor, G4KLX
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#ifndef FIRFilter_H
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#define FIRFilter_H
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/*
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* Direct-form FIR (Finite Impulse Response) filter operating on float samples.
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*
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* Used by the GMSK modulator and demodulator to implement the Gaussian pulse-
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* shaping filter required by the D-Star GMSK modulation scheme (BT=0.5).
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*
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* process() convolves input samples with the tap coefficients using a circular
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* delay buffer. reset() clears the delay line without changing the tap set.
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*/
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class CFIRFilter {
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public:
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CFIRFilter(const float* taps, unsigned int length);
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CFIRFilter();
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~CFIRFilter();
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void setTaps(const float* taps, unsigned int length);
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float process(float val);
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void process(float* inOut, unsigned int length);
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void process(const float* in, float* out, unsigned int length);
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void reset();
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private:
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float* m_taps;
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unsigned int m_length;
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float* m_buffer; // Circular delay line for the filter state.
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unsigned int m_bufLen;
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unsigned int m_pointer;
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};
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#endif
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