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79 lines
2.2 KiB
C
79 lines
2.2 KiB
C
// ----------------------------------------------------------------------------
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// misc.h -- Miscellaneous helper functions
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//
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// Copyright (C) 2006-2008
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// Dave Freese, W1HKJ
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//
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// This file is part of fldigi. These filters were adapted from code contained
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// in the gmfsk source code distribution.
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//
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// Fldigi 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, either version 3 of the License, or
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// (at your option) any later version.
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//
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// Fldigi 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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// You should have received a copy of the GNU General Public License
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// along with fldigi. If not, see <http://www.gnu.org/licenses/>.
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// ----------------------------------------------------------------------------
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#ifndef _MISC_H
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#define _MISC_H
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#include <math.h>
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#undef M_PI
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#define M_PI 3.14159265358979323846
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inline float sinc(float x)
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{
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return (fabs(x) < 1e-10) ? 1.0 : (sin(M_PI * x) / (M_PI * x));
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}
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inline float cosc(float x)
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{
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return (fabs(x) < 1e-10) ? 0.0 : ((1.0 - cos(M_PI * x)) / (M_PI * x));
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}
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inline float clamp(float x, float min, float max)
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{
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return (x < min) ? min : ((x > max) ? max : x);
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}
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/// This is always called with an int weight
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inline float decayavg(float average, float input, int weight)
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{
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if (weight <= 1) return input;
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return ( ( input - average ) / (float)weight ) + average ;
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}
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// following are defined inline to provide best performance
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inline float blackman(float x)
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{
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return (0.42 - 0.50 * cos(2 * M_PI * x) + 0.08 * cos(4 * M_PI * x));
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}
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inline float hamming(float x)
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{
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return 0.54 - 0.46 * cos(2 * M_PI * x);
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}
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inline float hanning(float x)
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{
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return 0.5 - 0.5 * cos(2 * M_PI * x);
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}
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inline float rcos( float t, float T, float alpha=1.0 )
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{
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if( t == 0 ) return 1.0;
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float taT = T / (2.0 * alpha);
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if( fabs(t) == taT ) return ((alpha/2.0) * sin(M_PI/(2.0*alpha)));
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return (sin(M_PI*t/T)/(M_PI*t/T))*cos(alpha*M_PI*t/T)/(1.0-(t/taT)*(t/taT));
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}
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#endif
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