222 lines
6.4 KiB
C
222 lines
6.4 KiB
C
/* icfir.c
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This file is part of a program that implements a Software-Defined Radio.
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Copyright (C) 2018 Warren Pratt, NR0V
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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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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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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The author can be reached by email at
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warren@pratt.one
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*/
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#define _CRT_SECURE_NO_DEPRECATE
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#include "comm.h"
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void calc_icfir (ICFIR a)
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{
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double* impulse;
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a->scale = 1.0 / (double)(2 * a->size);
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impulse = icfir_impulse (a->nc, a->DD, a->R, a->Pairs, a->runrate, a->cicrate, a->cutoff, a->xtype, a->xbw, 1, a->scale, a->wintype);
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a->p = create_fircore (a->size, a->in, a->out, a->nc, a->mp, impulse);
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_aligned_free (impulse);
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}
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void decalc_icfir (ICFIR a)
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{
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destroy_fircore (a->p);
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}
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ICFIR create_icfir (int run, int size, int nc, int mp, double* in, double* out, int runrate, int cicrate,
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int DD, int R, int Pairs, double cutoff, int xtype, double xbw, int wintype)
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// run: 0 - no action; 1 - operate
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// size: number of complex samples in an input buffer to the CFIR filter
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// nc: number of filter coefficients
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// mp: minimum phase flag
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// in: pointer to the input buffer
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// out: pointer to the output buffer
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// rate: samplerate
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// DD: differential delay of the CIC to be compensated (usually 1 or 2)
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// R: interpolation factor of CIC
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// Pairs: number of comb-integrator pairs in the CIC
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// cutoff: cutoff frequency
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// xtype: 0 - fourth power transition; 1 - raised cosine transition
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// xbw: width of raised cosine transition
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{
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ICFIR a = (ICFIR) malloc0 (sizeof (icfir));
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a->run = run;
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a->size = size;
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a->nc = nc;
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a->mp = mp;
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a->in = in;
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a->out = out;
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a->runrate = runrate;
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a->cicrate = cicrate;
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a->DD = DD;
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a->R = R;
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a->Pairs = Pairs;
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a->cutoff = cutoff;
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a->xtype = xtype;
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a->xbw = xbw;
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a->wintype = wintype;
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calc_icfir (a);
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return a;
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}
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void destroy_icfir (ICFIR a)
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{
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decalc_icfir (a);
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_aligned_free (a);
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}
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void flush_icfir (ICFIR a)
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{
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flush_fircore (a->p);
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}
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void xicfir (ICFIR a)
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{
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if (a->run)
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xfircore (a->p);
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else if (a->in != a->out)
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memcpy (a->out, a->in, a->size * sizeof (complex));
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}
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void setBuffers_icfir (ICFIR a, double* in, double* out)
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{
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decalc_icfir (a);
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a->in = in;
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a->out = out;
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calc_icfir (a);
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}
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void setSamplerate_icfir (ICFIR a, int rate)
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{
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decalc_icfir (a);
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a->runrate = rate;
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calc_icfir (a);
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}
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void setSize_icfir (ICFIR a, int size)
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{
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decalc_icfir (a);
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a->size = size;
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calc_icfir (a);
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}
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void setOutRate_icfir (ICFIR a, int rate)
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{
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decalc_icfir (a);
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a->cicrate = rate;
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calc_icfir (a);
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}
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double* icfir_impulse (int N, int DD, int R, int Pairs, double runrate, double cicrate, double cutoff, int xtype, double xbw, int rtype, double scale, int wintype)
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{
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// N: number of impulse response samples
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// DD: differential delay used in the CIC filter
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// R: interpolation / decimation factor of the CIC
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// Pairs: number of comb-integrator pairs in the CIC
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// runrate: sample rate at which this filter is to run (assumes there may be flat interp. between this filter and the CIC)
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// cicrate: sample rate at interface to CIC
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// cutoff: cutoff frequency
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// xtype: transition type, 0 for 4th-power rolloff, 1 for raised cosine
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// xbw: transition bandwidth for raised cosine
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// rtype: 0 for real output, 1 for complex output
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// scale: scale factor to be applied to the output
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int i, j;
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double tmp, local_scale, ri, fn, mag = 1.0;
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double* impulse;
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double* A = (double *) malloc0 (N * sizeof (double));
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double ft = cutoff / cicrate; // normalized cutoff frequency
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int u_samps = (N + 1) / 2; // number of unique samples, OK for odd or even N
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int c_samps = (int)(cutoff / runrate * N) + (N + 1) / 2 - N / 2; // number of unique samples within bandpass, OK for odd or even N
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int x_samps = (int)(xbw / runrate * N); // number of unique samples in transition region, OK for odd or even N
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double offset = 0.5 - 0.5 * (double)((N + 1) / 2 - N / 2); // sample offset from center, OK for odd or even N
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double* xistion = (double *) malloc0 ((x_samps + 1) * sizeof (double));
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double delta = PI / (double)x_samps;
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double L = cicrate / runrate;
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double phs = 0.0;
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for (i = 0; i <= x_samps; i++)
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{
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xistion[i] = 0.5 * (cos (phs) + 1.0);
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phs += delta;
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}
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if ((tmp = DD * R * sin (PI * ft / R) / sin (PI * DD * ft)) < 0.0) //normalize by peak gain
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tmp = -tmp;
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local_scale = scale / pow (tmp, Pairs);
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if (xtype == 0)
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{
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for (i = 0, ri = offset; i < u_samps; i++, ri += 1.0)
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{
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fn = ri / (L * (double)N);
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if (fn <= ft)
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{
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if (fn == 0.0) tmp = 1.0;
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else if ((tmp = sin (PI * DD * fn) / (DD * R * sin (PI * fn / R))) < 0.0)
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tmp = -tmp;
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mag = pow (tmp, Pairs) * local_scale;
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}
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else
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mag *= (ft * ft * ft * ft) / (fn * fn * fn * fn);
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A[i] = mag;
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}
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}
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else if (xtype == 1)
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{
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for (i = 0, ri = offset; i < u_samps; i++, ri += 1.0)
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{
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fn = ri / (L *(double)N);
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if (i < c_samps)
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{
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if (fn == 0.0) tmp = 1.0;
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else if ((tmp = sin (PI * DD * fn) / (DD * R * sin (PI * fn / R))) < 0.0)
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tmp = -tmp;
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mag = pow (tmp, Pairs) * local_scale;
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A[i] = mag;
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}
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else if ( i >= c_samps && i <= c_samps + x_samps)
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A[i] = mag * xistion[i - c_samps];
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else
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A[i] = 0.0;
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}
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}
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if (N & 1)
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for (i = u_samps, j = 2; i < N; i++, j++)
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A[i] = A[u_samps - j];
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else
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for (i = u_samps, j = 1; i < N; i++, j++)
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A[i] = A[u_samps - j];
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impulse = fir_fsamp (N, A, rtype, 1.0, wintype);
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// print_impulse ("icfirImpulse.txt", N, impulse, 1, 0);
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_aligned_free (A);
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return impulse;
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}
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/********************************************************************************************************
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* *
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* TXA Properties *
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* *
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********************************************************************************************************/
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//PORT void
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//SetTXAICFIRRun (int channel, int run)
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//{
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// EnterCriticalSection(&ch[channel].csDSP);
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// txa[channel].icfir.p->run = run;
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// LeaveCriticalSection(&ch[channel].csDSP);
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//}
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