kopia lustrzana https://github.com/Dsplib/libdspl-2.0
81 wiersze
2.8 KiB
C
81 wiersze
2.8 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "dspl.h"
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/* Filter order */
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#define ORD 4
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/* Frequency response vector size */
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#define N 1000
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int main(int argc, char* argv[])
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{
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void* hdspl; /* DSPL handle */
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void* hplot; /* GNUPLOT handle */
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double a[ORD+1]; /* H(s) numerator coefficients vector */
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double b[ORD+1]; /* H(s) denominator coefficients vector */
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double Rs = 60.0; /* Stopband suppression (dB) */
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double w[N]; /* Angular frequency (rad/s) */
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double mag[N]; /* Filter Magnitude (dB) */
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double phi[N]; /* Phase response */
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double tau[N]; /* Group delay */
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int k;
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/* Load DSPL function */
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hdspl = dspl_load();
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if(!hdspl)
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{
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printf("libdspl loading error!\n");
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return -1;
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}
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/* H(s) coefficients calculation */
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int res = cheby2_ap(Rs, ORD, b, a);
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if(res != RES_OK)
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printf("error code = 0x%8x\n", res);
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/* Print H(s) coefficients */
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for(k = 0; k < ORD+1; k++)
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printf("b[%2d] = %9.3f a[%2d] = %9.3f\n", k, b[k], k, a[k]);
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/* Frequency in logarithmic scale from 0.01 to 100 rad/s */
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logspace(-2.0, 2.0, N , DSPL_SYMMETRIC, w);
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/* Filter frequency parameter calculation */
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filter_freq_resp(b, a, ORD, w, N,
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DSPL_FLAG_LOGMAG|DSPL_FLAG_UNWRAP | DSPL_FLAG_ANALOG,
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mag, phi, tau);
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/* Write Magnitude, phase response and group delay to the files */
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writetxt(w, mag, N, "dat/cheby2_ap_test_mag.txt");
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writetxt(w, phi, N, "dat/cheby2_ap_test_phi.txt");
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writetxt(w, tau, N, "dat/cheby2_ap_test_tau.txt");
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/* plotting by GNUPLOT */
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gnuplot_create(argc, argv, 920, 260, "img/cheby2_ap_test.png", &hplot);
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gnuplot_cmd(hplot, "set logscale x");
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gnuplot_cmd(hplot, "unset key");
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gnuplot_cmd(hplot, "set grid");
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gnuplot_cmd(hplot, "set xlabel 'frequency, rad/s'");
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gnuplot_cmd(hplot, "set multiplot layout 1,3 rowsfirst");
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gnuplot_cmd(hplot, "set ylabel 'Magnitude, dB'");
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gnuplot_cmd(hplot, "set yrange [-100:5]");
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gnuplot_cmd(hplot, "plot 'dat/cheby2_ap_test_mag.txt' with lines");
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gnuplot_cmd(hplot, "set ylabel 'Phase response, rad'");
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gnuplot_cmd(hplot, "unset yrange");
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gnuplot_cmd(hplot, "plot 'dat/cheby2_ap_test_phi.txt' with lines");
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gnuplot_cmd(hplot, "set ylabel 'Groupdelay, sec'");
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gnuplot_cmd(hplot, "unset yrange");
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gnuplot_cmd(hplot, "plot 'dat/cheby2_ap_test_tau.txt' with lines");
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gnuplot_cmd(hplot, "unset multiplot");
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gnuplot_close(hplot);
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/* free dspl handle */
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dspl_free(hdspl);
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return res;
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}
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