mirror of
https://github.com/mborgerding/kissfft.git
synced 2025-05-27 21:20:27 -04:00
119 lines
2.9 KiB
C
119 lines
2.9 KiB
C
#include "kiss_fftr.h"
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#include "_kiss_fft_guts.h"
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#include <sys/times.h>
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#include <time.h>
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#include <unistd.h>
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static double cputime()
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{
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struct tms t;
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times(&t);
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return (double)(t.tms_utime + t.tms_stime)/ sysconf(_SC_CLK_TCK) ;
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}
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double snr_compare( kiss_fft_cpx * vec1,kiss_fft_cpx * vec2, int n)
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{
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int k;
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double sigpow,noisepow,err,snr,scale=0;
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sigpow = noisepow = .00000000000000000001;
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for (k=0;k<n;++k) {
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sigpow += (double)vec1[k].r * (double)vec1[k].r +
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(double)vec1[k].i * (double)vec1[k].i;
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err = (double)vec1[k].r - (double)vec2[k].r;
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noisepow += err * err;
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err = (double)vec1[k].i - (double)vec2[k].i;
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noisepow += err * err;
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if (vec1[k].r)
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scale +=(double) vec2[k].r / (double)vec1[k].r;
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/*
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fprintf(stderr,"vec1=");pcpx(vec1+k);
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fprintf(stderr,"vec2=");pcpx(vec2+k);
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*/
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}
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snr = 10*log10( sigpow / noisepow );
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scale /= n;
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if (snr<10)
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printf( "\npoor snr, try a scaling factor %f\n" , scale );
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return snr;
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}
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#define RANDOM
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#ifndef RANDOM
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#define NFFT 8
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#else
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#define NFFT 8*3*5
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#endif
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#ifndef NUMFFTS
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#define NUMFFTS 1000
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#endif
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int main()
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{
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double ts,tfft,trfft;
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int i;
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kiss_fft_cpx cin[NFFT];
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kiss_fft_scalar sin[NFFT] = {0.309655,0.815653,0.768570,0.591841,0.404767,0.637617,0.007803,0.012665};
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kiss_fft_cpx cout[NFFT];
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kiss_fft_cpx sout[NFFT];
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void * kiss_fft_state;
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void * kiss_fftr_state;
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srand(time(0));
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for (i=0;i<NFFT;++i) {
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#ifdef RANDOM
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sin[i] = (kiss_fft_scalar)(rand()-RAND_MAX/2);
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#endif
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cin[i].r = sin[i];
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cin[i].i = 0;
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}
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kiss_fft_state = kiss_fft_alloc(NFFT,0,0,0);
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kiss_fftr_state = kiss_fftr_alloc(NFFT,0,0,0);
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kiss_fft(kiss_fft_state,cin,cout);
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kiss_fftr(kiss_fftr_state,sin,sout);
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printf( "nfft=%d, inverse=%d, snr=%g\n",
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NFFT,0, snr_compare(cout,sout,(NFFT/2)+1) );
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#ifdef RANDOM
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ts = cputime();
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for (i=0;i<NUMFFTS;++i) {
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kiss_fft(kiss_fft_state,cin,cout);
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}
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tfft = cputime() - ts;
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ts = cputime();
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for (i=0;i<NUMFFTS;++i) {
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kiss_fftr( kiss_fftr_state, sin, cout );
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/* kiss_fftri(kiss_fftr_state,cout,sin); */
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}
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trfft = cputime() - ts;
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printf("%d complex ffts took %gs, real took %gs\n",NUMFFTS,tfft,trfft);
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#endif
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free(kiss_fft_state);
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free(kiss_fftr_state);
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kiss_fft_state = kiss_fft_alloc(NFFT,1,0,0);
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kiss_fftr_state = kiss_fftr_alloc(NFFT,1,0,0);
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kiss_fft(kiss_fft_state,cout,cin);
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kiss_fftri(kiss_fftr_state,cout,sin);
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for (i=0;i<NFFT;++i) {
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sout[i].r = sin[i];
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sout[i].i = 0;
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}
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printf( "nfft=%d, inverse=%d, snr=%g\n",
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NFFT,1, snr_compare(cin,cin,NFFT/2) );
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free(kiss_fft_state);
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free(kiss_fftr_state);
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return 0;
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}
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