mirror of
https://github.com/mborgerding/kissfft.git
synced 2025-05-27 21:20:27 -04:00
103 lines
2.4 KiB
C
103 lines
2.4 KiB
C
#include "kiss_fft.h"
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#include <sys/time.h>
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static double timesnap()
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{
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struct timeval tv;
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gettimeofday(&tv,NULL);
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return (double)tv.tv_sec + (double)tv.tv_usec/1000000;
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}
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void * kiss_fftr_alloc(int nfft,int inverse_fft);
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void kiss_fftr(const void * cfg,const kiss_fft_scalar *fin,kiss_fft_cpx *fout);
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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 = .000000000000000000000000000001;
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for (k=0;k<n;++k) {
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sigpow += vec1[k].r * vec1[k].i +
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vec1[k].i * vec1[k].i;
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err = vec1[k].r - vec2[k].r;
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noisepow += err * err;
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err = vec1[k].i - vec2[k].i;
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noisepow += err * err;
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if (vec1[k].r)
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scale += vec2[k].r / vec1[k].r;
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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 1800
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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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void pcpx(const char * msg, kiss_fft_cpx * c)
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{
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printf("%s: %g + %gi\n",msg,c->r,c->i);
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}
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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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const void * kiss_fft_state;
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const void * kiss_fftr_state;
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int inverse = 0;
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kiss_fft_state = kiss_fft_alloc(NFFT,inverse);
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kiss_fftr_state = kiss_fftr_alloc(NFFT,inverse);
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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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/* printf("in[%d]",i);pcpx("",cin+i); */
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}
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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,inverse, snr_compare(cout,sout,NFFT/2) );
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ts = timesnap();
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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 = timesnap() - ts;
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ts = timesnap();
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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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}
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trfft = timesnap() - ts;
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printf("%d complex ffts took %gs, real took %gs\n",NUMFFTS,tfft,trfft);
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return 0;
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}
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