75 lines
1.6 KiB
C
75 lines
1.6 KiB
C
#include "kiss_fft.h"
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void check(kiss_fft_cpx * in,kiss_fft_cpx * out,int nfft,int isinverse)
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{
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int bin,k;
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double errpow=0,sigpow=0;
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for (bin=0;bin<nfft;++bin) {
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double ansr = 0;
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double ansi = 0;
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double difr;
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double difi;
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for (k=0;k<nfft;++k) {
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double phase = -2*M_PI*bin*k/nfft;
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double re = cos(phase);
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double im = sin(phase);
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if (isinverse)
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im = -im;
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#ifdef FIXED_POINT
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re /= nfft;
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im /= nfft;
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#endif
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ansr += in[k].r * re - in[k].i * im;
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ansi += in[k].r * im + in[k].i * re;
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}
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difr = ansr - out[bin].r;
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difi = ansi - out[bin].i;
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errpow += difr*difr + difi*difi;
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sigpow += ansr*ansr+ansi*ansi;
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}
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printf("nfft=%d inverse=%d,snr = %f\n",nfft,isinverse,10*log10(sigpow/errpow) );
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}
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void test1d(int nfft,int isinverse)
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{
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size_t buflen = sizeof(kiss_fft_cpx)*nfft;
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kiss_fft_cpx * in = (kiss_fft_cpx*)malloc(buflen);
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kiss_fft_cpx * out= (kiss_fft_cpx*)malloc(buflen);
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kiss_fft_cfg cfg = kiss_fft_alloc(nfft,isinverse,0,0);
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int k;
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for (k=0;k<nfft;++k) {
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in[k].r = (rand() % 65536) - 32768;
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in[k].i = (rand() % 65536) - 32768;
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}
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kiss_fft(cfg,in,out);
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check(in,out,nfft,isinverse);
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free(in);
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free(out);
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free(cfg);
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}
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int main(int argc,char ** argv)
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{
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if (argc>1) {
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int k;
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for (k=1;k<argc;++k) {
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test1d(atoi(argv[k]),0);
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test1d(atoi(argv[k]),1);
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}
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}else{
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test1d(32,0);
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test1d(32,1);
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}
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return 0;
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}
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