Real FFT cleanup, plus some testcases

1 files changed, 176 insertions, 0 deletions

diff --git a/tests/real-fft-test.c b/tests/real-fft-test.c
new file mode 100644
index 0000000..532ed8d
--- /dev/null
+++ b/tests/real-fft-test.c
@@ -0,0 +1,176 @@
+#include "kiss_fftr.h"
+#include "_kiss_fft_guts.h"
+#include <sys/times.h>
+#include <time.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+
+static double cputime(void)
+{
+    struct tms t;
+    times(&t);
+    return (double)(t.tms_utime + t.tms_stime)/  sysconf(_SC_CLK_TCK) ;
+}
+
+static
+kiss_fft_scalar rand_scalar(void) 
+{
+#ifdef USE_SIMD
+    return _mm_set1_ps(rand()-RAND_MAX/2);
+#else
+    kiss_fft_scalar s = (kiss_fft_scalar)(rand() -RAND_MAX/2);
+    return s/2;
+#endif
+}
+
+static
+double snr_compare( kiss_fft_cpx * vec1,kiss_fft_scalar * vec2, int n)
+{
+    int k;
+    double sigpow=1e-10, noisepow=1e-10, err,snr;
+
+    for (k=1;k<n;++k) {
+        sigpow += (double)vec1[k].r * (double)vec1[k].r + 
+                  (double)vec1[k].i * (double)vec1[k].i;
+        err = (double)vec1[k].r - (double)vec2[2*k-1];
+        noisepow += err * err;
+        err = (double)vec1[k].i - (double)vec2[2*k];
+        noisepow += err * err;
+
+    }
+    snr = 10*log10( sigpow / noisepow );
+    if (snr<10) {
+        printf( "\npoor snr: %f\n", snr);
+        exit(1);
+    }
+    return snr;
+}
+
+static
+double snr_compare_scal( kiss_fft_scalar * vec1,kiss_fft_scalar * vec2, int n)
+{
+    int k;
+    double sigpow=1e-10, noisepow=1e-10, err,snr;
+
+    for (k=1;k<n;++k) {
+        sigpow += (double)vec1[k] * (double)vec1[k];
+        err = (double)vec1[k] - (double)vec2[k];
+        noisepow += err * err;
+    }
+    snr = 10*log10( sigpow / noisepow );
+    if (snr<10) {
+        printf( "\npoor snr: %f\n", snr);
+        exit(1);
+    }
+    return snr;
+}
+#define NFFT 8*3*5
+
+#ifndef NUMFFTS
+#define NUMFFTS 10000
+#endif
+
+
+int main(void)
+{
+    double ts,tfft,trfft;
+    int i;
+    kiss_fft_cpx cin[NFFT];
+    kiss_fft_cpx cout[NFFT];
+    kiss_fft_scalar fin[NFFT];
+    kiss_fft_scalar sout[NFFT];
+    kiss_fft_cfg  kiss_fft_state;
+    kiss_fftr_cfg  kiss_fftr_state;
+
+    kiss_fft_scalar rin[NFFT+2];
+    kiss_fft_scalar rout[NFFT+2];
+    kiss_fft_scalar zero;
+    memset(&zero,0,sizeof(zero) ); // ugly way of setting short,int,float,double, or __m128 to zero
+
+    srand(time(0));
+
+    for (i=0;i<NFFT;++i) {
+        rin[i] = rand_scalar();
+        cin[i].r = rin[i];
+        cin[i].i = zero;
+    }
+
+    kiss_fft_state = kiss_fft_alloc(NFFT,0,0,0);
+    kiss_fftr_state = kiss_fftr_alloc(NFFT,0,0,0);
+    kiss_fft(kiss_fft_state,cin,cout);
+    kiss_fftr(kiss_fftr_state,rin,sout);
+    
+    printf( "nfft=%d, inverse=%d, snr=%g\n",
+            NFFT,0, snr_compare(cout,sout,(NFFT/2)) );
+    ts = cputime();
+    for (i=0;i<NUMFFTS;++i) {
+        kiss_fft(kiss_fft_state,cin,cout);
+    }
+    tfft = cputime() - ts;
+    
+    ts = cputime();
+    for (i=0;i<NUMFFTS;++i) {
+        kiss_fftr( kiss_fftr_state, rin, sout );
+        /* kiss_fftri(kiss_fftr_state,cout,rin); */
+    }
+    trfft = cputime() - ts;
+
+    printf("%d complex ffts took %gs, real took %gs\n",NUMFFTS,tfft,trfft);
+
+    free(kiss_fft_state);
+    free(kiss_fftr_state);
+
+    kiss_fft_state = kiss_fft_alloc(NFFT,1,0,0);
+    kiss_fftr_state = kiss_fftr_alloc(NFFT,1,0,0);
+
+    memset(cin,0,sizeof(cin));
+#if 1
+    cin[0].r = rand_scalar();
+    cin[NFFT/2].r = rand_scalar();
+    for (i=1;i< NFFT/2;++i) {
+        //cin[i].r = (kiss_fft_scalar)(rand()-RAND_MAX/2);
+        cin[i].r = rand_scalar();
+        cin[i].i = rand_scalar();
+    }
+#else
+    cin[0].r = 12000;
+    cin[3].r = 12000;
+    cin[NFFT/2].r = 12000;
+#endif
+
+    // conjugate symmetry of real signal 
+    for (i=1;i< NFFT/2;++i) {
+        cin[NFFT-i].r = cin[i].r;
+        cin[NFFT-i].i = - cin[i].i;
+    }
+
+    fin[0] = cin[0].r;
+    fin[NFFT-1] = cin[NFFT/2].r;
+    for (i=1;i< NFFT/2;++i)
+    {
+       fin[2*i-1] = cin[i].r;
+       fin[2*i]   = cin[i].i;
+    }
+    
+    kiss_fft(kiss_fft_state,cin,cout);
+    kiss_fftri(kiss_fftr_state,fin,rout);
+    /*
+    printf(" results from inverse kiss_fft : (%f,%f), (%f,%f), (%f,%f), (%f,%f), (%f,%f) ...\n "
+            , (float)cout[0].r , (float)cout[0].i , (float)cout[1].r , (float)cout[1].i , (float)cout[2].r , (float)cout[2].i , (float)cout[3].r , (float)cout[3].i , (float)cout[4].r , (float)cout[4].i
+            ); 
+
+    printf(" results from inverse kiss_fftr: %f,%f,%f,%f,%f ... \n"
+            ,(float)rout[0] ,(float)rout[1] ,(float)rout[2] ,(float)rout[3] ,(float)rout[4]);
+*/
+    for (i=0;i<NFFT;++i) {
+        sout[i] = cout[i].r;
+    }
+
+    printf( "nfft=%d, inverse=%d, snr=%g\n",
+            NFFT,1, snr_compare_scal(rout,sout,NFFT) );
+    free(kiss_fft_state);
+    free(kiss_fftr_state);
+
+    return 0;
+}