kiss_fftr.c gives correct answers for forward

test/test_real.c

@@ -0,0 +1,75 @@
+#include "kiss_fft.h"
+
+
+void * kiss_fftr_alloc(int nfft,int inverse_fft);
+void kiss_fftr(const void * cfg,const kiss_fft_scalar *fin,kiss_fft_cpx *fout);
+
+double snr_compare( kiss_fft_cpx * vec1,kiss_fft_cpx * vec2, int n)
+{
+    int k;
+    double sigpow,noisepow,err,snr,scale=0;
+    sigpow = noisepow = .000000000000000000000000000001; 
+
+    for (k=0;k<n;++k) {
+        sigpow += vec1[k].r * vec1[k].i + 
+                  vec1[k].i * vec1[k].i;
+        err = vec1[k].r - vec2[k].r;
+        noisepow += err * err;
+        err = vec1[k].i - vec2[k].i;
+        noisepow += err * err;
+
+        if (vec1[k].r)
+            scale += vec2[k].r / vec1[k].r;
+    }
+    snr = 10*log10( sigpow / noisepow );
+    scale /= n;
+    if (snr<10)
+        printf( "\npoor snr, try a scaling factor %f\n" , scale );
+    return snr;
+}
+
+#define RANDOM
+#ifndef RANDOM
+#define NFFT 8
+#else
+#define NFFT 120
+#endif
+
+void pcpx(const char * msg, kiss_fft_cpx * c)
+{
+    printf("%s: %g + %gi\n",msg,c->r,c->i);
+}
+
+int main()
+{
+    int i;
+    kiss_fft_cpx cin[NFFT];
+    kiss_fft_scalar sin[NFFT] = {0.309655,0.815653,0.768570,0.591841,0.404767,0.637617,0.007803,0.012665};
+    kiss_fft_cpx cout[NFFT];
+    kiss_fft_cpx sout[NFFT];
+    
+    const void * kiss_fft_state;
+    const void * kiss_fftr_state;
+    int inverse = 0;
+    
+    kiss_fft_state = kiss_fft_alloc(NFFT,inverse);
+    kiss_fftr_state = kiss_fftr_alloc(NFFT,inverse);
+
+    for (i=0;i<NFFT;++i) {
+#ifdef RANDOM        
+        sin[i] = (kiss_fft_scalar)(rand()-RAND_MAX/2);
+#endif        
+        cin[i].r = sin[i];
+        cin[i].i = 0;
+/*        printf("in[%d]",i);pcpx("",cin+i); */
+    }
+
+    kiss_fft(kiss_fft_state,cin,cout);
+    kiss_fftr(kiss_fftr_state,sin,sout);
+
+    printf( "nfft=%d, inverse=%d, snr=%g\n",
+            NFFT,inverse, snr_compare(cout,sout,NFFT/2) );
+    
+    return 0;
+}
+