made easy to use longs for fixed point

test/twotonetest.c

@@ -0,0 +1,105 @@
+#include <complex.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include "kiss_fft.h"
+#include "kiss_fftr.h"
+#include <limits.h>
+
+#define pcpx(c)\
+        fprintf(stderr,"%g + %gi\n",(double)((c)->r),(double)((c)->i) )
+
+void fe_fft_test( int N, int bin1,int bin2)
+{
+    // static kiss_fft_cfg cfg = NULL;
+    static kiss_fftr_cfg cfg	= NULL;
+    static int lastN			= 0;
+    // kiss_fft_cpx *kin = NULL;
+    static kiss_fft_cpx *kout	= NULL;
+    static kiss_fft_scalar *kin_r = NULL;
+    static int halfN = 0;
+    int flipN;
+
+    int i;
+    double f1 = (bin1*2.0/N)*M_PI;
+    double f2 = (bin2*2.0/N)*M_PI;
+    double sigpow=0;
+    double noisepow=0;
+
+    if (lastN != N) {
+        // Free previous structures, if allocated.
+        if (cfg)
+            free(cfg);
+        if (kin_r)
+            free(kin_r);
+        if (kout)
+            free(kout);
+
+        halfN = N / 2;
+
+        // Allocate the KISS FFT configuration structure.
+        // Although the memory for these structures will be freed 
+        //  when the DLL unloads, to be squeaky clean it should be
+        //  freed explicitly.
+        // cfg = kiss_fft_alloc( N , 0, NULL, NULL);
+        cfg = kiss_fftr_alloc(N , 0, NULL, NULL);
+
+        // kin		= malloc(N * sizeof(kiss_fft_cpx));
+        // kin_r		= malloc(N * sizeof(kiss_fft_cpx));
+        kin_r		= malloc(N * sizeof(kiss_fft_scalar));
+        kout	= malloc(N * sizeof(kiss_fft_cpx));
+
+
+        lastN = N;
+    }
+
+#if FIXED_POINT==32
+    long maxrange = LONG_MAX;
+#else    
+    long maxrange = SHRT_MAX;
+#endif
+    // Convert the floating point "in" array to fixed point.
+    for (i = 0; i < N; i++)
+    {
+        kin_r[i] =  (maxrange>>1)*cos(f1*i)
+                  + (maxrange>>1)*cos(f2*i);
+    }
+
+    // Make the kiss FFT call.
+    kiss_fftr(cfg, kin_r, kout);
+
+    sigpow = 0;
+    //printf("[");
+    for (i=0;i < (N/2+1);++i) {
+        double tmpr = (double)kout[i].r / (double)maxrange;
+        double tmpi = (double)kout[i].i / (double)maxrange;
+        double mag2 = tmpr*tmpr + tmpi*tmpi;
+        if (i!=0 && i!= N/2)
+            mag2 *= 2; // all bins except DC and Nyquist have symmetric counterparts implied
+        sigpow += mag2;
+
+        // subtract out the expected result, anything left is noise
+        if ( i!=bin1 && i != bin2 ) 
+            noisepow += mag2;
+        //printf("%d%+di,",(int)kout[i].r,(int)kout[i].i);
+    }
+    //printf("]\n");
+    printf("TEST %d,%d,%d noise @ %fdB\n",N,bin1,bin2,10*log10(noisepow/sigpow +1e-20) );
+
+    return(0);
+}
+
+
+int main(int argc,char ** argv)
+{
+    int nfft = 16;
+    int i,j;
+    for (i=0;i<nfft/2;++i) { 
+        for (j=i;j<nfft/2;++j) {
+            fe_fft_test(nfft,i,j);
+        }
+    }
+    printf("sizeof(kiss_fft_scalar) = %d\n",sizeof(kiss_fft_scalar) );
+
+    return 0;
+}