Diff: main.cpp

Revision:

0:90ade34a3b71

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sun Dec 13 07:14:57 2009 +0000
@@ -0,0 +1,73 @@
+#include "mbed.h"
+#include <limits.h>
+
+DigitalOut myled(LED1);
+LocalFileSystem local("local");
+
+// code from FFTCM3.s by Ivan Mellen
+// http://www.luminarymicro.com/component/option,com_joomlaboard/Itemid,92/func,view/id,1636/catid,6/
+extern "C" void fftR4(short *y, short *x, int N);
+extern "C" void ifftR4(short *y, short *x, int N);
+
+// code from STM32 DSP Library
+/* 64 points*/
+extern "C" void cr4_fft_64_stm32(void *pssOUT, void *pssIN, uint16_t Nbin);
+/* 256 points */
+extern "C" void cr4_fft_256_stm32(void *pssOUT, void *pssIN, uint16_t Nbin);
+/* 1024 points */
+extern "C" void cr4_fft_1024_stm32(void *pssOUT, void *pssIN, uint16_t Nbin);
+
+void test_stm32()
+{
+#define N 64 /*Number of points*/
+    uint32_t x[N], y[N]; /* input and output arrays */
+    int16_t real[N], imag[N]; /* real and imaginary arrays */
+    memset(real, 0, sizeof(real));
+    memset(imag, 0, sizeof(imag));
+    real[1]=SHRT_MAX;
+    /* Fill the input array */
+    for (int i=0; i<N; i++)
+    {
+        x[i] = (((uint16_t)(real[i])) | ((uint32_t)(imag[i]<<16)));
+    }
+    cr4_fft_64_stm32(y, x, N); /*computes the FFT of the x[N] samples*/
+    FILE* log = fopen("/local/stm32.txt","w");
+    for (int i=0; i<N; i++)
+    {
+        fprintf(log, "%d: %d, %d -> %d, %d\n", i, real[i], imag[i], int16_t(y[i] & 0xFFFF), int16_t(y[i] >> 16));
+    }
+    fclose(log);    
+}
+
+void test_mellen()
+{
+    short x[512]; // input data 16 bit, 4 byte aligned  x0r,x0i,x1r,x1i,....
+    short y[512]; // output data 16 bit,4 byte aligned  y0r,y0i,y1r,y1i,....
+    short z[512]; // same format...
+    
+    for (int i=0;i<512;i++) x[i]=0;
+    for (int i=0;i<512;i=i+8)
+      { x[i+0]=16384; x[i+2]=16384;    x[i+4]=-16384;  x[i+6]=-16384;}
+    // x = [ 16384,16384,-16384,-16384,16384,...]  1/4 Fsampling
+    
+    //call functions
+    fftR4(y, x, 256);   // y is in frequency domain y[128]=
+    printf("fftR4 ok\n");
+    ifftR4(z, y, 256);  // z should be x/N + noise introduced by 16 bit truncating 
+    printf("ifftR4 ok\n");
+    FILE* log = fopen("/local/mellen.txt","w");
+    for (int i=0; i<256; i++)
+    {
+        fprintf(log, "%d: %d -> %d -> %d\n", i, x[i], y[i], z[i]);
+    }
+    fclose(log);    
+}
+
+int main()
+{
+    printf("Testing Mellen\n");
+    test_mellen();
+    printf("Testing STM32\n");
+    test_stm32();
+    printf("Done\n");
+}