X-Git-Url: http://sraa.de/git/?a=blobdiff_plain;f=dol%2Fexamples%2Fexample5%2Fsrc%2Ffft2.c;fp=dol%2Fexamples%2Fexample5%2Fsrc%2Ffft2.c;h=ec56b825dadf896b7f6f10ad7dd4962d735df423;hb=8c411cf24ed0eb889191aaeafd8fa1e69081df42;hp=0000000000000000000000000000000000000000;hpb=dea7a4fb1ed110d3ce6e6d9255103d724bd66c0e;p=jump.git

diff --git a/dol/examples/example5/src/fft2.c b/dol/examples/example5/src/fft2.c
new file mode 100644
index 0000000..ec56b82
--- /dev/null
+++ b/dol/examples/example5/src/fft2.c
@@ -0,0 +1,75 @@
+#include <stdio.h>
+#include <math.h>
+#include "fft2.h"
+
+/**
+ * Determines the twiddle factor of this 2-point FFT based on the
+ * indices of the process.
+ */
+void fft2_init(DOLProcess *p)
+{
+  const float PI = 2.0 * asin(1.0);
+  int layer_index = GETINDEX(0);
+  int process_index = GETINDEX(1);
+  float exponent = 2.0 * PI *
+          (float)(process_index % (1 << layer_index)) /
+          (float)(1 << (layer_index + 1));
+
+  sprintf(p->local->id, "FFT2_%d_%d",
+          GETINDEX(0),
+          GETINDEX(1));
+  p->local->twiddle_factor.real = cos(exponent);
+  p->local->twiddle_factor.imag = -sin(exponent);
+
+  printf("%15s: twiddle_factor %9f + j * %9f\n",
+          p->local->id,
+          p->local->twiddle_factor.real,
+          p->local->twiddle_factor.imag);
+}
+
+/**
+ * Computes 2-point FFT.
+ */
+int fft2_fire(DOLProcess *p)
+{
+  DOL_read((void*)PORT_INA, &(p->local->inA), sizeof(ComplexNumber), p);
+  DOL_read((void*)PORT_INB, &(p->local->inB), sizeof(ComplexNumber), p);
+
+  p->local->rotated_inB.real = p->local->inB.real
+           * p->local->twiddle_factor.real
+           - p->local->inB.imag
+           * p->local->twiddle_factor.imag ;
+  p->local->rotated_inB.imag = p->local->inB.real
+           * p->local->twiddle_factor.imag
+           + p->local->inB.imag
+           * p->local->twiddle_factor.real;
+
+  p->local->outA.real = p->local->inA.real
+           + p->local->rotated_inB.real;
+  p->local->outA.imag = p->local->inA.imag
+           + p->local->rotated_inB.imag;
+
+  p->local->outB.real = p->local->inA.real
+           - p->local->rotated_inB.real;
+  p->local->outB.imag = p->local->inA.imag
+           - p->local->rotated_inB.imag;
+
+  DOL_write((void*)PORT_OUTA, &(p->local->outA), sizeof(ComplexNumber), p);
+  DOL_write((void*)PORT_OUTB, &(p->local->outB), sizeof(ComplexNumber), p);
+
+  /*
+  printf("%15s: ", p->local->id);
+  printf("%9f + j * %9f, %9f + j * %9f => %9f + j * %9f, %9f + j * %9f\n",
+          p->local->inA.real,
+          p->local->inA.imag,
+          p->local->inB.real,
+          p->local->inB.imag,
+          p->local->outA.real,
+          p->local->outA.imag,
+          p->local->outB.real,
+          p->local->outB.imag);
+  */
+
+  DOL_detach(p);
+  return -1;
+}