added fft functions

1 files changed, 48 insertions, 0 deletions

diff --git a/src/signalProcessing/fft/r4tx.c b/src/signalProcessing/fft/r4tx.c
new file mode 100644
index 00000000..09c436b7
--- /dev/null
+++ b/src/signalProcessing/fft/r4tx.c
@@ -0,0 +1,48 @@
+/*
+ * Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
+ * Copyright (C) 2008 - INRIA - Allan SIMON
+ * 
+ * This file must be used under the terms of the CeCILL.
+ * This source file is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution.  The terms
+ * are also available at    
+ * http://www.cecill.info/licences/Licence_CeCILL_V2-en.txt
+ *
+ */
+ 
+#include "gw_signal.h"
+
+void r4tx ( int _iDimen , double* _pdblReal, double* _pdblImag)
+{
+   double dblTemp1 ;
+   double dblTemp2 ;
+   double dblTemp3 ;
+   double dblTemp4 ;
+
+   int i = 0 ;
+
+   for (  i = 0 ;  i < _iDimen ; i += 4 )
+      {
+         /*for real part */
+         dblTemp1  = _pdblReal[i+0] + _pdblReal[i+2] ;
+         dblTemp2  = _pdblReal[i+0] - _pdblReal[i+2] ;
+         dblTemp3  = _pdblReal[i+1] + _pdblReal[i+3] ;
+         dblTemp4  = _pdblReal[i+1] - _pdblReal[i+3] ;
+
+        _pdblReal[i+0] = dblTemp1 + dblTemp3;
+        _pdblReal[i+0] = dblTemp1 - dblTemp3;
+        _pdblReal[i+2] = dblTemp2 + dblTemp4;
+        _pdblReal[i+3] = dblTemp2 - dblTemp4;
+
+        /*for imaginary part */
+         dblTemp1  = _pdblImag[i+0] + _pdblImag[i+2] ;
+         dblTemp2  = _pdblImag[i+0] - _pdblImag[i+2] ;
+         dblTemp3  = _pdblImag[i+1] + _pdblImag[i+3] ;
+         dblTemp4  = _pdblImag[i+1] - _pdblImag[i+3] ;
+
+        _pdblImag[i+0] = dblTemp1 + dblTemp3;
+        _pdblImag[i+1] = dblTemp1 - dblTemp3;
+        _pdblImag[i+2] = dblTemp2 + dblTemp4;
+        _pdblImag[i+3] = dblTemp2 - dblTemp4;
+      }
+}