[MN-dev] [mndiff]: r209 - trunk/noe/gfft.c

[michael]

Author: michael
Date: Fri Jul 23 00:20:19 2010
New Revision: 209

Log:
Optimize ifft4() in line of fft4()

Modified:
   trunk/noe/gfft.c

Modified: trunk/noe/gfft.c
==============================================================================
--- trunk/noe/gfft.c	Mon Jul 19 17:23:53 2010	(r208)
+++ trunk/noe/gfft.c	Fri Jul 23 00:20:19 2010	(r209)
@@ -225,14 +225,16 @@ static inline void ifft2(GFF4Element *p)
 static inline void ifft4(GFF4Element *p){
     unsigned int a,b,c,d;
 
-    a= p[0] + p[1];
-    b= p[0] - p[1] + SIZE + (SIZE<<(SHIFT/2));
+    d= p[0] + SIZE*(SIZE/2ULL);
+
+    a= d + p[1];
+    b= d - p[1];
     c= p[2] + p[3];
     d=(p[2] - p[3])<<(SHIFT/2);
 
     p[0]= reduce(a+c);
+    p[2]= reduce(a-c);
     p[1]= reduce(b+d);
-    p[2]= reduce(a-c + 2*SIZE);
     p[3]= reduce(b-d);
 }