common subexpression

1 files changed, 5 insertions, 2 deletions

diff --git a/fft.c b/fft.c
index 3f4c6fe..b8af1f4 100644
--- a/fft.c
+++ b/fft.c
@@ -8,6 +8,7 @@ do_fft (complex_t *buffer, int n, complex_t principal)
 {
     complex_t *temp, *even, *odd;
     complex_t alpha;
+    complex_t p2;
     int i;
     
     if (n == 1)
@@ -23,8 +24,10 @@ do_fft (complex_t *buffer, int n, complex_t principal)
 	odd[i] = buffer[2 * i + 1];
     }
 
-    do_fft (even, n/2, complex_mul (principal, principal));
-    do_fft (odd, n/2, complex_mul (principal, principal));
+    p2 = complex_mul (principal, principal);
+    
+    do_fft (even, n/2, p2);
+    do_fft (odd, n/2, p2);
 
     alpha.re = 1.0;
     alpha.im = 0;