Add Fast case for u==1

Add Fast case for u a power of 2 (Call mul/div_2si).


git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@3650 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 3 insertions, 1 deletions

diff --git a/mul_ui.c b/mul_ui.c
index e9b595d49..ff5b7f797 100644
--- a/mul_ui.c
+++ b/mul_ui.c
@@ -63,7 +63,7 @@ mpfr_mul_ui (mpfr_ptr y, mpfr_srcptr x, unsigned long int u, mp_rnd_t rnd_mode)
     }
   else if (MPFR_UNLIKELY (u <= 1))
     {
-      if (u == 0)
+      if (u < 1)
 	{
 	  MPFR_SET_ZERO (y);
 	  MPFR_SET_SAME_SIGN (y, x);
@@ -72,6 +72,8 @@ mpfr_mul_ui (mpfr_ptr y, mpfr_srcptr x, unsigned long int u, mp_rnd_t rnd_mode)
       else
 	return mpfr_set (y, x, rnd_mode);
     }
+  else if (MPFR_UNLIKELY (IS_POW2 (u)))
+    return mpfr_mul_2si (y, x, MPFR_INT_CEIL_LOG2 (u)-1, rnd_mode);
 
   yp = MPFR_MANT (y);
   yn = MPFR_LIMB_SIZE (y);