Use of MPFR_UNLIKELY and MPFR_IS_SINGULAR for fast detection of special values (Nan, Inf or Zero).

Start to encapsulate the sign to be independant of the reprensation (Must be 1 or -1).


git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@2525 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 17 insertions, 14 deletions

diff --git a/acos.c b/acos.c
index 093734b65..74b95af54 100644
--- a/acos.c
+++ b/acos.c
@@ -40,11 +40,22 @@ mpfr_acos (mpfr_ptr acos, mpfr_srcptr x, mp_rnd_t rnd_mode)
   int compared;
   int inexact = 0;
 
-  /* Trivial cases */
-  if (MPFR_IS_NAN(x) || MPFR_IS_INF(x))
+  /* Special cases */
+  if (MPFR_UNLIKELY( MPFR_IS_SINGULAR(x) ))
     {
-      MPFR_SET_NAN(acos);
-      MPFR_RET_NAN;
+      if (MPFR_IS_NAN(x) || MPFR_IS_INF(x))
+	{
+	  MPFR_SET_NAN(acos);
+	  MPFR_RET_NAN;
+	}
+      else if (MPFR_IS_ZERO(x))
+	{
+	  /* acos(0)=Pi/2 */
+	  mpfr_const_pi (acos, rnd_mode);
+	  MPFR_SET_EXP (acos, MPFR_GET_EXP (acos) - 1);
+	  return 1; /* inexact */
+	}
+      MPFR_ASSERTN(1);
     }
 
   /* Set x_p=|x| */
@@ -64,7 +75,7 @@ mpfr_acos (mpfr_ptr acos, mpfr_srcptr x, mp_rnd_t rnd_mode)
   if (compared == 0)
     {
       mpfr_clear (xp);
-      if (signe > 0) /* acos(+1) = 0 */
+      if (MPFR_IS_POS_SIGN(signe)) /* acos(+1) = 0 */
 	return mpfr_set_ui (acos, 0, rnd_mode);
       else /* acos(-1) = Pi */
         {
@@ -73,18 +84,10 @@ mpfr_acos (mpfr_ptr acos, mpfr_srcptr x, mp_rnd_t rnd_mode)
         }
     }
 
-  if (MPFR_IS_ZERO(x)) /* acos(0)=Pi/2 */
-    {
-      mpfr_clear (xp);
-      mpfr_const_pi (acos, rnd_mode);
-      MPFR_SET_EXP (acos, MPFR_GET_EXP (acos) - 1);
-      return 1; /* inexact */
-    }
-
   prec_acos = MPFR_PREC(acos);
   mpfr_ui_sub (xp, 1, xp, GMP_RNDD);
 
-  if (signe > 0)
+  if (MPFR_IS_POS_SIGN(signe))
     supplement = 2 - 2 * MPFR_GET_EXP (xp);
   else
     supplement = 2 - MPFR_GET_EXP(xp);