check apart the case c=0 (otherwise some low significant limbs may be

non zero, which may produce a wrong result)


git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@1070 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 4 insertions, 0 deletions

diff --git a/cmp2.c b/cmp2.c
index aeb8f7c78..33d2b0cc9 100644
--- a/cmp2.c
+++ b/cmp2.c
@@ -30,6 +30,8 @@ MA 02111-1307, USA. */
    Assumes b>=c, which implies MPFR_EXP(b)>=MPFR_EXP(c).
    if b=c, returns prec(b).
 
+   Assumes neither of b or c is NaN or +/- infinity.
+
    In other terms mpfr_cmp2 (b, c) returns EXP(b) - EXP(b-c).
 */
 unsigned long
@@ -39,6 +41,8 @@ mpfr_cmp2 (mpfr_srcptr b, mpfr_srcptr c)
   long bn, cn, z;
   unsigned long diff_exp, res = 0;
 
+  if (MPFR_IS_ZERO(c)) return 0;
+
   bp = MPFR_MANT(b);
   cp = MPFR_MANT(c);