check overflow

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@1356 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 4 insertions, 0 deletions

diff --git a/add.c b/add.c
index c4f91398e..c4b982d11 100644
--- a/add.c
+++ b/add.c
@@ -351,6 +351,10 @@ mpfr_add1 (a, b, c, rnd_mode, diff_exp)
 
       /* shift one bit to the right */
 
+      /* first check overflow */
+      if (MPFR_EXP(a) == __mpfr_emax)
+	return mpfr_set_overflow (a, rnd_mode, MPFR_SIGN(a));
+
       c3 = (ap[0]&1) && (MPFR_PREC(a)%BITS_PER_MP_LIMB==0);
       mpn_rshift(ap, ap, an, 1);
       ap[an-1] += MP_LIMB_T_HIGHBIT;