[src/div.c] fixed bug in mpfr_div2_approx()

[tests/tdiv.c] added non-regression test
[tests/ttan.c] added test triggering bug in mpfr_div2_approx()


git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@12002 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 2 insertions, 1 deletions

diff --git a/src/div.c b/src/div.c
index 3ef62b6d5..7d208621f 100644
--- a/src/div.c
+++ b/src/div.c
@@ -71,7 +71,8 @@ mpfr_div2_approx (mpfr_limb_ptr Q1, mpfr_limb_ptr Q0,
 
   /* we ignore yy below, but first increment r0, to ensure we get a lower
      approximation of the remainder */
-  r0 += (yy != 0);
+  r0 += yy != 0;
+  r1 += r0 == 0 && yy != 0;
   r0 = u0 - r0;
   r1 = u1 - r1 - (r0 > u0);