[src/rem1.c]

  * Portability fix: when mpfr_exp_t <= long (which is the default),
    an addition was done in unsigned integer arithmetic instead of
    signed integer arithmetic, with a conversion back to a signed
    type, i.e. with potentially implementation-defined behavior.
    There could also be an integer overflow on huge-precision values
    if mp_bitcnt_t > unsigned long.
  * Updated a comment.

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@13793 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 4 insertions, 2 deletions

diff --git a/src/rem1.c b/src/rem1.c
index 1870b4ed3..9e75e4287 100644
--- a/src/rem1.c
+++ b/src/rem1.c
@@ -100,9 +100,11 @@ mpfr_rem1 (mpfr_ptr rem, long *quo, mpfr_rnd_t rnd_q,
   mpz_abs (my, my);
   q_is_odd = 0;
 
-  /* divide my by 2^k if possible to make operations mod my easier */
+  /* Divide my by 2^k if possible to make operations mod my easier.
+     Since my comes from a regular MPFR number, due to the constraints on the
+     exponent and the precision, there can be no integer overflow below. */
   {
-    unsigned long k = mpz_scan1 (my, 0);
+    mpfr_exp_t k = mpz_scan1 (my, 0);
     ey += k;
     mpz_fdiv_q_2exp (my, my, k);
   }