RNDF: fixed the fits functions

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/branches/faithful@10428 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 9 insertions, 3 deletions

diff --git a/src/fits_s.h b/src/fits_s.h
index c639fbb12..5e87ae10b 100644
--- a/src/fits_s.h
+++ b/src/fits_s.h
@@ -37,12 +37,14 @@ FUNCTION (mpfr_srcptr f, mpfr_rnd_t rnd)
   int res;
 
   if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (f)))
-    /* Zero always fit */
-    return MPFR_IS_ZERO (f) ? 1 : 0;
+    /* Zero always fit, except for RNDF, since 0 might be rounded to -1 */
+    return MPFR_IS_ZERO (f) ? (rnd != MPFR_RNDF) : 0;
 
   /* now it fits if either
      (a) MINIMUM <= f <= MAXIMUM
-     (b) or MINIMUM <= round(f, prec(slong), rnd) <= MAXIMUM */
+     (b) or MINIMUM <= round(f, prec(slong), rnd) <= MAXIMUM
+     except or rnd = RNDF: when f = MINIMUM or MAXIMUM, it might be
+     rounded to MINIMUM-1 or MAXIMUM+1 */
 
   e = MPFR_GET_EXP (f);
   if (e < 1)
@@ -91,6 +93,10 @@ FUNCTION (mpfr_srcptr f, mpfr_rnd_t rnd)
      that the number does not fit. That's why we use MPFR_EXP, not
      MPFR_GET_EXP. */
   res = neg ? (mpfr_cmp_si (x, MINIMUM) >= 0) : (MPFR_EXP (x) == e);
+  /* special case for RNDF and x = MINIMUM or MAXIMUM */
+  if (MPFR_UNLIKELY(rnd == MPFR_RNDF && (mpfr_cmp_si (x, MINIMUM) == 0 ||
+                                         mpfr_cmp_si (x, MAXIMUM) == 0)))
+      res = 0;
   mpfr_clear (x);
   __gmpfr_flags = saved_flags;
   return res;