deal with overflow/underflow in mpfr_div

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@2734 280ebfd0-de03-0410-8827-d642c229c3f4

3 files changed, 17 insertions, 3 deletions

diff --git a/div.c b/div.c
index 4f5c9db5e..1ccfae8f7 100644
--- a/div.c
+++ b/div.c
@@ -444,7 +444,19 @@ mpfr_div (mpfr_ptr q, mpfr_srcptr u, mpfr_srcptr v, mp_rnd_t rnd_mode)
   TMP_FREE (marker);
 
   MPFR_MANT(q)[0] &= ~((MPFR_LIMB_ONE << rw) - MPFR_LIMB_ONE);
-  MPFR_SET_EXP (q, qexp);
+  MPFR_EXP(q) = qexp;
+
+  /* check for underflow/overflow */
+
+  if (MPFR_UNLIKELY(qexp > __gmpfr_emax))
+    inex = mpfr_set_overflow (q, rnd_mode, sign_quotient);
+  else if (MPFR_UNLIKELY(qexp < __gmpfr_emin))
+    {
+      if (rnd_mode == GMP_RNDN && ((qexp < __gmpfr_emin - 1) ||
+                                   (inex == 0 && mpfr_powerof2_raw (q))))
+        rnd_mode = GMP_RNDZ;
+      inex = mpfr_set_underflow (q, rnd_mode, sign_quotient);
+    }
 
   MPFR_RET(inex);
 }
diff --git a/set_d.c b/set_d.c
index 4db207a2d..713326cdc 100644
--- a/set_d.c
+++ b/set_d.c
@@ -206,6 +206,8 @@ mpfr_set_d (mpfr_ptr r, double d, mp_rnd_t rnd_mode)
 
   /* now d is neither 0, nor NaN nor Inf */
 
+  mpfr_save_emin_emax ();
+
   /* warning: don't use tmp=r here, even if SIZE(r) >= MPFR_LIMBS_PER_DOUBLE,
      since PREC(r) may be different from PREC(tmp), and then both variables
      would have same precision in the mpfr_set4 call below. */
@@ -253,5 +255,7 @@ mpfr_set_d (mpfr_ptr r, double d, mp_rnd_t rnd_mode)
   /* tmp is exact since PREC(tmp)=53 */
   inexact = mpfr_set4 (r, tmp, rnd_mode, signd);
 
+  mpfr_restore_emin_emax ();
+
   return mpfr_check_range (r, inexact, rnd_mode);
 }
diff --git a/set_q.c b/set_q.c
index 54cc4a9fd..a8b58b33e 100644
--- a/set_q.c
+++ b/set_q.c
@@ -46,7 +46,6 @@ mpfr_set_q (mpfr_ptr f, mpq_srcptr q, mp_rnd_t rnd)
   if (prec < MPFR_PREC_MIN)
     prec = MPFR_PREC_MIN;
   mpfr_init2 (n, prec);
-  __gmpfr_emax = prec;
   MPFR_ASSERTN(mpfr_set_z (n, num, GMP_RNDZ) == 0);
   /* result is exact: overflow cannot occur since emax = prec */
 
@@ -54,7 +53,6 @@ mpfr_set_q (mpfr_ptr f, mpq_srcptr q, mp_rnd_t rnd)
   if (prec < MPFR_PREC_MIN)
     prec = MPFR_PREC_MIN;
   mpfr_init2 (d, prec);
-  __gmpfr_emax = prec;
   MPFR_ASSERTN(mpfr_set_z (d, den, GMP_RNDZ) == 0);
   /* result is exact: overflow cannot occur, as above */