[src] Fixed the behavior of the mpfr_get_* functions in a very reduced

exponent range.
(merged changesets r11770,11774,11775,11777 and r11779 manually from
the trunk)

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/branches/3.1@11783 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 17 insertions, 10 deletions

diff --git a/src/get_sj.c b/src/get_sj.c
index 5e92199d0..f270f375c 100644
--- a/src/get_sj.c
+++ b/src/get_sj.c
@@ -35,6 +35,7 @@ mpfr_get_sj (mpfr_srcptr f, mpfr_rnd_t rnd)
   intmax_t r;
   mpfr_prec_t prec;
   mpfr_t x;
+  MPFR_SAVE_EXPO_DECL (expo);
 
   if (MPFR_UNLIKELY (!mpfr_fits_intmax_p (f, rnd)))
     {
@@ -46,20 +47,24 @@ mpfr_get_sj (mpfr_srcptr f, mpfr_rnd_t rnd)
   if (MPFR_IS_ZERO (f))
      return (intmax_t) 0;
 
-  /* determine the precision of intmax_t */
-  for (r = MPFR_INTMAX_MIN, prec = 0; r != 0; r /= 2, prec++)
+  /* Determine the precision of intmax_t. |INTMAX_MIN| may have one
+     more bit as an integer, but in this case, this is a power of 2,
+     thus fits in a precision-prec floating-point number. */
+  for (r = MPFR_INTMAX_MAX, prec = 0; r != 0; r /= 2, prec++)
     { }
-  /* Note: though INTMAX_MAX would have been sufficient for the conversion,
-     we chose INTMAX_MIN so that INTMAX_MIN - 1 is always representable in
-     precision prec; this is useful to detect overflows in MPFR_RNDZ (will
-     be needed later). */
 
-  /* Now, r = 0. */
+  MPFR_ASSERTD (r == 0);
+
+  MPFR_SAVE_EXPO_MARK (expo);
 
   mpfr_init2 (x, prec);
   mpfr_rint (x, f, rnd);
   MPFR_ASSERTN (MPFR_IS_FP (x));
 
+  /* The flags from mpfr_rint are the wanted ones. In particular,
+     it sets the inexact flag when necessary. */
+  MPFR_SAVE_EXPO_UPDATE_FLAGS (expo, __gmpfr_flags);
+
   if (MPFR_NOTZERO (x))
     {
       mp_limb_t *xp;
@@ -67,15 +72,15 @@ mpfr_get_sj (mpfr_srcptr f, mpfr_rnd_t rnd)
 
       xp = MPFR_MANT (x);
       sh = MPFR_GET_EXP (x);
-      MPFR_ASSERTN ((mpfr_prec_t) sh <= prec);
+      MPFR_ASSERTN ((mpfr_prec_t) sh <= prec + 1);
       if (MPFR_INTMAX_MIN + MPFR_INTMAX_MAX != 0
-          && MPFR_UNLIKELY ((mpfr_prec_t) sh == prec))
+          && MPFR_UNLIKELY ((mpfr_prec_t) sh > prec))
         {
           /* 2's complement and x <= INTMAX_MIN: in the case mp_limb_t
              has the same size as intmax_t, we cannot use the code in
              the for loop since the operations would be performed in
              unsigned arithmetic. */
-          MPFR_ASSERTN (MPFR_IS_NEG (x) && (mpfr_powerof2_raw (x)));
+          MPFR_ASSERTN (MPFR_IS_NEG (x) && mpfr_powerof2_raw (x));
           r = MPFR_INTMAX_MIN;
         }
       else if (MPFR_IS_POS (x))
@@ -117,6 +122,8 @@ mpfr_get_sj (mpfr_srcptr f, mpfr_rnd_t rnd)
 
   mpfr_clear (x);
 
+  MPFR_SAVE_EXPO_FREE (expo);
+
   return r;
 }