From 6a2da610b91aa35bc66c8fc5f6206910c33bc02b Mon Sep 17 00:00:00 2001 From: vlefevre Date: Fri, 12 Jun 2015 13:27:00 +0000 Subject: [src/fma.c] Completely fixed the scaling in case of underflow. git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@9569 280ebfd0-de03-0410-8827-d642c229c3f4 --- src/fma.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'src/fma.c') diff --git a/src/fma.c b/src/fma.c index 297fe1355..33272125a 100644 --- a/src/fma.c +++ b/src/fma.c @@ -281,6 +281,7 @@ mpfr_fma (mpfr_ptr s, mpfr_srcptr x, mpfr_srcptr y, mpfr_srcptr z, MPFR_BLOCK_DECL (flags); MPFR_BLOCK (flags, inexact = mpfr_add (s, u, new_z, rnd_mode)); + MPFR_LOG_MSG (("inexact=%d\n", inexact)); MPFR_GROUP_CLEAR (group); if (scale != 0) { @@ -292,9 +293,15 @@ mpfr_fma (mpfr_ptr s, mpfr_srcptr x, mpfr_srcptr y, mpfr_srcptr z, is not possible, but let's check that anyway. */ MPFR_ASSERTN (! MPFR_OVERFLOW (flags)); /* TODO... */ MPFR_ASSERTN (! MPFR_UNDERFLOW (flags)); /* not possible */ + if (rnd_mode == MPFR_RNDN && + MPFR_GET_EXP (s) == __gmpfr_emin - 1 + scale && + mpfr_powerof2_raw (s)) + { + MPFR_LOG_MSG (("Double rounding\n", 0)); + rnd_mode = (MPFR_IS_NEG (s) ? inexact <= 0 : inexact >= 0) + ? MPFR_RNDZ : MPFR_RNDA; + } inex2 = mpfr_div_2ui (s, s, scale, rnd_mode); - /* FIXME: Handle the double rounding case: - s / 2^scale = 2^(emin - 2) in MPFR_RNDN. */ MPFR_LOG_MSG (("inex2=%d\n", inex2)); if (inex2) /* underflow */ inexact = inex2; -- cgit v1.2.1