diff options
Diffstat (limited to 'mpfr/sub_ui.c')
| -rw-r--r-- | mpfr/sub_ui.c | 44 |
1 files changed, 23 insertions, 21 deletions
diff --git a/mpfr/sub_ui.c b/mpfr/sub_ui.c index 4b64caff7..cb18307d0 100644 --- a/mpfr/sub_ui.c +++ b/mpfr/sub_ui.c @@ -1,20 +1,20 @@ /* mpfr_sub_ui -- subtract a floating-point number and a machine integer -Copyright (C) 2000 Free Software Foundation. +Copyright (C) 2000, 2001 Free Software Foundation, Inc. This file is part of the MPFR Library. The MPFR Library is free software; you can redistribute it and/or modify -it under the terms of the GNU Library General Public License as published by -the Free Software Foundation; either version 2 of the License, or (at your +it under the terms of the GNU Lesser General Public License as published by +the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The MPFR Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public +or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. -You should have received a copy of the GNU Library General Public License +You should have received a copy of the GNU Lesser General Public License along with the MPFR Library; see the file COPYING.LIB. If not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ @@ -26,29 +26,31 @@ MA 02111-1307, USA. */ #include "mpfr.h" #include "mpfr-impl.h" -void -#if __STDC__ +int mpfr_sub_ui (mpfr_ptr y, mpfr_srcptr x, unsigned long int u, mp_rnd_t rnd_mode) -#else -mpfr_sub_ui (y, x, u, rnd_mode) - mpfr_ptr y; - mpfr_srcptr x; - unsigned long int u; - mp_rnd_t rnd_mode; -#endif { - mpfr_t uu; - mp_limb_t up[1]; - unsigned long cnt; + if (u) /* if u=0, do nothing */ + { + mpfr_t uu; + mp_limb_t up[1]; + unsigned long cnt; + int inex_sub, inex_cr; - if (u) { /* if u=0, do nothing */ MPFR_INIT1(up, uu, BITS_PER_MP_LIMB, 1); count_leading_zeros(cnt, (mp_limb_t) u); *up = (mp_limb_t) u << cnt; MPFR_EXP(uu) = BITS_PER_MP_LIMB-cnt; - - mpfr_sub (y, x, uu, rnd_mode); + + /* Optimization note: Exponent operations may be removed + if mpfr_add works even when uu is out-of-range. */ + mpfr_save_emin_emax(); + inex_sub = mpfr_sub (y, x, uu, rnd_mode); + mpfr_restore_emin_emax(); + inex_cr = mpfr_check_range(y, rnd_mode); + if (inex_cr) + return inex_cr; /* underflow or overflow */ + MPFR_RET(inex_sub); } else - mpfr_set (y, x, rnd_mode); + return mpfr_set (y, x, rnd_mode); } |