1/* mpfr_sub_ui -- subtract a floating-point number and a machine integer 2 3Copyright 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Free Software Foundation, Inc. 4Contributed by the AriC and Caramel projects, INRIA. 5 6This file is part of the GNU MPFR Library. 7 8The GNU MPFR Library is free software; you can redistribute it and/or modify 9it under the terms of the GNU Lesser General Public License as published by 10the Free Software Foundation; either version 3 of the License, or (at your 11option) any later version. 12 13The GNU MPFR Library is distributed in the hope that it will be useful, but 14WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 15or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 16License for more details. 17 18You should have received a copy of the GNU Lesser General Public License 19along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see 20http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc., 2151 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */ 22 23 24#define MPFR_NEED_LONGLONG_H 25#include "mpfr-impl.h" 26 27int 28mpfr_sub_ui (mpfr_ptr y, mpfr_srcptr x, unsigned long int u, mpfr_rnd_t rnd_mode) 29{ 30 if (MPFR_LIKELY (u != 0)) /* if u=0, do nothing */ 31 { 32 mpfr_t uu; 33 mp_limb_t up[1]; 34 unsigned long cnt; 35 int inex; 36 37 MPFR_SAVE_EXPO_DECL (expo); 38 39 MPFR_LOG_FUNC 40 (("x[%Pu]=%.*Rg u=%lu rnd=%d", 41 mpfr_get_prec(x), mpfr_log_prec, x, u, rnd_mode), 42 ("y[%Pu]=%.*Rg inexact=%d", 43 mpfr_get_prec(y), mpfr_log_prec, y, inex)); 44 45 MPFR_TMP_INIT1 (up, uu, GMP_NUMB_BITS); 46 MPFR_ASSERTN (u == (mp_limb_t) u); 47 count_leading_zeros (cnt, (mp_limb_t) u); 48 *up = (mp_limb_t) u << cnt; 49 50 /* Optimization note: Exponent save/restore operations may be 51 removed if mpfr_sub works even when uu is out-of-range. */ 52 MPFR_SAVE_EXPO_MARK (expo); 53 MPFR_SET_EXP (uu, GMP_NUMB_BITS - cnt); 54 inex = mpfr_sub (y, x, uu, rnd_mode); 55 MPFR_SAVE_EXPO_FREE (expo); 56 return mpfr_check_range (y, inex, rnd_mode); 57 } 58 else 59 return mpfr_set (y, x, rnd_mode); 60} 61