1/* mpfr_ui_sub -- subtract a floating-point number from an integer 2 3Copyright 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc. 4Contributed by the Arenaire and Cacao 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#define MPFR_NEED_LONGLONG_H 24#include "mpfr-impl.h" 25 26int 27mpfr_ui_sub (mpfr_ptr y, unsigned long int u, mpfr_srcptr x, mpfr_rnd_t rnd_mode) 28{ 29 mpfr_t uu; 30 mp_limb_t up[1]; 31 unsigned long cnt; 32 33 if (MPFR_UNLIKELY (u == 0)) 34 return mpfr_neg (y, x, rnd_mode); 35 36 if (MPFR_UNLIKELY(MPFR_IS_SINGULAR(x))) 37 { 38 if (MPFR_IS_NAN(x)) 39 { 40 MPFR_SET_NAN(y); 41 MPFR_RET_NAN; 42 } 43 else if (MPFR_IS_INF(x)) 44 { 45 /* u - Inf = -Inf and u - -Inf = +Inf */ 46 MPFR_SET_INF(y); 47 MPFR_SET_OPPOSITE_SIGN(y,x); 48 MPFR_RET(0); /* +/-infinity is exact */ 49 } 50 else /* x is zero */ 51 /* u - 0 = u */ 52 return mpfr_set_ui(y, u, rnd_mode); 53 } 54 else 55 { 56 MPFR_TMP_INIT1 (up, uu, GMP_NUMB_BITS); 57 MPFR_ASSERTN(u == (mp_limb_t) u); 58 count_leading_zeros (cnt, (mp_limb_t) u); 59 *up = (mp_limb_t) u << cnt; 60 MPFR_SET_EXP (uu, GMP_NUMB_BITS - cnt); 61 return mpfr_sub (y, uu, x, rnd_mode); 62 } 63} 64