1 /* mpfr_ui_sub -- subtract a floating-point number from an integer
3 Copyright 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
4 Contributed by the Arenaire and Caramel projects, INRIA.
6 This file is part of the GNU MPFR Library.
8 The GNU MPFR Library is free software; you can redistribute it and/or modify
9 it under the terms of the GNU Lesser General Public License as published by
10 the Free Software Foundation; either version 3 of the License, or (at your
11 option) any later version.
13 The GNU MPFR Library is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
16 License for more details.
18 You should have received a copy of the GNU Lesser General Public License
19 along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see
20 http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
21 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
23 #define MPFR_NEED_LONGLONG_H
24 #include "mpfr-impl.h"
27 mpfr_ui_sub (mpfr_ptr y, unsigned long int u, mpfr_srcptr x, mpfr_rnd_t rnd_mode)
34 (("u=%lu x[%Pu]=%.*Rg rnd=%d",
35 u, mpfr_get_prec(x), mpfr_log_prec, x, rnd_mode),
36 ("y[%Pu]=%.*Rg", mpfr_get_prec(y), mpfr_log_prec, y));
38 if (MPFR_UNLIKELY (u == 0))
39 return mpfr_neg (y, x, rnd_mode);
41 if (MPFR_UNLIKELY(MPFR_IS_SINGULAR(x)))
48 else if (MPFR_IS_INF(x))
50 /* u - Inf = -Inf and u - -Inf = +Inf */
52 MPFR_SET_OPPOSITE_SIGN(y,x);
53 MPFR_RET(0); /* +/-infinity is exact */
57 return mpfr_set_ui(y, u, rnd_mode);
61 MPFR_TMP_INIT1 (up, uu, GMP_NUMB_BITS);
62 MPFR_ASSERTN(u == (mp_limb_t) u);
63 count_leading_zeros (cnt, (mp_limb_t) u);
64 *up = (mp_limb_t) u << cnt;
65 MPFR_SET_EXP (uu, GMP_NUMB_BITS - cnt);
66 return mpfr_sub (y, uu, x, rnd_mode);