1 /* mpfr_sub_ui -- subtract a floating-point number and a machine integer
3 Copyright 2000-2015 Free Software Foundation, Inc.
4 Contributed by the AriC 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. */
24 #define MPFR_NEED_LONGLONG_H
25 #include "mpfr-impl.h"
28 mpfr_sub_ui (mpfr_ptr y
, mpfr_srcptr x
, unsigned long int u
, mpfr_rnd_t rnd_mode
)
30 if (MPFR_LIKELY (u
!= 0)) /* if u=0, do nothing */
37 MPFR_SAVE_EXPO_DECL (expo
);
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
));
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
;
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
);
59 return mpfr_set (y
, x
, rnd_mode
);