1 /* mpfr_mul_2ui -- multiply a floating-point number by a power of two
3 Copyright 1999, 2001-2015 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. */
23 #include "mpfr-impl.h"
26 mpfr_mul_2ui (mpfr_ptr y
, mpfr_srcptr x
, unsigned long int n
, mpfr_rnd_t rnd_mode
)
31 (("x[%Pu]=%.*Rg n=%lu rnd=%d",
32 mpfr_get_prec (x
), mpfr_log_prec
, x
, n
, rnd_mode
),
33 ("y[%Pu]=%.*Rg inexact=%d",
34 mpfr_get_prec (y
), mpfr_log_prec
, y
, inexact
));
36 inexact
= MPFR_UNLIKELY(y
!= x
) ? mpfr_set (y
, x
, rnd_mode
) : 0;
38 if (MPFR_LIKELY( MPFR_IS_PURE_FP(y
)) )
40 /* n will have to be casted to long to make sure that the addition
41 and subtraction below (for overflow detection) are signed */
42 while (MPFR_UNLIKELY(n
> LONG_MAX
))
47 inex2
= mpfr_mul_2ui(y
, y
, LONG_MAX
, rnd_mode
);
49 return inex2
; /* overflow */
52 /* MPFR_EMIN_MIN + (long) n is signed and doesn't lead to an overflow;
53 the first test useful so that the real test can't lead to an
56 mpfr_exp_t exp
= MPFR_GET_EXP (y
);
57 if (MPFR_UNLIKELY( __gmpfr_emax
< MPFR_EMIN_MIN
+ (long) n
||
58 exp
> __gmpfr_emax
- (long) n
))
59 return mpfr_overflow (y
, rnd_mode
, MPFR_SIGN(y
));
61 MPFR_SET_EXP (y
, exp
+ (long) n
);