1 /* mpfr_mul_2ui -- multiply a floating-point number by a power of two
2
3 Copyright 1999, 2001-2023 Free Software Foundation, Inc.
4 Contributed by the AriC and Caramba projects, INRIA.
5
6 This file is part of the GNU MPFR Library.
7
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.
12
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.
17
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 https://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
21 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
22
23 #include "mpfr-impl.h"
24
25 int
mpfr_mul_2ui(mpfr_ptr y,mpfr_srcptr x,unsigned long int n,mpfr_rnd_t rnd_mode)26 mpfr_mul_2ui (mpfr_ptr y, mpfr_srcptr x, unsigned long int n, mpfr_rnd_t rnd_mode)
27 {
28 int inexact;
29
30 MPFR_LOG_FUNC
31 (("x[%Pd]=%.*Rg n=%lu rnd=%d",
32 mpfr_get_prec (x), mpfr_log_prec, x, n, rnd_mode),
33 ("y[%Pd]=%.*Rg inexact=%d",
34 mpfr_get_prec (y), mpfr_log_prec, y, inexact));
35
36 inexact = (y != x) ? mpfr_set (y, x, rnd_mode) : 0;
37
38 if (MPFR_LIKELY (MPFR_IS_PURE_FP (y)))
39 {
40 mpfr_exp_t exp = MPFR_GET_EXP (y);
41 mpfr_exp_t diffexp;
42
43 diffexp = __gmpfr_emax - exp; /* diff of two valid exponents */
44 if (MPFR_UNLIKELY (n > diffexp)) /* exp + n > emax */
45 return mpfr_overflow (y, rnd_mode, MPFR_SIGN (y));
46 /* Now, 0 <= n <= diffexp, thus n fits in a mpfr_exp_t,
47 and exp + n <= emax (no integer overflow). */
48 MPFR_SET_EXP (y, exp + (mpfr_exp_t) n);
49 }
50
51 return inexact;
52 }
53