1 /* mpfr_scale2 -- multiply a double float by 2^exp
3 Copyright 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 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 <float.h> /* for DBL_EPSILON */
24 #include "mpfr-impl.h"
26 /* Note: we could use the ldexp function, but since we want not to depend on
27 math.h, we write our own implementation. */
29 /* multiplies 1/2 <= d <= 1 by 2^exp */
31 mpfr_scale2 (double d
, int exp
)
35 union ieee_double_extract x
;
37 if (MPFR_UNLIKELY (d
== 1.0))
43 /* now 1/2 <= d < 1 */
45 /* infinities and zeroes have already been checked */
46 MPFR_ASSERTD (-1073 <= exp
&& exp
<= 1025);
49 if (MPFR_UNLIKELY (exp
< -1021)) /* subnormal case */
54 else /* normalized case */
60 #else /* _GMP_IEEE_FLOATS */
64 /* An overflow may occurs (example: 0.5*2^1024) */
70 /* Now 1.0 <= d < 2.0 */