1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
|
/* Copyright (C) 1995,1996,1997,2002,2003 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include "gmp.h"
#include "gmp-impl.h"
#include <ieee754.h>
#include <float.h>
/* Convert a multi-precision integer of the needed number of bits (53 for
double) and an integral power of two to a `double' in IEEE754 double-
precision format. */
double
__mpn_construct_double (mp_srcptr frac_ptr, int expt, int negative)
{
union ieee754_double u;
u.ieee.negative = negative;
u.ieee.exponent = expt + IEEE754_DOUBLE_BIAS;
#if BITS_PER_MP_LIMB == 32
u.ieee.mantissa1 = frac_ptr[0];
u.ieee.mantissa0 = frac_ptr[1] & (((mp_limb_t) 1
<< (DBL_MANT_DIG - 32)) - 1);
#elif BITS_PER_MP_LIMB == 64
u.ieee.mantissa1 = frac_ptr[0] & (((mp_limb_t) 1 << 32) - 1);
u.ieee.mantissa0 = (frac_ptr[0] >> 32) & (((mp_limb_t) 1
<< (DBL_MANT_DIG - 32)) - 1);
#else
#error "mp_limb size " BITS_PER_MP_LIMB "not accounted for"
#endif
return u.d;
}
|
