[project @ 2000-08-04 23:28:04 by lewie]
[ghc.git] / ghc / rts / gmp / insert-double.c
1 /* __gmp_insert_double -- convert from array of mp_limb_t to double.
2
3 Copyright (C) 1996 Free Software Foundation, Inc.
4
5 This file is part of the GNU MP Library.
6
7 The GNU MP Library is free software; you can redistribute it and/or modify
8 it under the terms of the GNU Library General Public License as published by
9 the Free Software Foundation; either version 2 of the License, or (at your
10 option) any later version.
11
12 The GNU MP Library is distributed in the hope that it will be useful, but
13 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
15 License for more details.
16
17 You should have received a copy of the GNU Library General Public License
18 along with the GNU MP Library; see the file COPYING.LIB. If not, write to
19 the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
20 MA 02111-1307, USA. */
21
22 #include "gmp.h"
23 #include "gmp-impl.h"
24
25 #ifdef XDEBUG
26 #undef _GMP_IEEE_FLOATS
27 #endif
28
29 #ifndef _GMP_IEEE_FLOATS
30 #define _GMP_IEEE_FLOATS 0
31 #endif
32
33 double
34 #if __STDC__
35 __gmp_scale2 (double d, int exp)
36 #else
37 __gmp_scale2 (d, exp)
38 double d;
39 int exp;
40 #endif
41 {
42 #if _GMP_IEEE_FLOATS
43 {
44 union ieee_double_extract x;
45 x.d = d;
46 x.s.exp += exp;
47 return x.d;
48 }
49 #else
50 {
51 double factor, r;
52
53 factor = 2.0;
54 if (exp < 0)
55 {
56 factor = 0.5;
57 exp = -exp;
58 }
59 r = d;
60 while (exp != 0)
61 {
62 if ((exp & 1) != 0)
63 r *= factor;
64 factor *= factor;
65 exp >>= 1;
66 }
67 return r;
68 }
69 #endif
70 }