1/*
2 * Copyright (c) 1998, 2001, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26/*
27 * for non-zero x
28 * x = frexp(arg,&exp);
29 * return a double fp quantity x such that 0.5 <= |x| <1.0
30 * and the corresponding binary exponent "exp". That is
31 * arg = x*2^exp.
32 * If arg is inf, 0.0, or NaN, then frexp(arg,&exp) returns arg
33 * with *exp=0.
34 */
35
36#include "fdlibm.h"
37
38#ifdef __STDC__
39static const double
40#else
41static double
42#endif
43two54 = 1.80143985094819840000e+16; /* 0x43500000, 0x00000000 */
44
45#ifdef __STDC__
46 double frexp(double x, int *eptr)
47#else
48 double frexp(x, eptr)
49 double x; int *eptr;
50#endif
51{
52 int hx, ix, lx;
53 hx = __HI(x);
54 ix = 0x7fffffff&hx;
55 lx = __LO(x);
56 *eptr = 0;
57 if(ix>=0x7ff00000||((ix|lx)==0)) return x; /* 0,inf,nan */
58 if (ix<0x00100000) { /* subnormal */
59 x *= two54;
60 hx = __HI(x);
61 ix = hx&0x7fffffff;
62 *eptr = -54;
63 }
64 *eptr += (ix>>20)-1022;
65 hx = (hx&0x800fffff)|0x3fe00000;
66 __HI(x) = hx;
67 return x;
68}
69