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 * modf(double x, double *iptr)
28 * return fraction part of x, and return x's integral part in *iptr.
29 * Method:
30 * Bit twiddling.
31 *
32 * Exception:
33 * No exception.
34 */
35
36#include "fdlibm.h"
37
38#ifdef __STDC__
39static const double one = 1.0;
40#else
41static double one = 1.0;
42#endif
43
44#ifdef __STDC__
45 double modf(double x, double *iptr)
46#else
47 double modf(x, iptr)
48 double x,*iptr;
49#endif
50{
51 int i0,i1,j0;
52 unsigned i;
53 i0 = __HI(x); /* high x */
54 i1 = __LO(x); /* low x */
55 j0 = ((i0>>20)&0x7ff)-0x3ff; /* exponent of x */
56 if(j0<20) { /* integer part in high x */
57 if(j0<0) { /* |x|<1 */
58 __HIp(iptr) = i0&0x80000000;
59 __LOp(iptr) = 0; /* *iptr = +-0 */
60 return x;
61 } else {
62 i = (0x000fffff)>>j0;
63 if(((i0&i)|i1)==0) { /* x is integral */
64 *iptr = x;
65 __HI(x) &= 0x80000000;
66 __LO(x) = 0; /* return +-0 */
67 return x;
68 } else {
69 __HIp(iptr) = i0&(~i);
70 __LOp(iptr) = 0;
71 return x - *iptr;
72 }
73 }
74 } else if (j0>51) { /* no fraction part */
75 *iptr = x*one;
76 __HI(x) &= 0x80000000;
77 __LO(x) = 0; /* return +-0 */
78 return x;
79 } else { /* fraction part in low x */
80 i = ((unsigned)(0xffffffff))>>(j0-20);
81 if((i1&i)==0) { /* x is integral */
82 *iptr = x;
83 __HI(x) &= 0x80000000;
84 __LO(x) = 0; /* return +-0 */
85 return x;
86 } else {
87 __HIp(iptr) = i0;
88 __LOp(iptr) = i1&(~i);
89 return x - *iptr;
90 }
91 }
92}
93