source: trunk/sys/libm/s_copysign.c @ 1

Last change on this file since 1 was 1, checked in by alain, 5 years ago

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File size: 937 bytes
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1
2/* @(#)s_copysign.c 5.1 93/09/24 */
3/*
4 * ====================================================
5 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
6 *
7 * Developed at SunPro, a Sun Microsystems, Inc. business.
8 * Permission to use, copy, modify, and distribute this
9 * software is freely granted, provided that this notice
10 * is preserved.
11 * ====================================================
12 */
13
14/*
15 * copysign(double x, double y)
16 * copysign(x,y) returns a value with the magnitude of x and
17 * with the sign bit of y.
18 */
19
20#include <libm/fdlibm.h>
21
22#ifdef __STDC__
23static const double one = 1.0;
24#else
25static double one = 1.0;
26#endif
27
28#ifdef __STDC__
29        double copysign(double x, double y)
30#else
31        double copysign(x,y)
32        double x,y;
33#endif
34{
35        int     n0;
36        n0 = ((*(int*)&one)>>29)^1;     /* high word index */
37        *(n0+(unsigned*)&x) =
38        (*(n0+(unsigned*)&x)&0x7fffffff)|(*(n0+(unsigned*)&y)&0x80000000);
39        return x;
40}
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