newlib/libm/common/s_copysign.c

   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 FUNCTION
  16 <<copysign>>, <<copysignf>>---sign of <[y]>, magnitude of <[x]>
  17
  18 INDEX
  19         copysign
  20 INDEX
  21         copysignf
  22
  23 SYNOPSIS
  24         #include <math.h>
  25         double copysign (double <[x]>, double <[y]>);
  26         float copysignf (float <[x]>, float <[y]>);
  27
  28 DESCRIPTION
  29 <<copysign>> constructs a number with the magnitude (absolute value)
  30 of its first argument, <[x]>, and the sign of its second argument,
  31 <[y]>.
  32
  33 <<copysignf>> does the same thing; the two functions differ only in
  34 the type of their arguments and result.
  35
  36 RETURNS
  37 <<copysign>> returns a <<double>> with the magnitude of
  38 <[x]> and the sign of <[y]>.
  39 <<copysignf>> returns a <<float>> with the magnitude of
  40 <[x]> and the sign of <[y]>.
  41
  42 PORTABILITY
  43 <<copysign>> is not required by either ANSI C or the System V Interface
  44 Definition (Issue 2).
  45
  46 */
  47
  48 /*
  49  * copysign(double x, double y)
  50  * copysign(x,y) returns a value with the magnitude of x and
  51  * with the sign bit of y.
  52  */
  53
  54 #include "fdlibm.h"
  55
  56 #ifndef _DOUBLE_IS_32BITS
  57
  58 #ifdef __STDC__
  59         double copysign(double x, double y)
  60 #else
  61         double copysign(x,y)
  62         double x,y;
  63 #endif
  64 {
  65         __uint32_t hx,hy;
  66         GET_HIGH_WORD(hx,x);
  67         GET_HIGH_WORD(hy,y);
  68         SET_HIGH_WORD(x,(hx&0x7fffffff)|(hy&0x80000000));
  69         return x;
  70 }
  71
  72 #endif /* _DOUBLE_IS_32BITS */