newlib/libm/common/s_signbit.c

   1 /* Copyright (C) 2002 by  Red Hat, Incorporated. All rights reserved.
   2  *
   3  * Permission to use, copy, modify, and distribute this software
   4  * is freely granted, provided that this notice is preserved.
   5  */
   6 /*
   7 FUNCTION
   8 <<signbit>>---Does floating-point number have negative sign?
   9
  10 INDEX
  11         signbit
  12
  13 SYNOPSIS
  14         #include <math.h>
  15         int signbit(real-floating <[x]>);
  16
  17 DESCRIPTION
  18 The <<signbit>> macro determines whether the sign of its argument value is
  19 negative.  The macro reports the sign of all values, including infinities,
  20 zeros, and NaNs.  If zero is unsigned, it is treated as positive.  As shown in
  21 the synopsis, the argument is "real-floating," meaning that any of the real
  22 floating-point types (float, double, etc.) may be given to it.
  23
  24 Note that because of the possibilities of signed 0 and NaNs, the expression
  25 "<[x]> < 0.0" does not give the same result as <<signbit>> in all cases.
  26
  27 RETURNS
  28 The <<signbit>> macro returns a nonzero value if and only if the sign of its
  29 argument value is negative.
  30
  31 PORTABILITY
  32 C99, POSIX.
  33
  34 */
  35
  36 #include "fdlibm.h"
  37
  38 int __signbitf (float x);
  39 int __signbitd (double x);
  40
  41 int
  42 __signbitf (float x)
  43 {
  44   __uint32_t w;
  45
  46   GET_FLOAT_WORD(w,x);
  47
  48   return (w & 0x80000000) != 0;
  49 }
  50
  51 int
  52 __signbitd (double x)
  53 {
  54   __uint32_t msw;
  55
  56   GET_HIGH_WORD(msw, x);
  57
  58   return (msw & 0x80000000) != 0;
  59 }