60 lines
1.3 KiB
C
60 lines
1.3 KiB
C
/* Copyright (C) 2002 by Red Hat, Incorporated. All rights reserved.
|
|
*
|
|
* Permission to use, copy, modify, and distribute this software
|
|
* is freely granted, provided that this notice is preserved.
|
|
*/
|
|
/*
|
|
FUNCTION
|
|
<<signbit>>---Does floating-point number have negative sign?
|
|
|
|
INDEX
|
|
signbit
|
|
|
|
SYNOPSIS
|
|
#include <math.h>
|
|
int signbit(real-floating <[x]>);
|
|
|
|
DESCRIPTION
|
|
The <<signbit>> macro determines whether the sign of its argument value is
|
|
negative. The macro reports the sign of all values, including infinities,
|
|
zeros, and NaNs. If zero is unsigned, it is treated as positive. As shown in
|
|
the synopsis, the argument is "real-floating," meaning that any of the real
|
|
floating-point types (float, double, etc.) may be given to it.
|
|
|
|
Note that because of the possibilities of signed 0 and NaNs, the expression
|
|
"<[x]> < 0.0" does not give the same result as <<signbit>> in all cases.
|
|
|
|
RETURNS
|
|
The <<signbit>> macro returns a nonzero value if and only if the sign of its
|
|
argument value is negative.
|
|
|
|
PORTABILITY
|
|
C99, POSIX.
|
|
|
|
*/
|
|
|
|
#include "fdlibm.h"
|
|
|
|
int __signbitf (float x);
|
|
int __signbitd (double x);
|
|
|
|
int
|
|
__signbitf (float x)
|
|
{
|
|
__uint32_t w;
|
|
|
|
GET_FLOAT_WORD(w,x);
|
|
|
|
return (w & 0x80000000) != 0;
|
|
}
|
|
|
|
int
|
|
__signbitd (double x)
|
|
{
|
|
__uint32_t msw;
|
|
|
|
GET_HIGH_WORD(msw, x);
|
|
|
|
return (msw & 0x80000000) != 0;
|
|
}
|