mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-25 20:21:07 +00:00
79 lines
1.8 KiB
C
79 lines
1.8 KiB
C
/* Adapted for use as nearbyint by Ulrich Drepper <drepper@cygnus.com>. */
|
|
/*
|
|
* ====================================================
|
|
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
|
|
*
|
|
* Developed at SunPro, a Sun Microsystems, Inc. business.
|
|
* Permission to use, copy, modify, and distribute this
|
|
* software is freely granted, provided that this notice
|
|
* is preserved.
|
|
* ====================================================
|
|
*/
|
|
|
|
#if defined(LIBM_SCCS) && !defined(lint)
|
|
static char rcsid[] = "$NetBSD: s_rint.c,v 1.8 1995/05/10 20:48:04 jtc Exp $";
|
|
#endif
|
|
|
|
/*
|
|
* rint(x)
|
|
* Return x rounded to integral value according to the prevailing
|
|
* rounding mode.
|
|
* Method:
|
|
* Using floating addition.
|
|
* Exception:
|
|
* Inexact flag raised if x not equal to rint(x).
|
|
*/
|
|
|
|
#include <fenv.h>
|
|
#include <math.h>
|
|
#include <math_private.h>
|
|
|
|
static const double
|
|
TWO52[2] = {
|
|
4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
|
|
-4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
|
|
};
|
|
|
|
double
|
|
__nearbyint (double x)
|
|
{
|
|
fenv_t env;
|
|
int32_t i0, j0, sx;
|
|
double w, t;
|
|
GET_HIGH_WORD (i0, x);
|
|
sx = (i0 >> 31) & 1;
|
|
j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
|
|
if (j0 < 52)
|
|
{
|
|
if (j0 < 0)
|
|
{
|
|
libc_feholdexcept (&env);
|
|
w = TWO52[sx] + x;
|
|
t = w - TWO52[sx];
|
|
math_force_eval (t);
|
|
libc_fesetenv (&env);
|
|
GET_HIGH_WORD (i0, t);
|
|
SET_HIGH_WORD (t, (i0 & 0x7fffffff) | (sx << 31));
|
|
return t;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
if (j0 == 0x400)
|
|
return x + x; /* inf or NaN */
|
|
else
|
|
return x; /* x is integral */
|
|
}
|
|
libc_feholdexcept (&env);
|
|
w = TWO52[sx] + x;
|
|
t = w - TWO52[sx];
|
|
math_force_eval (t);
|
|
libc_fesetenv (&env);
|
|
return t;
|
|
}
|
|
weak_alias (__nearbyint, nearbyint)
|
|
#ifdef NO_LONG_DOUBLE
|
|
strong_alias (__nearbyint, __nearbyintl)
|
|
weak_alias (__nearbyint, nearbyintl)
|
|
#endif
|