glibc/sysdeps/ieee754/ldbl-96/s_roundl.c
Ulrich Drepper abfbdde177 Update.
1999-07-14 00:54:57 +00:00

107 lines
2.3 KiB
C

/* Round long double to integer away from zero.
Copyright (C) 1997 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <math.h>
#include "math_private.h"
static const long double huge = 1.0e4930;
long double
__roundl (long double x)
{
int32_t j0;
u_int32_t se, i1, i0;
GET_LDOUBLE_WORDS (se, i0, i1, x);
j0 = (se & 0x7fff) - 0x3fff;
if (j0 < 31)
{
if (j0 < 0)
{
if (huge + x > 0.0)
{
se &= 0x8000;
i0 = i1 = 0;
if (j0 == -1)
{
se |= 0x3fff;
i0 = 0x80000000;
}
}
}
else
{
u_int32_t i = 0x7fffffff >> j0;
if (((i0 & i) | i1) == 0)
/* X is integral. */
return x;
if (huge + x > 0.0)
{
/* Raise inexact if x != 0. */
u_int32_t j = i0 + (0x40000000 >> j0);
if (j < i0)
se += 1;
i0 = (j & ~i) | 0x80000000;
i1 = 0;
}
}
}
else if (j0 > 62)
{
if (j0 == 0x4000)
/* Inf or NaN. */
return x + x;
else
return x;
}
else
{
u_int32_t i = 0xffffffff >> (j0 - 31);
if ((i1 & i) == 0)
/* X is integral. */
return x;
if (huge + x > 0.0)
{
/* Raise inexact if x != 0. */
u_int32_t j = i1 + (1 << (62 - j0));
if (j < i1)
{
u_int32_t k = i0 + 1;
if (k < i0)
{
se += 1;
k |= 0x80000000;
}
i0 = k;
}
i1 = j;
}
i1 &= ~i;
}
SET_LDOUBLE_WORDS (x, se, i0, i1);
return x;
}
weak_alias (__roundl, roundl)