glibc/sysdeps/ieee754/ldbl-128ibm/s_roundl.c
Joseph Myers bba1419589 Fix ldbl-128ibm ceill, rintl etc. for sNaN arguments (bug 20156).
The ldbl-128ibm implementations of ceill, floorl, roundl, truncl,
rintl and nearbyintl wrongly return an sNaN when given an sNaN
argument.  This patch fixes them to add such an argument to itself to
turn it into a quiet NaN.  (The code structure means this "else" case
applies to any argument which is zero or not finite; it's OK to do
this in all such cases.)

Tested for powerpc.

	[BZ #20156]
	* sysdeps/ieee754/ldbl-128ibm/s_ceill.c (__ceill): Add high part
	to itself when zero or not finite.
	* sysdeps/ieee754/ldbl-128ibm/s_floorl.c (__floorl): Likewise.
	* sysdeps/ieee754/ldbl-128ibm/s_rintl.c (__rintl): Likewise.
	* sysdeps/ieee754/ldbl-128ibm/s_roundl.c (__roundl): Likewise.
	* sysdeps/ieee754/ldbl-128ibm/s_truncl.c (__truncl): Likewise.
2016-05-27 13:59:24 +00:00

88 lines
2.2 KiB
C

/* Round to int long double floating-point values.
IBM extended format long double version.
Copyright (C) 2006-2016 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
/* This has been coded in assembler because GCC makes such a mess of it
when it's coded in C. */
#include <math.h>
#include <math_ldbl_opt.h>
#include <float.h>
#include <ieee754.h>
long double
__roundl (long double x)
{
double xh, xl, hi, lo;
ldbl_unpack (x, &xh, &xl);
/* Return Inf, Nan, +/-0 unchanged. */
if (__builtin_expect (xh != 0.0
&& __builtin_isless (__builtin_fabs (xh),
__builtin_inf ()), 1))
{
hi = __round (xh);
if (hi != xh)
{
/* The high part is not an integer; the low part only
affects the result if the high part is exactly half way
between two integers and the low part is nonzero with the
opposite sign. */
if (fabs (hi - xh) == 0.5)
{
if (xh > 0 && xl < 0)
xh = hi - 1;
else if (xh < 0 && xl > 0)
xh = hi + 1;
else
xh = hi;
}
else
xh = hi;
xl = 0;
}
else
{
/* The high part is a nonzero integer. */
lo = __round (xl);
if (fabs (lo - xl) == 0.5)
{
if (xh > 0 && xl < 0)
xl = lo + 1;
else if (xh < 0 && lo > 0)
xl = lo - 1;
else
xl = lo;
}
else
xl = lo;
xh = hi;
ldbl_canonicalize_int (&xh, &xl);
}
}
else
/* Quiet signaling NaN arguments. */
xh += xh;
return ldbl_pack (xh, xl);
}
long_double_symbol (libm, __roundl, roundl);