glibc/sysdeps/powerpc/fpu/s_llroundf.c
Alan Modra da13146da1 PowerPC floating point little-endian [10 of 15]
http://sourceware.org/ml/libc-alpha/2013-07/msg00201.html

These two functions oddly test x+1>0 when a double x is >= 0.0, and
similarly when x is negative.  I don't see the point of that since the
test should always be true.  I also don't see any need to convert x+1
to integer rather than simply using xr+1.  Note that the standard
allows these functions to return any value when the input is outside
the range of long long, but it's not too hard to prevent xr+1
overflowing so that's what I've done.

(With rounding mode FE_UPWARD, x+1 can be a lot more than what you
might naively expect, but perhaps that situation was covered by the
x - xrf < 1.0 test.)

	* sysdeps/powerpc/fpu/s_llround.c (__llround): Rewrite.
	* sysdeps/powerpc/fpu/s_llroundf.c (__llroundf): Rewrite.
2013-10-04 10:35:10 +09:30

45 lines
1.4 KiB
C

/* Round float value to long long int.
Copyright (C) 1997-2013 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/>. */
#include <math.h>
/* Round to the nearest integer, with values exactly on a 0.5 boundary
rounded away from zero, regardless of the current rounding mode.
If (long long)x, when x is out of range of a long long, clips at
LLONG_MAX or LLONG_MIN, then this implementation also clips. */
long long int
__llroundf (float x)
{
long long xr = (long long) x;
float xrf = (float) xr;
if (x >= 0.0)
{
if (x - xrf >= 0.5)
xr += (long long) ((unsigned long long) xr + 1) > 0;
}
else
{
if (xrf - x >= 0.5)
xr -= (long long) ((unsigned long long) xr - 1) < 0;
}
return xr;
}
weak_alias (__llroundf, llroundf)