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glibc  2.9
s_rint.c
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00001 /* Copyright (C) 2000, 2006, 2007 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003    Contributed by Richard Henderson.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public
00007    License as published by the Free Software Foundation; either
00008    version 2.1 of the License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; if not, write to the Free
00017    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00018    02111-1307 USA.  */
00019 
00020 #include <math.h>
00021 #include <math_ldbl_opt.h>
00022 
00023 
00024 double
00025 __rint (double x)
00026 {
00027   double two52 = copysign (0x1.0p52, x);
00028   double r;
00029   
00030   r = x + two52;
00031   r = r - two52;
00032 
00033   /* rint(-0.1) == -0, and in general we'll always have the same sign
00034      as our input.  */
00035   return copysign (r, x);
00036 }
00037 
00038 weak_alias (__rint, rint)
00039 #ifdef NO_LONG_DOUBLE
00040 strong_alias (__rint, __rintl)
00041 weak_alias (__rint, rintl)
00042 #endif
00043 #if LONG_DOUBLE_COMPAT(libm, GLIBC_2_0)
00044 compat_symbol (libm, __rint, rintl, GLIBC_2_0);
00045 #endif