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glibc  2.9
s_truncl.c
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00001 /* Truncate argument to nearest integral value not larger than the argument.
00002    Copyright (C) 1997, 1999 Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
00004    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997 and
00005                 Jakub Jelinek <jj@ultra.linux.cz>, 1999.
00006 
00007    The GNU C Library is free software; you can redistribute it and/or
00008    modify it under the terms of the GNU Lesser General Public
00009    License as published by the Free Software Foundation; either
00010    version 2.1 of the License, or (at your option) any later version.
00011 
00012    The GNU C Library is distributed in the hope that it will be useful,
00013    but WITHOUT ANY WARRANTY; without even the implied warranty of
00014    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015    Lesser General Public License for more details.
00016 
00017    You should have received a copy of the GNU Lesser General Public
00018    License along with the GNU C Library; if not, write to the Free
00019    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00020    02111-1307 USA.  */
00021 
00022 #include <math.h>
00023 
00024 #include "math_private.h"
00025 
00026 
00027 long double
00028 __truncl (long double x)
00029 {
00030   int32_t j0;
00031   u_int64_t i0, i1, sx;
00032 
00033   GET_LDOUBLE_WORDS64 (i0, i1, x);
00034   sx = i0 & 0x8000000000000000ULL;
00035   j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
00036   if (j0 < 48)
00037     {
00038       if (j0 < 0)
00039        /* The magnitude of the number is < 1 so the result is +-0.  */
00040        SET_LDOUBLE_WORDS64 (x, sx, 0);
00041       else
00042        SET_LDOUBLE_WORDS64 (x, i0 & ~(0x0000ffffffffffffLL >> j0), 0);
00043     }
00044   else if (j0 > 111)
00045     {
00046       if (j0 == 0x4000)
00047        /* x is inf or NaN.  */
00048        return x + x;
00049     }
00050   else
00051     {
00052       SET_LDOUBLE_WORDS64 (x, i0, i1 & ~(0xffffffffffffffffULL >> (j0 - 48)));
00053     }
00054 
00055   return x;
00056 }
00057 weak_alias (__truncl, truncl)