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glibc  2.9
s_lroundl.c
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00001 /* Round long double value to long int.
00002    Copyright (C) 1997, 2004 Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
00004    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
00005 
00006    The GNU C Library is free software; you can redistribute it and/or
00007    modify it under the terms of the GNU Lesser General Public
00008    License as published by the Free Software Foundation; either
00009    version 2.1 of the License, or (at your option) any later version.
00010 
00011    The GNU C Library is distributed in the hope that it will be useful,
00012    but WITHOUT ANY WARRANTY; without even the implied warranty of
00013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00014    Lesser General Public License for more details.
00015 
00016    You should have received a copy of the GNU Lesser General Public
00017    License along with the GNU C Library; if not, write to the Free
00018    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00019    02111-1307 USA.  */
00020 
00021 #include <math.h>
00022 
00023 #include "math_private.h"
00024 
00025 
00026 long int
00027 __lroundl (long double x)
00028 {
00029   int32_t j0;
00030   u_int32_t se, i1, i0;
00031   long int result;
00032   int sign;
00033 
00034   GET_LDOUBLE_WORDS (se, i0, i1, x);
00035   j0 = (se & 0x7fff) - 0x3fff;
00036   sign = (se & 0x8000) != 0 ? -1 : 1;
00037 
00038   if (j0 < 31)
00039     {
00040       if (j0 < 0)
00041        return j0 < -1 ? 0 : sign;
00042       else
00043        {
00044          u_int32_t j = i0 + (0x40000000 >> j0);
00045          if (j < i0)
00046            {
00047              j >>= 1;
00048              j |= 0x80000000;
00049              ++j0;
00050            }
00051 
00052          result = j >> (31 - j0);
00053        }
00054     }
00055   else if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
00056     {
00057       if (j0 >= 63)
00058        result = ((long int) i0 << (j0 - 31)) | (i1 << (j0 - 63));
00059       else
00060        {
00061          u_int32_t j = i1 + (0x80000000 >> (j0 - 31));
00062          if (j < i1)
00063            ++i0;
00064 
00065          if (j0 == 31)
00066            result = (long int) i0;
00067          else
00068            result = ((long int) i0 << (j0 - 31)) | (j >> (63 - j0));
00069        }
00070     }
00071   else
00072     {
00073       /* The number is too large.  It is left implementation defined
00074         what happens.  */
00075       return (long int) x;
00076     }
00077 
00078   return sign * result;
00079 }
00080 
00081 weak_alias (__lroundl, lroundl)