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glibc  2.9
s_llroundl.c
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00001 /* Round long double value to long long int.
00002    Copyright (C) 1997, 1999, 2004 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 long int
00028 __llroundl (long double x)
00029 {
00030   int64_t j0;
00031   u_int64_t i1, i0;
00032   long long int result;
00033   int sign;
00034 
00035   GET_LDOUBLE_WORDS64 (i0, i1, x);
00036   j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
00037   sign = (i0 & 0x8000000000000000ULL) != 0 ? -1 : 1;
00038   i0 &= 0x0000ffffffffffffLL;
00039   i0 |= 0x0001000000000000LL;
00040 
00041   if (j0 < 48)
00042     {
00043       if (j0 < 0)
00044        return j0 < -1 ? 0 : sign;
00045       else
00046        {
00047          i0 += 0x0000800000000000LL >> j0;
00048          result = i0 >> (48 - j0);
00049        }
00050     }
00051   else if (j0 < (int32_t) (8 * sizeof (long long int)) - 1)
00052     {
00053       if (j0 >= 112)
00054        result = ((long long int) i0 << (j0 - 48)) | (i1 << (j0 - 112));
00055       else
00056        {
00057          u_int64_t j = i1 + (0x8000000000000000ULL >> (j0 - 48));
00058          if (j < i1)
00059            ++i0;
00060 
00061          if (j0 == 48)
00062            result = (long long int) i0;
00063          else
00064            result = ((long long int) i0 << (j0 - 48)) | (j >> (112 - j0));
00065        }
00066     }
00067   else
00068     {
00069       /* The number is too large.  It is left implementation defined
00070         what happens.  */
00071       return (long long int) x;
00072     }
00073 
00074   return sign * result;
00075 }
00076 
00077 weak_alias (__llroundl, llroundl)