Back to index

glibc  2.9
s_llrintl.c
Go to the documentation of this file.
00001 /* Round argument to nearest integral value according to current rounding
00002    direction.
00003    Copyright (C) 1997, 1999, 2006 Free Software Foundation, Inc.
00004    This file is part of the GNU C Library.
00005    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997 and
00006                 Jakub Jelinek <jj@ultra.linux.cz>, 1999.
00007 
00008    The GNU C Library is free software; you can redistribute it and/or
00009    modify it under the terms of the GNU Lesser General Public
00010    License as published by the Free Software Foundation; either
00011    version 2.1 of the License, or (at your option) any later version.
00012 
00013    The GNU C Library is distributed in the hope that it will be useful,
00014    but WITHOUT ANY WARRANTY; without even the implied warranty of
00015    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00016    Lesser General Public License for more details.
00017 
00018    You should have received a copy of the GNU Lesser General Public
00019    License along with the GNU C Library; if not, write to the Free
00020    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00021    02111-1307 USA.  */
00022 
00023 #include <math.h>
00024 
00025 #include "math_private.h"
00026 
00027 static const long double two112[2] =
00028 {
00029   5.19229685853482762853049632922009600E+33L, /* 0x406F000000000000, 0 */
00030  -5.19229685853482762853049632922009600E+33L  /* 0xC06F000000000000, 0 */
00031 };
00032 
00033 long long int
00034 __llrintl (long double x)
00035 {
00036   int32_t j0;
00037   u_int64_t i0,i1;
00038   volatile long double w;
00039   long double t;
00040   long long int result;
00041   int sx;
00042 
00043   GET_LDOUBLE_WORDS64 (i0, i1, x);
00044   j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
00045   sx = i0 >> 63;
00046   i0 &= 0x0000ffffffffffffLL;
00047   i0 |= 0x0001000000000000LL;
00048 
00049   if (j0 < (int32_t) (8 * sizeof (long long int)) - 1)
00050     {
00051       w = two112[sx] + x;
00052       t = w - two112[sx];
00053       GET_LDOUBLE_WORDS64 (i0, i1, t);
00054       j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
00055       i0 &= 0x0000ffffffffffffLL;
00056       i0 |= 0x0001000000000000LL;
00057 
00058       if (j0 < 0)
00059        result = 0;
00060       else if (j0 <= 48)
00061        result = i0 >> (48 - j0);
00062       else
00063        result = ((long long int) i0 << (j0 - 48)) | (i1 >> (112 - j0));
00064     }
00065   else
00066     {
00067       /* The number is too large.  It is left implementation defined
00068         what happens.  */
00069       return (long long int) x;
00070     }
00071 
00072   return sx ? -result : result;
00073 }
00074 
00075 weak_alias (__llrintl, llrintl)