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glibc  2.9
s_lrintl.c
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00001 /* Round argument to nearest integral value according to current rounding
00002    direction.
00003    Copyright (C) 1997, 2004, 2006 Free Software Foundation, Inc.
00004    This file is part of the GNU C Library.
00005    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
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 static const long double two63[2] =
00027 {
00028   9.223372036854775808000000e+18, /* 0x403E, 0x00000000, 0x00000000 */
00029  -9.223372036854775808000000e+18  /* 0xC03E, 0x00000000, 0x00000000 */
00030 };
00031 
00032 
00033 long int
00034 __lrintl (long double x)
00035 {
00036   int32_t se,j0;
00037   u_int32_t i0, i1;
00038   long int result;
00039   volatile long double w;
00040   long double t;
00041   int sx;
00042 
00043   GET_LDOUBLE_WORDS (se, i0, i1, x);
00044 
00045   sx = (se >> 15) & 1;
00046   j0 = (se & 0x7fff) - 0x3fff;
00047 
00048   if (j0 < 31)
00049     {
00050       w = two63[sx] + x;
00051       t = w - two63[sx];
00052       GET_LDOUBLE_WORDS (se, i0, i1, t);
00053       j0 = (se & 0x7fff) - 0x3fff;
00054 
00055       result = (j0 < 0 ? 0 : i0 >> (31 - j0));
00056     }
00057   else if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
00058     {
00059       if (j0 >= 63)
00060        result = ((long int) i0 << (j0 - 31)) | (i1 << (j0 - 63));
00061       else
00062        {
00063          w = two63[sx] + x;
00064          t = w - two63[sx];
00065          GET_LDOUBLE_WORDS (se, i0, i1, t);
00066          j0 = (se & 0x7fff) - 0x3fff;
00067 
00068          if (j0 == 31)
00069            result = (long int) i0;
00070          else
00071            result = ((long int) i0 << (j0 - 31)) | (i1 >> (63 - j0));
00072        }
00073     }
00074   else
00075     {
00076       /* The number is too large.  It is left implementation defined
00077         what happens.  */
00078       return (long int) x;
00079     }
00080 
00081   return sx ? -result : result;
00082 }
00083 
00084 weak_alias (__lrintl, lrintl)