sysdeps/libm-ieee754/s_lrintl.c

   1 /* Round argument to nearest integral value according to current rounding
   2    direction.
   3    Copyright (C) 1997 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Library General Public License as
   9    published by the Free Software Foundation; either version 2 of the
  10    License, or (at your option) any later version.
  11
  12    The GNU C Library is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    Library General Public License for more details.
  16
  17    You should have received a copy of the GNU Library General Public
  18    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  19    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  20    Boston, MA 02111-1307, USA.  */
  21
  22 #include <math.h>
  23
  24 #include "math_private.h"
  25
  26 static const long double two63[2] =
  27 {
  28   9.223372036854775808000000e+18, /* 0x403E, 0x00000000, 0x00000000 */
  29  -9.223372036854775808000000e+18  /* 0xC03E, 0x00000000, 0x00000000 */
  30 };
  31
  32
  33 long int
  34 __lrintl (long double x)
  35 {
  36   int32_t se,j0;
  37   u_int32_t i0,i1,i;
  38   long int result;
  39   volatile long double w;
  40   long double t;
  41   int sx;
  42
  43   GET_LDOUBLE_WORDS (se, i0, i1, x);
  44
  45   sx = (se >> 15) & 1;
  46   j0 = (se & 0x7fff) - 0x3fff;
  47
  48   if (j0 < 31)
  49     {
  50       if (j0 < -1)
  51         return 0;
  52       else
  53         {
  54           w = two63[sx] + x;
  55           t = w - two63[sx];
  56           GET_LDOUBLE_WORDS (se, i0, i1, t);
  57           j0 = (se & 0x7fff) - 0x3fff;
  58
  59           result = i0 >> (31 - j0);
  60         }
  61     }
  62   else if (j0 < (int32_t) (8 * sizeof (long int)))
  63     {
  64       if (j0 >= 63)
  65         result = ((long int) i0 << (j0 - 31)) | (i1 << (j0 - 63));
  66       else
  67         {
  68           w = two63[sx] + x;
  69           t = w - two63[sx];
  70           GET_LDOUBLE_WORDS (se, i0, i1, t);
  71           j0 = (se & 0x7fff) - 0x3fff;
  72
  73           result = ((long int) i0 << (j0 - 31)) | (j >> (63 - j0));
  74         }
  75     }
  76   else
  77     {
  78       /* The number is too large.  It is left implementation defined
  79          what happens.  */
  80       return (long int) x;
  81     }
  82
  83   return sx ? -result : result;
  84 }
  85
  86 weak_alias (__lrintl, lrintl)