summaryrefslogtreecommitdiff
path: root/sysdeps/libm-ieee754/s_lrintf.c
blob: d80d81a718ff925b98483b21d9bc654731b9da1a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
/* Round argument to nearest integral value according to current rounding
   direction.
   Copyright (C) 1997 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <math.h>

#include "math_private.h"

static const double two23[2] =
{
  8.3886080000e+06, /* 0x4B000000 */
 -8.3886080000e+06, /* 0xCB000000 */
};


long int
__lrintf (float x)
{
  int32_t j0;
  u_int32_t i, i0;
  volatile float w;
  float t;
  long int result;
  int sx;

  GET_FLOAT_WORD (i, x);

  sx = i0 >> 31;
  j0 = ((i0 >> 23) & 0xff) - 0x7f;
  i0 = i & 0x7fffff;
  i0 |= 0x800000;

  if (j0 < (int32_t) (sizeof (long int) * 8) - 1)
    {
      if (j0 < -1)
	return 0;
      else if (j0 >= 23)
	result = (long int) i0 << (j0 - 23);
      else
	{
	  w = two23[sx] + x;
	  t = w - two23[sx];
	  GET_FLOAT_WORD (i, t);
	  i0 = i & 0x7fffff;
	  i0 |= 0x800000;
	  j0 = ((i0 >> 23) & 0xff) - 0x7f;

	  result = i0 >> (23 - j0);
	}
    }
  else
    {
      /* The number is too large.  It is left implementation defined
	 what happens.  */
      return (long int) x;
    }

  return sx ? -result : result;
}

weak_alias (__lrintf, lrintf)