summaryrefslogtreecommitdiff
path: root/sysdeps/alpha/fpu/s_trunc.c
blob: 4b986a6926ebc323e89747dcfe201d13a15634e5 (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
/* Copyright (C) 2007-2016 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Richard Henderson.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library.  If not, see
   <http://www.gnu.org/licenses/>.  */

#include <math.h>
#include <math_ldbl_opt.h>


/* Use the chopped rounding mode conversion instructions to implement trunc. */

double
__trunc (double x)
{
  double two52 = copysign (0x1.0p52, x);
  double r, tmp;

  if (isgreaterequal (fabs (x), 0x1.0p52))
    return x;

  __asm (
	 "addt/suc %2, %3, %1\n\tsubt/suc %1, %3, %0"
	 : "=&f"(r), "=&f"(tmp)
	 : "f"(x), "f"(two52));

  /* trunc(-0) == -0, and in general we'll always have the same
     sign as our input.  */
  return copysign (r, x);
}

weak_alias (__trunc, trunc)
#ifdef NO_LONG_DOUBLE
strong_alias (__trunc, __truncl)
weak_alias (__trunc, truncl)
#endif
#if LONG_DOUBLE_COMPAT(libm, GLIBC_2_1)
compat_symbol (libm, __trunc, truncl, GLIBC_2_1);
#endif