1/* Round double value to long int.
2 Copyright (C) 1997-2016 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
18
19#include <fenv.h>
20#include <limits.h>
21#include <math.h>
22
23#include <math_private.h>
24
25/* For LP64, lround is an alias for llround. */
26#ifndef _LP64
27
28long int
29__lround (double x)
30{
31 int32_t j0;
32 int64_t i0;
33 long int result;
34 int sign;
35
36 EXTRACT_WORDS64 (i0, x);
37 j0 = ((i0 >> 52) & 0x7ff) - 0x3ff;
38 sign = i0 < 0 ? -1 : 1;
39 i0 &= UINT64_C(0xfffffffffffff);
40 i0 |= UINT64_C(0x10000000000000);
41
42 if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
43 {
44 if (j0 < 0)
45 return j0 < -1 ? 0 : sign;
46 else if (j0 >= 52)
47 result = i0 << (j0 - 52);
48 else
49 {
50 i0 += UINT64_C(0x8000000000000) >> j0;
51
52 result = i0 >> (52 - j0);
53#ifdef FE_INVALID
54 if (sizeof (long int) == 4
55 && sign == 1
56 && result == LONG_MIN)
57 /* Rounding brought the value out of range. */
58 feraiseexcept (FE_INVALID);
59#endif
60 }
61 }
62 else
63 {
64 /* The number is too large. Unless it rounds to LONG_MIN,
65 FE_INVALID must be raised and the return value is
66 unspecified. */
67#ifdef FE_INVALID
68 if (sizeof (long int) == 4
69 && x <= (double) LONG_MIN - 0.5)
70 {
71 /* If truncation produces LONG_MIN, the cast will not raise
72 the exception, but may raise "inexact". */
73 feraiseexcept (FE_INVALID);
74 return LONG_MIN;
75 }
76#endif
77 return (long int) x;
78 }
79
80 return sign * result;
81}
82
83weak_alias (__lround, lround)
84# ifdef NO_LONG_DOUBLE
85strong_alias (__lround, __lroundl)
86weak_alias (__lround, lroundl)
87# endif
88
89#endif
90