1/* Round double value to long int.
2 Copyright (C) 1997-2020 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 <https://www.gnu.org/licenses/>. */
18
19#include <fenv.h>
20#include <limits.h>
21#include <math.h>
22
23#include <math_private.h>
24#include <libm-alias-double.h>
25
26/* For LP64, lround is an alias for llround. */
27#ifndef _LP64
28
29long int
30__lround (double x)
31{
32 int32_t j0;
33 int64_t i0;
34 long int result;
35 int sign;
36
37 EXTRACT_WORDS64 (i0, x);
38 j0 = ((i0 >> 52) & 0x7ff) - 0x3ff;
39 sign = i0 < 0 ? -1 : 1;
40 i0 &= UINT64_C(0xfffffffffffff);
41 i0 |= UINT64_C(0x10000000000000);
42
43 if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
44 {
45 if (j0 < 0)
46 return j0 < -1 ? 0 : sign;
47 else if (j0 >= 52)
48 result = i0 << (j0 - 52);
49 else
50 {
51 i0 += UINT64_C(0x8000000000000) >> j0;
52
53 result = i0 >> (52 - j0);
54#ifdef FE_INVALID
55 if (sizeof (long int) == 4
56 && sign == 1
57 && result == LONG_MIN)
58 /* Rounding brought the value out of range. */
59 feraiseexcept (FE_INVALID);
60#endif
61 }
62 }
63 else
64 {
65 /* The number is too large. Unless it rounds to LONG_MIN,
66 FE_INVALID must be raised and the return value is
67 unspecified. */
68#ifdef FE_INVALID
69 if (sizeof (long int) == 4
70 && x <= (double) LONG_MIN - 0.5)
71 {
72 /* If truncation produces LONG_MIN, the cast will not raise
73 the exception, but may raise "inexact". */
74 feraiseexcept (FE_INVALID);
75 return LONG_MIN;
76 }
77#endif
78 return (long int) x;
79 }
80
81 return sign * result;
82}
83
84libm_alias_double (__lround, lround)
85
86#endif
87