1 /* Round long double value to long int.
2 Copyright (C) 1997-2018 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997 and
5 Jakub Jelinek <jj@ultra.linux.cz>, 1999.
6
7 The GNU C Library is free software; you can redistribute it and/or
8 modify it under the terms of the GNU Lesser General Public
9 License as published by the Free Software Foundation; either
10 version 2.1 of the 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 Lesser General Public License for more details.
16
17 You should have received a copy of the GNU Lesser General Public
18 License along with the GNU C Library; if not, see
19 <http://www.gnu.org/licenses/>. */
20
21 #include "quadmath-imp.h"
22
23 long int
lroundq(__float128 x)24 lroundq (__float128 x)
25 {
26 int64_t j0;
27 uint64_t i1, i0;
28 long int result;
29 int sign;
30
31 GET_FLT128_WORDS64 (i0, i1, x);
32 j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
33 sign = (i0 & 0x8000000000000000ULL) != 0 ? -1 : 1;
34 i0 &= 0x0000ffffffffffffLL;
35 i0 |= 0x0001000000000000LL;
36
37 if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
38 {
39 if (j0 < 48)
40 {
41 if (j0 < 0)
42 return j0 < -1 ? 0 : sign;
43 else
44 {
45 i0 += 0x0000800000000000LL >> j0;
46 result = i0 >> (48 - j0);
47 #ifdef FE_INVALID
48 if (sizeof (long int) == 4
49 && sign == 1
50 && result == LONG_MIN)
51 /* Rounding brought the value out of range. */
52 feraiseexcept (FE_INVALID);
53 #endif
54 }
55 }
56 else if (j0 >= 112)
57 result = ((long int) i0 << (j0 - 48)) | (i1 << (j0 - 112));
58 else
59 {
60 uint64_t j = i1 + (0x8000000000000000ULL >> (j0 - 48));
61 if (j < i1)
62 ++i0;
63
64 if (j0 == 48)
65 result = (long int) i0;
66 else
67 {
68 result = ((long int) i0 << (j0 - 48)) | (j >> (112 - j0));
69 #ifdef FE_INVALID
70 if (sizeof (long int) == 8
71 && sign == 1
72 && result == LONG_MIN)
73 /* Rounding brought the value out of range. */
74 feraiseexcept (FE_INVALID);
75 #endif
76 }
77 }
78 }
79 else
80 {
81 /* The number is too large. Unless it rounds to LONG_MIN,
82 FE_INVALID must be raised and the return value is
83 unspecified. */
84 #ifdef FE_INVALID
85 if (FIX_FLT128_LONG_CONVERT_OVERFLOW
86 && !(sign == -1 && x > (__float128) LONG_MIN - 0.5Q))
87 {
88 feraiseexcept (FE_INVALID);
89 return sign == 1 ? LONG_MAX : LONG_MIN;
90 }
91 else if (!FIX_FLT128_LONG_CONVERT_OVERFLOW
92 && x <= (__float128) LONG_MIN - 0.5Q)
93 {
94 /* If truncation produces LONG_MIN, the cast will not raise
95 the exception, but may raise "inexact". */
96 feraiseexcept (FE_INVALID);
97 return LONG_MIN;
98 }
99 #endif
100 /* The number is too large. It is left implementation defined
101 what happens. */
102 return (long int) x;
103 }
104
105 return sign * result;
106 }
107