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git.ipfire.org Git - thirdparty/glibc.git/blob - sysdeps/ieee754/ldbl-96/s_roundevenl.c
1 /* Round to nearest integer value, rounding halfway cases to even.
3 Copyright (C) 2016-2017 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <http://www.gnu.org/licenses/>. */
21 #include <math_private.h>
26 #define MAX_EXP (2 * BIAS + 1)
29 roundevenl (long double x
)
33 GET_LDOUBLE_WORDS (se
, hx
, lx
, x
);
34 int exponent
= se
& 0x7fff;
35 if (exponent
>= BIAS
+ MANT_DIG
- 1)
37 /* Integer, infinity or NaN. */
38 if (exponent
== MAX_EXP
)
39 /* Infinity or NaN; quiet signaling NaNs. */
44 else if (exponent
>= BIAS
+ MANT_DIG
- 32)
46 /* Not necessarily an integer; integer bit is in low word.
47 Locate the bits with exponents 0 and -1. */
48 int int_pos
= (BIAS
+ MANT_DIG
- 1) - exponent
;
49 int half_pos
= int_pos
- 1;
50 uint32_t half_bit
= 1U << half_pos
;
51 uint32_t int_bit
= 1U << int_pos
;
52 if ((lx
& (int_bit
| (half_bit
- 1))) != 0)
54 /* No need to test whether HALF_BIT is set. */
68 else if (exponent
== BIAS
+ MANT_DIG
- 33)
70 /* Not necessarily an integer; integer bit is bottom of high
71 word, half bit is top of low word. */
72 if (((hx
& 1) | (lx
& 0x7fffffff)) != 0)
87 else if (exponent
>= BIAS
)
89 /* At least 1; not necessarily an integer, integer bit and half
90 bit are in the high word. Locate the bits with exponents 0
92 int int_pos
= (BIAS
+ MANT_DIG
- 33) - exponent
;
93 int half_pos
= int_pos
- 1;
94 uint32_t half_bit
= 1U << half_pos
;
95 uint32_t int_bit
= 1U << int_pos
;
96 if (((hx
& (int_bit
| (half_bit
- 1))) | lx
) != 0)
105 hx
&= ~(int_bit
- 1);
108 else if (exponent
== BIAS
- 1 && (hx
> 0x80000000 || lx
!= 0))
110 /* Interval (0.5, 1). */
111 se
= (se
& 0x8000) | 0x3fff;
122 SET_LDOUBLE_WORDS (x
, se
, hx
, lx
);