]>
git.ipfire.org Git - thirdparty/glibc.git/blob - sysdeps/ieee754/ldbl-128/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 (_Float128 x
)
32 GET_LDOUBLE_WORDS64 (hx
, lx
, x
);
33 uhx
= hx
& 0x7fffffffffffffffULL
;
34 int exponent
= uhx
>> (MANT_DIG
- 1 - 64);
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
- 64)
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 uint64_t half_bit
= 1ULL << half_pos
;
51 uint64_t int_bit
= 1ULL << int_pos
;
52 if ((lx
& (int_bit
| (half_bit
- 1))) != 0)
54 /* Carry into the exponent works correctly. No need to test
55 whether HALF_BIT is set. */
61 else if (exponent
== BIAS
+ MANT_DIG
- 65)
63 /* Not necessarily an integer; integer bit is bottom of high
64 word, half bit is top of low word. */
65 if (((hx
& 1) | (lx
& 0x7fffffffffffffffULL
)) != 0)
67 lx
+= 0x8000000000000000ULL
;
68 hx
+= lx
< 0x8000000000000000ULL
;
72 else if (exponent
>= BIAS
)
74 /* At least 1; not necessarily an integer, integer bit and half
75 bit are in the high word. Locate the bits with exponents 0
76 and -1 (when the unbiased exponent is 0, the bit with
77 exponent 0 is implicit, but as the bias is odd it is OK to
78 take it from the low bit of the exponent). */
79 int int_pos
= (BIAS
+ MANT_DIG
- 65) - exponent
;
80 int half_pos
= int_pos
- 1;
81 uint64_t half_bit
= 1ULL << half_pos
;
82 uint64_t int_bit
= 1ULL << int_pos
;
83 if (((hx
& (int_bit
| (half_bit
- 1))) | lx
) != 0)
88 else if (exponent
== BIAS
- 1 && (uhx
> 0x3ffe000000000000ULL
|| lx
!= 0))
90 /* Interval (0.5, 1). */
91 hx
= (hx
& 0x8000000000000000ULL
) | 0x3fff000000000000ULL
;
97 hx
&= 0x8000000000000000ULL
;
100 SET_LDOUBLE_WORDS64 (x
, hx
, lx
);