1 /* Round to nearest integer value, rounding halfway cases to even.
3 Copyright (C) 2016-2023 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 <https://www.gnu.org/licenses/>. */
20 #define NO_MATH_REDIRECT
22 #include <math_private.h>
23 #include <libm-alias-float.h>
24 #include <math-use-builtins.h>
29 #define MAX_EXP (2 * BIAS + 1)
32 __roundevenf (float x
)
34 #if USE_ROUNDEVENF_BUILTIN
35 return __builtin_roundevenf (x
);
38 GET_FLOAT_WORD (ix
, x
);
40 int exponent
= ux
>> (MANT_DIG
- 1);
41 if (exponent
>= BIAS
+ MANT_DIG
- 1)
43 /* Integer, infinity or NaN. */
44 if (exponent
== MAX_EXP
)
45 /* Infinity or NaN; quiet signaling NaNs. */
50 else if (exponent
>= BIAS
)
52 /* At least 1; not necessarily an integer. Locate the bits with
53 exponents 0 and -1 (when the unbiased exponent is 0, the bit
54 with exponent 0 is implicit, but as the bias is odd it is OK
55 to take it from the low bit of the exponent). */
56 int int_pos
= (BIAS
+ MANT_DIG
- 1) - exponent
;
57 int half_pos
= int_pos
- 1;
58 uint32_t half_bit
= 1U << half_pos
;
59 uint32_t int_bit
= 1U << int_pos
;
60 if ((ix
& (int_bit
| (half_bit
- 1))) != 0)
61 /* Carry into the exponent works correctly. No need to test
62 whether HALF_BIT is set. */
66 else if (exponent
== BIAS
- 1 && ux
> 0x3f000000)
67 /* Interval (0.5, 1). */
68 ix
= (ix
& 0x80000000) | 0x3f800000;
72 SET_FLOAT_WORD (x
, ix
);
74 #endif /* ! USE_ROUNDEVENF_BUILTIN */
77 libm_alias_float (__roundeven
, roundeven
)