xref: /freebsd/lib/msun/src/s_lround.c (revision 2008043f386721d58158e37e0d7e50df8095942d)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2005 David Schultz <das@FreeBSD.ORG>
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 #include <sys/cdefs.h>
30 #include <sys/limits.h>
31 #include <fenv.h>
32 #include <math.h>
33 
34 #ifndef type
35 #define type		double
36 #define	roundit		round
37 #define dtype		long
38 #define	DTYPE_MIN	LONG_MIN
39 #define	DTYPE_MAX	LONG_MAX
40 #define	fn		lround
41 #endif
42 
43 /*
44  * If type has more precision than dtype, the endpoints dtype_(min|max) are
45  * of the form xxx.5; they are "out of range" because lround() rounds away
46  * from 0.  On the other hand, if type has less precision than dtype, then
47  * all values that are out of range are integral, so we might as well assume
48  * that everything is in range.  At compile time, INRANGE(x) should reduce to
49  * two floating-point comparisons in the former case, or TRUE otherwise.
50  */
51 static const type type_min = (type)DTYPE_MIN;
52 static const type type_max = (type)DTYPE_MAX;
53 static const type dtype_min = (type)DTYPE_MIN - 0.5;
54 static const type dtype_max = (type)DTYPE_MAX + 0.5;
55 #define	INRANGE(x)	(dtype_max - type_max != 0.5 || \
56 			 ((x) > dtype_min && (x) < dtype_max))
57 
58 dtype
59 fn(type x)
60 {
61 
62 	if (INRANGE(x)) {
63 		x = roundit(x);
64 		return ((dtype)x);
65 	} else {
66 		feraiseexcept(FE_INVALID);
67 		return (DTYPE_MAX);
68 	}
69 }
70