xref: /freebsd/lib/msun/src/s_lround.c (revision 4f52dfbb8d6c4d446500c5b097e3806ec219fbd4)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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 __FBSDID("$FreeBSD$");
36 #define type		double
37 #define	roundit		round
38 #define dtype		long
39 #define	DTYPE_MIN	LONG_MIN
40 #define	DTYPE_MAX	LONG_MAX
41 #define	fn		lround
42 #endif
43 
44 /*
45  * If type has more precision than dtype, the endpoints dtype_(min|max) are
46  * of the form xxx.5; they are "out of range" because lround() rounds away
47  * from 0.  On the other hand, if type has less precision than dtype, then
48  * all values that are out of range are integral, so we might as well assume
49  * that everything is in range.  At compile time, INRANGE(x) should reduce to
50  * two floating-point comparisons in the former case, or TRUE otherwise.
51  */
52 static const type dtype_min = DTYPE_MIN - 0.5;
53 static const type dtype_max = DTYPE_MAX + 0.5;
54 #define	INRANGE(x)	(dtype_max - DTYPE_MAX != 0.5 || \
55 			 ((x) > dtype_min && (x) < dtype_max))
56 
57 dtype
58 fn(type x)
59 {
60 
61 	if (INRANGE(x)) {
62 		x = roundit(x);
63 		return ((dtype)x);
64 	} else {
65 		feraiseexcept(FE_INVALID);
66 		return (DTYPE_MAX);
67 	}
68 }
69