xref: /freebsd/lib/msun/src/s_lrint.c (revision 6580f5c38dd5b01aeeaed16b370f1a12423437f0)
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 <fenv.h>
30 #include <math.h>
31 
32 #ifndef type
33 #define type		double
34 #define	roundit		rint
35 #define dtype		long
36 #define	fn		lrint
37 #endif
38 
39 /*
40  * C99 says we should not raise a spurious inexact exception when an
41  * invalid exception is raised.  Unfortunately, the set of inputs
42  * that overflows depends on the rounding mode when 'dtype' has more
43  * significant bits than 'type'.  Hence, we bend over backwards for the
44  * sake of correctness; an MD implementation could be more efficient.
45  */
46 dtype
47 fn(type x)
48 {
49 	fenv_t env;
50 	dtype d;
51 
52 	feholdexcept(&env);
53 	d = (dtype)roundit(x);
54 	if (fetestexcept(FE_INVALID))
55 		feclearexcept(FE_INEXACT);
56 	feupdateenv(&env);
57 	return (d);
58 }
59