xref: /netbsd-src/lib/libm/src/s_nearbyint.c (revision 7748d96434ce3103b51cdc71a32b3a6dcaea4c88)
1 /*	$NetBSD: s_nearbyint.c,v 1.6 2024/10/30 16:57:16 riastradh Exp $	*/
2 
3 /*-
4  * Copyright (c) 2004 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 #if 0
31 __FBSDID("$FreeBSD: src/lib/msun/src/s_nearbyint.c,v 1.2 2008/01/14 02:12:06 das Exp $");
32 #else
33 __RCSID("$NetBSD: s_nearbyint.c,v 1.6 2024/10/30 16:57:16 riastradh Exp $");
34 #endif
35 
36 #include "namespace.h"
37 
38 #include <machine/ieee.h>
39 #include <fenv.h>
40 #include <math.h>
41 
42 /*
43  * We save and restore the floating-point environment to avoid raising
44  * an inexact exception.  We can get away with using fesetenv()
45  * instead of feclearexcept()/feupdateenv() to restore the environment
46  * because the only exception defined for rint() is overflow, and
47  * rounding can't overflow as long as emax >= p.
48  */
49 #define	DECL(type, fn, rintfn)	\
50 type				\
51 fn(type x)			\
52 {				\
53 	type ret;		\
54 	fenv_t env;		\
55 				\
56 	fegetenv(&env);		\
57 	ret = rintfn(x);	\
58 	fesetenv(&env);		\
59 	return (ret);		\
60 }
61 
62 DECL(double, nearbyint, rint)
63 DECL(float, nearbyintf, rintf)
64 DECL(long double, nearbyintl, rintl)
65