xref: /freebsd/lib/msun/src/s_roundl.c (revision 6580f5c38dd5b01aeeaed16b370f1a12423437f0)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2003, Steven G. Kargl
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 unmodified, this list of conditions, and the following
12  *    disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27  */
28 
29 #include <float.h>
30 #ifdef __i386__
31 #include <ieeefp.h>
32 #endif
33 
34 #include "fpmath.h"
35 #include "math.h"
36 #include "math_private.h"
37 
38 long double
39 roundl(long double x)
40 {
41 	long double t;
42 	uint16_t hx;
43 
44 	GET_LDBL_EXPSIGN(hx, x);
45 	if ((hx & 0x7fff) == 0x7fff)
46 		return (x + x);
47 
48 	ENTERI();
49 
50 	if (!(hx & 0x8000)) {
51 		t = floorl(x);
52 		if (t - x <= -0.5L)
53 			t += 1;
54 		RETURNI(t);
55 	} else {
56 		t = floorl(-x);
57 		if (t + x <= -0.5L)
58 			t += 1;
59 		RETURNI(-t);
60 	}
61 }
62