s_round.c revision 271779 
1/*-
2 * Copyright (c) 2003, Steven G. Kargl
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice unmodified, this list of conditions, and the following
10 *    disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: stable/10/lib/msun/src/s_round.c 271779 2014-09-18 15:10:22Z tijl $");
29
30#include <float.h>
31
32#include "math.h"
33#include "math_private.h"
34
35double
36round(double x)
37{
38	double t;
39	uint32_t hx;
40
41	GET_HIGH_WORD(hx, x);
42	if ((hx & 0x7fffffff) == 0x7ff00000)
43		return (x + x);
44
45	if (!(hx & 0x80000000)) {
46		t = floor(x);
47		if (t - x <= -0.5)
48			t += 1;
49		return (t);
50	} else {
51		t = floor(-x);
52		if (t + x <= -0.5)
53			t += 1;
54		return (-t);
55	}
56}
57
58#if (LDBL_MANT_DIG == 53)
59__weak_reference(round, roundl);
60#endif
61