ipiq: Add simple IPI latency measure sysctls (2)
[dragonfly.git] / lib / libm / src / s_rintl.c
CommitLineData
2fedfd5c
JM
1/*-
2 * Copyright (c) 2008 David Schultz <das@FreeBSD.ORG>
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, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD: head/lib/msun/src/s_rintl.c 176461 2008-02-22 11:59:05Z bde $
27 */
28
29
30#include <float.h>
31#include <math.h>
32
33#include "fpmath.h"
34
35#if LDBL_MAX_EXP != 0x4000
36/* We also require the usual bias, min exp and expsign packing. */
37#error "Unsupported long double format"
38#endif
39
40#define BIAS (LDBL_MAX_EXP - 1)
41
42static const float
43shift[2] = {
44#if LDBL_MANT_DIG == 64
45 0x1.0p63, -0x1.0p63
46#elif LDBL_MANT_DIG == 113
47 0x1.0p112, -0x1.0p112
48#else
49#error "Unsupported long double format"
50#endif
51};
52static const float zero[2] = { 0.0, -0.0 };
53
54long double
55rintl(long double x)
56{
57 union IEEEl2bits u;
58 uint32_t expsign;
59 int ex, sign;
60
61 u.e = x;
62 expsign = u.xbits.expsign;
63 ex = expsign & 0x7fff;
64
65 if (ex >= BIAS + LDBL_MANT_DIG - 1) {
66 if (ex == BIAS + LDBL_MAX_EXP)
67 return (x + x); /* Inf, NaN, or unsupported format */
68 return (x); /* finite and already an integer */
69 }
70 sign = expsign >> 15;
71
72 /*
73 * The following code assumes that intermediate results are
74 * evaluated in long double precision. If they are evaluated in
75 * greater precision, double rounding may occur, and if they are
76 * evaluated in less precision (as on i386), results will be
77 * wildly incorrect.
78 */
79 x += shift[sign];
80 x -= shift[sign];
81
82 /*
83 * If the result is +-0, then it must have the same sign as x, but
84 * the above calculation doesn't always give this. Fix up the sign.
85 */
86 if (ex < BIAS && x == 0.0L)
87 return (zero[sign]);
88
89 return (x);
90}