ipiq: Add simple IPI latency measure sysctls (2)
[dragonfly.git] / lib / libm / src / s_nan.c
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1/*-
2 * Copyright (c) 2007 David Schultz
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 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 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_nan.c 174759 2007-12-18 23:46:32Z das $
27 */
28
29#include <sys/endian.h>
30#include <ctype.h>
31#include <float.h>
32#include <math.h>
33#include <stdint.h>
34#include <strings.h>
35
36#include "math_private.h"
37
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38/*
39 * Scan a string of hexadecimal digits (the format nan(3) expects) and
40 * make a bit array (using the local endianness). We stop when we
41 * encounter an invalid character, NUL, etc. If we overflow, we do
42 * the same as gcc's __builtin_nan(), namely, discard the high order bits.
43 *
44 * The format this routine accepts needs to be compatible with what is used
45 * in contrib/gdtoa/hexnan.c (for strtod/scanf) and what is used in
46 * __builtin_nan(). In fact, we're only 100% compatible for strings we
47 * consider valid, so we might be violating the C standard. But it's
48 * impossible to use nan(3) portably anyway, so this seems good enough.
49 */
50void
51_scan_nan(uint32_t *words, int num_words, const char *s)
52{
53 int si; /* index into s */
54 int bitpos; /* index into words (in bits) */
55
56 bzero(words, num_words * sizeof(uint32_t));
57
58 /* Allow a leading '0x'. (It's expected, but redundant.) */
59 if (s[0] == '0' && (s[1] == 'x' || s[1] == 'X'))
60 s += 2;
61
62 /* Scan forwards in the string, looking for the end of the sequence. */
63 for (si = 0; isxdigit(s[si]); si++)
64 ;
65
66 /* Scan backwards, filling in the bits in words[] as we go. */
67#if _BYTE_ORDER == _LITTLE_ENDIAN
68 for (bitpos = 0; bitpos < 32 * num_words; bitpos += 4) {
69#else
70 for (bitpos = 32 * num_words - 4; bitpos >= 0; bitpos -= 4) {
71#endif
72 if (--si < 0)
73 break;
74 words[bitpos / 32] |= digittoint(s[si]) << (bitpos % 32);
75 }
76}
77
78double
79nan(const char *s)
80{
81 union {
82 double d;
83 uint32_t bits[2];
84 } u;
85
86 _scan_nan(u.bits, 2, s);
87#if _BYTE_ORDER == _LITTLE_ENDIAN
88 u.bits[1] |= 0x7ff80000;
89#else
90 u.bits[0] |= 0x7ff80000;
91#endif
92 return (u.d);
93}
94
95float
96nanf(const char *s)
97{
98 union {
99 float f;
100 uint32_t bits[1];
101 } u;
102
103 _scan_nan(u.bits, 1, s);
104 u.bits[0] |= 0x7fc00000;
105 return (u.f);
106}
107
108#if (LDBL_MANT_DIG == 53)
109__weak_reference(nan, nanl);
110#endif