1 /* $OpenBSD: s_nan.c,v 1.13 2014/07/21 01:51:11 guenther Exp $ */
3 * Copyright (c) 2007 David Schultz
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following 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.
15 * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * $FreeBSD: src/lib/msun/src/s_nan.c,v 1.2 2007/12/18 23:46:32 das Exp $
30 #include <sys/types.h>
38 #include "math_private.h"
41 * OpenBSD's ctype doesn't have digittoint, so we define it here.
52 return isupper(c) ? c - 'A' + 10 : c - 'a' + 10;
56 * Scan a string of hexadecimal digits (the format nan(3) expects) and
57 * make a bit array (using the local endianness). We stop when we
58 * encounter an invalid character, NUL, etc. If we overflow, we do
59 * the same as gcc's __builtin_nan(), namely, discard the high order bits.
61 * The format this routine accepts needs to be compatible with what is used
62 * in contrib/gdtoa/hexnan.c (for strtod/scanf) and what is used in
63 * __builtin_nan(). In fact, we're only 100% compatible for strings we
64 * consider valid, so we might be violating the C standard. But it's
65 * impossible to use nan(3) portably anyway, so this seems good enough.
68 _scan_nan(uint32_t *words, int num_words, const char *s)
70 int si; /* index into s */
71 int bitpos; /* index into words (in bits) */
73 bzero(words, num_words * sizeof(uint32_t));
75 /* Allow a leading '0x'. (It's expected, but redundant.) */
76 if (s[0] == '0' && (s[1] == 'x' || s[1] == 'X'))
79 /* Scan forwards in the string, looking for the end of the sequence. */
80 for (si = 0; isxdigit((unsigned char)s[si]); si++)
83 /* Scan backwards, filling in the bits in words[] as we go. */
84 #if BYTE_ORDER == LITTLE_ENDIAN
85 for (bitpos = 0; bitpos < 32 * num_words; bitpos += 4) {
87 for (bitpos = 32 * num_words - 4; bitpos >= 0; bitpos -= 4) {
91 words[bitpos / 32] |= _digittoint((unsigned char)s[si]) << (bitpos % 32);
103 _scan_nan(u.bits, 2, s);
104 #if BYTE_ORDER == LITTLE_ENDIAN
105 u.bits[1] |= 0x7ff80000;
107 u.bits[0] |= 0x7ff80000;
120 _scan_nan(u.bits, 1, s);
121 u.bits[0] |= 0x7fc00000;
125 #if LDBL_MANT_DIG == DBL_MANT_DIG
126 __strong_alias(nanl, nan);
127 #endif /* LDBL_MANT_DIG == DBL_MANT_DIG */