2 * Copyright (c) 2007 David Schultz
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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
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23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * $FreeBSD: head/lib/msun/src/s_nan.c 174759 2007-12-18 23:46:32Z das $
29 #include <sys/endian.h>
36 #include "math_private.h"
45 return (c - 'a' + 10);
46 return (c - 'A' + 10);
50 * Scan a string of hexadecimal digits (the format nan(3) expects) and
51 * make a bit array (using the local endianness). We stop when we
52 * encounter an invalid character, NUL, etc. If we overflow, we do
53 * the same as gcc's __builtin_nan(), namely, discard the high order bits.
55 * The format this routine accepts needs to be compatible with what is used
56 * in contrib/gdtoa/hexnan.c (for strtod/scanf) and what is used in
57 * __builtin_nan(). In fact, we're only 100% compatible for strings we
58 * consider valid, so we might be violating the C standard. But it's
59 * impossible to use nan(3) portably anyway, so this seems good enough.
62 _scan_nan(uint32_t *words, int num_words, const char *s)
64 int si; /* index into s */
65 int bitpos; /* index into words (in bits) */
67 bzero(words, num_words * sizeof(uint32_t));
69 /* Allow a leading '0x'. (It's expected, but redundant.) */
70 if (s[0] == '0' && (s[1] == 'x' || s[1] == 'X'))
73 /* Scan forwards in the string, looking for the end of the sequence. */
74 for (si = 0; isxdigit(s[si]); si++)
77 /* Scan backwards, filling in the bits in words[] as we go. */
78 #if _BYTE_ORDER == _LITTLE_ENDIAN
79 for (bitpos = 0; bitpos < 32 * num_words; bitpos += 4) {
81 for (bitpos = 32 * num_words - 4; bitpos >= 0; bitpos -= 4) {
85 words[bitpos / 32] |= digittoint(s[si]) << (bitpos % 32);
97 _scan_nan(u.bits, 2, s);
98 #if _BYTE_ORDER == _LITTLE_ENDIAN
99 u.bits[1] |= 0x7ff80000;
101 u.bits[0] |= 0x7ff80000;
114 _scan_nan(u.bits, 1, s);
115 u.bits[0] |= 0x7fc00000;
119 #if (LDBL_MANT_DIG == 53)
120 __weak_reference(nan, nanl);