1 /* $OpenBSD: s_nan.c,v 1.7 2011/05/30 18:34:38 martynas Exp $ */ 2 /*- 3 * Copyright (c) 2007 David Schultz 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 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. 14 * 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 25 * SUCH DAMAGE. 26 * 27 * $FreeBSD: src/lib/msun/src/s_nan.c,v 1.2 2007/12/18 23:46:32 das Exp $ 28 */ 29 30 /* LINTLIBRARY */ 31 32 #include <sys/cdefs.h> 33 #include <sys/types.h> 34 #include <sys/endian.h> 35 #include <ctype.h> 36 #include <float.h> 37 #include <math.h> 38 #include <stdint.h> 39 #include <strings.h> 40 41 #include "math_private.h" 42 43 /* 44 * OpenBSD's ctype doesn't have digittoint, so we define it here. 45 */ 46 static int 47 _digittoint(int c) 48 { 49 if (!isxdigit(c)) 50 return 0; 51 52 if (isdigit(c)) 53 return c - '0'; 54 else 55 return isupper(c) ? c - 'A' + 10 : c - 'a' + 10; 56 } 57 58 /* 59 * Scan a string of hexadecimal digits (the format nan(3) expects) and 60 * make a bit array (using the local endianness). We stop when we 61 * encounter an invalid character, NUL, etc. If we overflow, we do 62 * the same as gcc's __builtin_nan(), namely, discard the high order bits. 63 * 64 * The format this routine accepts needs to be compatible with what is used 65 * in contrib/gdtoa/hexnan.c (for strtod/scanf) and what is used in 66 * __builtin_nan(). In fact, we're only 100% compatible for strings we 67 * consider valid, so we might be violating the C standard. But it's 68 * impossible to use nan(3) portably anyway, so this seems good enough. 69 */ 70 void 71 _scan_nan(uint32_t *words, int num_words, const char *s) 72 { 73 int si; /* index into s */ 74 int bitpos; /* index into words (in bits) */ 75 76 bzero(words, num_words * sizeof(uint32_t)); 77 78 /* Allow a leading '0x'. (It's expected, but redundant.) */ 79 if (s[0] == '0' && (s[1] == 'x' || s[1] == 'X')) 80 s += 2; 81 82 /* Scan forwards in the string, looking for the end of the sequence. */ 83 for (si = 0; isxdigit(s[si]); si++) 84 ; 85 86 /* Scan backwards, filling in the bits in words[] as we go. */ 87 #if _BYTE_ORDER == _LITTLE_ENDIAN 88 for (bitpos = 0; bitpos < 32 * num_words; bitpos += 4) { 89 #else 90 for (bitpos = 32 * num_words - 4; bitpos >= 0; bitpos -= 4) { 91 #endif 92 if (--si < 0) 93 break; 94 words[bitpos / 32] |= _digittoint(s[si]) << (bitpos % 32); 95 } 96 } 97 98 double 99 nan(const char *s) 100 { 101 union { 102 double d; 103 uint32_t bits[2]; 104 } u; 105 106 _scan_nan(u.bits, 2, s); 107 #if _BYTE_ORDER == _LITTLE_ENDIAN 108 u.bits[1] |= 0x7ff80000; 109 #else 110 u.bits[0] |= 0x7ff80000; 111 #endif 112 return (u.d); 113 } 114 115 float 116 nanf(const char *s) 117 { 118 union { 119 float f; 120 uint32_t bits[1]; 121 } u; 122 123 _scan_nan(u.bits, 1, s); 124 u.bits[0] |= 0x7fc00000; 125 return (u.f); 126 } 127 128 #if LDBL_MANT_DIG == 53 129 #ifdef lint 130 /* PROTOLIB1 */ 131 long double nanl(const char *); 132 #else /* lint */ 133 __weak_alias(nanl, nan); 134 #endif /* lint */ 135 #endif /* LDBL_MANT_DIG == 53 */ 136