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: src/lib/msun/src/s_nan.c,v 1.2 2007/12/18 23:46:32 das Exp $ 27 */ 28 29 //VBS 30 //#include <sys/endian.h> 31 #include <ctype.h> 32 #include <float.h> 33 #include <openlibm_math.h> 34 #include <stdint.h> 35 #include <string.h> //for memset 36 37 #include "math_private.h" 38 39 #if !defined(__APPLE__) && !defined(__FreeBSD__) 40 static __inline int digittoint(int c) { 41 if ('0' <= c && c <= '9') 42 return (c - '0'); 43 else if ('A' <= c && c <= 'F') 44 return (c - 'A' + 10); 45 else if ('a' <= c && c <= 'f') 46 return (c - 'a' + 10); 47 return 0; 48 } 49 #endif 50 51 52 /* 53 * Scan a string of hexadecimal digits (the format nan(3) expects) and 54 * make a bit array (using the local endianness). We stop when we 55 * encounter an invalid character, NUL, etc. If we overflow, we do 56 * the same as gcc's __builtin_nan(), namely, discard the high order bits. 57 * 58 * The format this routine accepts needs to be compatible with what is used 59 * in contrib/gdtoa/hexnan.c (for strtod/scanf) and what is used in 60 * __builtin_nan(). In fact, we're only 100% compatible for strings we 61 * consider valid, so we might be violating the C standard. But it's 62 * impossible to use nan(3) portably anyway, so this seems good enough. 63 */ 64 OLM_DLLEXPORT void 65 __scan_nan(u_int32_t *words, int num_words, const char *s) 66 { 67 int si; /* index into s */ 68 int bitpos; /* index into words (in bits) */ 69 70 memset(words, 0, num_words * sizeof(u_int32_t)); 71 72 /* Allow a leading '0x'. (It's expected, but redundant.) */ 73 if (s[0] == '0' && (s[1] == 'x' || s[1] == 'X')) 74 s += 2; 75 76 /* Scan forwards in the string, looking for the end of the sequence. */ 77 for (si = 0; isxdigit(s[si]); si++) 78 ; 79 80 /* Scan backwards, filling in the bits in words[] as we go. */ 81 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ 82 for (bitpos = 0; bitpos < 32 * num_words; bitpos += 4) { 83 #else 84 for (bitpos = 32 * num_words - 4; bitpos >= 0; bitpos -= 4) { 85 #endif 86 if (--si < 0) 87 break; 88 words[bitpos / 32] |= digittoint(s[si]) << (bitpos % 32); 89 } 90 } 91 92 OLM_DLLEXPORT double 93 nan(const char *s) 94 { 95 union { 96 double d; 97 u_int32_t bits[2]; 98 } u; 99 100 __scan_nan(u.bits, 2, s); 101 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ 102 u.bits[1] |= 0x7ff80000; 103 #else 104 u.bits[0] |= 0x7ff80000; 105 #endif 106 return (u.d); 107 } 108 109 OLM_DLLEXPORT float 110 nanf(const char *s) 111 { 112 union { 113 float f; 114 u_int32_t bits[1]; 115 } u; 116 117 __scan_nan(u.bits, 1, s); 118 u.bits[0] |= 0x7fc00000; 119 return (u.f); 120 } 121 122 #if (LDBL_MANT_DIG == 53) 123 __weak_reference(nan, nanl); 124 #endif 125