/* $OpenBSD: s_nan.c,v 1.1 2008/07/24 09:40:16 martynas Exp $ */ /*- * Copyright (c) 2007 David Schultz * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * $FreeBSD: src/lib/msun/src/s_nan.c,v 1.2 2007/12/18 23:46:32 das Exp $ */ #include #include #include #include #include #include #include #include "math_private.h" /* * OpenBSD's ctype doesn't have digittoint, so we define it here. */ int _digittoint(int c) { if (!isxdigit(c)) return 0; if (isdigit(c)) return c - '0'; else return isupper(c) ? c - 'A' + 10 : c - 'a' + 10; } /* * Scan a string of hexadecimal digits (the format nan(3) expects) and * make a bit array (using the local endianness). We stop when we * encounter an invalid character, NUL, etc. If we overflow, we do * the same as gcc's __builtin_nan(), namely, discard the high order bits. * * The format this routine accepts needs to be compatible with what is used * in contrib/gdtoa/hexnan.c (for strtod/scanf) and what is used in * __builtin_nan(). In fact, we're only 100% compatible for strings we * consider valid, so we might be violating the C standard. But it's * impossible to use nan(3) portably anyway, so this seems good enough. */ void _scan_nan(uint32_t *words, int num_words, const char *s) { int si; /* index into s */ int bitpos; /* index into words (in bits) */ bzero(words, num_words * sizeof(uint32_t)); /* Allow a leading '0x'. (It's expected, but redundant.) */ if (s[0] == '0' && (s[1] == 'x' || s[1] == 'X')) s += 2; /* Scan forwards in the string, looking for the end of the sequence. */ for (si = 0; isxdigit(s[si]); si++) ; /* Scan backwards, filling in the bits in words[] as we go. */ #if _BYTE_ORDER == _LITTLE_ENDIAN for (bitpos = 0; bitpos < 32 * num_words; bitpos += 4) { #else for (bitpos = 32 * num_words - 4; bitpos >= 0; bitpos -= 4) { #endif if (--si < 0) break; words[bitpos / 32] |= _digittoint(s[si]) << (bitpos % 32); } } double nan(const char *s) { union { double d; uint32_t bits[2]; } u; _scan_nan(u.bits, 2, s); #if _BYTE_ORDER == _LITTLE_ENDIAN u.bits[1] |= 0x7ff80000; #else u.bits[0] |= 0x7ff80000; #endif return (u.d); } float nanf(const char *s) { union { float f; uint32_t bits[1]; } u; _scan_nan(u.bits, 1, s); u.bits[0] |= 0x7fc00000; return (u.f); }