David 'Digit' Turner | 8e2ff16 | 2011-01-25 17:05:50 +0100 | [diff] [blame] | 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 | * $FreeBSD$ |
| 27 | */ |
| 28 | |
| 29 | #include <sys/endian.h> |
| 30 | #include <ctype.h> |
| 31 | #include <float.h> |
| 32 | #include <math.h> |
| 33 | #include <stdint.h> |
| 34 | #include <strings.h> |
| 35 | |
| 36 | #include "math_private.h" |
| 37 | |
David 'Digit' Turner | 8e2ff16 | 2011-01-25 17:05:50 +0100 | [diff] [blame] | 38 | /* |
| 39 | * Scan a string of hexadecimal digits (the format nan(3) expects) and |
| 40 | * make a bit array (using the local endianness). We stop when we |
| 41 | * encounter an invalid character, NUL, etc. If we overflow, we do |
| 42 | * the same as gcc's __builtin_nan(), namely, discard the high order bits. |
| 43 | * |
| 44 | * The format this routine accepts needs to be compatible with what is used |
| 45 | * in contrib/gdtoa/hexnan.c (for strtod/scanf) and what is used in |
| 46 | * __builtin_nan(). In fact, we're only 100% compatible for strings we |
| 47 | * consider valid, so we might be violating the C standard. But it's |
| 48 | * impossible to use nan(3) portably anyway, so this seems good enough. |
| 49 | */ |
| 50 | void |
| 51 | _scan_nan(uint32_t *words, int num_words, const char *s) |
| 52 | { |
| 53 | int si; /* index into s */ |
| 54 | int bitpos; /* index into words (in bits) */ |
| 55 | |
| 56 | bzero(words, num_words * sizeof(uint32_t)); |
| 57 | |
| 58 | /* Allow a leading '0x'. (It's expected, but redundant.) */ |
| 59 | if (s[0] == '0' && (s[1] == 'x' || s[1] == 'X')) |
| 60 | s += 2; |
| 61 | |
| 62 | /* Scan forwards in the string, looking for the end of the sequence. */ |
| 63 | for (si = 0; isxdigit(s[si]); si++) |
| 64 | ; |
| 65 | |
| 66 | /* Scan backwards, filling in the bits in words[] as we go. */ |
| 67 | #if _BYTE_ORDER == _LITTLE_ENDIAN |
| 68 | for (bitpos = 0; bitpos < 32 * num_words; bitpos += 4) { |
| 69 | #else |
| 70 | for (bitpos = 32 * num_words - 4; bitpos >= 0; bitpos -= 4) { |
| 71 | #endif |
| 72 | if (--si < 0) |
| 73 | break; |
| 74 | words[bitpos / 32] |= digittoint(s[si]) << (bitpos % 32); |
| 75 | } |
| 76 | } |
| 77 | |
| 78 | double |
| 79 | nan(const char *s) |
| 80 | { |
| 81 | union { |
| 82 | double d; |
| 83 | uint32_t bits[2]; |
| 84 | } u; |
| 85 | |
| 86 | _scan_nan(u.bits, 2, s); |
| 87 | #if _BYTE_ORDER == _LITTLE_ENDIAN |
| 88 | u.bits[1] |= 0x7ff80000; |
| 89 | #else |
| 90 | u.bits[0] |= 0x7ff80000; |
| 91 | #endif |
| 92 | return (u.d); |
| 93 | } |
| 94 | |
| 95 | float |
| 96 | nanf(const char *s) |
| 97 | { |
| 98 | union { |
| 99 | float f; |
| 100 | uint32_t bits[1]; |
| 101 | } u; |
| 102 | |
| 103 | _scan_nan(u.bits, 1, s); |
| 104 | u.bits[0] |= 0x7fc00000; |
| 105 | return (u.f); |
| 106 | } |
| 107 | |
| 108 | #if (LDBL_MANT_DIG == 53) |
Elliott Hughes | a0ee078 | 2013-01-30 19:06:37 -0800 | [diff] [blame] | 109 | __weak_reference(nan, nanl); |
David 'Digit' Turner | 8e2ff16 | 2011-01-25 17:05:50 +0100 | [diff] [blame] | 110 | #endif |