125 lines
3.7 KiB
C
125 lines
3.7 KiB
C
/*-
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* Copyright (c) 2007 David Schultz
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD: src/lib/msun/src/s_nan.c,v 1.2 2007/12/18 23:46:32 das Exp $
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*/
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//VBS
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//#include <sys/endian.h>
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#include <ctype.h>
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#include <float.h>
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#include <openlibm_math.h>
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#include <stdint.h>
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#include <string.h> //for memset
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#include "math_private.h"
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#if !defined(__APPLE__) && !defined(__FreeBSD__) && !defined(__DragonFly__)
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static __inline int digittoint(int c) {
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if ('0' <= c && c <= '9')
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return (c - '0');
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else if ('A' <= c && c <= 'F')
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return (c - 'A' + 10);
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else if ('a' <= c && c <= 'f')
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return (c - 'a' + 10);
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return 0;
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}
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#endif
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/*
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* Scan a string of hexadecimal digits (the format nan(3) expects) and
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* make a bit array (using the local endianness). We stop when we
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* encounter an invalid character, NUL, etc. If we overflow, we do
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* the same as gcc's __builtin_nan(), namely, discard the high order bits.
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*
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* The format this routine accepts needs to be compatible with what is used
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* in contrib/gdtoa/hexnan.c (for strtod/scanf) and what is used in
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* __builtin_nan(). In fact, we're only 100% compatible for strings we
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* consider valid, so we might be violating the C standard. But it's
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* impossible to use nan(3) portably anyway, so this seems good enough.
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*/
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OLM_DLLEXPORT void
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__scan_nan(u_int32_t *words, int num_words, const char *s)
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{
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int si; /* index into s */
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int bitpos; /* index into words (in bits) */
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memset(words, 0, num_words * sizeof(u_int32_t));
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/* Allow a leading '0x'. (It's expected, but redundant.) */
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if (s[0] == '0' && (s[1] == 'x' || s[1] == 'X'))
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s += 2;
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/* Scan forwards in the string, looking for the end of the sequence. */
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for (si = 0; isxdigit(s[si]); si++)
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;
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/* Scan backwards, filling in the bits in words[] as we go. */
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#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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for (bitpos = 0; bitpos < 32 * num_words; bitpos += 4) {
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#else
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for (bitpos = 32 * num_words - 4; bitpos >= 0; bitpos -= 4) {
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#endif
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if (--si < 0)
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break;
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words[bitpos / 32] |= digittoint(s[si]) << (bitpos % 32);
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}
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}
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OLM_DLLEXPORT double
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nan(const char *s)
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{
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union {
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double d;
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u_int32_t bits[2];
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} u;
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__scan_nan(u.bits, 2, s);
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#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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u.bits[1] |= 0x7ff80000;
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#else
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u.bits[0] |= 0x7ff80000;
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#endif
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return (u.d);
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}
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OLM_DLLEXPORT float
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nanf(const char *s)
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{
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union {
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float f;
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u_int32_t bits[1];
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} u;
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__scan_nan(u.bits, 1, s);
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u.bits[0] |= 0x7fc00000;
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return (u.f);
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}
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#if (LDBL_MANT_DIG == 53)
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openlibm_weak_reference(nan, nanl);
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#endif
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