compiler/stdc/math/s_nan.c

   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 #include <aros/cpu.h>
  30
  31 #include <ctype.h>
  32 #include <float.h>
  33 #include <math.h>
  34 #include <stdint.h>
  35 #include <string.h> //for memset
  36 #include <math.h>
  37
  38 #if !defined(__APPLE__) && !defined(__FreeBSD__) && !defined(__DragonFly__)
  39 static __inline int digittoint(int c) {
  40         if ('0' <= c && c <= '9')
  41                 return (c - '0');
  42         else if ('A' <= c && c <= 'F')
  43                 return (c - 'A' + 10);
  44         else if ('a' <= c && c <= 'f')
  45                 return (c - 'a' + 10);
  46         return 0;
  47 }
  48 #endif
  49
  50 /*
  51  * Scan a string of hexadecimal digits (the format nan(3) expects) and
  52  * make a bit array (using the local endianness). We stop when we
  53  * encounter an invalid character, NUL, etc.  If we overflow, we do
  54  * the same as gcc's __builtin_nan(), namely, discard the high order bits.
  55  *
  56  * The format this routine accepts needs to be compatible with what is used
  57  * in contrib/gdtoa/hexnan.c (for strtod/scanf) and what is used in
  58  * __builtin_nan(). In fact, we're only 100% compatible for strings we
  59  * consider valid, so we might be violating the C standard. But it's
  60  * impossible to use nan(3) portably anyway, so this seems good enough.
  61  */
  62 void
  63 _scan_nan(uint32_t *words, int num_words, const char *s)
  64 {
  65         int si;         /* index into s */
  66         int bitpos;     /* index into words (in bits) */
  67
  68         bzero(words, num_words * sizeof(uint32_t));
  69
  70         /* Allow a leading '0x'. (It's expected, but redundant.) */
  71         if (s[0] == '0' && (s[1] == 'x' || s[1] == 'X'))
  72                 s += 2;
  73
  74         /* Scan forwards in the string, looking for the end of the sequence. */
  75         for (si = 0; isxdigit(s[si]); si++)
  76                 ;
  77
  78         /* Scan backwards, filling in the bits in words[] as we go. */
  79 #if !AROS_BIG_ENDIAN
  80         for (bitpos = 0; bitpos < 32 * num_words; bitpos += 4) {
  81 #else
  82         for (bitpos = 32 * num_words - 4; bitpos >= 0; bitpos -= 4) {
  83 #endif
  84                 if (--si < 0)
  85                         break;
  86                 words[bitpos / 32] |= digittoint(s[si]) << (bitpos % 32);
  87         }
  88 }
  89
  90 double
  91 nan(const char *s)
  92 {
  93         union {
  94                 double d;
  95                 uint32_t bits[2];
  96         } u;
  97
  98         _scan_nan(u.bits, 2, s);
  99 #if !AROS_BIG_ENDIAN
 100         u.bits[1] |= 0x7ff80000;
 101 #else
 102         u.bits[0] |= 0x7ff80000;
 103 #endif
 104         return (u.d);
 105 }
 106
 107 float
 108 nanf(const char *s)
 109 {
 110         union {
 111                 float f;
 112                 uint32_t bits[1];
 113         } u;
 114
 115         _scan_nan(u.bits, 1, s);
 116         u.bits[0] |= 0x7fc00000;
 117         return (u.f);
 118 }
 119
 120 #if (LDBL_MANT_DIG == 53)
 121 /* Alias nan -> nanl */
 122 AROS_MAKE_ASM_SYM(typeof(nanl), nanl, AROS_CSYM_FROM_ASM_NAME(nanl), AROS_CSYM_FROM_ASM_NAME(nan));
 123 AROS_EXPORT_ASM_SYM(AROS_CSYM_FROM_ASM_NAME(nanl));
 124 #endif