lib/libm/gen/nan.c

   1 /* $NetBSD: nan.c,v 1.2 2008/04/28 20:23:01 martin Exp $ */
   2
   3 /*-
   4  * Copyright (c) 2006 The NetBSD Foundation, Inc.
   5  * All rights reserved.
   6  *
   7  * This code is derived from software contributed to The NetBSD Foundation
   8  * by Klaus Klein.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29  * POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 #include <sys/cdefs.h>
  33 #if defined(LIBM_SCCS) && !defined(lint) && !defined(NAN_FUNCTION)
  34 __RCSID("$NetBSD: nan.c,v 1.2 2008/04/28 20:23:01 martin Exp $");
  35 #endif /* LIBM_SCCS and not lint */
  36
  37 #include <assert.h>
  38 #include <math.h>
  39 #include <stddef.h>
  40 #include <stdlib.h>
  41 #include <string.h>
  42
  43
  44 #ifndef NAN_FUNCTION
  45 #define NAN_FUNCTION    nan
  46 #define NAN_TYPE        double
  47 #define NAN_STRTOD      strtod
  48 #endif
  49
  50 NAN_TYPE
  51 NAN_FUNCTION(const char *tagp)
  52 {
  53         const char *nstr;
  54         char *buf;
  55         NAN_TYPE res;
  56
  57         _DIAGASSERT(tagp != NULL);
  58
  59         nstr = "NAN()";
  60         buf = NULL;
  61
  62         if (tagp[0] != '\0') {
  63                 size_t l;
  64
  65                 l = strlen(tagp);
  66                 buf = malloc(5 + l + 1);
  67
  68                 if (buf != NULL) {
  69                         /* Avoiding stdio in libm. */
  70                         memcpy(buf,             "NAN(", 4);
  71                         memcpy(buf + 4,         tagp,   l);
  72                         memcpy(buf + 4 + l,     ")",    2);
  73                         nstr = buf;
  74                 } else {
  75                         /* Best effort: Fall back to "NAN()". */
  76                 }
  77         }
  78
  79         res = NAN_STRTOD(nstr, NULL);
  80
  81         if (buf != NULL)
  82                 free(buf);
  83
  84         return res;
  85 }