1/* Copyright (C) 1991, 1992 Free Software Foundation, Inc.
2
3   This program is free software; you can redistribute it and/or modify
4   it under the terms of the GNU General Public License as published by
5   the Free Software Foundation; either version 2, or (at your option)
6   any later version.
7
8   This program is distributed in the hope that it will be useful,
9   but WITHOUT ANY WARRANTY; without even the implied warranty of
10   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11   GNU General Public License for more details.
12
13   You should have received a copy of the GNU General Public License
14   along with this program; if not, write to the Free Software Foundation,
15   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
16
17#if HAVE_CONFIG_H
18# include <config.h>
19#endif
20
21#ifndef HAVE_STRTOD
22
23#include <errno.h>
24#ifndef errno
25extern int errno;
26#endif
27
28#include <chartypes.h>
29#include <math.h>
30
31#if HAVE_FLOAT_H
32# include <float.h>
33#else
34# define DBL_MAX 1.7976931348623159e+308
35# define DBL_MIN 2.2250738585072010e-308
36#endif
37
38#include <bashansi.h>
39
40#ifndef NULL
41#  define NULL 0
42#endif
43
44#ifndef HUGE_VAL
45#  define HUGE_VAL HUGE
46#endif
47
48/* Convert NPTR to a double.  If ENDPTR is not NULL, a pointer to the
49   character after the last one used in the number is put in *ENDPTR.  */
50double
51strtod (nptr, endptr)
52     const char *nptr;
53     char **endptr;
54{
55  register const char *s;
56  short sign;
57
58  /* The number so far.  */
59  double num;
60
61  int got_dot;			/* Found a decimal point.  */
62  int got_digit;		/* Seen any digits.  */
63
64  /* The exponent of the number.  */
65  long int exponent;
66
67  if (nptr == NULL)
68    {
69      errno = EINVAL;
70      goto noconv;
71    }
72
73  s = nptr;
74
75  /* Eat whitespace.  */
76  while (ISSPACE ((unsigned char)*s))
77    ++s;
78
79  /* Get the sign.  */
80  sign = *s == '-' ? -1 : 1;
81  if (*s == '-' || *s == '+')
82    ++s;
83
84  num = 0.0;
85  got_dot = 0;
86  got_digit = 0;
87  exponent = 0;
88  for (;; ++s)
89    {
90      if (DIGIT (*s))
91	{
92	  got_digit = 1;
93
94	  /* Make sure that multiplication by 10 will not overflow.  */
95	  if (num > DBL_MAX * 0.1)
96	    /* The value of the digit doesn't matter, since we have already
97	       gotten as many digits as can be represented in a `double'.
98	       This doesn't necessarily mean the result will overflow.
99	       The exponent may reduce it to within range.
100
101	       We just need to record that there was another
102	       digit so that we can multiply by 10 later.  */
103	    ++exponent;
104	  else
105	    num = (num * 10.0) + (*s - '0');
106
107	  /* Keep track of the number of digits after the decimal point.
108	     If we just divided by 10 here, we would lose precision.  */
109	  if (got_dot)
110	    --exponent;
111	}
112      else if (!got_dot && *s == '.')
113	/* Record that we have found the decimal point.  */
114	got_dot = 1;
115      else
116	/* Any other character terminates the number.  */
117	break;
118    }
119
120  if (!got_digit)
121    goto noconv;
122
123  if (TOLOWER ((unsigned char)*s) == 'e')
124    {
125      /* Get the exponent specified after the `e' or `E'.  */
126      int save = errno;
127      char *end;
128      long int exp;
129
130      errno = 0;
131      ++s;
132      exp = strtol (s, &end, 10);
133      if (errno == ERANGE)
134	{
135	  /* The exponent overflowed a `long int'.  It is probably a safe
136	     assumption that an exponent that cannot be represented by
137	     a `long int' exceeds the limits of a `double'.  */
138	  if (endptr != NULL)
139	    *endptr = end;
140	  if (exp < 0)
141	    goto underflow;
142	  else
143	    goto overflow;
144	}
145      else if (end == s)
146	/* There was no exponent.  Reset END to point to
147	   the 'e' or 'E', so *ENDPTR will be set there.  */
148	end = (char *) s - 1;
149      errno = save;
150      s = end;
151      exponent += exp;
152    }
153
154  if (endptr != NULL)
155    *endptr = (char *) s;
156
157  if (num == 0.0)
158    return 0.0;
159
160  /* Multiply NUM by 10 to the EXPONENT power,
161     checking for overflow and underflow.  */
162
163  if (exponent < 0)
164    {
165      if (num < DBL_MIN * pow (10.0, (double) -exponent))
166	goto underflow;
167    }
168  else if (exponent > 0)
169    {
170      if (num > DBL_MAX * pow (10.0, (double) -exponent))
171	goto overflow;
172    }
173
174  num *= pow (10.0, (double) exponent);
175
176  return num * sign;
177
178overflow:
179  /* Return an overflow error.  */
180  errno = ERANGE;
181  return HUGE_VAL * sign;
182
183underflow:
184  /* Return an underflow error.  */
185  if (endptr != NULL)
186    *endptr = (char *) nptr;
187  errno = ERANGE;
188  return 0.0;
189
190noconv:
191  /* There was no number.  */
192  if (endptr != NULL)
193    *endptr = (char *) nptr;
194  return 0.0;
195}
196
197#endif /* !HAVE_STRTOD */
198