1/* strtod.c - convert string to double-precision floating-point value. */
2
3/* Copyright (C) 1991, 1992 Free Software Foundation, Inc.
4
5   This file is part of GNU Bash, the Bourne Again SHell.
6
7   Bash is free software: you can redistribute it and/or modify
8   it under the terms of the GNU General Public License as published by
9   the Free Software Foundation, either version 3 of the License, or
10   (at your option) any later version.
11
12   Bash is distributed in the hope that it will be useful,
13   but WITHOUT ANY WARRANTY; without even the implied warranty of
14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15   GNU General Public License for more details.
16
17   You should have received a copy of the GNU General Public License
18   along with Bash.  If not, see <http://www.gnu.org/licenses/>.
19*/
20
21#if HAVE_CONFIG_H
22# include <config.h>
23#endif
24
25#ifndef HAVE_STRTOD
26
27#include <errno.h>
28#ifndef errno
29extern int errno;
30#endif
31
32#include <chartypes.h>
33#include <math.h>
34
35#if HAVE_FLOAT_H
36# include <float.h>
37#else
38# define DBL_MAX 1.7976931348623159e+308
39# define DBL_MIN 2.2250738585072010e-308
40#endif
41
42#include <bashansi.h>
43
44#ifndef NULL
45#  define NULL 0
46#endif
47
48#ifndef HUGE_VAL
49#  define HUGE_VAL HUGE
50#endif
51
52/* Convert NPTR to a double.  If ENDPTR is not NULL, a pointer to the
53   character after the last one used in the number is put in *ENDPTR.  */
54double
55strtod (nptr, endptr)
56     const char *nptr;
57     char **endptr;
58{
59  register const char *s;
60  short sign;
61
62  /* The number so far.  */
63  double num;
64
65  int got_dot;			/* Found a decimal point.  */
66  int got_digit;		/* Seen any digits.  */
67
68  /* The exponent of the number.  */
69  long int exponent;
70
71  if (nptr == NULL)
72    {
73      errno = EINVAL;
74      goto noconv;
75    }
76
77  s = nptr;
78
79  /* Eat whitespace.  */
80  while (ISSPACE ((unsigned char)*s))
81    ++s;
82
83  /* Get the sign.  */
84  sign = *s == '-' ? -1 : 1;
85  if (*s == '-' || *s == '+')
86    ++s;
87
88  num = 0.0;
89  got_dot = 0;
90  got_digit = 0;
91  exponent = 0;
92  for (;; ++s)
93    {
94      if (DIGIT (*s))
95	{
96	  got_digit = 1;
97
98	  /* Make sure that multiplication by 10 will not overflow.  */
99	  if (num > DBL_MAX * 0.1)
100	    /* The value of the digit doesn't matter, since we have already
101	       gotten as many digits as can be represented in a `double'.
102	       This doesn't necessarily mean the result will overflow.
103	       The exponent may reduce it to within range.
104
105	       We just need to record that there was another
106	       digit so that we can multiply by 10 later.  */
107	    ++exponent;
108	  else
109	    num = (num * 10.0) + (*s - '0');
110
111	  /* Keep track of the number of digits after the decimal point.
112	     If we just divided by 10 here, we would lose precision.  */
113	  if (got_dot)
114	    --exponent;
115	}
116      else if (!got_dot && *s == '.')
117	/* Record that we have found the decimal point.  */
118	got_dot = 1;
119      else
120	/* Any other character terminates the number.  */
121	break;
122    }
123
124  if (!got_digit)
125    goto noconv;
126
127  if (TOLOWER ((unsigned char)*s) == 'e')
128    {
129      /* Get the exponent specified after the `e' or `E'.  */
130      int save = errno;
131      char *end;
132      long int exp;
133
134      errno = 0;
135      ++s;
136      exp = strtol (s, &end, 10);
137      if (errno == ERANGE)
138	{
139	  /* The exponent overflowed a `long int'.  It is probably a safe
140	     assumption that an exponent that cannot be represented by
141	     a `long int' exceeds the limits of a `double'.  */
142	  if (endptr != NULL)
143	    *endptr = end;
144	  if (exp < 0)
145	    goto underflow;
146	  else
147	    goto overflow;
148	}
149      else if (end == s)
150	/* There was no exponent.  Reset END to point to
151	   the 'e' or 'E', so *ENDPTR will be set there.  */
152	end = (char *) s - 1;
153      errno = save;
154      s = end;
155      exponent += exp;
156    }
157
158  if (endptr != NULL)
159    *endptr = (char *) s;
160
161  if (num == 0.0)
162    return 0.0;
163
164  /* Multiply NUM by 10 to the EXPONENT power,
165     checking for overflow and underflow.  */
166
167  if (exponent < 0)
168    {
169      if (num < DBL_MIN * pow (10.0, (double) -exponent))
170	goto underflow;
171    }
172  else if (exponent > 0)
173    {
174      if (num > DBL_MAX * pow (10.0, (double) -exponent))
175	goto overflow;
176    }
177
178  num *= pow (10.0, (double) exponent);
179
180  return num * sign;
181
182overflow:
183  /* Return an overflow error.  */
184  errno = ERANGE;
185  return HUGE_VAL * sign;
186
187underflow:
188  /* Return an underflow error.  */
189  if (endptr != NULL)
190    *endptr = (char *) nptr;
191  errno = ERANGE;
192  return 0.0;
193
194noconv:
195  /* There was no number.  */
196  if (endptr != NULL)
197    *endptr = (char *) nptr;
198  return 0.0;
199}
200
201#endif /* !HAVE_STRTOD */
202