1 /* Copyright (C) 1991, 1992, 1997, 1999, 2003, 2006, 2008 Free
2 Software Foundation, Inc.
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 3 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
30 /* Convert NPTR to a double. If ENDPTR is not NULL, a pointer to the
31 character after the last one used in the number is put in *ENDPTR. */
33 strtod (const char *nptr, char **endptr)
35 const unsigned char *s;
36 bool negative = false;
38 /* The number so far. */
41 bool got_dot; /* Found a decimal point. */
42 bool got_digit; /* Seen any digits. */
43 bool hex = false; /* Look for hex float exponent. */
45 /* The exponent of the number. */
54 /* Use unsigned char for the ctype routines. */
55 s = (unsigned char *) nptr;
63 if (*s == '-' || *s == '+')
71 /* Check for hex float. */
72 if (*s == '0' && c_tolower (s[1]) == 'x'
73 && (c_isxdigit (s[2]) || ('.' == s[2] && c_isxdigit (s[3]))))
83 /* Make sure that multiplication by 16 will not overflow. */
84 if (num > DBL_MAX / 16)
85 /* The value of the digit doesn't matter, since we have already
86 gotten as many digits as can be represented in a `double'.
87 This doesn't necessarily mean the result will overflow.
88 The exponent may reduce it to within range.
90 We just need to record that there was another
91 digit so that we can multiply by 16 later. */
95 + (c_tolower (*s) - (c_isdigit (*s) ? '0' : 'a' - 10)));
97 /* Keep track of the number of digits after the decimal point.
98 If we just divided by 16 here, we would lose precision. */
102 else if (!got_dot && *s == '.')
103 /* Record that we have found the decimal point. */
106 /* Any other character terminates the number. */
111 /* Not a hex float. */
120 /* Make sure that multiplication by 10 will not overflow. */
121 if (num > DBL_MAX * 0.1)
122 /* The value of the digit doesn't matter, since we have already
123 gotten as many digits as can be represented in a `double'.
124 This doesn't necessarily mean the result will overflow.
125 The exponent may reduce it to within range.
127 We just need to record that there was another
128 digit so that we can multiply by 10 later. */
131 num = (num * 10.0) + (*s - '0');
133 /* Keep track of the number of digits after the decimal point.
134 If we just divided by 10 here, we would lose precision. */
138 else if (!got_dot && *s == '.')
139 /* Record that we have found the decimal point. */
142 /* Any other character terminates the number. */
149 /* Check for infinities and NaNs. */
150 if (c_tolower (*s) == 'i'
151 && c_tolower (s[1]) == 'n'
152 && c_tolower (s[2]) == 'f')
156 if (c_tolower (*s) == 'i'
157 && c_tolower (s[1]) == 'n'
158 && c_tolower (s[2]) == 'i'
159 && c_tolower (s[3]) == 't'
160 && c_tolower (s[4]) == 'y')
165 else if (c_tolower (*s) == 'n'
166 && c_tolower (s[1]) == 'a'
167 && c_tolower (s[2]) == 'n')
171 /* Since nan(<n-char-sequence>) is implementation-defined,
172 we define it by ignoring <n-char-sequence>. A nicer
173 implementation would populate the bits of the NaN
174 according to interpreting n-char-sequence as a
175 hexadecimal number, but the result is still a NaN. */
178 const unsigned char *p = s + 1;
179 while (c_isalnum (*p))
190 if (c_tolower (*s) == (hex ? 'p' : 'e') && !isspace (s[1]))
192 /* Get the exponent specified after the `e' or `E'. */
199 value = strtol ((char *) s, &end, 10);
200 if (errno == ERANGE && num)
202 /* The exponent overflowed a `long int'. It is probably a safe
203 assumption that an exponent that cannot be represented by
204 a `long int' exceeds the limits of a `double'. */
212 else if (end == (char *) s)
213 /* There was no exponent. Reset END to point to
214 the 'e' or 'E', so *ENDPTR will be set there. */
215 end = (char *) s - 1;
217 s = (unsigned char *) end;
226 /* ldexp takes care of range errors. */
227 num = ldexp (num, exponent);
231 /* Multiply NUM by 10 to the EXPONENT power,
232 checking for overflow and underflow. */
236 if (num < DBL_MIN * pow (10.0, (double) -exponent))
239 else if (exponent > 0)
241 if (num > DBL_MAX * pow (10.0, (double) -exponent))
245 num *= pow (10.0, (double) exponent);
249 *endptr = (char *) s;
250 return negative ? -num : num;
253 /* Return an overflow error. */
255 *endptr = (char *) s;
257 return negative ? -HUGE_VAL : HUGE_VAL;
260 /* Return an underflow error. */
262 *endptr = (char *) s;
264 return negative ? -0.0 : 0.0;
267 /* There was no number. */
269 *endptr = (char *) nptr;