Mercurial > gnulib
annotate lib/strtod.c @ 9822:fb687649f177
Add hex float support.
* modules/strtod (Depends-on): Add c-ctype.
(Link): Mention POW_LIB.
* lib/strtod.c (strtod): Recognize hex floats. Don't allow
whitespace between 'e' and exponent.
* tests/test-strtod.c (main): Enable hex float tests.
* doc/posix-functions/strtod.texi (strtod): Document what gnulib
now provides.
Signed-off-by: Eric Blake <ebb9@byu.net>
| author | Eric Blake <ebb9@byu.net> |
|---|---|
| date | Sat, 29 Mar 2008 21:24:07 -0600 |
| parents | 18bab9955c43 |
| children | 48eddbd8edd5 |
| rev | line source |
|---|---|
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1 /* Copyright (C) 1991, 1992, 1997, 1999, 2003, 2006, 2008 Free |
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2 Software Foundation, Inc. |
| 9 | 3 |
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4 This program is free software: you can redistribute it and/or modify |
| 311 | 5 it under the terms of the GNU General Public License as published by |
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6 the Free Software Foundation; either version 3 of the License, or |
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7 (at your option) any later version. |
| 9 | 8 |
| 311 | 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. | |
| 13 | |
| 14 You should have received a copy of the GNU General Public License | |
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15 along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 309 | 16 |
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17 #include <config.h> |
| 311 | 18 |
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19 #include <stdlib.h> |
| 373 | 20 |
| 311 | 21 #include <ctype.h> |
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22 #include <errno.h> |
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23 #include <float.h> |
| 311 | 24 #include <math.h> |
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25 #include <stdbool.h> |
| 4691 | 26 #include <string.h> |
| 9 | 27 |
| 9822 | 28 #include "c-ctype.h" |
| 29 | |
| 9 | 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. */ | |
| 32 double | |
| 1691 | 33 strtod (const char *nptr, char **endptr) |
| 9 | 34 { |
| 9822 | 35 const unsigned char *s; |
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36 bool negative = false; |
| 9 | 37 |
| 38 /* The number so far. */ | |
| 39 double num; | |
| 40 | |
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41 bool got_dot; /* Found a decimal point. */ |
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42 bool got_digit; /* Seen any digits. */ |
| 9822 | 43 bool hex = false; /* Look for hex float exponent. */ |
| 9 | 44 |
| 45 /* The exponent of the number. */ | |
| 46 long int exponent; | |
| 47 | |
| 48 if (nptr == NULL) | |
| 49 { | |
| 50 errno = EINVAL; | |
| 51 goto noconv; | |
| 52 } | |
| 53 | |
| 54 s = nptr; | |
| 55 | |
| 56 /* Eat whitespace. */ | |
| 9822 | 57 while (isspace (*s)) |
| 9 | 58 ++s; |
| 59 | |
| 60 /* Get the sign. */ | |
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61 negative = *s == '-'; |
| 9 | 62 if (*s == '-' || *s == '+') |
| 63 ++s; | |
| 64 | |
| 65 num = 0.0; | |
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66 got_dot = false; |
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67 got_digit = false; |
| 9 | 68 exponent = 0; |
| 9822 | 69 |
| 70 /* Check for hex float. */ | |
| 71 if (*s == '0' && c_tolower (s[1]) == 'x' | |
| 72 && (c_isxdigit (s[2]) || ('.' == s[2] && c_isxdigit (s[3])))) | |
| 9 | 73 { |
| 9822 | 74 hex = true; |
| 75 s += 2; | |
| 76 for (;; ++s) | |
| 9 | 77 { |
| 9822 | 78 if (c_isxdigit (*s)) |
| 79 { | |
| 80 got_digit = true; | |
| 9 | 81 |
| 9822 | 82 /* Make sure that multiplication by 16 will not overflow. */ |
| 83 if (num > DBL_MAX / 16) | |
| 84 /* The value of the digit doesn't matter, since we have already | |
| 85 gotten as many digits as can be represented in a `double'. | |
| 86 This doesn't necessarily mean the result will overflow. | |
| 87 The exponent may reduce it to within range. | |
| 88 | |
| 89 We just need to record that there was another | |
| 90 digit so that we can multiply by 16 later. */ | |
| 91 ++exponent; | |
| 92 else | |
| 93 num = ((num * 16.0) | |
| 94 + (c_tolower (*s) - (c_isdigit (*s) ? '0' : 'a' - 10))); | |
| 9 | 95 |
| 9822 | 96 /* Keep track of the number of digits after the decimal point. |
| 97 If we just divided by 16 here, we would lose precision. */ | |
| 98 if (got_dot) | |
| 99 --exponent; | |
| 100 } | |
| 101 else if (!got_dot && *s == '.') | |
| 102 /* Record that we have found the decimal point. */ | |
| 103 got_dot = true; | |
| 9 | 104 else |
| 9822 | 105 /* Any other character terminates the number. */ |
| 106 break; | |
| 107 } | |
| 108 } | |
| 109 | |
| 110 /* Not a hex float. */ | |
| 111 else | |
| 112 { | |
| 113 for (;; ++s) | |
| 114 { | |
| 115 if (c_isdigit (*s)) | |
| 116 { | |
| 117 got_digit = true; | |
| 9 | 118 |
| 9822 | 119 /* Make sure that multiplication by 10 will not overflow. */ |
| 120 if (num > DBL_MAX * 0.1) | |
| 121 /* The value of the digit doesn't matter, since we have already | |
| 122 gotten as many digits as can be represented in a `double'. | |
| 123 This doesn't necessarily mean the result will overflow. | |
| 124 The exponent may reduce it to within range. | |
| 125 | |
| 126 We just need to record that there was another | |
| 127 digit so that we can multiply by 10 later. */ | |
| 128 ++exponent; | |
| 129 else | |
| 130 num = (num * 10.0) + (*s - '0'); | |
| 131 | |
| 132 /* Keep track of the number of digits after the decimal point. | |
| 133 If we just divided by 10 here, we would lose precision. */ | |
| 134 if (got_dot) | |
| 135 --exponent; | |
| 136 } | |
| 137 else if (!got_dot && *s == '.') | |
| 138 /* Record that we have found the decimal point. */ | |
| 139 got_dot = true; | |
| 140 else | |
| 141 /* Any other character terminates the number. */ | |
| 142 break; | |
| 9 | 143 } |
| 144 } | |
| 145 | |
| 146 if (!got_digit) | |
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147 { |
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148 /* Check for infinities and NaNs. */ |
| 9822 | 149 if (c_tolower (*s) == 'i' |
| 150 && c_tolower (s[1]) == 'n' | |
| 151 && c_tolower (s[2]) == 'f') | |
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152 { |
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153 s += 3; |
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154 num = HUGE_VAL; |
| 9822 | 155 if (c_tolower (*s) == 'i' |
| 156 && c_tolower (s[1]) == 'n' | |
| 157 && c_tolower (s[2]) == 'i' | |
| 158 && c_tolower (s[3]) == 't' | |
| 159 && c_tolower (s[4]) == 'y') | |
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160 s += 5; |
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161 goto valid; |
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162 } |
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163 #ifdef NAN |
| 9822 | 164 else if (c_tolower (*s) == 'n' |
| 165 && c_tolower (s[1]) == 'a' | |
| 166 && c_tolower (s[2]) == 'n') | |
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167 { |
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168 s += 3; |
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169 num = NAN; |
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170 /* Since nan(<n-char-sequence>) is implementation-defined, |
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171 we define it by ignoring <n-char-sequence>. A nicer |
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172 implementation would populate the bits of the NaN |
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173 according to interpreting n-char-sequence as a |
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174 hexadecimal number, but the result is still a NaN. */ |
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175 if (*s == '(') |
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176 { |
| 9822 | 177 const unsigned char *p = s + 1; |
| 178 while (c_isalnum (*p)) | |
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179 p++; |
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180 if (*p == ')') |
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181 s = p + 1; |
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182 } |
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183 goto valid; |
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184 } |
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185 #endif |
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186 goto noconv; |
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187 } |
| 9 | 188 |
| 9822 | 189 if (c_tolower (*s) == (hex ? 'p' : 'e') && !isspace (s[1])) |
| 9 | 190 { |
| 191 /* Get the exponent specified after the `e' or `E'. */ | |
| 192 int save = errno; | |
| 193 char *end; | |
| 194 long int exp; | |
| 195 | |
| 196 errno = 0; | |
| 197 ++s; | |
| 311 | 198 exp = strtol (s, &end, 10); |
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199 if (errno == ERANGE && num) |
| 9 | 200 { |
| 201 /* The exponent overflowed a `long int'. It is probably a safe | |
| 202 assumption that an exponent that cannot be represented by | |
| 203 a `long int' exceeds the limits of a `double'. */ | |
| 204 if (endptr != NULL) | |
| 205 *endptr = end; | |
| 206 if (exp < 0) | |
| 207 goto underflow; | |
| 208 else | |
| 209 goto overflow; | |
| 210 } | |
| 9822 | 211 else if (end == (char *) s) |
| 9 | 212 /* There was no exponent. Reset END to point to |
| 213 the 'e' or 'E', so *ENDPTR will be set there. */ | |
| 214 end = (char *) s - 1; | |
| 215 errno = save; | |
| 216 s = end; | |
| 217 exponent += exp; | |
| 218 } | |
| 219 | |
| 220 if (num == 0.0) | |
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221 goto valid; |
| 9 | 222 |
| 9822 | 223 if (hex) |
| 224 { | |
| 225 /* ldexp takes care of range errors. */ | |
| 226 num = ldexp (num, exponent); | |
| 227 goto valid; | |
| 228 } | |
| 229 | |
| 9 | 230 /* Multiply NUM by 10 to the EXPONENT power, |
| 231 checking for overflow and underflow. */ | |
| 232 | |
| 233 if (exponent < 0) | |
| 234 { | |
| 311 | 235 if (num < DBL_MIN * pow (10.0, (double) -exponent)) |
| 9 | 236 goto underflow; |
| 237 } | |
| 238 else if (exponent > 0) | |
| 239 { | |
| 311 | 240 if (num > DBL_MAX * pow (10.0, (double) -exponent)) |
| 9 | 241 goto overflow; |
| 242 } | |
| 243 | |
| 311 | 244 num *= pow (10.0, (double) exponent); |
| 9 | 245 |
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246 valid: |
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247 if (endptr != NULL) |
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248 *endptr = (char *) s; |
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249 return negative ? -num : num; |
| 9 | 250 |
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251 overflow: |
| 9 | 252 /* Return an overflow error. */ |
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253 if (endptr != NULL) |
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254 *endptr = (char *) s; |
| 9 | 255 errno = ERANGE; |
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256 return negative ? -HUGE_VAL : HUGE_VAL; |
| 9 | 257 |
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258 underflow: |
| 9 | 259 /* Return an underflow error. */ |
| 260 if (endptr != NULL) | |
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261 *endptr = (char *) s; |
| 9 | 262 errno = ERANGE; |
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263 return negative ? -0.0 : 0.0; |
| 9 | 264 |
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265 noconv: |
| 9 | 266 /* There was no number. */ |
| 267 if (endptr != NULL) | |
| 268 *endptr = (char *) nptr; | |
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269 errno = EINVAL; |
| 9 | 270 return 0.0; |
| 271 } |