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comparison lib/strtod.c @ 9822:fb687649f177

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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
comparison
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9821:18bab9955c43 9822:fb687649f177
23 #include <float.h> 23 #include <float.h>
24 #include <math.h> 24 #include <math.h>
25 #include <stdbool.h> 25 #include <stdbool.h>
26 #include <string.h> 26 #include <string.h>
27 27
28 #include "c-ctype.h"
29
28 /* Convert NPTR to a double. If ENDPTR is not NULL, a pointer to the 30 /* Convert NPTR to a double. If ENDPTR is not NULL, a pointer to the
29 character after the last one used in the number is put in *ENDPTR. */ 31 character after the last one used in the number is put in *ENDPTR. */
30 double 32 double
31 strtod (const char *nptr, char **endptr) 33 strtod (const char *nptr, char **endptr)
32 { 34 {
33 const char *s; 35 const unsigned char *s;
34 bool negative = false; 36 bool negative = false;
35 37
36 /* The number so far. */ 38 /* The number so far. */
37 double num; 39 double num;
38 40
39 bool got_dot; /* Found a decimal point. */ 41 bool got_dot; /* Found a decimal point. */
40 bool got_digit; /* Seen any digits. */ 42 bool got_digit; /* Seen any digits. */
43 bool hex = false; /* Look for hex float exponent. */
41 44
42 /* The exponent of the number. */ 45 /* The exponent of the number. */
43 long int exponent; 46 long int exponent;
44 47
45 if (nptr == NULL) 48 if (nptr == NULL)
49 } 52 }
50 53
51 s = nptr; 54 s = nptr;
52 55
53 /* Eat whitespace. */ 56 /* Eat whitespace. */
54 while (isspace ((unsigned char) *s)) 57 while (isspace (*s))
55 ++s; 58 ++s;
56 59
57 /* Get the sign. */ 60 /* Get the sign. */
58 negative = *s == '-'; 61 negative = *s == '-';
59 if (*s == '-' || *s == '+') 62 if (*s == '-' || *s == '+')
61 64
62 num = 0.0; 65 num = 0.0;
63 got_dot = false; 66 got_dot = false;
64 got_digit = false; 67 got_digit = false;
65 exponent = 0; 68 exponent = 0;
66 for (;; ++s) 69
67 { 70 /* Check for hex float. */
68 if ('0' <= *s && *s <= '9') 71 if (*s == '0' && c_tolower (s[1]) == 'x'
69 { 72 && (c_isxdigit (s[2]) || ('.' == s[2] && c_isxdigit (s[3]))))
70 got_digit = true; 73 {
71 74 hex = true;
72 /* Make sure that multiplication by 10 will not overflow. */ 75 s += 2;
73 if (num > DBL_MAX * 0.1) 76 for (;; ++s)
74 /* The value of the digit doesn't matter, since we have already 77 {
75 gotten as many digits as can be represented in a `double'. 78 if (c_isxdigit (*s))
76 This doesn't necessarily mean the result will overflow. 79 {
77 The exponent may reduce it to within range. 80 got_digit = true;
78 81
79 We just need to record that there was another 82 /* Make sure that multiplication by 16 will not overflow. */
80 digit so that we can multiply by 10 later. */ 83 if (num > DBL_MAX / 16)
81 ++exponent; 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)));
95
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;
82 else 104 else
83 num = (num * 10.0) + (*s - '0'); 105 /* Any other character terminates the number. */
84 106 break;
85 /* Keep track of the number of digits after the decimal point. 107 }
86 If we just divided by 10 here, we would lose precision. */ 108 }
87 if (got_dot) 109
88 --exponent; 110 /* Not a hex float. */
89 } 111 else
90 else if (!got_dot && *s == '.') 112 {
91 /* Record that we have found the decimal point. */ 113 for (;; ++s)
92 got_dot = true; 114 {
93 else 115 if (c_isdigit (*s))
94 /* Any other character terminates the number. */ 116 {
95 break; 117 got_digit = true;
118
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;
143 }
96 } 144 }
97 145
98 if (!got_digit) 146 if (!got_digit)
99 { 147 {
100 /* Check for infinities and NaNs. */ 148 /* Check for infinities and NaNs. */
101 if (tolower ((unsigned char) *s) == 'i' 149 if (c_tolower (*s) == 'i'
102 && tolower ((unsigned char) s[1]) == 'n' 150 && c_tolower (s[1]) == 'n'
103 && tolower ((unsigned char) s[2]) == 'f') 151 && c_tolower (s[2]) == 'f')
104 { 152 {
105 s += 3; 153 s += 3;
106 num = HUGE_VAL; 154 num = HUGE_VAL;
107 if (tolower ((unsigned char) *s) == 'i' 155 if (c_tolower (*s) == 'i'
108 && tolower ((unsigned char) s[1]) == 'n' 156 && c_tolower (s[1]) == 'n'
109 && tolower ((unsigned char) s[2]) == 'i' 157 && c_tolower (s[2]) == 'i'
110 && tolower ((unsigned char) s[3]) == 't' 158 && c_tolower (s[3]) == 't'
111 && tolower ((unsigned char) s[4]) == 'y') 159 && c_tolower (s[4]) == 'y')
112 s += 5; 160 s += 5;
113 goto valid; 161 goto valid;
114 } 162 }
115 #ifdef NAN 163 #ifdef NAN
116 else if (tolower ((unsigned char) *s) == 'n' 164 else if (c_tolower (*s) == 'n'
117 && tolower ((unsigned char) s[1]) == 'a' 165 && c_tolower (s[1]) == 'a'
118 && tolower ((unsigned char) s[2]) == 'n') 166 && c_tolower (s[2]) == 'n')
119 { 167 {
120 s += 3; 168 s += 3;
121 num = NAN; 169 num = NAN;
122 /* Since nan(<n-char-sequence>) is implementation-defined, 170 /* Since nan(<n-char-sequence>) is implementation-defined,
123 we define it by ignoring <n-char-sequence>. A nicer 171 we define it by ignoring <n-char-sequence>. A nicer
124 implementation would populate the bits of the NaN 172 implementation would populate the bits of the NaN
125 according to interpreting n-char-sequence as a 173 according to interpreting n-char-sequence as a
126 hexadecimal number, but the result is still a NaN. */ 174 hexadecimal number, but the result is still a NaN. */
127 if (*s == '(') 175 if (*s == '(')
128 { 176 {
129 const char *p = s + 1; 177 const unsigned char *p = s + 1;
130 while (isalnum ((unsigned char) *p)) 178 while (c_isalnum (*p))
131 p++; 179 p++;
132 if (*p == ')') 180 if (*p == ')')
133 s = p + 1; 181 s = p + 1;
134 } 182 }
135 goto valid; 183 goto valid;
136 } 184 }
137 #endif 185 #endif
138 goto noconv; 186 goto noconv;
139 } 187 }
140 188
141 if (tolower ((unsigned char) *s) == 'e') 189 if (c_tolower (*s) == (hex ? 'p' : 'e') && !isspace (s[1]))
142 { 190 {
143 /* Get the exponent specified after the `e' or `E'. */ 191 /* Get the exponent specified after the `e' or `E'. */
144 int save = errno; 192 int save = errno;
145 char *end; 193 char *end;
146 long int exp; 194 long int exp;
158 if (exp < 0) 206 if (exp < 0)
159 goto underflow; 207 goto underflow;
160 else 208 else
161 goto overflow; 209 goto overflow;
162 } 210 }
163 else if (end == s) 211 else if (end == (char *) s)
164 /* There was no exponent. Reset END to point to 212 /* There was no exponent. Reset END to point to
165 the 'e' or 'E', so *ENDPTR will be set there. */ 213 the 'e' or 'E', so *ENDPTR will be set there. */
166 end = (char *) s - 1; 214 end = (char *) s - 1;
167 errno = save; 215 errno = save;
168 s = end; 216 s = end;
170 } 218 }
171 219
172 if (num == 0.0) 220 if (num == 0.0)
173 goto valid; 221 goto valid;
174 222
223 if (hex)
224 {
225 /* ldexp takes care of range errors. */
226 num = ldexp (num, exponent);
227 goto valid;
228 }
229
175 /* Multiply NUM by 10 to the EXPONENT power, 230 /* Multiply NUM by 10 to the EXPONENT power,
176 checking for overflow and underflow. */ 231 checking for overflow and underflow. */
177 232
178 if (exponent < 0) 233 if (exponent < 0)
179 { 234 {