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1 | /* |
2 | * Copyright (c) 1990 Regents of the University of California. | |
3 | * All rights reserved. | |
4 | * | |
5 | * %sccs.include.redist.c% | |
6 | */ | |
7 | ||
8 | #if defined(LIBC_SCCS) && !defined(lint) | |
9 | static char sccsid[] = "@(#)strtoul.c 5.1 (Berkeley) %G%"; | |
10 | #endif /* LIBC_SCCS and not lint */ | |
11 | ||
12 | #include <limits.h> | |
13 | #include <ctype.h> | |
14 | #include <errno.h> | |
15 | ||
16 | /* | |
17 | * Convert a string to an unsigned long integer. | |
18 | * | |
19 | * Ignores `locale' stuff. Assumes that the upper and lower case | |
20 | * alphabets and digits are each contiguous. | |
21 | */ | |
22 | unsigned long | |
23 | strtoul(nptr, endptr, base) | |
24 | char *nptr, **endptr; | |
25 | register int base; | |
26 | { | |
27 | register char *s = nptr; | |
28 | register unsigned long acc; | |
29 | register int c; | |
30 | register unsigned long cutoff; | |
31 | register int neg = 0, any, cutlim; | |
32 | ||
33 | /* | |
34 | * See strtol for comments as to the logic used. | |
35 | */ | |
36 | do { | |
37 | c = *s++; | |
38 | } while (isspace(c)); | |
39 | if (c == '-') { | |
40 | neg = 1; | |
41 | c = *s++; | |
42 | } else if (c == '+') | |
43 | c = *s++; | |
44 | if ((base == 0 || base == 16) && | |
45 | c == '0' && (*s == 'x' || *s == 'X')) { | |
46 | c = s[1]; | |
47 | s += 2; | |
48 | base = 16; | |
49 | } | |
50 | if (base == 0) | |
51 | base = c == '0' ? 8 : 10; | |
52 | cutoff = (unsigned long)ULONG_MAX / (unsigned long)base; | |
53 | cutlim = (unsigned long)ULONG_MAX % (unsigned long)base; | |
54 | for (acc = 0, any = 0;; c = *s++) { | |
55 | if (isdigit(c)) | |
56 | c -= '0'; | |
57 | else if (isalpha(c)) | |
58 | c -= isupper(c) ? 'A' - 10 : 'a' - 10; | |
59 | else | |
60 | break; | |
61 | if (c >= base) | |
62 | break; | |
63 | if (any < 0 || acc > cutoff || acc == cutoff && c > cutlim) | |
64 | any = -1; | |
65 | else { | |
66 | any = 1; | |
67 | acc *= base; | |
68 | acc += c; | |
69 | } | |
70 | } | |
71 | if (any < 0) { | |
72 | acc = ULONG_MAX; | |
73 | errno = ERANGE; | |
74 | } else if (neg) | |
75 | acc = -acc; | |
76 | if (endptr != 0) | |
77 | *endptr = any ? s - 1 : nptr; | |
78 | return (acc); | |
79 | } |