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) 05/16/90"; 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 } 80