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 5.2 (Berkeley) 05/17/90"; 10 #endif /* LIBC_SCCS and not lint */ 11 12 #include <limits.h> 13 #include <ctype.h> 14 #include <errno.h> 15 #include <stdlib.h> 16 17 /* 18 * Convert a string to an unsigned long integer. 19 * 20 * Ignores `locale' stuff. Assumes that the upper and lower case 21 * alphabets and digits are each contiguous. 22 */ 23 unsigned long 24 strtoul(nptr, endptr, base) 25 char *nptr, **endptr; 26 register int base; 27 { 28 register char *s = nptr; 29 register unsigned long acc; 30 register int c; 31 register unsigned long cutoff; 32 register int neg = 0, any, cutlim; 33 34 /* 35 * See strtol for comments as to the logic used. 36 */ 37 do { 38 c = *s++; 39 } while (isspace(c)); 40 if (c == '-') { 41 neg = 1; 42 c = *s++; 43 } else if (c == '+') 44 c = *s++; 45 if ((base == 0 || base == 16) && 46 c == '0' && (*s == 'x' || *s == 'X')) { 47 c = s[1]; 48 s += 2; 49 base = 16; 50 } 51 if (base == 0) 52 base = c == '0' ? 8 : 10; 53 cutoff = (unsigned long)ULONG_MAX / (unsigned long)base; 54 cutlim = (unsigned long)ULONG_MAX % (unsigned long)base; 55 for (acc = 0, any = 0;; c = *s++) { 56 if (isdigit(c)) 57 c -= '0'; 58 else if (isalpha(c)) 59 c -= isupper(c) ? 'A' - 10 : 'a' - 10; 60 else 61 break; 62 if (c >= base) 63 break; 64 if (any < 0 || acc > cutoff || acc == cutoff && c > cutlim) 65 any = -1; 66 else { 67 any = 1; 68 acc *= base; 69 acc += c; 70 } 71 } 72 if (any < 0) { 73 acc = ULONG_MAX; 74 errno = ERANGE; 75 } else if (neg) 76 acc = -acc; 77 if (endptr != 0) 78 *endptr = any ? s - 1 : nptr; 79 return (acc); 80 } 81