1 /* 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 */ 7 8 #if defined(LIBC_SCCS) && !defined(lint) 9 static char sccsid[] = "@(#)strtoul.c 8.1 (Berkeley) 06/04/93"; 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 const char *nptr; 26 char **endptr; 27 register int base; 28 { 29 register const char *s = nptr; 30 register unsigned long acc; 31 register int c; 32 register unsigned long cutoff; 33 register int neg = 0, any, cutlim; 34 35 /* 36 * See strtol for comments as to the logic used. 37 */ 38 do { 39 c = *s++; 40 } while (isspace(c)); 41 if (c == '-') { 42 neg = 1; 43 c = *s++; 44 } else if (c == '+') 45 c = *s++; 46 if ((base == 0 || base == 16) && 47 c == '0' && (*s == 'x' || *s == 'X')) { 48 c = s[1]; 49 s += 2; 50 base = 16; 51 } 52 if (base == 0) 53 base = c == '0' ? 8 : 10; 54 cutoff = (unsigned long)ULONG_MAX / (unsigned long)base; 55 cutlim = (unsigned long)ULONG_MAX % (unsigned long)base; 56 for (acc = 0, any = 0;; c = *s++) { 57 if (isdigit(c)) 58 c -= '0'; 59 else if (isalpha(c)) 60 c -= isupper(c) ? 'A' - 10 : 'a' - 10; 61 else 62 break; 63 if (c >= base) 64 break; 65 if (any < 0 || acc > cutoff || acc == cutoff && c > cutlim) 66 any = -1; 67 else { 68 any = 1; 69 acc *= base; 70 acc += c; 71 } 72 } 73 if (any < 0) { 74 acc = ULONG_MAX; 75 errno = ERANGE; 76 } else if (neg) 77 acc = -acc; 78 if (endptr != 0) 79 *endptr = (char *)(any ? s - 1 : nptr); 80 return (acc); 81 } 82