/*
 * Copyright (c) 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *	  notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *	  notice, this list of conditions and the following disclaimer in the
 *	  documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *	  may be used to endorse or promote products derived from this software
 *	  without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.	IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)strtoul.c	8.1 (Berkeley) 6/4/93";
#endif   /* LIBC_SCCS and not lint */

#include "c.h"

#include <limits.h>
#include <ctype.h>


/*
 * Convert a string to an unsigned long integer.
 *
 * Ignores `locale' stuff.  Assumes that the upper and lower case
 * alphabets and digits are each contiguous.
 */
unsigned long
strtoul(nptr, endptr, base)
const char *nptr;
char	  **endptr;
register int base;
{
	register const char *s = nptr;
	register unsigned long acc;
	register unsigned char c;
	register unsigned long cutoff;
	register int neg = 0,
				any,
				cutlim;

	/*
	 * See strtol for comments as to the logic used.
	 */
	do
	{
		c = *s++;
	} while (isspace(c));
	if (c == '-')
	{
		neg = 1;
		c = *s++;
	}
	else if (c == '+')
		c = *s++;
	if ((base == 0 || base == 16) &&
		c == '0' && (*s == 'x' || *s == 'X'))
	{
		c = s[1];
		s += 2;
		base = 16;
	}
	if (base == 0)
		base = c == '0' ? 8 : 10;
	cutoff = (unsigned long) ULONG_MAX / (unsigned long) base;
	cutlim = (unsigned long) ULONG_MAX % (unsigned long) base;
	for (acc = 0, any = 0;; c = *s++)
	{
		if (!isascii(c))
			break;
		if (isdigit(c))
			c -= '0';
		else if (isalpha(c))
			c -= isupper(c) ? 'A' - 10 : 'a' - 10;
		else
			break;
		if ((int) c >= base)
			break;
		if (any < 0 || acc > cutoff || (acc == cutoff && (int) c > cutlim))
			any = -1;
		else
		{
			any = 1;
			acc *= base;
			acc += c;
		}
	}
	if (any < 0)
	{
		acc = ULONG_MAX;
		errno = ERANGE;
	}
	else if (neg)
		acc = -acc;
	if (endptr != 0)
		*endptr = (char *) (any ? s - 1 : nptr);
	return acc;
}