/*	$OpenBSD: strtol.c,v 1.7 2005/08/08 08:05:37 espie Exp $ */
/*-
 * Copyright (c) 1990 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.
 */

#include <limits.h>
#include <stdlib.h>
#define ISSPACE(c) \
    ((sizeof(c) == sizeof(char)) \
     ? ((((c) == ' ') || (((unsigned char)((c) - 9)) <= (13 - 9)))) \
     : ((((c) == ' ') || (((unsigned int)((c) - 9)) <= (13 - 9)))))

static inline unsigned char readhex(char c)
{       
        int o = 0;

        switch (c) {
            case '0'...'9': o = c - '0';      break;
            case 'a'...'f': o = c - 'a' + 10; break;
            case 'A'...'F': o = c - 'A' + 10; break;
            default: o = -1; break;
        }
        return o;
}

static const unsigned long cutoffvals[16] =
{
  0x0000000000000000, /* invalid */
  0x7fffffffffffffff, /* base=2 */
  0x5555555555555555,
  0x3fffffffffffffff,
  0x3333333333333333, /* base=5 */
  0x2aaaaaaaaaaaaaaa,
  0x2492492492492492,
  0x1fffffffffffffff, /* base=8 */
  0x1c71c71c71c71c71,
  0x1999999999999999, /* base=10 */
  0x1745d1745d1745d1,
  0x1555555555555555,
  0x13b13b13b13b13b1,
  0x1249249249249249,
  0x1111111111111111,
  0x0fffffffffffffff  /* base=16 */
};

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

    /*
     * Ensure that base is between 2 and 16 inclusive, or the special value of 0.
     */
    //if (base < 0 || base == 1 || base > 16) {
    if (base < 0 || base > 16) {
        if (endptr != 0)
            *endptr = (char *)nptr;
        return 0;
    }

	/*
	 * Skip white space and pick up leading +/- sign if any.
	 * If base is 0, allow 0x for hex and 0 for octal, else
	 * assume decimal; if base is already 16, allow 0x.
	 */
	s = nptr;
	do {
		c = (unsigned char) *s++;
	} while (ISSPACE(c));
	if ((c == '-') || (c == '+')) {
        neg = (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;

	/*
	 * Compute the cutoff value between legal numbers and illegal
	 * numbers.  That is the largest legal value, divided by the
	 * base.  An input number that is greater than this value, if
	 * followed by a legal input character, is too big.  One that
	 * is equal to this value may be valid or not; the limit
	 * between valid and invalid numbers is then based on the last
	 * digit.  For instance, if the range for longs is
	 * [-2147483648..2147483647] and the input base is 10,
	 * cutoff will be set to 214748364 and cutlim to either
	 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
	 * a value > 214748364, or equal but the next digit is > 7 (or 8),
	 * the number is too big, and we will return a range error.
	 *
	 * Set any if any `digits' consumed; make it negative to indicate
	 * overflow.
	 */
    //cutoff = ULONG_MAX / (unsigned long)base;
    cutoff = cutoffvals[((unsigned long)base - 1) & 0x0f];
	for (acc = 0;; c = (unsigned char) *s++) {
        c = readhex(c);
        if((c == -1) || (c >= base))
            break;
        if (any < 0)
            continue;
        if (acc > cutoff) {
            any = -1;
            acc = ULONG_MAX;
            //errno = ERANGE;
        } else {
		    any = 1;
		    acc *= base;
		    acc += c;
        }
	}
    if (neg && (any > 0)) {
        acc = -acc;
    }
	if (endptr != 0)
		*endptr = (char *) (any ? s - 1 : nptr);
	return (acc);
}