/* $NetBSD: _strtol.h,v 1.2 2009/05/20 22:03:29 christos Exp $ */

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * 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.
 *
 * Original version ID:
 * NetBSD: src/lib/libc/locale/_wcstol.h,v 1.2 2003/08/07 16:43:03 agc Exp
 */

/*
 * function template for strtol, strtoll and strtoimax.
 *
 * parameters:
 *      _FUNCNAME : function name
 *      __INT     : return type
 *      __INT_MIN : lower limit of the return type
 *      __INT_MAX : upper limit of the return type
 */

__INT
_FUNCNAME(const char *nptr, char **endptr, int base)
{
        const char *s;
        __INT acc, cutoff;
        unsigned char c;
        int any, cutlim, i, neg;

        /* check base value */
        if (base && (base < 2 || base > 36)) {
#if !defined(_KERNEL) && !defined(_STANDALONE)
                errno = EINVAL;
                if (endptr != NULL)
                        /* LINTED interface specification */
                        *endptr = __DECONST(void *, nptr);
                return (0);
#else
                panic("%s: invalid base %d", __func__, base);
#endif
        }

        /*
         * 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 = *s++;
        } while (isspace(c));
        if (c == '-') {
                neg = 1;
                c = *s++;
        } else {
                neg = 0;
                if (c == '+')
                        c = *s++;
        }
        if ((base == 0 || base == 16) &&
            c == '0' && (*s == 'x' || *s == 'X') &&
            ((s[1] >= '0' && s[1] <= '9') ||
            (s[1] >= 'A' && s[1] <= 'F') ||
            (s[1] >= 'a' && s[1] <= 'f'))) {
                c = s[1];
                s += 2;
                base = 16;
        }
        if ((base == 0 || base == 2) &&
            c == '0' && (*s == 'b' || *s == 'B') &&
            (s[1] >= '0' && s[1] <= '1')) {
                c = s[1];
                s += 2;
                base = 2;
        }
        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 = (neg ? __INT_MIN : __INT_MAX);
        cutlim = (int)(cutoff % base);
        cutoff /= base;
        if (neg) {
                if (cutlim > 0) {
                        cutlim -= base;
                        cutoff += 1;
                }
                cutlim = -cutlim;
        }
        for (acc = 0, any = 0;; c = *s++) {
                if (isdigit(c))
                        i = c - '0';
                else if (isalpha(c))
                        i = c - (isupper(c) ? 'A' - 10 : 'a' - 10);
                else
                        break;
                if (i >= base)
                        break;
                if (any < 0)
                        continue;
                if (neg) {
                        if (acc < cutoff || (acc == cutoff && i > cutlim)) {
                                acc = __INT_MIN;
#if !defined(_KERNEL) && !defined(_STANDALONE)
                                any = -1;
                                errno = ERANGE;
#else
                                any = 0;
                                break;
#endif
                        } else {
                                any = 1;
                                acc *= base;
                                acc -= i;
                        }
                } else {
                        if (acc > cutoff || (acc == cutoff && i > cutlim)) {
                                acc = __INT_MAX;
#if !defined(_KERNEL) && !defined(_STANDALONE)
                                any = -1;
                                errno = ERANGE;
#else
                                any = 0;
                                break;
#endif
                        } else {
                                any = 1;
                                acc *= base;
                                acc += i;
                        }
                }
        }
        if (endptr != NULL)
                /* LINTED interface specification */
                *endptr = __DECONST(void *, any ? s - 1 : nptr);
        return(acc);
}