/* 

 * strtoul.c --

 *

 *	Source code for the "strtoul" library procedure.

 *

 * Copyright (c) 1988 The Regents of the University of California.

 * Copyright (c) 1994 Sun Microsystems, Inc.

 *

 * See the file "license.terms" for information on usage and redistribution

 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.

 *

 * RCS: @(#) $Id: strtoul.c,v 1.5 2002/02/25 10:36:32 dkf Exp $

 */

#include "tclInt.h"

#include "tclPort.h"

/*

 * The table below is used to convert from ASCII digits to a

 * numerical equivalent.  It maps from '0' through 'z' to integers

 * (100 for non-digit characters).

 */

static char cvtIn[] = {

    0, 1, 2, 3, 4, 5, 6, 7, 8, 9,		/* '0' - '9' */

    100, 100, 100, 100, 100, 100, 100,		/* punctuation */

    10, 11, 12, 13, 14, 15, 16, 17, 18, 19,	/* 'A' - 'Z' */

    20, 21, 22, 23, 24, 25, 26, 27, 28, 29,

    30, 31, 32, 33, 34, 35,

    100, 100, 100, 100, 100, 100,		/* punctuation */

    10, 11, 12, 13, 14, 15, 16, 17, 18, 19,	/* 'a' - 'z' */

    20, 21, 22, 23, 24, 25, 26, 27, 28, 29,

    30, 31, 32, 33, 34, 35};

/*

 *----------------------------------------------------------------------

 *

 * strtoul --

 *

 *	Convert an ASCII string into an integer.

 *

 * Results:

 *	The return value is the integer equivalent of string.  If endPtr

 *	is non-NULL, then *endPtr is filled in with the character

 *	after the last one that was part of the integer.  If string

 *	doesn't contain a valid integer value, then zero is returned

 *	and *endPtr is set to string.

 *

 * Side effects:

 *	None.

 *

 *----------------------------------------------------------------------

 */

unsigned long int

strtoul(string, endPtr, base)

    CONST char *string;		/* String of ASCII digits, possibly

				 * preceded by white space.  For bases

				 * greater than 10, either lower- or

				 * upper-case digits may be used.

				 */

    char **endPtr;		/* Where to store address of terminating

				 * character, or NULL. */

    int base;			/* Base for conversion.  Must be less

				 * than 37.  If 0, then the base is chosen

				 * from the leading characters of string:

				 * "0x" means hex, "0" means octal, anything

				 * else means decimal.

				 */

{

    register CONST char *p;

    register unsigned long int result = 0;

    register unsigned digit;

    int anyDigits = 0;

    int negative=0;

    int overflow=0;

    /*

     * Skip any leading blanks.

     */

    p = string;

    while (isspace(UCHAR(*p))) {

	p += 1;

    }

    if (*p == '-') {

        negative = 1;

        p += 1;

    } else {

        if (*p == '+') {

            p += 1;

        }

    }

    /*

     * If no base was provided, pick one from the leading characters

     * of the string.

     */

    if (base == 0)

    {

	if (*p == '0') {

	    p += 1;

	    if ((*p == 'x') || (*p == 'X')) {

		p += 1;

		base = 16;

	    } else {

		/*

		 * Must set anyDigits here, otherwise "0" produces a

		 * "no digits" error.

		 */

		anyDigits = 1;

		base = 8;

	    }

	}

	else base = 10;

    } else if (base == 16) {

	/*

	 * Skip a leading "0x" from hex numbers.

	 */

	if ((p[0] == '0') && ((p[1] == 'x') || (p[1] == 'X'))) {

	    p += 2;

	}

    }

    /*

     * Sorry this code is so messy, but speed seems important.  Do

     * different things for base 8, 10, 16, and other.

     */

    if (base == 8) {

	unsigned long maxres = ULONG_MAX >> 3;

	for ( ; ; p += 1) {

	    digit = *p - '0';

	    if (digit > 7) {

		break;

	    }

	    if (result > maxres) { overflow = 1; }

	    result = (result << 3);

	    if (digit > (ULONG_MAX - result)) { overflow = 1; }

	    result += digit;

	    anyDigits = 1;

	}

    } else if (base == 10) {

	unsigned long maxres = ULONG_MAX / 10;

	for ( ; ; p += 1) {

	    digit = *p - '0';

	    if (digit > 9) {

		break;

	    }

	    if (result > maxres) { overflow = 1; }

	    result *= 10;

	    if (digit > (ULONG_MAX - result)) { overflow = 1; }

	    result += digit;

	    anyDigits = 1;

	}

    } else if (base == 16) {

	unsigned long maxres = ULONG_MAX >> 4;

	for ( ; ; p += 1) {

	    digit = *p - '0';

	    if (digit > ('z' - '0')) {

		break;

	    }

	    digit = cvtIn[digit];

	    if (digit > 15) {

		break;

	    }

	    if (result > maxres) { overflow = 1; }

	    result = (result << 4);

	    if (digit > (ULONG_MAX - result)) { overflow = 1; }

	    result += digit;

	    anyDigits = 1;

	}

    } else if ( base >= 2 && base <= 36 ) {

	unsigned long maxres = ULONG_MAX / base;

	for ( ; ; p += 1) {

	    digit = *p - '0';

	    if (digit > ('z' - '0')) {

		break;

	    }

	    digit = cvtIn[digit];

	    if (digit >= ( (unsigned) base )) {

		break;

	    }

	    if (result > maxres) { overflow = 1; }

	    result *= base;

	    if (digit > (ULONG_MAX - result)) { overflow = 1; }

	    result += digit;

	    anyDigits = 1;

	}

    }

    /*

     * See if there were any digits at all.

     */

    if (!anyDigits) {

	p = string;

    }

    if (endPtr != 0) {

	/* unsafe, but required by the strtoul prototype */

	*endPtr = (char *) p;

    }

    if (overflow) {

	errno = ERANGE;

	return ULONG_MAX;

    } 

    if (negative) {

	return -result;

    }

    return result;

}