/********************************************
*	My AtoI
*	lovepump
*	lovepump@gatheringofgray.com
*	
*	Convert ascii (base anything up to 35) to base 10 integer
*
*	This Version - Positive numbers only
*
********************************************/


#define ATOI_ERROR_BASE -1
#define ATOI_ERROR_NODIGIT -2
#define ATOI_INVALID_DIGIT -3

/*

Usage:

	str* - pointer to a NULL terminated string, base 'base' ascii "number"
	base - number system basis for conversion up to 36 (Z)

*/


int pow(int num, int exp) {
	int i, result = 1;
	if(exp == 0) return 1;

	for(i = 0; i < exp; i++) result *= num;
	
	return result;
}


int my_atoi(const char *str, unsigned int base) {

	
	if(base > 36) return ATOI_ERROR_BASE;
	if(str == 0) return ATOI_ERROR_NODIGIT;

	unsigned int result = 0;
	const char *cursor, *low;
	
	cursor = str;
	for(;*cursor != '\0'; cursor++);
	cursor--;
	low = cursor;

	while(cursor >= str) 
	{

		if(*cursor >= 48 && (base > 10?*cursor <=57:*cursor <= (48 + base))) 
			result += (*cursor - 48) * pow(base,(low - cursor));
		else if(base > 10 && (*cursor >= 65 && *cursor < (65 + base - 10)))
			result += (*cursor - 65 + 10) * pow(base,(low - cursor));
		else return ATOI_INVALID_DIGIT;
	
	cursor--;
	}

	return result;

}

void my_itoa(unsigned int num, unsigned int base, char *str) 	{

	const char digits[] = 	{'0', '1', '2', '3', '4', '5',
				'6', '7', '8', '9', 'A', 'B',
				'C', 'D', 'E', 'F', 'G', 'H',
				'I', 'J', 'K', 'L', 'M', 'N',
				'O', 'P', 'Q', 'R', 'S', 'T',
				'U', 'V', 'W', 'X', 'Y', 'Z'};

	
	unsigned int magnitude = 0, remainder;
	int length = 0, cursor = 0;

	if(base < 2 || base > 36)
	{
		*str = '\0';
		return;
	}

	while(pow(base, length) < num)length++;

	remainder = num;
	
	str[length] = '\0';	
	cursor = length - 1;

	while(length >= 0) 
	{
		while(pow(base, length) * magnitude <= remainder) magnitude++;
		magnitude--;
		str[cursor - length] = digits[magnitude];
		remainder -= pow(base,length)*magnitude;
		length--;
		magnitude = 0;
	}
}