/* ex: set ts=2 et: */
/* A crappy game of Tic-Tac-Toe! Enjoy! */

#include <stdio.h>
#include <stdlib.h>

/**
 * +------+------+------+
 * | 0x100| 0x80 | 0x40 |
 * +------+------+------+
 * | 0x20 | 0x10 | 0x08 |
 * +------+------+------+
 * | 0x04 | 0x02 | 0x01 |
 * +------+------+------+
 */

/* all winning bit sets */
static const unsigned Win[] = {
  0x0184, 0x0038, 0x0007, 0x0124, 0x0092, 0x0049, 0x0111, 0x0054
};

static unsigned Player[2],
		            Turn;

static void print_board(void)
{
	unsigned i, n;
	for (i = 0, n = 1 << 8; n; i++, n >>= 1) {
		if (0 == i % 3)
			printf("\n+---+---+---+\n|");
		printf(" %c |", ((Player[0] & n) ? 'X' : (Player[1] & n) ? 'O' : ' '));
	}
	printf("\n+---+---+---+");
}

static unsigned check_win(unsigned state)
{
	unsigned i = sizeof Win / sizeof Win[0] + 1,
	         won = 0;
	while (i--)
		won = won | ((Win[i] & state) == Win[i]);
	return won;
}

static unsigned do_turn(void)
{
	int cell = 0;
	print_board();
	do {
		printf("\nPlayer %d: Which cell (1-9): ", (Turn & 1) + 1);
		fflush(stdout);
		cell = getc(stdin);
    if ('\n' != cell)
      getc(stdin); /* toss newline */
		cell -= '0'; /* NOTE: assume ASCII */
		cell--;
		cell = 8 - cell;
	} while (cell < 0 || cell > 8 || (Player[0] & (1 << cell)) || (Player[1] & (1 << cell)));
	Player[Turn & 1] |= 1 << cell;
	return Turn++ & 1;
}

main()
{
	while (!check_win(Player[do_turn()]));
	print_board();
	printf("\nPlayer %d is the winner!\n", !(Turn & 1)+1);
	return 0;
}