initial commit

tictactoe_game.c

@@ -0,0 +1,145 @@
+#include "tictactoe_game.h"
+#include "tictactoe_internal.h"
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/printk.h>
+
+int tictactoe_game_init(ttt_game_t *game)
+{
+	game->next_turn = 'X';
+	game->winner = 0;
+	for (int x = 0; x < 3; x++) {
+		for (int y = 0; y < 3; y++) {
+			game->board[x][y] = ' ';
+		}
+	}
+
+	return 0;
+}
+
+// returns 0 if there is no winner yet, -1 if it's a tie, and the respective player if they win
+char tictactoe_game_check_winner(ttt_game_t *game)
+{
+	char winner;
+
+	// check columns
+	for (int x = 0; x < 3; x++) {
+		winner = game->board[x][0];
+		if (winner != ' ') {
+			for (int y = 1; y < 3; y++) {
+				if (game->board[x][y] != winner) {
+					winner = 0;
+					break;
+				}
+			}
+			if (winner != 0)
+				return winner;
+		}
+	}
+
+	// check rows
+	for (int y = 0; y < 3; y++) {
+		winner = game->board[0][y];
+		if (winner != ' ') {
+			for (int x = 1; x < 3; x++) {
+				if (game->board[x][y] != winner) {
+					winner = 0;
+					break;
+				}
+			}
+			if (winner != 0)
+				return winner;
+		}
+	}
+
+	// check diagonal top-left <-> bottom-right
+	winner = game->board[0][0];
+	if (winner != ' ') {
+		for (int i = 0; i < 3; i++) {
+			if (game->board[i][i] != winner) {
+				winner = 0;
+				break;
+			}
+		}
+		if (winner != 0)
+			return winner;
+	}
+
+	// check diagonal bottom-left <-> top-right
+	winner = game->board[2][0];
+	if (winner != ' ') {
+		for (int i = 0; i < 3; i++) {
+			if (game->board[2 - i][i] != winner) {
+				winner = 0;
+				break;
+			}
+		}
+		if (winner != 0)
+			return winner;
+	}
+
+	// check for tie
+	winner = -1;
+	for (int x = 0; x < 3; x++) {
+		for (int y = 0; y < 3; y++) {
+			if (game->board[x][y] == ' ') {
+				winner = 0;
+				break;
+			}
+		}
+	}
+
+	return winner;
+}
+
+int tictactoe_game_make_turn(ttt_game_t *game, size_t x, size_t y)
+{
+	if (game->board[x][y] != ' ') {
+		pr_notice("position already occupied\n");
+		return -1;
+	}
+
+	game->board[x][y] = game->next_turn;
+	game->winner = tictactoe_game_check_winner(game);
+
+	if (game->next_turn == 'X')
+		game->next_turn = 'O';
+	else
+		game->next_turn = 'X';
+
+	return 0;
+}
+
+int tictactoe_game_snprint(ttt_game_t *game, char *buf, size_t count)
+{
+	int pos;
+	int ret;
+
+	pos = 0;
+
+	ret = snprintf(buf + pos, count - pos,
+		       "#####\n#%.3s#\n#%.3s#\n#%.3s#\n#####\n\n",
+		       game->board[0], game->board[1], game->board[2]);
+	if (ret < 0)
+		goto fail;
+	pos += ret;
+
+	if (game->winner == 0) {
+		ret = snprintf(buf + pos, count - pos, "It's %c's turn!\n",
+			       game->next_turn);
+	} else if (game->winner == -1) {
+		ret = snprintf(buf + pos, count - pos, "It's a tie!\n");
+	} else {
+		ret = snprintf(buf + pos, count - pos, "Player %c won!\n",
+			       game->winner);
+	}
+	if (ret < 0)
+		goto fail;
+	pos += ret;
+
+	return pos;
+
+fail:
+	tictactoe_error("snprintf failed\n");
+	return -1;
+}