Simple Forsyth-Edwards Notation (FEN) for GameMaker 0.1.0

// Simple Forsyth-Edwards Notation (FEN) for GameMaker | Version 0.1.0
// CC0 License

// Example use: my_board = fen_sort("r1bq1rk1/pp3ppp/3n4/2p1N3/2B5/7P/PPP2PP1/R1BQR1K1");
// Returns an array, white pieces are 1 - 6, black pieces are 7 - 12. 0 = no piece.

function fen_sort(fen_string) {

    var color_pieces = [0, 6];
    var pieces = { k: 1, p: 2, n: 3, b: 4, r: 5, q: 6 };
    var board = array_create(64, 0);

    var file = 0;
    var rank = 7;
    var squares = 0;

    for (var i = 0; i < string_length(fen_string); i++) {

        var symbol = string_char_at(fen_string, i + 1);

        switch symbol {
            case "-":
                // depends on how you want to code your chess game. empty
                break;
            case "/":
                file = 0;
                rank--;
                break;
            default:
                if (string(string_digits(symbol)) == symbol) {
                    file += real(symbol)
                    squares += real(symbol);
                } else {
                    var c = (string_upper(symbol) == symbol) ? 0 : 1;
                    var piece_name = color_pieces[c] + pieces[$string_lower(symbol)];
                    board[squares] = piece_name;
                    squares++;
                }
                break;
        }

    }

    return board;

}