Re: midnight chess (work in progress)

[Richard Frost]

These data statements define most moves.   The format is up/down/left/right, and the
numbers indicate the number of squares that can be moved.  Castling and en passant
have to be handled special.  Pretty simple, eh?

DATA R,8000,0800,0080,0008,0000,0000,0000,0000
DATA N,2010,2001,0210,0201,1020,1002,0120,0102
DATA B,8080,8008,0880,0808,0000,0000,0000,0000
DATA Q,8000,0800,0080,0008,8080,8008,0880,0808
DATA K,1000,0100,0010,0001,1010,1001,0110,0101
DATA P,1000,1001,1010,0000,0000,0000,0000,0000

[romichess]

These data statements define most moves.   The format is up/down/left/right, and the
numbers indicate the number of squares that can be moved.  Castling and en passant
have to be handled special.  Pretty simple, eh?

DATA R,8000,0800,0080,0008,0000,0000,0000,0000
DATA N,2010,2001,0210,0201,1020,1002,0120,0102
DATA B,8080,8008,0880,0808,0000,0000,0000,0000
DATA Q,8000,0800,0080,0008,8080,8008,0880,0808
DATA K,1000,0100,0010,0001,1010,1001,0110,0101
DATA P,1000,1001,1010,0000,0000,0000,0000,0000

I can't make sense of those numbers. There is no piece that can move 8 squares in one direction.

[SMcNeill]

I can't make sense of those numbers. There is no piece that can move 8 squares in one direction.

I would guess 8 means “unlimited” in that direction.  What I’m curious about, if these represent max movement, is how a knight works.

DATA 0201 would be a max of 2 down, 1 right, but how dose it know it it *has* to be 2/1??  If the figures represent max movement, why can’t the knight move 1 down 0 right, or 0 down, 1 right?  Those figures are within the “max” movement range.

[Richard Frost]

Duh.  Indeed, I should be using 7, not 8 for unlimited.  Make it a tad faster!

Indeed, the knight is a special case, handled in this snippet:

Code: QB64: [Select]

1.     mp = b(fr, fc) '                                                 moving piece
2.     mc = -(mp > 6) - (mp = 0) * 2 '                                  moving color
3.     mp = mp + (mp > 6) * 6 '                                         white is 1 2 3 4 5 6, black 7 8 9 10 11 12
4.     IF mc = 1 THEN s = -1 ELSE s = 1 '                               direction a pawn moves
5.  
6.     FOR n = 0 TO 7 '                                                 possible 8 dirs
7.         udlr$ = mp$(mp, n) '                                         up/down/left/right
8.         IF udlr$ = "0000" THEN EXIT FOR
9.         du = VAL(MID$(udlr$, 1, 1)) '                                direction up
10.         dd = VAL(MID$(udlr$, 2, 1)) '                                direction down
11.         dl = VAL(MID$(udlr$, 3, 1)) '                                direction left
12.         dr = VAL(MID$(udlr$, 4, 1)) '                                direction right
13.         IF mp <> Knight THEN '                                       not knight
14.             du = SGN(du) * s '                                       one square at a time
15.             dd = SGN(dd) * s
16.             dl = SGN(dl) * s
17.             dr = SGN(dr) * s
18.         END IF
19.         IF INSTR(udlr$, "8") THEN TrySq = 8 ELSE TrySq = 1
20.