Tic-Tac-Toe benchmark in Forth for https://github.com/BartMassey/ttt-bench

tictactoe.forth

( Tic-Tac-Toe benchmark for https://github.com/BartMassey/ttt-bench  )

VARIABLE BOARD 9 CELLS ALLOT BOARD 9 CELLS ERASE

: B@ CELLS BOARD + @ ;
: B! CELLS BOARD + ! ;

: NEGALINE ( a b c - filled )
  B@ SWAP B@ + SWAP B@ + ABS 3 =
;

: GAMEVALUE 
  0 4 8 NEGALINE IF 0 B@ * EXIT THEN 
  2 4 6 NEGALINE IF 2 B@ * EXIT THEN 
  0 1 2 NEGALINE IF 0 B@ * EXIT THEN 
  3 4 5 NEGALINE IF 3 B@ * EXIT THEN 
  6 7 8 NEGALINE IF 6 B@ * EXIT THEN 
  0 3 6 NEGALINE IF 0 B@ * EXIT THEN 
  1 4 7 NEGALINE IF 1 B@ * EXIT THEN 
  2 5 8 NEGALINE IF 2 B@ * EXIT THEN 
  DROP 
  9 0 DO I B@ 0= IF UNLOOP -2 EXIT THEN LOOP
  0
;

: NEGAMAX ( a - a )
  DUP GAMEVALUE DUP -2 <> IF NIP EXIT THEN DROP
  -1
  9 0 DO
    I B@ 0= IF
      OVER I B!
      OVER NEGATE RECURSE NEGATE
      OVER OVER < IF NIP ELSE DROP THEN
      0 I B!
    THEN
  LOOP
  NIP
;

: MAIN
  1 NEGAMAX . CR
;

MAIN
BYE