EXTERNALROUTINE DRAUGHTS(STRING(12) S)
EXTERNALROUTINESPEC CPULIMIT (STRING(255) S)
EXTERNALROUTINESPEC PROMPT(STRING(15) S)
OWNINTEGER MOB WT = 6
CONSTINTEGER TRUE =1, FALSE = 0

OWNINTEGER BACK WT = 4
OWNINTEGER CENT WT = 4
OWNINTEGER ADV1 WT = 450
OWNINTEGER ADV2 WT = 50
OWNINTEGER CRAMP WT = 6
OWNINTEGER MON = 'Q'
OWNINTEGER A WIN = 0
OWNINTEGER SEARCH LIMIT = 3
OWNINTEGER CROWN = 1800
OWNINTEGERARRAY BACK1(1:5) = 77, 75, 73, 71, 64
OWNINTEGERARRAY BACK2(1:5) =  0,  2,  4,  6, 13
OWNINTEGERARRAY CENTSQ(0:7) = 51, 53, 42, 44, 33, 35, 24, 26
OWNINTEGERARRAY MOVE(0:7) =  9, 18, 11, 22, -9,-18,-11,-22
OWNINTEGERARRAY PLAYER1(-1:26) =     'W',    1,  
   77,   75,   73,   71,   64,   66,   62,   60,   57,   55,   53,   51,
 1000, 1000, 1000, 1000, 1000, 1000, 1000, 1000, 1000, 1000, 1000, 1000,
   12,    0
OWNINTEGERARRAY PLAYER2(-1:26) =     'B',    2,
    0,    2,    4,    6,   13,   11,   15,   17,   20,   22,   24,   26,
 1000, 1000, 1000, 1000, 1000, 1000, 1000, 1000, 1000, 1000, 1000, 1000,
   12,    0
OWNINTEGERARRAY BOARD(-1:78) = C
  ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ',
  ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ',
  ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ',
  ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ',
  ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ',
  ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ',
  ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ',
  ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' '
INTEGERARRAY MIN, MAX(1:12)
INTEGERARRAY REPLY(1:9)
INTEGERARRAY COMP, OPP(-1:26)
INTEGERNAME COMPNUM, OPPNUM
INTEGERARRAY PSTACK(1:12);             ! piece position take stack
INTEGERARRAY TSTACK(1:12);             ! piece type stack
INTEGERARRAY NSTACK(1:12);             ! piece number stack
OWNINTEGER SP;                         ! stack pointer
OWNINTEGER ME = 1
OWNINTEGER ONE = 1
OWNINTEGER TWO = 2
OWNINTEGER THREE = 3
INTEGER BEST PIECE, BEST MOVE, BEST TAKE
INTEGER VALUEB, I, P, M, PIECE, JMAN, JUMP, DIF, MODIF, MORE
INTEGER OLDPOS, NEWPOS, LASTPOS, COMPOS
INTEGER NODES, PLY NUMBER, EXPECTED MOVE
INTEGER A,B,C,POS

!*   P L A Y I N G   F U N C T I O N S

   INTEGERFN VALID POS(INTEGER POS)
   INTEGER I
      ! on the board?
      I = POS>>1
      RESULT = -1 IF POS < 0 OR POS > 77 C
                   OR I = 4 OR I = 14 OR I = 24 OR I = 34
      ! square vacant?
      CYCLE I = 1, 1, 12 
         RESULT = 1 IF (I <= COMPNUM AND POS = COMP(I)) C
                     OR (I <= OPPNUM AND POS = OPP(I))
      REPEAT
      RESULT = 0
   END

   INTEGERFN VALID MOVE(INTEGER M, P, INTEGERARRAYNAME COMP, OPP)
      INTEGER CPOS, I, T
      UNLESS COMP(P+12) = CROWN START
         IF COMP(0) = 1 START;         ! player 1
            RESULT = -1 IF M&4 = 0;    ! backward move
         FINISH ELSE START;            ! else player 2
            RESULT = -1 IF M&4 # 0;    ! backward move
         FINISH
      FINISH
      CPOS = COMP(P)
      RESULT = -1 UNLESS VALID POS(CPOS+MOVE(M)) = 0
      RESULT = 0 IF M&1 = 0;           ! ordinary move
      RESULT = -1 IF OPP(25)=0
      I = CPOS+MOVE(M-1);              !  else take-move
      CYCLE T = 1, 1, OPP(25) 
         RESULT = T IF I = OPP(T);     ! piece to take?
      REPEAT
      RESULT = -1
   END

   INTEGERFN PENDING MOVE(INTEGERARRAYNAME COMP, OPP)
   INTEGER P, M, T, COMPNUM
      COMPNUM = COMP(25)
      RESULT = -1 IF COMPNUM = 0;      ! no pieces left!!
      CYCLE P = 1, 1, COMPNUM 
         CYCLE M = 1, 2, 7 
            T = VALID MOVE(M, P, COMP, OPP)
            RESULT = P IF T > 0;       ! return piece doing take
         REPEAT
      REPEAT
      ! ordinary moves
      CYCLE P = 1, 1, COMPNUM 
         CYCLE M = 0, 2, 6 
            T = VALID MOVE(M, P, COMP, OPP)
            RESULT = 0 IF T = 0;       ! move ok
         REPEAT
      REPEAT
      RESULT = -1;                    ! no moves
   END

   INTEGERFN CROWNING(INTEGER POS, PLAYER)
      ! assumes valid pos
      RESULT=TRUE IF (PLAYER = 1 AND POS < 7) C
            OR (PLAYER = 2 AND POS > 70)
      RESULT=FALSE
   END

   INTEGERFN MOD(INTEGER N)

      RESULT = -N IF N<0
      RESULT = N

   END

   INTEGERFN VALUE OF SIDE(INTEGERARRAYNAME COMP, OPP)
   INTEGER V1, V2, V3, V4, V5, V6, V7
   INTEGER P, PP, M, MM, MV, ADV1, VM, PLAYER
   INTEGERNAME CPOS, CTYPE
      PLAYER = COMP(0)

      ! back control
      V2 = 0
      IF OPP(26) = 0 START;            ! OPP has no crowns yet
         IF PLAYER = 1 START;          ! player 1
            CYCLE P = 1, 1, 5 
               V2 = V2+BACK WT IF COMP(P) = BACK1(P)
            REPEAT
         FINISH ELSE START;            ! player 2
            CYCLE P = 1, 1, 5 
               V2 = V2+BACK WT IF COMP(P) = BACK2(P)
            REPEAT
         FINISH
      FINISH

      V1 = 0;  V3 = 0;  V4 = 0;  V5 = 0;  V6 = 0;  V7 = 0
      CYCLE P = 1, 1, COMP(25) 
         CPOS ==COMP(P);  CTYPE ==  COMP(P+12)
         ADV1 = 0

         ! add up piece values
         V1 = V1+CTYPE

         CYCLE M = 0, 1, 7 
            VM = VALID MOVE(M, P, COMP, OPP)
            MV = MOVE(M)

            ! centre control
            IF CPOS = CENTSQ(M) START
               V4 = V4+CENT WT
               V4 = V4+CENT WT+1 IF CTYPE = CROWN
            FINISH

            IF VM >= 0 START

               ! mobility
               V3 = V3+MOB WT
               V3 = V3+MOB WT IF VM > 0

               IF CTYPE # CROWN START

                  ! advancement 1
                  IF ADV1 = 0 AND TRUE=CROWNING(CPOS+MV, PLAYER) THEN C
                   V5 = V5+ADV1 WT AND ADV1 = 1

                  ! advancement 2
                  IF VM = 0 START;     ! ignore jumps to crown
                     CPOS = CPOS+MV
                     CYCLE MM = 0, 2, 6 
                        IF TRUE=CROWNING(CPOS+MOVE(MM), PLAYER) C
                         AND VALID MOVE(MM, P, COMP, OPP) >= 0 START
                           V6 = V6+ADV2 WT;  EXIT
                        FINISH
                     REPEAT
                     CPOS = CPOS-MV
                  FINISH
               FINISH

               ! cramp
               IF VM = 0 AND CTYPE = CROWN AND OPP(25) > 0 START
                  CPOS = CPOS+MV
                  CYCLE PP = 1, 1, OPP(25) 
                     CYCLE MM = 1, 2, 7 
                        IF VALID MOVE(MM, PP, OPP, COMP) >= 0 START
                           V5 = V5-CRAMP WT;  EXIT
                        FINISH
                     REPEAT
                  REPEAT
                  CPOS = CPOS-MV
               FINISH
            FINISH
         REPEAT
      REPEAT
      RESULT = V1+V2+V3+V4+V5+V6+V7
   END

   INTEGERFN VALUE OF POS(INTEGERARRAYNAME COMP, OPP)
   INTEGER VALUE
      IF PENDING MOVE(COMP, OPP) >= 0 START
         VALUE = VALUE OF SIDE(COMP, OPP)-VALUE OF SIDE(OPP, COMP)-PLY NUMBER
      FINISH ELSE VALUE = -100000+PLYNUMBER;     ! no mobility!!
      RESULT = VALUE IF COMP(0) = ME
      RESULT = -VALUE
   END

   ROUTINE MAKE MOVE(INTEGER MV, P, INTEGERNAME T, C
                                     INTEGERARRAYNAME COMP, OPP)
   INTEGERNAME CPOS, CTYPE, OPOS, OTYPE, ONUM, ONUMC
      CPOS == COMP(P);  CTYPE == COMP(P+12)
      CPOS = CPOS+MV
      IF T # 0 START;                  ! a take
         OPOS == OPP(T);  OTYPE == OPP(T+12)
         ONUM == OPP(25);  ONUMC == OPP(26)
         SP = SP+1
         PSTACK(SP) = OPOS;            ! save position of taken piece
         TSTACK(SP) = OTYPE;           ! save piece type
         NSTACK(SP) = T;               ! save piece number
         OPOS = OPP(ONUM);             ! remove piece from board
         ONUM = ONUM-1;                ! reduce piece count for opp
         ONUMC = ONUMC-1 IF OTYPE = CROWN
         OTYPE = OPP(ONUM+13)
      FINISH
      IF CTYPE # CROWN AND TRUE=CROWNING(CPOS, COMP(0)) START
         CTYPE = CROWN;                ! crown piece
         COMP(26) = COMP(26)+1;        ! increase crown count
         T = 0;                        ! no more takes
      FINISH
   END

   INTEGERFN TRY POSSIBLE MOVES(INTEGER PLY, DEPTH, C
                                 INTEGERARRAYNAME COMP, OPP)
   INTEGER M,MM,MMM,MMF,P,T,TT,APT,VALUE,TAKES,OLDPOS,OLDTYPE
   INTEGERNAME MAXPLY, MINPLY

      INTEGERFN PURSUIT
         RESULT = 1 IF PLY = 1
         RESULT = ¬M&1
      END

      NODES = NODES+1
      APT = PENDING MOVE(COMP, OPP)
      PLY NUMBER = PLY-1 AND RESULT = VALUE OF POS(COMP, OPP) C
       IF (DEPTH >= SEARCH LIMIT AND APT <=0) OR PLY > 12
      MINPLY == MIN(PLY);  MINPLY = 100000
      MAXPLY == MAX(PLY);  MAXPLY =-100000
      IF APT >= 0 START;               ! COMP able to move
         IF APT > 0 START;             ! take priority
            P = APT;  APT = 2;  MMM = 1 ; MMF = 7
            SEARCH LIMIT = 2 IF PLY = 1
         FINISH ELSE START
            P = 1;  APT = 2;  MMM = 0; MMF=6
         FINISH
         CYCLE P = P, 1, COMP(25) 
            OLDPOS = COMP(P);  OLDTYPE = COMP(P+12)
            CYCLE M = MMM, APT, MMF 
               TAKES = 0
               T = VALID MOVE(M, P, COMP, OPP)
               IF T >= 0 START;                 ! valid move
                  MM = M;  TT = T
ANOTHER TAKE:     TAKES = TAKES+1 IF TT > 0
                  MAKE MOVE(MOVE(MM), P, TT, COMP, OPP);! try this move
                  IF TT > 0 START;               ! another take
                     CYCLE MM = 1, 2, 7 
                        TT = VALID MOVE(MM, P, COMP, OPP)
                        -> ANOTHER TAKE IF TT > 0
                     REPEAT
                  FINISH
                  VALUE = TRY POSSIBLE MOVES(PLY+1, DEPTH+PURSUIT, OPP, COMP)
                  COMP(P) = OLDPOS;  COMP(P+12) = OLDTYPE
                  OPP(25) = OPP(25)+TAKES
                  WHILE TAKES > 0 CYCLE
                     TT = NSTACK(SP)
                     OPP(TT) = PSTACK(SP)
                     OPP(TT+12) = TSTACK(SP)
                     TAKES = TAKES-1
                     SP = SP-1
                  REPEAT
                  IF COMP(0) = ME START
                     IF VALUE > MAXPLY START
                        MAXPLY = VALUE
                        IF PLY = 1 START
                           BEST MOVE = M
                           BEST TAKE = T
                           BEST PIECE = P
                        FINISH
                     FINISH
                     RESULT = MAXPLY IF PLY # 1 AND MAXPLY >= MIN(PLY-1)
                  FINISH ELSE START
                     MINPLY = VALUE IF VALUE < MINPLY
                     RESULT = MINPLY IF MINPLY <= MAX(PLY-1)
                  FINISH
               FINISH
            REPEAT
         REPEAT
      FINISH
      RESULT = MAXPLY IF COMP(0) = ME
      RESULT = MINPLY
   END

   ROUTINE SAY PLEASE
      PRINTSTRING("Please re-type your move
")
   END

   ROUTINE PRINT BOARD
   INTEGER I, J, POS
      CYCLE I = 0, 1, 7 
         CYCLE J = 0, 2, 6 
            BOARD(10*I+J+I&1) = '#'
         REPEAT
      REPEAT
      CYCLE I = 1, 1, 12 
         IF I <= COMP(25) START
            POS = COMP(I)
           IF COMP(I+12) = CROWN THEN BOARD(POS) = 'X' C
             ELSE BOARD(POS) = 'x'
         FINISH
         IF I <= OPP(25) START
            POS = OPP(I)
            IF OPP(I+12) = CROWN THEN BOARD(POS) = 'O' C
             ELSE BOARD(POS) = 'o'
         FINISH
      REPEAT
      PRINTSTRING("
  A B C D E F G H")
      CYCLE I = 70, -10, 0 
         NEWLINE
         PRINTSYMBOL(I//10+'1')
         CYCLE J = 0, 1, 7 
            SPACE
            PRINTSYMBOL(BOARD(J+I))
         REPEAT
         SPACE
         PRINTSYMBOL(I//10+'1')
      REPEAT
      PRINTSTRING("
  A B C D E F G H
")
   END

   ROUTINE TROUT(INTEGER OLDPOS, NEWPOS, INTEGERNAME MODE)
   INTEGER OLDX, OLDY, NEWX, NEWY
      OLDY = OLDPOS//10;  OLDX = OLDPOS-10*OLDY
      NEWY = NEWPOS//10;  NEWX = NEWPOS-10*NEWY
      IF MODE = 0 THEN PRINTSTRING("DRAFT4's move is ") AND MODE = 1  C
                   ELSE PRINTSTRING(" , ")
      PRINTSYMBOL(OLDX+'A')
      PRINTSYMBOL(OLDY+'1')
      PRINTSYMBOL('-')
      PRINTSYMBOL(NEWX+'A')
      PRINTSYMBOL(NEWY+'1')
   END

   INTEGERFN POSITION OF(INTEGER S1, S2)
      RESULT = (S1-'A')+10*(S2-'1')
   END

   ROUTINE SKIP SPACES AND NLS
      SKIP SYMBOL WHILE NEXT SYMBOL=' ' OR NEXT SYMBOL=NL
   END

   COMPNUM == COMP(25);  OPPNUM == OPP(25)
   CPULIMIT ("12"); ! FOR EMAS - JGH MOD, AS CS1 WERE RUNNING OUT
   PRINTSTRING("The Draughts programme  DRAFT4.4

")
   PRINT STRING("Do you want some help?"); NEWLINE
   PROMPT(":")
   READ SYMBOL(REPLY(1)); SKIP SYMBOL WHILE NEXT SYMBOL#NL; SKIP SYMBOL
   REPLY(1) = REPLY(1)-32 IF REPLY(1)>='a'
   IF REPLY(1)='Y' START
      PRINTSTRING("

   Moves are typed in in the following form:  (e.g.)

      C3-D4      move the piece on square C3 to square D4.")
PRINTSTRING("
      C3-E5      move C3 to E5, taking the piece on D4
"); PRINTSTRING("      C3-E5,
      E5-C7      an example of a multiple jump

                                                    e.t.c.")
   FINISH
RESTART:
   EXPECTED MOVE = 0
   ! setting up the pieces
   CYCLE P = -1, 1, 26 
      COMP(P) = PLAYER1(P)
      OPP(P) = PLAYER2(P)
   REPEAT
   NEWLINE
   PRINT STRING("Do you want to start?")
   NEWLINE
   PROMPT(":")
   READ SYMBOL(REPLY(1))
   REPLY(1) = REPLY(1)-32 IF REPLY(1)>='a'
   SKIP SYMBOL WHILE NEXT SYMBOL#NL; SKIP SYMBOL
   IF REPLY(1)='R' START
      ! Read board position
      CYCLE P = -1,1,26 
         COMP(P) = 0
         OPP(P) = 0
      REPEAT
      PRINT STRING("Where are your pieces?"); NEWLINE
      PROMPT(":")
      CYCLE P = 1,1,12 
         SKIP SPACES AND NLS
         READ SYMBOL(A); IF A='.' THEN EXIT
         READ SYMBOL(B); READ SYMBOL(C)
         A = A-32 IF A>='a'
         B = B-32 IF A>='a'
         POS = POSITION OF(A,B)
         OPP(P) = POS
         IF C=' ' THEN OPP(P+12) = 1000 ELSE OPP(P+12) = CROWN
      REPEAT
      OPP(0) = 2
      OPP(25) = P;        ! no of pieces.
      PRINT STRING("Where are my pieces?"); NEWLINE
      CYCLE P = 1,1,12 
         SKIP SPACES AND NLS
         READ SYMBOL(A); IF A='.' THEN EXIT
         READ SYMBOL(B); READ SYMBOL(C)
         A = A-32 IF A>='a'
         B = B-32 IF B>='a'
         POS = POSITION OF(A,B)
         COMP(P) = POS
         IF C=' ' THEN COMP(P+12) = 1000 ELSE COMP(P+12) = CROWN
      REPEAT
      COMP(0)  = ME
      COMP(25) = P;        ! NO OF PIECES
      SKIP SYMBOL;       ! NL
      PROMPT("Your move?")
      READ SYMBOL(A)
      SKIP SYMBOL WHILE NEXT SYMBOL#NL; SKIP SYMBOL
      A = A-32 IF A>='a'
      IF A='Y' THEN -> READ MOVE ELSE -> COMP MOVE
   FINISH
   IF REPLY(1) = 'N' START
      PRINT STRING("Think of a number please"); NEWLINE
      READ SYMBOL(I); SKIP SYMBOL
      I = (I-'0')&3
      COMP(-1) = 'B';  OPP(-1) = 'W'
      PRINTSTRING("DRAFT4's opening move is ")
      IF I = 1 THEN PRINTSTRING("D6-C5") AND COMP(11) = 42
      IF I = 2 THEN PRINTSTRING("D6-E5") AND COMP(11) = 44
      IF I = 3 THEN PRINTSTRING("F6-E5") AND COMP(10) = 44
      NEWLINE
   FINISH
READ MOVE: 
   PRINT BOARD
   PROMPT("Your move:")
   SKIP SYMBOL WHILE NEXT SYMBOL <= ' '
   CYCLE I = 1, 1, 8 
      READ SYMBOL(REPLY(I))
      REPLY(I) = REPLY(I)-32 IF REPLY(I)>='a'
      EXIT IF REPLY(I) = NL
   REPEAT
   REPLY(I) = ' ' AND I = I+1 UNTIL I = 9
   IF REPLY(1) = 'M' THEN MON = 'M' AND -> READ MOVE
   IF REPLY(1) = 'Q' THEN MON = 'Q' AND -> READ MOVE
TRANS:
   IF REPLY(1) = 'I' THEN -> STOP
   IF REPLY(6) = ','THEN MORE = 'M' ELSE MORE = ' '
   OLDPOS = POSITION OF(REPLY(1), REPLY(2))
   NEWPOS = POSITION OF(REPLY(4), REPLY(5))
   IF VALID POS(OLDPOS) = -1 START
      PRINTSTRING("The square ")
      PRINT SYMBOL(REPLY(1));  PRINT SYMBOL(REPLY(2))
      PRINTSTRING(" does not exist!
")
      SAY PLEASE
      -> READ MOVE
   FINISH
   M = VALID POS(NEWPOS)
   IF M = -1 START
      PRINTSTRING("You cannot move to square ")
      PRINTSYMBOL(REPLY(4));  PRINTSYMBOL(REPLY(5))
      PRINTSTRING(";  it does not exist!
")
      SAY PLEASE
      -> READ MOVE
   FINISH
   IF M = 1 START
      PRINTSTRING("You cannot move to square ")
      PRINT SYMBOL(REPLY(4));  PRINT SYMBOL(REPLY(5))
      PRINTSTRING(";  it is already occupied!
")
      SAY PLEASE
      -> READ MOVE
   FINISH
   CYCLE P = 1, 1, OPP(25) 
      IF OLDPOS = OPP(P) THENEXIT
   REPEAT
   UNLESS OLDPOS = OPP(P) START
      PRINTSTRING("You do not have a piece on square ")
      PRINT SYMBOL(REPLY(1));  PRINT SYMBOL(REPLY(2))
      NEWLINE
      SAY PLEASE
      -> READ MOVE
   FINISH
   PIECE = P
   DIF = NEWPOS-OLDPOS
   MODIF = MOD(DIF)
   IF MODIF < 12 AND EXPECTED MOVE > 0 START
      PRINTSTRING("You MUST take the piece that I am offering you
")
      SAY PLEASE
      -> READ MOVE
   FINISH
   IF MODIF < 12 AND MORE = 'M' START
      PRINTSTRING("That's not part of a multiple jump move
")
      SAY PLEASE
      -> READ MOVE
   FINISH
   IF DIF < 0 AND OPP(PIECE+12) # CROWN START
      PRINTSTRING("You cannot move that piece backwards!
")
      SAY PLEASE 
      -> READ MOVE
   FINISH
   UNLESS MODIF = 11 OR MODIF = 9 OR MODIF = 22 OR MODIF = 18 START
      PRINTSTRING("That move does not exist in my rule book!
")
      SAY PLEASE
      -> READ MOVE
   FINISH
   IF MODIF > 11 START
      JUMP = DIF//2
      COMPOS = OLDPOS+JUMP
      CYCLE I = 1, 1, COMP(25) 
         EXIT IF COMPOS = COMP(I)
      REPEAT
      UNLESS COMPOS = COMP(I) START
         PRINTSTRING("You cannot do that.  You are not jumping one of my pieces
")
         SAY PLEASE
         -> READ MOVE
      FINISH
      JMAN = I
   FINISH ELSE JMAN = 0
   MAKE MOVE(DIF, PIECE, JMAN, OPP, COMP)
   IF MORE = 'M' START
      LASTPOS = NEWPOS
READ AGAIN:
      PROMPT("and:")
      CYCLE I = 1, 1, 8 
         READ SYMBOL(REPLY(I))
         REPLY(I) = REPLY(I)-32 IF REPLY(I)>='a'
         EXIT IF REPLY(I) = NL
      REPEAT
      IF REPLY(1) = '.'THEN -> COMP MOVE
      REPLY(I) = ' ' AND I = I+1 UNTIL I = 9
      OLDPOS = POSITION OF(REPLY(1), REPLY(2))
      NEWPOS = POSITION OF(REPLY(4), REPLY(5))
      DIF = NEWPOS-OLDPOS
      DIF = MOD(DIF)
      IF DIF > 11 AND OLDPOS = LASTPOS THEN -> TRANS
      PRINTSTRING("That's not part of a multiple jump
Please re-type that part
")
      -> READ AGAIN
   FINISH
COMP MOVE: ! COMPUTER MAKES MOVE.
   IF COMPNUM = 0 START
      PRINTSTRING(" I have no pieces left so I suppose you have won
")
      -> STOP
   FINISH
   IF PENDING MOVE(COMP, OPP) = -1 START
      PRINTSTRING("I cannot move any of my pieces so you win
")
       -> STOP
   FINISH
   ! If in end game then increase search.
   I = COMPNUM+OPPNUM
   IF I <= 6 THEN SEARCH LIMIT = 4
   ! FIND BEST MOVE.
   NODES = 0;  SP = 0
   VALUEB = TRY POSSIBLE MOVES(1, 1, COMP, OPP)
   IF VALUEB <= -99990 START
       PRINTSTRING("I resign
")
       -> STOP
   FINISH
   I = 0
ANOTHER TAKE:
   TROUT(COMP(BEST PIECE), COMP(BEST PIECE)+MOVE(BEST MOVE), I)
   MAKE MOVE(MOVE(BEST MOVE), BEST PIECE, BEST TAKE, COMP, OPP)
   IF BEST TAKE > 0 START
      CYCLE BEST MOVE = 1, 2, 7 
         BEST TAKE = VALID MOVE(BEST MOVE, BEST PIECE, COMP, OPP)
         -> ANOTHER TAKE IF BEST TAKE>0
      REPEAT
   FINISH
   NEWLINE
   IF MON = 'M' START
      PRINTSTRING("Nodes considered =");  WRITE(NODES, 4)
      PRINTSTRING("
Value of board =");  WRITE(VALUEB, 4)
      NEWLINE
   FINISH
   IF OPPNUM = 0 START
       PRINTSTRING("You have no pieces left so I win
")
      -> STOP
   FINISH
   EXPECTED MOVE = PENDING MOVE(OPP, COMP)
   IF EXPECTED MOVE = -1 START
      PRINTSTRING("You cannot move any of your pieces so I win
")
      -> STOP
   FINISH
   IF VALUEB >= 99990  AND AWIN = 0 START
      PRINTSTRING("He-He!  I am going to win!!
")
      AWIN = 1
   FINISH
   -> READ MOVE
STOP:
   PRINTSTRING("
The final board position is -
")
   PRINT BOARD
END
ENDOFFILE