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Text File | 2008-03-07 | 15KB | 880 lines

; Zero-page registers r0 = $fb ; a pointer c4Player = $07 c4GameState = $08 ; and $09 c4Depth = $0a c4Level = $0b c4BestIndex = $0c c4BestWorst = $0d c4Goodness = $0e c4Alpha = $0f c4Beta = $10 c4MaxAB = $11 c4Best = $12 c4Temp1 = $13 c4Temp2 = $14 c4Temp3 = $15 c4Temp4 = $16 c4Temp5 = $17 c4Temp6 = $18 ; Game state offsets c4BoardOffset = 0 ; assumed c4ScoreArrayOffset = 48 c4ScoresOffset = 186 c4WinnerOffset = 188 c4TopPiecesOffset = 189 c4StateSize = 189 ; Other constants c4None = $ff c4HighestGoodness = $7f c4LowestGoodness = $81 ; Kernal routines chrOut = $ffd2 getIn = $ffe4 ; Start of program * = 2049 .obj "0:connect4" .byte 74, 8 ; end of BASIC program .byte 0, 0 ; line number .byte $9e ; SYS .asc "2124:" .byte $8f ; REM .byte $22 ; quote c4IntroText = * .byte 147 ; clear screen .byte 13+128 .byte 9, 14 ; switch to lower case .asc "Connect 4" .byte 13+128, 13+128 .asc "by Keith Pomakis" .byte 13+128 .asc "pomakis@pobox.com" .byte 13+128 .asc "May, 1997" .byte 13+128 .byte 0, 0, 0 ldx #19 - lda $06,x sta c4ZeroPageSave-1,x dex bne - lda #<c4IntroText sta r0 lda #>c4IntroText sta r0+1 jsr printStr jsr c4PlayGame ldx #19 - lda c4ZeroPageSave-1,x sta $06,x dex bne - rts getNum = * ; Gets a single digit between 0 and ; 7 from the keyboard. 'q' returns ; 0 as well. ; Input: r0 - pointer to prompt ; Retrn: .Y - the number ; Ruins: .A jsr printStr - jsr getIn cmp #0 beq - cmp #"q" bne + jsr chrOut ldy #0 beq ++ ; always true + cmp #"0" bmi ++ cmp #"8" bpl ++ pha jsr chrOut pla sec sbc #"0" tay + jsr printCR jmp printCR ; jsr/rts + ldy 53280 lda #2 sta 53280 lda $a2 ; low byte of jiffy clock clc adc #4 - cmp $a2 bne - sty 53280 beq -- ; always true printStr = * ; Prints a null-terminated string. ; Input: r0 - pointer to string ; Retrn: .Y - length of string pha ldy #0 - lda (r0),y beq + jsr chrOut iny bne - ; always true + pla rts printCR = * ; Prints a carraige return. ; Ruins: .A lda #13 jmp chrOut ; jsr/rts ;---------------------------------------------------------------------------- c4PlayGame = * jsr c4NewGame lda #<c4PlayGameLevelStr sta r0 lda #>c4PlayGameLevelStr sta r0+1 jsr getNum cpy #0 bne + rts + sty c4Level lda #0 sta c4Player - jsr c4PrintBoard ldy #c4WinnerOffset lda (c4GameState),y cmp #c4None beq + lda #<c4PlayGame1WinStr sta r0 lda #>c4PlayGame1WinStr sta r0+1 jsr printStr jmp c4PlayGame + ldy #c4TopPiecesOffset lda (c4GameState),y cmp #7 bne + rts / ldy c4Player lda c4PlayGameTable,y sta c4PlayGameMovePieceChar lda #<c4PlayGameMoveStr sta r0 lda #>c4PlayGameMoveStr sta r0+1 jsr getNum cpy #0 beq c4PlayGame ; always true dey jsr c4DropPiece bcs - jsr c4PrintBoard jsr printCR ldy #c4WinnerOffset lda (c4GameState),y cmp #c4None beq + lda #<c4PlayGame0WinStr sta r0 lda #>c4PlayGame0WinStr sta r0+1 jsr printStr jmp c4PlayGame + ldy #c4TopPiecesOffset lda (c4GameState),y cmp #7 bne + lda #<c4PlayGameTieStr sta r0 lda #>c4PlayGameTieStr sta r0+1 jsr printStr jmp c4PlayGame + lda c4Player eor #$01 sta c4Player lda #<c4PlayGameThinkingStr sta r0 lda #>c4PlayGameThinkingStr sta r0+1 jsr printStr jsr c4AutoMove jsr printCR jsr printCR lda c4Player eor #$01 sta c4Player jmp -- c4PlayGameTable = * .asc "XO" c4PlayGameLevelStr = * .byte 13 .asc "Level? " .byte 0 c4PlayGameMoveStr = * .byte 13 .asc "Move " c4PlayGameMovePieceChar = * .asc " ? " .byte 0 c4PlayGameThinkingStr = * .asc "Thinking" .byte 0 c4PlayGameTieStr = * .byte 13 .asc "Tie!" .byte 13, 0 c4PlayGame0WinStr = * .byte 13 .asc "You win!" .byte 13, 0 c4PlayGame1WinStr = * .byte 13 .asc "I win!" .byte 13, 0 c4PrintBoard = * ; Ruins: .A, .Y, R0 ldy #40 - lda (c4GameState),y bne + lda #"X" bne +++ ; always true + cmp #1 bne + lda #"O" bne ++ ; always true + lda #"." + jsr chrOut iny tya and #$07 cmp #$07 bne - jsr printCR cpy #$07 beq + tya sec sbc #15 tay jmp - + lda #<c4PrintBoardStr sta r0 lda #>c4PrintBoardStr sta r0+1 jmp printStr ; jsr/rts c4PrintBoardStr = * .asc "1234567" .byte 13, 0 c4NewGame = * ; Retrn: .A - 0 ; Ruins: .Y ; Set up the "real" game state. ; Make sure it starts at a page ; boundary. ldx #0 stx c4GameState ldx #>c4EndOfProgram inx stx c4GameState+1 lda #c4None ldy #47 - sta (c4GameState),y dey bpl - lda #1 ldy #c4ScoreArrayOffset - sta (c4GameState),y iny cpy #c4ScoreArrayOffset+138 bne - lda #69 ldy #c4ScoresOffset sta (c4GameState),y iny sta (c4GameState),y lda #c4None ldy #c4WinnerOffset sta (c4GameState),y lda #0 ldy #c4TopPiecesOffset sta (c4GameState),y sta c4Depth rts c4DropPieceSpecial = * ; Input: .Y - c4DropOrder index of column to drop into ; Retrn: .C - 0 success, 1 failure ; Ruins: .A, .X, .Y, R0, c4Temp1 ; c4Temp2, c4Temp3, c4Temp4 tya tax ldy c4DropOrder,x ; Fall through to c4DropPiece. c4DropPiece = * ; Input: .Y - column to drop into ; Retrn: .C - 0 success, 1 failure ; Ruins: .A, .X, .Y, R0, c4Temp1 ; c4Temp2, c4Temp3, c4Temp4 - lda (c4GameState),y cmp #c4None beq + tya clc adc #8 tay cpy #48 bmi - sec rts + lda c4Player sta (c4GameState),y ; Keep track of the number of ; pieces on the top row of the ; board so a tie can be spotted. cpy #40 bmi + sty c4Temp1 ldy #c4TopPiecesOffset lda (c4GameState),y clc adc #1 sta (c4GameState),y ldy c4Temp1 + tya jsr c4UpdateScore clc rts c4UpdateScore = * ; Input: c4Player - player (0 or 1) ; .A - index of new piece ; (x*8 + y) ; Ruins: .A, .X, .Y, R0, c4Temp1, ; c4Temp2, c4Temp3, c4Temp4 c4ScoreDiffOfThisPlayer = c4Temp3 c4ScoreDiffOfOtherPlayer = c4Temp4 ; Calculate the index of the proper ; array of score array indexes. ; i.e., one of c4Map00, c4Map01, ... asl tay lda c4Map,y sta c4ProperMap lda c4Map+1,y sta c4ProperMap+1 lda #0 sta c4ScoreDiffOfThisPlayer sta c4ScoreDiffOfOtherPlayer ; Loop through each of the score ; units in the indexed array. ldx #0 c4ProperMap = *+1 - lda $ffff,x cmp #c4None bne ++ ; We're done. Update the scores. lda c4Player beq + ldy #c4ScoresOffset lda (c4GameState),y clc adc c4ScoreDiffOfOtherPlayer sta (c4GameState),y iny lda (c4GameState),y clc adc c4ScoreDiffOfThisPlayer sta (c4GameState),y rts + ldy #c4ScoresOffset lda (c4GameState),y clc adc c4ScoreDiffOfThisPlayer sta (c4GameState),y iny lda (c4GameState),y clc adc c4ScoreDiffOfOtherPlayer sta (c4GameState),y rts + clc adc #c4ScoreArrayOffset ; .A now contains the index of the ; proper score unit of player 0. ; Double the score unit of the ; current player. sta c4Temp1 ldy #0 cpy c4Player beq + clc adc #69 + tay lda (c4GameState),y sta c4Temp2 asl sta (c4GameState),y ; Is this a winning move? cmp #16 bne + lda c4Player ldy #c4WinnerOffset sta (c4GameState),y lda #16 + sec sbc c4Temp2 clc adc c4ScoreDiffOfThisPlayer sta c4ScoreDiffOfThisPlayer ; Zero the score unit of the other ; player. lda c4Temp1 ldy #1 cpy c4Player beq + clc adc #69 + tay lda c4ScoreDiffOfOtherPlayer sec sbc (c4GameState),y sta c4ScoreDiffOfOtherPlayer lda #0 sta (c4GameState),y inx bne - ; always true c4GoodnessOfCurrentPlayer = * ; Calculates the "goodness" of the ; current board relative to the ; current player. This amounts to ; score(player)-score(other(player)). ; Retrn: .A - goodness ; .Y - current player ldy #c4ScoresOffset lda (c4GameState),y iny sec sbc (c4GameState),y ldy c4Player beq + eor #$ff clc adc #1 + rts c4PushState = * ; Ruins: .A, .X ldx c4GameState+1 stx c4OldStateAddr1 stx c4OldStateAddr2 inx stx c4NewStateAddr1 stx c4NewStateAddr2 stx c4GameState+1 ldx #c4StateSize c4OldStateAddr1 = *+2 - lda $ff00,x c4NewStateAddr1 = *+2 sta $ff00,x dex bne - c4OldStateAddr2 = *+2 lda $ff00,x c4NewStateAddr2 = *+2 sta $ff00,x inc c4Depth rts c4PollFn = * ; Protect .Y! lda #"." jmp chrOut ; jsr/rts c4AutoMove = * ; Retrn: c4BestIndex ; - c4DropOrder index of column dropped into lda #c4LowestGoodness sta c4BestWorst lda #c4None sta c4BestIndex ldy c4GameState+1 iny sty c4GameStatePage lda #0 sta c4Goodness ldy #0 - jsr c4PushState jsr c4PollFn - sty c4Temp5 jsr c4DropPieceSpecial ldy c4Temp5 bcc + iny cpy #7 bne - dec c4Depth ; pop state dec c4GameState+1 bne c4AutoMoveFinish ; always true ; We have just dropped a piece ; into column .Y + lda c4Player ldx #c4WinnerOffset c4GameStatePage = *+2 cmp $ff00,x bne + lda #c4HighestGoodness sta c4Goodness bne ++ ; always true ; Call c4Evaluate + lda #c4LowestGoodness sta c4Alpha lda #0 sec sbc c4BestWorst sta c4Beta sty c4Temp5 jsr c4Evaluate ldy c4Temp5 + lda c4Goodness sec sbc c4BestWorst bne + ; Make a random decision lda $a2 ; low byte of jiffy clock ror bcc c4AutoMoveContinue bcs +++ + bmi + bvs c4AutoMoveContinue bvc ++ + bvc c4AutoMoveContinue + lda c4Goodness sta c4BestWorst sty c4BestIndex c4AutoMoveContinue = * dec c4Depth ; pop state dec c4GameState+1 iny cpy #7 bne -- c4AutoMoveFinish = * ldy c4BestIndex cpy #c4None beq + jmp c4DropPieceSpecial ; jsr/rts + rts c4Evaluate = * lda c4Level cmp c4Depth bne + jsr c4GoodnessOfCurrentPlayer sta c4Goodness rts + lda #c4LowestGoodness sta c4Best lda c4Alpha sta c4MaxAB ldy #0 sty c4Temp6 lda c4Player eor #1 sta c4Player - jsr c4PushState jsr c4DropPieceSpecial bcc + dec c4Depth ; pop state dec c4GameState+1 jmp c4EvaluateContinue2 + ldy #c4WinnerOffset lda (c4GameState),y cmp #c4None beq + lda #c4HighestGoodness sec sbc c4Depth sta c4Goodness bne ++ ; always true ; Recurse + lda c4Best pha lda c4MaxAB pha lda c4Temp6 pha lda c4Alpha pha lda c4Beta pha lda #0 sec sbc c4Beta sta c4Alpha lda #0 sec sbc c4MaxAB sta c4Beta jsr c4Evaluate pla sta c4Beta pla sta c4Alpha pla sta c4Temp6 pla sta c4MaxAB pla sta c4Best + lda c4Goodness sec sbc c4Best bmi + bvs c4EvaluateContinue1 bvc ++ + bvc c4EvaluateContinue1 + beq c4EvaluateContinue1 lda c4Goodness sta c4Best lda c4Best sec sbc c4MaxAB bmi + bvs c4EvaluateContinue1 bvc ++ + bvc c4EvaluateContinue1 + beq c4EvaluateContinue1 lda c4Best sta c4MaxAB c4EvaluateContinue1 = * dec c4Depth ; pop state dec c4GameState+1 lda c4Beta sec sbc c4Best bmi + bvs ++ bvc c4EvaluateContinue2 + bvc + c4EvaluateContinue2 = * inc c4Temp6 ldy c4Temp6 cpy #7 beq + jmp - + lda c4Player eor #1 sta c4Player lda #0 sec sbc c4Best sta c4Goodness rts c4Map = * .word c4Map00, c4Map01, c4Map02, c4Map03, c4Map04, c4Map05, c4Map06, 0 .word c4Map10, c4Map11, c4Map12, c4Map13, c4Map14, c4Map15, c4Map16, 0 .word c4Map20, c4Map21, c4Map22, c4Map23, c4Map24, c4Map25, c4Map26, 0 .word c4Map30, c4Map31, c4Map32, c4Map33, c4Map34, c4Map35, c4Map36, 0 .word c4Map40, c4Map41, c4Map42, c4Map43, c4Map44, c4Map45, c4Map46, 0 .word c4Map50, c4Map51, c4Map52, c4Map53, c4Map54, c4Map55, c4Map56 c4Map00 .byte 03, 24, 45, c4None c4Map01 .byte 03, 02, 27, 48, c4None c4Map02 .byte 03, 02, 04, 30, 51, c4None c4DropOrder = * ; This is an evil thing to do, but it saves 7 bytes! ; I've organized the map so that c4Map03 is overloaded to represent the ; order in which the computer tries dropping pieces. c4Map03 .byte 03, 02, 04, 01, 05, 00, 06, c4None c4Map04 .byte 02, 04, 01, 36, 60, c4None c4Map05 .byte 04, 01, 39, 63, c4None c4Map06 .byte 01, 42, 66, c4None c4Map10 .byte 33, 24, 25, 46, c4None c4Map11 .byte 33, 54, 27, 28, 45, 49, c4None c4Map12 .byte 33, 54, 57, 30, 31, 48, 52, 06, c4None c4Map13 .byte 33, 54, 57, 07, 05, 34, 51, 55, 58, 60, c4None c4Map14 .byte 54, 57, 07, 36, 37, 00, 61, 63, c4None c4Map15 .byte 57, 07, 39, 40, 64, 66, c4None c4Map16 .byte 07, 42, 43, 67, c4None c4Map20 .byte 08, 24, 25, 26, 47, c4None c4Map21 .byte 08, 09, 27, 28, 29, 46, 50, 06, c4None c4Map22 .byte 08, 09, 10, 30, 31, 32, 45, 49, 53, 58, 60, c4None c4Map23 .byte 08, 09, 10, 11, 05, 34, 35, 48, 52, 56, 59, 61, 63, c4None c4Map24 .byte 09, 10, 11, 36, 37, 38, 51, 55, 62, 64, 66, c4None c4Map25 .byte 10, 11, 39, 40, 41, 00, 65, 67, c4None c4Map26 .byte 11, 42, 43, 44, 68, c4None c4Map30 .byte 12, 24, 25, 26, 06, c4None c4Map31 .byte 12, 13, 27, 28, 29, 47, 58, 60, c4None c4Map32 .byte 12, 13, 14, 30, 31, 32, 46, 50, 59, 61, 63, c4None c4Map33 .byte 12, 13, 14, 15, 05, 34, 35, 45, 49, 53, 62, 64, 66, c4None c4Map34 .byte 13, 14, 15, 36, 37, 38, 48, 52, 56, 65, 67, c4None c4Map35 .byte 14, 15, 39, 40, 41, 51, 55, 68, c4None c4Map36 .byte 15, 42, 43, 44, 00, c4None c4Map40 .byte 16, 25, 26, 58, c4None c4Map41 .byte 16, 17, 28, 29, 59, 61, c4None c4Map42 .byte 16, 17, 18, 31, 32, 47, 62, 64, c4None c4Map43 .byte 16, 17, 18, 19, 34, 35, 46, 50, 65, 67, c4None c4Map44 .byte 17, 18, 19, 37, 38, 49, 53, 68, c4None c4Map45 .byte 18, 19, 40, 41, 52, 56, c4None c4Map46 .byte 19, 43, 44, 55, c4None c4Map50 .byte 20, 26, 59, c4None c4Map51 .byte 20, 21, 29, 62, c4None c4Map52 .byte 20, 21, 22, 32, 65, c4None c4Map53 .byte 20, 21, 22, 23, 35, 47, 68, c4None c4Map54 .byte 21, 22, 23, 38, 50, c4None c4Map55 .byte 22, 23, 41, 53, c4None c4Map56 .byte 23, 44, 56, c4None c4ZeroPageSave = * c4EndOfProgram = *+18