Updated CHESS
Properly labelled and commented ATTACK and its subroutines. There is no guarantee of the correctness of the comments, because I don't know how to play chess.
This commit is contained in:
Broken Pipe
@@ -870,180 +870,252 @@ IC5: MOV AL,[BX] ; Fetch King position
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AND AL,7 ; Get piece type
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MOV [T1],AL ; Save
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;***********************************************************
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; ATTACK ROUTINE
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;***********************************************************
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; FUNCTION: -- To find all attackers on a given square
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; by scanning outward from the square
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; until a piece is found that attacks
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; that square, or a piece is found that
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; doesn't attack that square, or the edge
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; of the board is reached.
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;
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; *** NOTE FROM BROKEN PIPE ***
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; In determining which pieces attack
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; a square, this routine also takes into
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; account the ability of certain pieces to
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; attack through another attacking piece. (For
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; example a queen lined up behind a bishop
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; of her same color along a diagonal.) The
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; bishop is then said to be transparent to the
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; queen, since both participate in the
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; attack.
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;
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; THIS ATTACK ROUTINE DOES NOT MATCH SARGON'S ATTACK ROUTINE,
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; IT IS MOST LIKELY TIM PATERSON'S OWN IMPLEMENTATION.
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; In the case where this routine is called
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; by CASTLE or INCHK, the routine is
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; terminated as soon as an attacker of the
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; opposite color is encountered.
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;
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; I DO NOT KNOW HOW TO PLAY CHESS, SO I CANNOT UNDERSTAND ANY
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; OF THE CODE. I NEED SOMEONE EXPERIENCED IN CHESS AND CHESS
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; PROGRAMMING TO DISASSEMBLE THIS ROUTINE AND ITS SUBROUTINES.
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; CALLED BY: -- POINTS
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; PINFND
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; CASTLE
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; INCHK
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;
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ATTACK: PUSH CX
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MOV BP,[M3]
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ADD BP,BOARD
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MOV DH,0
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MOV SI,DIRECT+TBASE
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MOV AH,6
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CALL L102D
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MOV AH,2
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CALL L102D
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MOV AH,32
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MOV AL,[BP+11]
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AND AL,87H
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CMP AL,81H
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JNZ L0FF8
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OR [BP+11],AH
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L0FF8: MOV AL,[BP+9]
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AND AL,87H
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CMP AL,81H
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JNZ L1004
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OR [BP+9],AH
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L1004: MOV AL,[BP-11]
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AND AL,87H
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CMP AL,1
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JNZ L1010
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OR [BP-11],AH
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L1010: MOV AL,[BP-9]
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AND AL,87H
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CMP AL,1
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JNZ L101C
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OR [BP-9],AH
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L101C: MOV SI,DIRECT+TBASE
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MOV AH,3
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CALL L1046
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MOV AH,4
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CALL L1046
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XOR AL,AL
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POP CX
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RET
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; CALLS: -- ATKADJ
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; ATKOUT
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;
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; ARGUMENTS: -- None
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;***********************************************************
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ATTACK: PUSH CX ; Save Register CX
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MOV BP,[M3] ; Get piece index
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ADD BP,BOARD ; Add board pointer to it
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MOV DH,0 ; Init. scan count/flags
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MOV SI,DIRECT+TBASE ; Load direction table
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MOV AH,KING ; Check for a King
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CALL ATKADJ ; Scan adjacent squares
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MOV AH,KNIGHT ; Check for a Knight
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CALL ATKADJ ; Scan adjacent squares
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MOV AH,20H ; Bit 5 set
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MOV AL,[BP+11] ; Get piece at +11
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AND AL,87H ; Clear flag bit
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CMP AL,BPAWN ; Black Pawn ?
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JNZ AT5 ; No - jump
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OR [BP+11],AH ; Turn on bit 5
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AT5: MOV AL,[BP+9] ; Get piece at +9
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AND AL,87H ; Clear flag bit
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CMP AL,BPAWN ; Black Pawn ?
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JNZ AT10 ; No - jump
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OR [BP+9],AH ; Turn on bit 5
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AT10: MOV AL,[BP-11] ; Get piece at -11
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AND AL,87H ; Clear flag bit
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CMP AL,PAWN ; White Pawn ?
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JNZ AT15 ; No - jump
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OR [BP-11],AH ; Turn on bit 5
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AT15: MOV AL,[BP-9] ; Get piece at -9
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AND AL,87H ; Clear flag bit
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CMP AL,PAWN ; White Pawn ?
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JNZ AT20 ; No - jump
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OR [BP-9],AH ; Turn on bit 5
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AT20: MOV SI,DIRECT+TBASE ; Load direction table
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MOV AH,BISHOP ; Check for a Bishop
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CALL ATKOUT ; Scan outwards
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MOV AH,ROOK ; Check for a Rook
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CALL ATKOUT ; Scan outwards
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XOR AL,AL ; No attackers
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POP CX ; Restore CX reg
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RET ; Return
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L102D: MOV CX,8
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L1030: XCHG AX,BX
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LODB
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CBW
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XCHG AX,BX
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MOV DI,BP
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ADD DI,BX
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MOV AL,[DI]
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AND AL,7
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CMP AL,AH
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JNZ L1043
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CALL L107C
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L1043: LOOP L1030
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RET
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;***********************************************************
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; ATTACK ADJACENT SCAN ROUTINE
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;***********************************************************
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; FUNCTION: -- To scan for a specified attacker on adjacent
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; squares.
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;
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; CALLED BY: -- ATTACK
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;
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; CALLS: -- ATKCHK
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;
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; ARGUMENTS: -- The piece under attack. The attacker.
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;***********************************************************
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ATKADJ: MOV CX,8 ; 8 directions to scan
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AA5: XCHG AX,BX ; Save AX
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LODB ; Get direction byte
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CBW ; Convert to word
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XCHG AX,BX ; Save direction and restore AX
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MOV DI,BP ; Load pointer to piece
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ADD DI,BX ; Add direction constant
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MOV AL,[DI] ; Get attacking piece
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AND AL,7 ; Get piece type
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CMP AL,AH ; Same as what we want ?
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JNZ AA10 ; No - jump
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CALL ATKCHK ; Check and save attacker
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AA10: LOOP AA5 ; Go check for next direction
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RET ; Return
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L1046: MOV CL,4
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L1048: MOV DX,0C0H
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XCHG AX,BX
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LODB
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CBW
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XCHG AX,BX
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MOV DI,BP
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L1051: ADD DI,BX
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MOV AL,[DI]
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AND AL,27H
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JZ L1051
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CMP AL,AH
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JZ L106D
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CMP AL,5
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JZ L1068
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CMP AL,33
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JZ L106A
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L1065: LOOP L1048
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RET
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L1068: INC DH
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L106A: AND B,[DI],0DFH
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L106D: MOV AL,[DI]
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ADD AL,128
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RCR AL
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AND DL,AL
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JZ L1065
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CALL L107C
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JP L1051
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;***********************************************************
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; ATTACK OUTWARD SCAN ROUTINE
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;***********************************************************
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; FUNCTION: -- To scan for a specified attacker outwards
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; from the piece under attack, until found
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; or edge of the board is reached.
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;
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; CALLED BY: -- ATTACK
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;
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; CALLS: -- ATKCHK
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;
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; ARGUMENTS: -- The piece under attack. The attacker.
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;***********************************************************
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ATKOUT: MOV CL,4 ; 4 directions to scan
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AO5: MOV DX,0C0H ; Bitmask for color flags
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XCHG AX,BX ; Save AX
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LODB ; Get direction byte
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CBW ; Convert to word
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XCHG AX,BX ; Save direction and restore AX
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MOV DI,BP ; Load pointer to piece
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AO10: ADD DI,BX ; Add direction constant
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MOV AL,[DI] ; Get attacking piece
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AND AL,27H ; Get piece type and bit 5
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JZ AO10 ; No piece, keep going
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CMP AL,AH ; Same as what we want ?
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JZ AO22 ; Yes - jump
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CMP AL,QUEEN ; Queen ?
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JZ AO20 ; Yes - jump
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CMP AL,PAWN+20H ; Pawn with bit 5 ?
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JZ AO21 ; Yes - jump
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AO15: LOOP AO5 ; Go check for next direction
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RET ; Return
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AO20: INC DH ; Set Queen found flag
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AO21: AND B,[DI],0DFH ; Remove bit 5 for piece
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AO22: MOV AL,[DI] ; Get piece
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ADD AL,80H ; CY if back, NC if white
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RCR AL ; Bit 7 set if black, bit 6 if white
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AND DL,AL ; Keep only bits 6 and 7
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JZ AO15 ; Nothing, next direction
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CALL ATKCHK ; Check and save attack
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JP AO10 ; Keeping going that direction
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L107C: MOV AL,[DI]
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CMP B,[T1],7
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JZ L10B3
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XOR AL,[BP]
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JNS RET
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;***********************************************************
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; ATTACK CHECK AND SAVE ROUTINE
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;***********************************************************
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; FUNCTION: -- To check if a piece can attack the target
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; square and save the attacking piece value
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; in the attack list.
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;
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; The pin piece list is checked for the
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; attacking piece, and if found there, the
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; piece is not included in the attack list.
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;
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; In the case where ATTACK is called by
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; CASTLE or INCHK, control is returned to
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; the aforementioned routines as soon as an
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; attacker of the opposite color is encountered.
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;
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; CALLED BY: -- ATTACK
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;
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; CALLS: -- None
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;
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; ARGUMENTS: -- The attacking piece. The piece under attack.
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;***********************************************************
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ATKCHK: MOV AL,[DI] ; Get piece
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CMP B,[T1],7 ; Call from POINTS ?
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JZ ACK10 ; Yes - jump
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XOR AL,[BP] ; Attacker and target same color ?
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JNS RET ; Yes - return
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POP AX
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POP AX
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MOV AX,0DFFFH
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CMP [BP+9],AL
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JZ L1097
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AND [BP+9],AH
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L1097: CMP [BP+11],AL
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JZ L109F
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AND [BP+11],AH
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L109F: CMP [BP-9],AL
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JZ L10A7
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AND [BP-9],AH
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L10A7: CMP [BP-11],AL
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JZ L10AF
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AND [BP-11],AH
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L10AF: MOV AL,1
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POP CX
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RET
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L10B3: PUSH CX
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POP AX ; Set SP level to ATTACK
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MOV AX,0DFFFH ; FF (border) in AL and DF in AH
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CMP [BP+9],AL ; Is +9 border ?
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JZ ACK5 ; Yes, jump
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AND [BP+9],AH ; Remove bit 5 for piece
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ACK5: CMP [BP+11],AL ; Is +11 border ?
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JZ ACK6 ; Yes - jump
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AND [BP+11],AH ; Remove bit 5 for piece
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ACK6: CMP [BP-9],AL ; Is -9 border ?
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JZ ACK7 ; Yes - jump
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AND [BP-9],AH ; Remove bit 5 for piece
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ACK7: CMP [BP-11],AL ; Is -11 border ?
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JZ ACK8 ; Yes - jump
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AND [BP-11],AH ; Remove bit 5 for piece
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ACK8: MOV AL,1 ; Set attacker found flag
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POP CX ; Restore CX reg
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RET ; Return from ATTACK
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ACK10: PUSH CX ; Save regs
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PUSH DI
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MOV CL,[NPINS]
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JCXZ L10E0
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PUSH AX
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MOV AX,DI
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SUB AX,BOARDA
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MOV DI,PLISTA
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L10C4: OR AL,AL
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REPE
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SCAB
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JNZ L10DF
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OR AH,AH
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JNZ L10DB
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MOV AH,[DI+9]
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CMP AH,BL
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JZ L10C4
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NEG AH
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CMP AH,BL
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JZ L10C4
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L10DB: POP AX
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MOV CL,[NPINS] ; Number of pinned pieces
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JCXZ ACK26 ; No pins - jump
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PUSH AX ; Save AX
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MOV AX,DI ; Load piece pointer in AX
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SUB AX,BOARDA ; Minus BOARDA for position
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MOV DI,PLISTA ; Pin list address
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ACK15: OR AL,AL ; Set flags for REP
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REPZ
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SCAB ; Search list for position
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JNZ ACK25 ; Continue if not found
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OR AH,AH ; Is this the first find ?
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JNZ ACK20 ; No - jump
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MOV AH,[DI+9] ; Get direction
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CMP AH,BL ; Same as attacking direction ?
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JZ ACK15 ; Yes - jump
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NEG AH ; Opposite direction ?
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CMP AH,BL ; Same as attacking direction ?
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JZ ACK15 ; Yes - jump
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ACK20: POP AX ; Restore regs.
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POP DI
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POP CX
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RET
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L10DF: POP AX
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L10E0: MOV CL,AL
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AND CL,7
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MOV DI,PVALUE+TBASE
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ADD DI,CX
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MOV CL,[DI]
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MOV DI,ATKLST
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TEST AL,80H
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JZ L10F6
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ADD DI,7
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L10F6: OR DH,DH
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JZ L10FC
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MOV AL,5
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L10FC: AND AL,7
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INC B,[DI]
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XCHG AL,CL
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ADD DI,CX
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MOV CH,[DI]
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TEST CH,0FH
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JZ L111F
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TEST CH,0F0H
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JZ L1115
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INC DI
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MOV CH,[DI]
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XCHG AL,CH
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L1115: SHL AL
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RET ; Return to ATTACK
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ACK25: POP AX ; Restore AX
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ACK26: MOV CL,AL ; Put piece in CL
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AND CL,7 ; Get piece type
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MOV DI,PVALUE+TBASE ; PVALUE list address
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ADD DI,CX ; Point to piece value
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MOV CL,[DI] ; Get point value of piece
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MOV DI,ATKLST ; Init address of attack list
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TEST AL,80H ; Is it white ?
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JZ ACK30 ; Yes - jump
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ADD DI,7 ; Attack list address
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ACK30: OR DH,DH ; Queen found this scan ?
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JZ ACK31 ; No - jump
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MOV AL,QUEEN ; Use Queen slot in attack list
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ACK31: AND AL,7 ; Attacking piece type
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INC B,[DI] ; Increment list count
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XCHG AL,CL ; Save point value in AL
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ADD DI,CX ; Attack list slot address
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MOV CH,[DI] ; Get data already there
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TEST CH,0FH ; Is first slot empty ?
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JZ ACK40 ; Yes - jump
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TEST CH,0F0H ; Is second slot empty ?
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JZ ACK35 ; Yes - jump
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INC DI ; Increment to King slot
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MOV CH,[DI] ; Get byte
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XCHG AL,CH ; Byte to AL, point value to CH
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ACK35: SHL AL ; Lower bits to upper
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SHL AL
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SHL AL
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SHL AL
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OR AL,CH
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L111F: MOV [DI],AL
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POP DI
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OR AL,CH ; Combine with point value
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ACK40: MOV [DI],AL ; Put back into attack list
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POP DI ; Restore regs
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POP CX
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RET
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RET ; Return
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;***********************************************************
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; PIN FIND ROUTINE
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@@ -2231,4 +2303,4 @@ IY: DS 2
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BC: DS 2
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DE: DS 2
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HL: DS 2
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Block a user