GLOBAL RDCHR GLOBAL WRCHR GLOBAL PTXT GLOBAL SPACE GLOBAL CRLF GLOBAL JTASK GLOBAL JIOCS PSECT ABS ;*********************************************************************** ; ; SARGON ; ; Sargon is a computer chess playing program designed ; and coded by Dan and Kathe Spracklen. Copyright 1978. All ; rights reserved. No part of this publication may be ; reproduced without the prior written consent of the authors. ; ;*********************************************************************** ; EQUATES ;*********************************************************************** ; PAWN EQU 1 KNIGHT EQU 2 BISHOP EQU 3 ROOK EQU 4 QUEEN EQU 5 KING EQU 6 WHITE EQU 0 BLACK EQU 80H BPAWN EQU BLACK+PAWN START ORG 0 JP DRIVER TBASE EQU 0 ;*********************************************************************** ; TABLES SECTION ;*********************************************************************** ;*********************************************************************** ;DIRECT -- Direction Table. Used to determine the direction ; of movement of each piece. ;*********************************************************************** DIRECT EQU $ DEFB +09,+11,-11,-09 DEFB +10,-10,+01,-01 DEFB -21,-12,+08,+19 DEFB +21,+12,-08,-19 DEFB +10,+10,+11,+09 DEFB -10,-10,-11,-09 ;*********************************************************************** ; DPOINT -- Direction Table Pointer. Used to determine ; where to begin in the direction table for any ; given piece. ;*********************************************************************** DPOINT EQU $ DEFB 20,16,8,0,4,0,0 ;*********************************************************************** ; DCOUNT -- Direction Table Counter. Used to determine ; the number directions of movement for any ; given piece. ;*********************************************************************** DCOUNT EQU $ DEFB 4,4,8,4,4,8,8 ;*********************************************************************** ; PVALUE -- Point Value. Gives the point value of each ; piece, or the worth of each piece. ;*********************************************************************** PVALUE EQU $-1 DEFB 1,3,3,5,9,10 ;*********************************************************************** ; PLIST -- Pinned Piece Array. This is a two part array. ; PLISTA contains the pinned piece position. ; PLISTD contains the direction from the pinned ; piece to the attacker. ;*********************************************************************** PLIST EQU $-1 PLISTD EQU PLIST+10 PLISTA: DEFW 0,0,0,0,0,0,0,0,0,0 ;*********************************************************************** ;*********************************************************************** ; PIECES -- The initial arrangement of te first rank of ; pieces on the board. Use to set up the board ; for the start of the game. ;*********************************************************************** PIECES EQU $ DEFB 4,2,3,5,6,3,2,4 ;*********************************************************************** ; BOARD -- Board Array. Used to hold the current position ; of the board during play. The board itself ; looks like: ; FFFFFFFFFFFFFFFFFFFF ; FFFFFFFFFFFFFFFFFFFF ; FF0402030506030204FF ; FF0101010101010101FF ; FF0000000000000000FF ; FF0000000000000000FF ; FF0000000000000000FF ; FF0000000000000000FF ; FF8181818181818181FF ; FF8482838586838284FF ; FFFFFFFFFFFFFFFFFFFF ; FFFFFFFFFFFFFFFFFFFF ; The valuesof FF form the border of the ; board, and are used to indicate when a piece ; moves off the board. The individual bits of ; other bytes in the board array are as ; follows: ; Bit 7 -- Color of the piece ; 1 -- Black ; 0 -- White ; Bit 6 -- Not used ; Bit 5 -- Not used ; Bit 4 -- Castle flag for Kings only ; Bit 3 -- Piece has moved flag ; Bits 2-0 Piece type ; 1 -- Pawn ; 2 -- Knight ; 3 -- Bishop ; 4 -- Rook ; 5 -- Queen ; 6 -- King ; 7 -- Not used ; 0 -- Empty square ;*********************************************************************** BOARD EQU $ BOARDA: DEFS 120 FILEND DEFB 04H ; EOT ;*********************************************************************** ; ATKLIST -- Attack List. A two part array, the first ; half for the white and the second half for black. ; It is used to hold the attackers of any given ; square in the order of their value. ; ; WACT -- White Attack Count. This is the first ; byte of the array and tells how many pieces are ; in the white portion of the attack list. ; ; ; BACT -- Black Attack Count. This is the eigth byte of ; the array and does the same for black. ;*********************************************************************** ATKLST: DEFW 0,0,0,0,0,0,0 WACT EQU ATKLST BACT EQU ATKLST+7 ;*********************************************************************** ; POSK -- Position of Kings. A two byte area, the first ; byte of which holds the position of the white ; king and the second holds the position of ; the black king. ; ; POSQ -- Position of Queens. Like POSK, but for queens. ;*********************************************************************** POSK: DEFB 25,95 POSQ: DEFB 24,94 DEFB -1 ;*********************************************************************** ; SCORE -- Score Array. Used during Alpha-Beta pruning to ; hold the scores at each ply. It includes two ; "dummy" entries for ply -1 and ply 0. ;*********************************************************************** SCORE: DEFW 0,0,0,0,0,0 ;*********************************************************************** ; PLYIX -- Ply Table. Contains pairs of pointers, a pair ; for each ply. The first pointer points to the ; top of the list of possible moves at that ply. ; The second pointer points to which move in the ; list is the one currently being considered. ;*********************************************************************** PLYIX: DEFW 0,0,0,0,0,0,0,0,0,0 DEFW 0,0,0,0,0,0,0,0,0,0 ;*********************************************************************** ; TABLE INDICES SECTION ; M1-M4 -- Working indices used to index into ; the board array. ; ; T1-T3 -- Working indices used to index into Direction ; Count, Direction Value, and Piece Value tables. ; ; INDX1 -- General working indices. Used for various ; INDX2 purposes. ; ; NPINS -- Number of Pins. Count and pointer into the ; pinned piece list. ; ; MLPTRI -- Pointer into the ply table which tells ; which pair of pointers are in current use. ; ; MLPTRJ -- Pointer into the move list to the move which is ; currently being processed. ; ; SCRIX -- Score index. Pointer to the score table for ; the ply being examined. ; ; BESTM -- Pointer into the move list for the move that ; is currently considered the best by the ; Alpha-Beta pruning process. ; ; MLLST -- Pointer to the previous move placed in the move ; list. Used during generation of the move list. ; ;*********************************************************************** M1: DEFW TBASE M2: DEFW TBASE M3: DEFW TBASE M4: DEFW TBASE T1: DEFW TBASE T2: DEFW TBASE T3: DEFW TBASE INDX1: DEFW TBASE INDX2: DEFW TBASE NPINS: DEFW TBASE MLPTRI: DEFW PLYIX MLPTRJ: DEFW 0 SCRIX: DEFW 0 BESTM: DEFW 0 MLLST: DEFW 0 ;*********************************************************************** ; VARIABLES SECTION ; ; KOLOR -- Indicates computer's color. White is 0, and ; Black is 80H. ; ; COLOR -- Indicates color of the side with the move ; ; P1-P3 -- Working area to hold the contents of the board ; array for a given square. ; ; PMATE -- The move number at which a checkmate is ; discovered during look ahead. ; ; MOVENO -- Current move number. ; ; PLYMAX -- Maximum depth of search using Alpha-Beta ; pruning. ; ; NPLY -- Current ply number during Alpha-Beta pruning. ; ; CKFLG -- A non-zero value indicates the king is in check. ; ; MATEF -- A zero value indicates no legal moves. ; ; VALM -- The score of the current move being examined. ; ; BRDC -- A measure of mobility equal to the total number ; of squares to which white can move minus the ; number to which black can move. ; ; PTSL -- The maximum number of points which could be lost ; through an exchange by the player not on the move. ; ; PTSW1 -- The maximum number of points which could be won ; through an exchange by the player not on the move. ; ; PTSW2 -- The second highest number of points which could ; be won through a different exchange by the player ; on the move. ; ; MTRL -- A measure of the difference in material currently ; on the board. It is the total value of the white ; pieces minus the total value of the black pieces. ; ; BC0 -- The value of board control (BRDC) at ply 0. ; ; MV0 -- The value of material (MTRL) at ply 0. ; ; PTSCK -- A on-zero value indicates that the piece has ; just moved itself into a losing exchange of ; material. ; ; BMOVES -- Our very tiny book of openings. Determines ; the first move for the computer. ;*********************************************************************** KOLOR: DEFB 0 COLOR: DEFB 0 P1: DEFB 0 P2: DEFB 0 P3: DEFB 0 PMATE: DEFB 0 MOVENO: DEFB 2 PLYMAX: DEFB 2 NPLY: DEFB 0 CKFLG: DEFB 0 MATEF: DEFB 0 VALM: DEFB 0 BRDC: DEFB 0 PTSL: DEFB 0 PTSW1: DEFB 0 PTSW2: DEFB 0 MTRL: DEFB 0 BC0: DEFB 0 MV0: DEFB 0 PTSCK: DEFB 0 BMOVES: DEFB 35,55,10H DEFB 34,54,10H DEFB 85,65,10H DEFB 84,64,10H ;*********************************************************************** ; STACK -- Contains the stack for the program. ;*********************************************************************** ORG START+2FFH STACK: ;*********************************************************************** ; MOVE LIST SECTION ; ; MLIST -- A 2048 byte storage area for generated moves. ; This area must be large enough to hold all ; the moves for a single leg of the move tree. ; ; MLNXT -- Pointer to the next available space in the move ; list. ; ; MLEND -- The address of the last available location ; in the Move List. ; ; MLPTR -- The Move List is a linked list of individual ; moves each of which is 6 bytes in length. The ; move list pointer (MLPTR) is the link field ; within a move. ; ; MLFRP -- The field in the move entry which gives the ; board position from which the piece is moving. ; ; MLTOP -- The field in the move entry which gives the ; board position to which the piece is moving. ; ; MLFLG -- A field in the move entry which contains flag ; information. The meaning of each bit is as ; follows: ; Bit 7 -- The color of any captured piece ; 0 -- White ; 1 -- Black ; Bit 6 -- Double move flag (set for castling and ; en passant pawn captures) ; Bit 5 -- Pawn Promotion flag; set when pawn ; promotes. ; Bit 4 -- When set, this flag indicates that ; this is the first move for the piece ; on the move. ; Bit 3 -- This flag is set when a piece is ; captured, and the piece has moved at ; least once. ; Bits 2-0 Describe the captured piece. A ; zero value indicates no capture. ; ; MLVAL -- The field in the move entry which contains the ; score assigned to the move. ; ;*********************************************************************** ORG START+300H MLIST: DEFS 2048 MLNXT: DEFW MLIST MLEND EQU MLIST+2040 MLPTR EQU 0 MLFRP EQU 2 MLTOP EQU 3 MLFLG EQU 4 MLVAL EQU 5 BMOVE1 DEFS 120 BMOVE2 DEFS 120 ;*********************************************************************** ; STANDARD MESSAGES ;*********************************************************************** GRTTNG: DEFM 'WELCOME TO CHESS! CARE FOR A GAME? ' ANAMSG: DEFM 'WOULD YOU LIKE TO ANALYZE A POSITION? ' CLRMSG: DEFM 'DO YOU WANT TO PLAY WHITE(W) OR BLACK(B)? ' TITLE1: DEFM 'SARGON' TITLE2: DEFM 'PLAYER' MVENUM: DEFM '02 ' TITLE3: DEFM ' ' DEFB 42,42,42,42,42,42 DEFM ' ' DEFB 42,42,42,42,42,42 MVEMSG: DEFM 'a1-a1' OO: DEFM 'O-O ' OOO: DEFM 'O-O-O' CKMSG: DEFM 'CHECK' MTMSG: DEFM 'MATE IN ' MTPL: DEFM '2' PCS: DEFM 'KQRBNP' ; Valid piece characters UWIN: DEFM 'YOU WIN' IWIN: DEFM 'I WIN' AGAIN: DEFM 'CARE FOR ANOTHER GAME? ' CRTNES: DEFM 'IS THIS RIGHT? ' PLYDEP: DEFM 'SELECT LOOK AHEAD (1-6) ' TITLE4: DEFM ' ' WSMOVE: DEFM 'WHOSE MOVE IS IT? ' PPEP: DEFM 'PxPep' INVAL1: DEFM 'INVALID MOVE -- TRY AGAIN' ;*********************************************************************** ; VARIABLES ;*********************************************************************** BRDPOS: DEFB 0 ; Index into the board array ANBDPS: DEFB 0 ; Additional indes required for ANALYS LINECT: DEFB 0 ; Current line number YSET: DEFS 1 ; The MOSTEK video terminal Y pointer XSET: DEFS 1 ; The MOSTEK video terminal X pointer VIDBIT: DEFS 1 ; Normal or inverse video register VIDBI: DEFS 1 ; Normal or inverse video regoster COLBIT: DEFS 1 ; Color of piece for INSPCE PCODE: DEFM 'PNBRQK' DEFB 32 STUCK: DEFS 1 ; Piece register for INSPCE RIP: DEFM 'RIP' XSETS: DEFS 1 YSETS: DEFS 1 TEB1: DEFB 23,32,32,32,32,32 ; First grid output DEFB 25,32,32,32,32,32 ; TEB1 and TEB2 contain the text DEFB 23,32,32,32,32,32 ; which is used by DSPBRD to DEFB 25,32,32,32,32,32 ; form the chess board DEFB 23,32,32,32,32,32 DEFB 25,32,32,32,32,32 DEFB 23,32,32,32,32,32 DEFB 25,32,32,32,32,32,124 DEFB 03H ; ETX TEB2: DEFB 25,32,32,32,32,32 ; Complement of first grid output DEFB 23,32,32,32,32,32 DEFB 25,32,32,32,32,32 DEFB 23,32,32,32,32,32 DEFB 25,32,32,32,32,32 DEFB 23,32,32,32,32,32 DEFB 25,32,32,32,32,32 DEFB 23,32,32,32,32,32,25,124 DEFB 03H ; ETX TEB3: DEFB 42,42,32,97,32,42 DEFB 42,32,98,32,42 DEFB 42,32,99,32,42 DEFB 42,32,100,32,42 DEFB 42,32,101,32,42 DEFB 42,32,102,32,42 DEFB 42,32,103,32,42 DEFB 42,32,104,32,42,42 DEFB 03H ; ETX TEXT5: DEFM 'FILE NAME? ' DEFB 03H ; ETX TEXT6: DEFM 'DO YOU HAVE A BOARD POSITION STORED' DEFM ' IN A FILE? ' DEFB 03H ; ETX TEXT7: DEFM 'WHAT IS THE NAME OF YOUR BOARD POSITION' DEFM ' DATA FILE? ' DEFB 03H ; ETX RANK: DEFS 1 FILE: DEFS 1 YPOINT: DEFS 1 XPOINT: DEFS 1 SQHOLD: DEFB 32,32,32,32,32 DEFB 32,32,32,32,32 HOLDER: DEFW 0 VEHOLD: DEFS 16 ;*********************************************************************** ; MOSTEK TERMINAL ORIENTED CONTROL FUNCTIONS ;*********************************************************************** ; CLSCR will home the cursor and clear the screen of a MOSTEK video ; terminal ; ESCAPE sets the ESCAPE function for a MOSTEK video terminal ; LINSET gives a line feed when the board is being displayed ; CURSOR determines the position of the cursor for a MOSTEK video ; terminal ; LINOUT outputs a message to the terminal using the WRCHR subroutine ; RANFIL determines if a given square is black or white ; TITLES writes the move list headings to the terminal ; RESET1 sets the IOCS vector to 0 ;*********************************************************************** CLRSCR: DEFB 30,29 LINSET: CALL PGIFND LIN1: LD A,149 LD HL,LINECT SUB (HL) LD (YSET),A CURSOR: LD E,1 LD D,27 CALL WRCHR ; Output an ESCAPE LD D,61 CALL WRCHR ; Output an = sign LD HL,YSET LD D,(HL) CALL WRCHR ; Output Y coordinate LD HL,XSET LD D,(HL) CALL WRCHR ; Output X coordinate LD HL,0FF12H ; Reset carriage return counter SET 1,(HL) ; Set BIT 1 of (0FF12H) RET LINOUT: LD D,(HL) CALL WRCHR INC HL DJNZ LINOUT-$ RET RANFIL: LD A,(RANK) ; Y - position LD HL,FILE ; X - position ADD A,(HL) ; Add RANK and FILE BL50: DEC A ; If (RANK) + (FILE) / 2 leaves no DEC A ; remainder, then te square is white. CP 2 ; Otherwise the square is black. JR Z,BL52-$ ; Repeat the loop until a decision JR NC,BL50-$ ; can be made. BL54: LD HL,VIDBIT ; Set normal video LD (HL),25 LD HL,VIDBI LD (HL),23 JR BL56-$ BL52: LD HL,VIDBIT ; Set inverse video. LD (HL),23 LD HL,VIDBI LD (HL),25 BL56: RET TITLES: LD D,30 CALL WRCHR LD B,15 LD HL,TITLE4 CALL LINOUT ; Put up player headings LD A,-1 LD (LINECT),A CALL LIN1 LD B,15 LD HL,TITLE3 CALL LINOUT CALL LINSET ; Set cursor RET RESET1: LD A,10 ; Get the IOCS vector start address CALL JTASK LD (HOLDER),IY ; Store IY address in IYHOLD LD HL,(HOLDER) XOR A LD B,48 BS30: LD (HL),A ; Set the IOS vector = 0 INC HL DJNZ BS30-$ CALL LINSET ; Carriage Return RET ;*********************************************************************** ; MAIN PROGRAM DRIVER ;*********************************************************************** ; FUNCTION: To coordinate the game moves ; ; CALLED BY: None ; ; CALLS: INTERR INITBD DSPBRD LINSET ; CPTRMV PLYRMV TBCPCL LINOUT ; PGIFND ANALYS CHARTR SPACE ; ; ARGUMENTS: None ;*********************************************************************** DRIVER: LD BC,2047 LD HL,MLIST XOR A LD (HL),A LD DE,MLIST+1 LDIR LD SP,STACK ; Set stack pointer CALL INITBD ; Initialize the board array LD BC,120 ; Initialize the BMOVE1 array LD HL,BOARDA LD DE,BMOVE1 LDIR LD BC,120 ; Initialize the BMOVE2 array LD HL,BOARDA LD DE,BMOVE2 LDIR LD E,1 LD A,-1 LD (LINECT),A ; Line number is -1 at start LD B,2 LD HL,CLRSCR ; Blank the video screen CALL LINOUT LD HL,GRTTNG ; Output greeting LD B,36 CALL LINOUT LD A,128 LD (XSET),A DRIV01: CALL CHARTR ; Accept the answer PUSH AF CALL LINSET ; Carriage return POP AF CP 59H ; Is it a 'Y'? JP NZ,ANALYS ; Yes - Jump SUB A ; Code of White is zero LD (COLOR),A ; White always moves first CALL INTERR ; Player's color/search depth LD A,1 ; Move number is 1 at start LD (MOVENO),A ; Save LD HL,MVENUM ; Address of ASCII move number LD (HL),30H ; Init to '01' INC HL LD (HL),31H INC HL LD (HL),20H CALL DSPBRD CALL TITLES ; Put up player headings DRIV04: LD B,3 LD HL,MVENUM ; Display move number CALL LINOUT LD A,(KOLOR) ; Bring in computer's color AND A ; Is it white? JR NZ,DR08-$ ; No - Jump CALL PGIFND ; New page if needed CP 0 ; Was page turned? CALL Z,TBCPCL ; Yes - Tab to computer's column CALL CPTRMV ; Make and write computer's move CALL SPACE ; Output a space CALL SPACE ; Output a space CALL PLYRMV ; Accept and make player's move LD A,128 LD (XSET),A CALL LIN1 JR DR0C-$ ; Jump DR08: CALL PLYRMV ; Accept and make player's move CALL SPACE ; Output a space CALL SPACE ; Output a space CALL PGIFND ; New page if needed CP 0 ; Was page turned? CALL Z,TBCPCL ; Yes - Tab to computer's column CALL CPTRMV ; Make and write computer's move LD A,128 LD (XSET),A CALL LIN1 DR0C: LD HL,MVENUM+2 ; Addr of 3rd char of move LD A,20H ; ASCII space CP (HL) ; Is char a space? LD A,3AH ; Set up test value JR Z,DR10-$ ; Yes - Jump INC (HL) ; Increment value CP (HL) ; Over ASCII 9? JR NZ,DR14-$ ; No - Jump LD (HL),30H ; Set char to zero DR10: DEC HL ; 2nd char of ASCII move no. INC (HL) ; Increment value CP (HL) ; Over ASCII 9? JR NZ,DR14-$ ; No - Jump LD (HL),30H ; Set char to zero DEC HL ; 1st char of ASCII move number INC (HL) ; Increment value CP (HL) ; Over ASCII 9? JR NZ,DR14-$ ; No - Jump LD (HL),31H ; Make 1st char a one LD A,30H ; Make 3rd char a zero LD (MVENUM+2),A DR14: LD HL,MOVENO ; Hexadecimal move number INC (HL) ; Increment JP DRIV04 ; Jump ;*********************************************************************** ; INTERROGATION FOR PLY AND COLOR ;*********************************************************************** ; FUNCTION: To query the player for his choice of ply ; depth and color. ; ; CALLED BY: DRIVER ; ; CALLS: CHARTR LINSET LINOUT ; ; ARGUEMENTS: None ;*********************************************************************** INTERR: LD B,42 LD HL,CLRMSG IN22: CALL LINOUT ; Request color choice CALL CHARTR ; Accept response PUSH AF CALL LINSET ; Carriage return POP AF CP 57H ; Did player request white? JR Z,IN04-$ ; Yes - Branch SUB A ; Set computer's color to white LD (KOLOR),A LD DE,TITLE4+2 LD HL,TITLE1 ; Prepare move list titles LD BC,6 LDIR LD DE,TITLE4+9 LD HL,TITLE2 LD BC,6 LDIR JR IN08-$ ; Jump IN04: LD A,80H ; Set computer's color to black LD (KOLOR),A LD DE,TITLE4+2 LD HL,TITLE2 ; Prepare move list titles LD BC,6 LDIR LD HL,TITLE1 LD DE,TITLE4+9 LD BC,6 LDIR IN08: LD B,24 LD A,128 LD (XSET),A CALL LINSET LD HL,PLYDEP ; Request depth of search IN24: CALL LINOUT CALL CHARTR ; Accept response PUSH AF CALL LINSET POP AF LD HL,PLYMAX ; Address of ply depth variable LD (HL),2 ; Default depth of search CP 31H ; Under minimum of 1? RET M ; Yes - Return CP 37H ; Over maximum of 6? RET P ; Yes - Return SUB 30H ; Subtract ASCII constant LD (HL),A ; Set desired depth RET ;*********************************************************************** ; NEW PAGE IF NEEDED ;*********************************************************************** ; FUNCTION: To clear move list output when the column ; has been filled ; ; CALLED BY: DRIVER PLYRMV CPTRMV ; ; CALLS: DSPBRD ; ; ARGUMENTS: Returns a 1 on the A register if ; a new page was turned. ;*********************************************************************** PGIFND: LD HL,LINECT ; Addr of page position countr INC (HL) ; Increment LD A,16H ; Page bottom? CP (HL) RET NC ; No - Return CALL DSPBRD ; Put up new page LD E,1 LD A,151 LD (YSET),A LD A,128 LD (XSET),A LD D,25 CALL WRCHR CALL CURSOR LD B,15 LD HL,TITLE4 ; Re-print titles PG20: LD D,(HL) CALL WRCHR INC HL DJNZ PG20-$ LD A,-1 LD (LINECT),A CALL LIN1 LD B,15 LD HL,TITLE3 PG30: LD D,(HL) CALL WRCHR INC HL DJNZ PG30-$ LD A,128 LD (XSET),A LD A,0 ; Set line count to 0 LD (LINECT),A CALL LIN1 LD A,1 LD (LINECT),A ; Set line count to 1 XOR A RET ; Return ;*********************************************************************** ; ACCEPT INPUT CHARACTER ;*********************************************************************** ; FUNCTION: Accepts a single character input from the ; console keyboard and places it in the A ; register. The character is also echoed on ; the video screen, unless it is a carriage ; return, line feed, or backspace. Lower ; case alphabetic characters are folded to ; upper case. ; ; CALLED BY: DRIVER INTERR PLYRMV ANALYS ; ; CALLS: None ; ; ARGUMENTS: Character input is output in register A. ;*********************************************************************** CHARTR: LD E,0 ; Input single character CALL RDCHR CP 0DH ; Carriage return? RET Z ; Yes - Return CP 0AH ; Line feed? RET Z ; Yes - Return CP 08H ; Backspace? RET Z ; Yes - Return CHART1: CALL WRCHR ; Output single character LD A,D AND 7FH ; Mask off parity bit CP 7BH ; Upper range check (z+1) RET P ; No need to fold -- Return CP 61H ; Lower range check (a) RET M ; No need to fold -- Return SUB 20H ; Change to one of A-Z RET ; Return ;*********************************************************************** ; SET UP EMPTY BOARD ;*********************************************************************** ; FUNCTION: Display graphics board and pieces ; ; CALLED BY: DRIVER ANALYS PGIFND ; ; CALLS: CONVRT INSPCE CURSOR WHCHR ; LINSET ; ; ARGUMENTS: None ;*********************************************************************** DSPBRD: PUSH BC PUSH DE PUSH HL PUSH AF LD E,1 LD B,2 LD HL,CLRSCR ; Clear the screen DB20: LD D,(HL) CALL WRCHR INC HL DJNZ DB20-$ LD A,149 LD (YSET),A LD A,165 LD (XSET),A CALL CURSOR LD B,42 LD D,42 ; Output a top line of *'s DB22: CALL WRCHR DJNZ DB22-$ LD A,132 LD (YSET),A LD A,165 LD (XSET),A CALL CURSOR LD HL,TEB3 DB24: CALL PTXT ; Output bottom border of the board LD HL,XSET LD (HL),165 LD HL,YSET LD (HL),148 LD B,4 ; Repeat 4 times LD A,56 PUSH AF DB26: CALL CURSOR ; Output a line of grid POP AF LD D,A DEC A PUSH AF CALL WRCHR LD HL,TEB1 CALL PTXT LD HL,YSET DEC (HL) CALL CURSOR LD D,124 CALL WRCHR LD HL,TEB1 ; Repeat first line CALL PTXT ; This completes one rank LD HL,YSET DEC (HL) CALL CURSOR POP AF LD D,A DEC A PUSH AF CALL WRCHR LD HL,TEB2 ; Output complement grid line CALL PTXT LD HL,YSET DEC (HL) CALL CURSOR LD D,124 CALL WRCHR LD HL,TEB2 ; Repeat output of complement CALL PTXT ; grid line LD HL,YSET DEC (HL) ; The next rank is completed DJNZ DB26-$ POP AF BSETUP: LD A,21 ; First board index BSET04: LD (BRDPOS),A ; Ready parameter CALL CONVRT ; Determine norm address CALL INSPCE ; Insert that piece onto board INC A ; Next square CP 99 ; Done? JR C,BSET04-$ ; No - Jump DB50: LD A,128 ; Set X-pointer to 128 LD (XSET),A POP AF POP HL POP DE POP BC RET ;*********************************************************************** ; BOARD SETUP ROUTINE ;*********************************************************************** ; FUNCTION: To initialize the board array, setting the ; pieces in their initial positions for the start ; start of the game. ; ; CALLED BY: DRIVER ; ; CALLS: None ; ; ARGUMENTS: None ; ;*********************************************************************** INITBD: LD B,120 ; Pre-fill board with -1's LD HL,BOARDA IB10: LD (HL),-1 INC HL DJNZ IB10-$ LD B,8 LD IX,BOARDA IB2: LD A,(IX-8) ; Fill non-border squares LD (IX+21),A ; White pieces SET 7,A ; Change to black LD (IX+91),A ; Black pieces LD (IX+31),PAWN ; White Pawns LD (IX+81),BPAWN ; Black Pawns LD (IX+41),0 ; Empty squares LD (IX+51),0 LD (IX+61),0 LD (IX+71),0 INC IX DJNZ IB2-$ LD IX,POSK ; Init King/Queen position list LD (IX+0),25 LD (IX+1),95 LD (IX+2),24 LD (IX+3),94 RET ;*********************************************************************** ; INSERT PIECE SUBROUTINE ;*********************************************************************** ; FUNCTION: This subroutine places a piece onto a ; given square on the video board. The piece ; inserted is that stored in the board array ; for that square. ; ; CALLED BY: DSPRD MATED ; ; CALLS: MLTPLY ; ; ARGUMENTS: None ;*********************************************************************** INSPCE: PUSH HL ; Save registers PUSH BC PUSH DE PUSH IX PUSH AF LD A,(BRDPOS) ; Get board index LD (M1),A ; Save LD IX,(M1) ; Index into board array LD A,(IX+BOARD) ; Contents of board array AND A ; Is square empty? JR NZ,IP22-$ ; No - Jump LD A,32 LD (COLBIT),A LD E,6 JR IP25-$ IP22: CP 0FFH ; Is it a border square? JR Z,IP2C-$ ; Yes - Jump BIT 7,A ; Is piece white? LD HL,COLBIT ; Load color bit address JR Z,IP30-$ ; Yes - Jump LD (HL),42H ; Color is black(B) JR IP04-$ ; Jump IP30: LD (HL),57H ; Color is white(W) IP04: AND 7 ; Delete flags, leave piece DEC A ; Piece on a 0-5 basis LD E,A ; Save IP25: CALL RANFIL IP56: LD HL,PCODE ; Determine piece to insert LD D,0 ADD HL,DE LD A,(HL) LD (STUCK),A ; Load piece select to (STUCK) LD A,(YPOINT) ; Convert norm address to pointer LD (YSET),A ; address LD A,(XPOINT) ADD A,2 LD (XSET),A CALL CURSOR ; Set the cursor LD E,1 LD HL,VIDBIT LD D,(HL) CALL WRCHR ; Output video signal (inverse or LD HL,COLBIT ; normal) LD D,(HL) CALL WRCHR ; Output piece color LD HL,STUCK LD D,(HL) CALL WRCHR ; Output piece name LD D,25 CALL WRCHR ; Set normal video IP2C: POP AF ; Restore registers POP IX POP DE POP BC POP HL RET ; Return ;*********************************************************************** ; BOARD INDEX TO NORM ADDRESS SUBROUTINE ;*********************************************************************** ; FUNCTION: Converts a hexadecimal board index into ; a Norm address for the square. ; ; CALLED BY: DSPBRD INSPCE ANALYS MATED ; ; CALLS: DIVIDE MLTPLY ; ; ARGUMENTS: Returns the Norm address in register pair ; HL. ;*********************************************************************** CONVRT: PUSH BC ; Save registers PUSH DE PUSH AF LD A,(BRDPOS) ; Get board index LD D,A ; Set up dividend SUB A LD E,10 ; Divisor CALL DIVIDE ; Index into rank and file ; File (1-8) & Rank (2-9) PUSH AF LD (FILE),A ; Store file pointer LD A,D LD (RANK),A ; Store rank pointer POP AF ; Restore A register LD HL,XPOINT ; For file (1-8) LD (HL),161 LD B,A CNVRT1: INC (HL) ; File Norm address INC (HL) INC (HL) INC (HL) INC (HL) DJNZ CNVRT1-$ LD HL,YPOINT LD (HL),130 LD B,D CNVRT2: INC (HL) ; Rank Norm address INC (HL) DJNZ CNVRT2-$ POP AF ; Restore registers POP DE POP BC RET ; Return ;*********************************************************************** ; POSITIVE INTEGER MULTIPLICATION ;*********************************************************************** MLTPLY: PUSH BC SUB A LD B,8 ML04: BIT 0,D JR Z,ML10-$ ADD A,E ML10: SRA A RR D DJNZ ML04-$ POP BC RET ;*********************************************************************** ; POSITIVE INTEGER DIVISION ;*********************************************************************** DIVIDE: PUSH BC LD B,8 DD04: SLA D RLA SUB E JP M,DD9 INC D JR DD10-$ DD9: ADD A,E DD10: DJNZ DD04-$ POP BC RET ;*********************************************************************** ; PATH ROUTINE ;*********************************************************************** ; FUNCTION: To generate a single position move for a given ; piece along its current path of motion including: ; ; Fetching the contents of the board at the new ; position, and setting a flag describing the ; contents: ; 0 -- New position is empty ; 1 -- Encountered a piece of the ; opposite color ; 2 -- Encountered a piece of the ; same color ; 3 -- New position is off the board ; ; CALLED BY: MPIECE ATTACK PINFND ; ; CALLS: None ; ; ARGUMENTS: Direction from the direction array giving the ; constant to be added for the new position. ;*********************************************************************** PATH: LD HL,M2 ; Get previous position LD A,(HL) ADD A,C ; Add direction constant LD (HL),A ; Save new position LD IX,(M2) ; Load board index LD A,(IX+BOARD) ; Get contents of board CP -1 ; In border area? JR Z,PA2-$ ; Yes - Jump LD (P2),A ; Save piece AND 7 ; Clear flags LD (T2),A ; Save piece type RET Z ; Return if empty LD A,(P2) ; Get piece if encountered LD HL,P1 ; Get moving piece address XOR (HL) ; Compare BIT 7,A ; Do colors match? JR Z,PA1-$ ; Yes - Jump LD A,1 ; Set different color flag RET ; Return PA1: LD A,2 ; Set same color flag RET ; Return PA2: LD A,3 ; Set off board flag RET ; Return ;*********************************************************************** ; PIECE MOVER ROUTINE ;*********************************************************************** ; FUNCTION: To generate all the legal possible moves for a ; given piece. ; ; CALLED BY: GENMOV ; ; CALLS: PATH ADMOVE CASTLE ENPSNT ; ; ARGUMENTS: The piece to be moved. ;*********************************************************************** MPIECE: XOR (HL) ; Piece to move AND 87H ; Clear flag bit CP BPAWN ; Is it a black Pawn? JR NZ,MP50-$ ; No - Skip DEC A ; Decrement for black Pawns MP50: AND 7 ; Get piece type LD (T1),A ; Save piece type LD IY,(T1) ; Load index to DCOUNT/DPOINT LD B,(IY+DCOUNT) ; Get direction count LD A,(IY+DPOINT) ; Get direction pointer LD (INDX2),A ; Save as index to direct LD IY,(INDX2) ; Load index MP5: LD C,(IY+DIRECT) ; Get move direction LD A,(M1) ; From position LD (M2),A ; Initialize to position MP10: CALL PATH ; Calcuate next position CP 2 ; Ready for new direction? JR NC,MP15-$ ; Yes - Jump AND A ; Test for empty square EX AF,AF' ; Save result LD A,(T1) ; Get piece moved CP PAWN+1 ; Is it a Pawn? JR C,MP20-$ ; Yes - Jump CALL ADMOVE ; Add move to list EX AF,AF' ; Empty square? JR NZ,MP15-$ ; No - Jump LD A,(T1) ; Piece type CP KING ; King? JR Z,MP15-$ ; Yes - Jump CP BISHOP ; Bishop, Rook, or Queen? JR NC,MP10-$ ; Yes - Jump MP15: INC IY ; Increment direction index DJNZ MP5-$ ; Decrement count - Jump if non-zero LD A,(T1) ; Piece type CP KING ; King? CALL Z,CASTLE ; Yes - Try Castling RET ; **** PAWN LOGIC ***** MP20: LD A,B ; Counter for direction CP 3 ; On diagonal moves? JR C,MP35-$ ; Yes - Jump JR Z,MP30-$ ; -or- Jump if on 2 square move EX AF,AF' ; Is forward square empty? JR NZ,MP15-$ ; No - Jump LD A,(M2) ; Get "to" position CP 91 ; Promote white Pawn? JR NC,MP25-$ ; Yes - Jump CP 29 ; Promote black Pawn? JR NC,MP26-$ ; No - Jump MP25: LD HL,P2 ; Flag address SET 5,(HL) ; Set promote flag MP26: CALL ADMOVE ; Add to move list INC IY ; Adjust to two square move DEC B LD HL,P1 ; Check Pawn moved flag BIT 3,(HL) ; Has it been moved before? JR Z,MP10-$ ; No - Jump JR MP15-$ ; Jump MP30: EX AF,AF' ; Is the forward square empty? JR NZ,MP15-$ ; No - Jump MP31: CALL ADMOVE ; Add to move list JR MP15-$ ; Jump MP35: EX AF,AF' ; Is the diagonal square empty? JR Z,MP36-$ ; Yes - Jump LD A,(M2) ; Get "to" position CP 91 ; Promote white Pawn? JR NC,MP37-$ ; Yes - Jump CP 29 ; Black Pawn promotion? JR NC,MP31-$ ; No - Jump MP37: LD HL,P2 ; Get flag address SET 5,(HL) ; Set promote flag JR MP31-$ ; Jump MP36: CALL ENPSNT ; Try en passant capture JP MP15 ; Jump ;*********************************************************************** ; EN PASSANT ROUTINE ;*********************************************************************** ; FUNCTION: To test for en passant Pawn capture and ; to add it to the move list if it is legal. ; ; CALLED BY: MPIECE ; ; CALLS: ADMOVE ADJPTR ; ; ARGUMENTS: None ;*********************************************************************** ENPSNT: LD A,(M1) ; Set position of Pawn LD HL,P1 ; Check color BIT 7,(HL) ; Is it white? JR Z,EP20-$ ; Yes - skip ADD A,10 ; Add 10 for black EP20: CP 61 ; On en passant capture rank? RET C ; No - Return CP 69 ; On en passant capture rank? RET NC ; No - Return LD IX,(MLPTRJ) ; Get pointer to previous move BIT 4,(IX+MLFLG) ; First move for that piece? RET Z ; No - Return LD A,(IX+MLTOP) ; Get "to" position LD (M4),A ; Store as index to board LD IX,(M4) ; Load board index LD A,(IX+BOARD) ; Get piece moved LD (P3),A ; Save it AND 7 ; Get piece type CP PAWN ; Is it a Pawn? RET NZ ; No - Return LD A,(M4) ; Get "to" position LD HL,M2 ; Get present "to" position SUB (HL) ; Find difference JP P,EP30 ; Positive? Yes - Jump NEG ; Else take absolute value EP30: CP 10 ; Is difference 10? RET NZ ; No - return LD HL,P2 ; Address of flags SET 6,(HL) ; Set double move flag CALL ADMOVE ; Add Pawn move to move list LD A,(M1) ; Save initial Pawn position LD (M3),A LD A,(M4) ; Set "from" and "to" positions ; for dummy move LD (M1),A LD (M2),A LD A,(P3) ; Save captured Pawn LD (P2),A CALL ADMOVE ; Add Pawn capture to move list LD A,(M3) ; Restore "from" position LD (M1),A ;*********************************************************************** ; ADJUST MOVE LIST POINTER FOR DOUBLE MOVE ;*********************************************************************** ; FUNCTION: To adjust move list pointer to link around ; second move in double move. ; ; CALLED BY: ENPSNT ; CASTLE ; (This mini-routine is not really called, ; but is jumped to to save time.) ; ; CALLS: None ; ; ARGUMENTS: None ;*********************************************************************** ADJPTR: LD HL,(MLLST) ; Get list pointer LD DE,-6 ; Size of a move entry ADD HL,DE ; Back up list pointer LD (MLLST),HL ; Save list pointer LD (HL),0 ; Zero out link, first byte INC HL ; Next byte LD (HL),0 ; Zero out link, second byte RET ;*********************************************************************** ; CASTLE ROUTINE ;*********************************************************************** ; FUNCTION To determine whether castling is legal ; (Queen side, King side, or both) and add it ; to the move list if it is. ; ; CALLED BY: MPIECE ; ; CALLS: ATTACK ADMOVE ADJPTR ; ; ARGUMENTS: None ;*********************************************************************** CASTLE: LD A,(P1) ; Get King BIT 3,A ; Has it moved? RET NZ ; Yes - return? LD A,(CKFLG) ; Fetch Check Flag AND A ; Is the King in check? RET NZ ; Yes - Return LD BC,0FF03H ; Initialize King-side values CA5: LD A,(M1) ; King position ADD A,C ; Rook position LD C,A ; Save LD (M3),A ; Store as board index LD IX,(M3) ; Load board index LD A,(IX+BOARD) ; Get contents of board AND 7FH ; Clear color bit CP ROOK ; Has Rook ever moved? JR NZ,CA20-$ ; Yes - Jump LD A,C ; Restore Rook position JR CA15-$ ; Jump CA10: LD IX,(M3) ; Load board index LD A,(IX+BOARD) ; Get contents of board AND A ; Empty? JR NZ,CA20-$ ; No - Jump LD A,(M3) ; Current position CP 22 ; White Queen Knight square? JR Z,CA15-$ ; Yes - Jump CP 92 ; Black Queen Knight square? JR Z,CA15-$ ; Yes - Jump CALL ATTACK ; Look for an attack on square AND A ; Any attackers? JR NZ,CA20-$ ; Yes - Jump LD A,(M3) ; Current position CA15: ADD A,B ; Next position LD (M3),A ; Save as board index LD HL,M1 ; King position CP (HL) ; Reached King? JR NZ,CA10-$ ; No - Jump SUB B ; Determine King's position SUB B LD (M2),A ; Save it LD HL,P2 ; Address of flags LD (HL),40H ; Set double move flag CALL ADMOVE ; Put King move in list LD HL,M1 ; Addr of King "from" position LD A,(HL) ; Get King's "from" position LD (HL),C ; Store Rook "from" positon SUB B ; Get Rook "to" position LD (M2),A ; Store Rook "to" position XOR A ; Zero LD (P2),A ; Zero move flags CALL ADMOVE ; Put Rook move in list CALL ADJPTR ; Re-adjust move list pointer LD A,(M3) ; Restore King position LD (M1),A ; Store CA20: LD A,B ; Scan index CP 1 ; Done? RET Z ; Yes - Return LD BC,01FCH ; Set Queen-side initial values JP CA5 ; Jump ;*********************************************************************** ; ADMOVE ROUTINE ;*********************************************************************** ; FUNCTION: To add a move to the move list ; ; CALLED BY: MPIECE ENPSNT CASTLE ; ; CALLS: None ; ; ARGUMENTS: None ;*********************************************************************** ADMOVE: LD DE,(MLNXT) ; Addr of next loc in move list LD HL,MLEND ; Address of list end AND A ; Clear carry flag SBC HL,DE ; Calcuate difference JR C,AM10-$ ; Jump if out of space LD HL,(MLLST) ; Addr of prev. list area LD (MLLST),DE ; Save next as previous LD (HL),E ; Store link address INC HL LD (HL),D LD HL,P1 ; Address of moved piece BIT 3,(HL) ; Has it moved before? JR NZ,AD20-$ ; Yes - Jump LD HL,P2 ; Address of move flags SET 4,(HL) ; Set first move flag AD20: EX DE,HL ; Address of move area LD (HL),0 ; Store zero in link address INC HL LD (HL),0 INC HL LD A,(M1) ; Store "from" move position LD (HL),A INC HL LD A,(M2) ; Store "to" move position LD (HL),A INC HL LD A,(P2) ; Store move flags/capt. piece LD (HL),A INC HL LD (HL),0 ; Store initial move value INC HL LD (MLNXT),HL ; Save address for next move RET ; Return AM10: LD (HL),0 ; Abort entry on table overflow INC HL LD (HL),0 DEC HL RET ;*********************************************************************** ; GENERATE MOVE ROUTINE ;*********************************************************************** ; FUNCTION: To generate the move set for all of ; pieces of a given color. ; ; CALLED BY: FNDMOV ; ; CALLS: MPIECE INCHK ; ; ARGUMENTS: None ;*********************************************************************** GENMOV: CALL INCHK ; Test for King in check LD (CKFLG),A ; Save attack count as flag LD DE,(MLNXT) ; Addr of next available list space LD HL,(MLPTRI) ; Ply list pointer index INC HL ; Increment to next ply INC HL LD (HL),E ; Save move list pointer INC HL LD (HL),D INC HL LD (MLPTRI),HL ; Save new index LD (MLLST),HL ; Last pointer for chain initialization LD A,21 ; First position on board GM5: LD (M1),A ; Save as index LD IX,(M1) ; Load board index LD A,(IX+BOARD) ; Fetch board contents AND A ; Is it empty? JR Z,GM10-$ ; Yes - Jump CP -1 ; Is it a border square? JR Z,GM10-$ ; Yes - Jump LD (P1),A ; Save piece LD HL,COLOR ; Address of color of piece XOR (HL) ; Test color of piece BIT 7,A ; Match? CALL Z,MPIECE ; Yes - Call Move Piece GM10: LD A,(M1) ; Fetch current position INC A ; Increment to next board position CP 99 ; End of board array? JR NZ,GM5-$ ; No - Jump RET ; Return ;*********************************************************************** ; CHECK ROUTINE ;*********************************************************************** ; FUNCTION To determine whether or not the King is in check. ; ; CALLED BY: GENMOV FNDMOV EVAL ; ; CALLS: ATTACK ; ; ARGUEMENTS: Color of King ;*********************************************************************** INCHK: LD A,(COLOR) ; Get color INCHK1: LD HL,POSK ; Addr of white King position AND A ; White? JR Z,INCK5-$ ; Yes - Skip INC HL ; Addr of black King position INCK5: LD A,(HL) ; Fetch King position LD (M3),A ; Save LD IX,(M3) ; Load board index LD A,(IX+BOARD) ; Fetch board contents LD (P1),A AND 7 ; Save LD (T1),A ; Get piece type CALL ATTACK ; Save RET ; Return ;*********************************************************************** ; ATTACK ROUTINE ;*********************************************************************** ; FUNCTION: To determine all attackers on a given square ; by scanning outward from the square ; until a piece is found that attacks ; that square or a piece is found that ; does not attack that square, or the edge ; of the board is reached. ; ; In determining which pieces attack ; square, this routine also takes into ; account the ability of certain pieces to ; attack through another attacking piece. (For ; example a Queen lined up behind a Bishop ; of her sane color along a diagonal.) The ; Bishop is then said to be transparent to the ; Queen, since both participate in the attack. ; ; In the case where this routine is called ; by CASTLE or INCHK, the routine is ; terminated as soon as an attacker of the ; opposite color is encountered. ; ; CALLED BY: POINTS PINFND CASTLE INCHK ; ; CALLS: PATH ATKSAV ; ; ARGUMENTS: None ;*********************************************************************** ATTACK: PUSH BC ; Save Register B XOR A ; Clear LD B,16 ; Initial direction count LD (INDX2),A ; Initial direction index LD IY,(INDX2) ; Load index AT5: LD C,(IY+DIRECT) ; Get direction LD D,0 ; Init. scan count/flags LD A,(M3) ; Init. board start position LD (M2),A ; Save AT10: INC D ; Increment scan count CALL PATH ; Next position CP 1 ; Piece of an opposite color? JR Z,AT14A-$ ; Yes - Jump CP 2 ; Piece of the same color? JR Z,AT14B-$ ; Yes - Jump AND A ; Empty position? JR NZ,AT12-$ ; No - Jump LD A,B ; Fetch direction count CP 9 ; On Knight scan? JR NC,AT10-$ ; No - Jump AT12: INC IY ; Increment direction index DJNZ AT5-$ ; Done? No - Jump XOR A ; There are no attackers AT13: POP BC ; Restore register B RET ; Return AT14A: BIT 6,D ; Same color found already? JR NZ,AT12-$ ; Yes - Jump SET 5,D ; Set opposite color found flag JR AT14-$ ; Jump AT14B: BIT 5,D ; Same color found already? JR NZ,AT12-$ ; Yes - Jump SET 6,D ; Set same color found flag ; ***** DETERMINE IF PIECE ENCOUNTERED ATTACKS SQUARE ***** AT14: LD A,(T2) ; Fetch piece type encountered LD E,A ; Save LD A,B ; Get direction counter CP 9 ; Look for Knights? JR C,AT25-$ ; Yes - Jump LD A,E ; Get piece type CP QUEEN ; Is it a Queen? JR NZ,AT15-$ ; No - Jump SET 7,D ; Set Queen found flag JR AT30-$ ; Jump AT15: LD A,D ; Get flag/scan count AND 0FH ; Isolate count CP 1 ; On first position? JR NZ,AT16-$ ; No - Jump LD A,E ; Get encountered piece type CP KING ; Is it a King? JR Z,AT30-$ ; Yes - Jump AT16: LD A,B ; Get direction counter CP 13 ; Scanning files or ranks JR C,AT21-$ ; Yes - Jump LD A,E ; Get piece type CP BISHOP ; Is it a Bishop? JR Z,AT30-$ ; Yes - Jump LD A,D ; Get flags/scan count AND 0FH ; Isolate count CP 1 ; On first position? JR NZ,AT12-$ ; No - Jump CP E ; Is it a Pawn? JR NZ,AT12-$ ; No - Jump LD A,(P2) ; Fetch piece including color BIT 7,A ; Is it white? JR Z,AT20-$ ; Yes - Jump LD A,B ; Get direction counter CP 15 ; On a non-attacking diagonal? JR C,AT12-$ ; Yes - Jump JR AT30-$ ; Jump AT20: LD A,B ; Get direction counter CP 15 ; On a non-attacking diagonal? JR NC,AT12-$ ; Yes - Jump JR AT30-$ ; Jump AT21: LD A,E ; Get piece type CP ROOK ; Is it a Rook? JR NZ,AT12-$ ; No - Jump JR AT30-$ ; Jump AT25: LD A,E ; Get piece type CP KNIGHT ; Is it a Knight? JR NZ,AT12-$ ; No - Jump AT30: LD A,(T1) ; Attacked piece type/flag CP 7 ; Call from POINTS? JR Z,AT31-$ ; Yes - Jump BIT 5,D ; Is attacker opposite color JR Z,AT32-$ ; No - Jump LD A,1 ; Set attacker found flag JP AT13 ; Jump AT31: CALL ATKSAV ; Save attacker in attack list AT32: LD A,(T2) ; Attacking piece type CP KING ; Is it a King? JP Z,AT12 ; Yes - Jump CP KNIGHT ; Is it a Knight? JP Z,AT12 ; Yes - Jump JP AT10 ; Jump ;*********************************************************************** ; ATTACK SAVE ROUTINE ;*********************************************************************** ; FUNCTION: To save an attacking piece value in the ; attack list, and to increment the attack ; count for that color piece. ; ; The pin piece list is checked for the ; attacking piece, and if found there, the ; piece is not included in the attack list. ; ; CALLED BY: ATTACK ; ; CALLS: PNCK ; ; ARGUMENTS: None ;************************************************************************** ATKSAV: PUSH BC ; Save Regs BC PUSH DE ; Save Regs DE LD A,(NPINS) ; Number of pinned pieces AND A ; Any? CALL NZ,PNCK ; Yes - check pin list LD IX,(T2) ; Initialize index to value table LD HL,ATKLST ; Initialize address of attack list LD BC,0 ; Initialize increment for white LD A,(P2) ; Attacking piece BIT 7,A ; Is it white? JR Z,AS30-$ ; Yes - Jump LD C,7 ; Initialize increment for black AS30: AND 7 ; Attacking piece type LD E,A ; Initialize increment tor type BIT 7,D ; Queen found this scan JR Z,AS40-$ ; No - Jump LD E,QUEEN ; Use Queen slot in attack list AS40: ADD HL,BC ; Attack list adddress INC (HL) ; Increment list count LD D,0 ADD HL,DE ; Attack list slot address LD A,(HL) ; Get data already there AND 0FH ; Is first slot empty JR Z,AS20-$ ; Yes - Jump LD A,(HL) ; Get data again AND 0F0H ; Is second slot empty? JR Z,AS19-$ ; Yes - Jump INC HL ; Increment to King slot JR AS20-$ ; Jump AS19: RLD ; Temp save lower in upper LD A,(IX+PVALUE) ; Get new value for attack list RRD ; Put in 2nd attack list slot JR AS25-$ ; Jump AS20: LD A,(IX+PVALUE) ; Get new value for attack list RLD ; Put in 1st attack list slot AS25: POP DE ; Restore DE registers POP BC ; Restore BC registers RET ; Return ;*************************************************************************** ; PIN CHECK ROUTINE ;************************************************************************** ; FUNCTION: Checks to see if the attacker is in the ; pinned piece list. If so he is not a valid ; attacker unless the direction in which he ; attacks is the same as the direction along ; which he is pinned. If the piece is ; found to be invalid as an attacker, the ; return to the calling routinne is aborted ; and this routine returns directly to ATTACK. ; ; CALLED BY: ATKSAV ; ; CALLS: None ; ; ARGUMENTS: The direction of the attack. ; The pinned piece count. ;*************************************************************************** PNCK: LD D,C ; Save attack direction LD E,0 ; Clear flag LD C,A ; Load pin count for search LD B,0 LD A,(M2) ; Position of piece LD HL,PLISTA ; Pin list adress PC1: CPIR ; Search list for position RET NZ ; Return if not found EX AF,AF' ; Save search parameters BIT 0,E ; Is this the first find? JR NZ,PC5-$ ; No - Jump SET 0,E ; Set first find flag PUSH HL ; Get corresponding index to dir list POP IX LD A,(IX+9) ; Get direction CP D ; Same as attacking direction JR Z,PC3-$ ; Yes - Jump NEG ; Opposite direction? CP D ; Same as attacking direction? JR NZ,PC5-$ ; No - Jump PC3: EX AF,AF' ; Restore search parameters JP PE,PC1 ; Jump if search not complete RET ; Return PC5: POP AF ; Abnormal exit POP DE ; Restore registers POP BC RET ; Return to attack ;*************************************************************************** ; PIN FIND ROUTINE ;*************************************************************************** ; FUNCTION: To produce a list of all pieces pinned ; against a King or Queen, for both white and black. ; ; CALLED BY: FNDMOV EVAL ; ; CALLS: PATH ATTACK ; ; ARGUEMENTS: None ;**************************************************************************** PINFND: XOR A ; Zero pin count LD (NPINS),A LD DE,POSK ; Address of King/Queen position list PF1: LD A,(DE) ; Get position of royal piece AND A ; Is it on the board JP Z,PF26 ; No - Jump CP -1 ; At end of list RET Z ; Yes - Return LD (M3),A ; Save position as board index LD IX,(M3) ; Load index to board LD A,(IX+BOARD) ; Get contents of board LD (P1),A ; Save LD B,8 ; Init scan direction count XOR A LD (INDX2),A ; Init direction index LD IY,(INDX2) PF2: LD A,(M3) ; Get King/Queen position LD (M2),A ; Save XOR A LD (M4),A ; Clear pinned piece saved position LD C,(IY+DIRECT) ; Get direction of scan PF5: CALL PATH ; Compute nextt position AND A ; Is it empty JR Z,PF5-$ ; Yes - Jump CP 3 ; Off the board? JP Z,PF25 ; Yes - Jump CP 2 ; Piece of the same color found? LD A,(M4) ; Load pinned piece position JR Z,PF15-$ ; Yes - jump AND A ; Possible pin? JP Z,PF25 ; No - Jump LD A,(T2) ; Piece type encountered CP QUEEN ; Queen? JR Z,PF19-$ ; Yes - Jump LD L,A ; Save piece type LD A,B ; Direction counter CP 5 ; Non-diagonal direction JR C,PF10-$ ; Yes - Jump LD A,L ; Piece type CP BISHOP ; Bishop? JR NZ,PF25-$ ; No - Jump JR PF20-$ ; Jump PF10: LD A,L ; Piece type CP ROOK ; Rook? JR NZ,PF25-$ ; No - Jump JR PF20-$ ; Jump PF15: AND A ; Possible pin? JR NZ,PF25-$ ; No - Jump LD A,(M2) ; Save possible pin position LD (M4),A JR PF5-$ ; Jump PF19: LD A,(P1) ; Load King or Queen AND 7 ; Clear flags CP QUEEN ; Queen? JR NZ,PF20-$ ; No - Jump PUSH BC ; Save regs. PUSH DE PUSH IY XOR A ; Zero out attack list LD B,14 LD HL,ATKLST PF50: LD (HL),A INC HL DJNZ PF50-$ LD A,7 ; Set attack flag LD (T1),A CALL ATTACK ; Find attackers/defenders LD HL,WACT ; White Queen attackers LD DE,BACT ; Black Queen attackers LD A,(P1) ; Get Queen BIT 7,A ; Is she white? JR Z,PF30-$ ; Yes - Jump EX DE,HL ; Reverse for black PF30: LD A,(HL) ; Number of defenders EX DE,HL ; Reverse for attackers SUB (HL) ; Defenders minus attackers DEC A ; Less 1 POP IY ; Restore registers POP DE POP BC JP P,PF25 ; Jump if pin not valid PF20: LD HL,NPINS ; Address of pinned piece count INC (HL) ; Increment LD IX,(NPINS) ; Load pin list index LD (IX+PLISTD),C ; Save direction of pin LD A,(M4) ; Position of pinned piece LD (IX+PLIST),A ; Save in list PF25: INC IY ; Increment direction index DJNZ PF27-$ ; Done? No - Jump PF26: INC DE ; Incr king/queen pos index JP PF1 ; Jump PF27: JP PF2 ; Jump ;************************************************************************** ; EXCHANGE ROUTINE ;************************************************************************** ; FUNCTION: To determine the exchange value of a ; on a given square by examining all ; attackers and defenders of that piece. ; ; CALLED BY: POINTS ; ; CALLS: NEXTAD ; ; ARGUMENTS: None ;************************************************************************** XCHNG: EXX ; Swap registers LD A,(P1) ; Piece attacked LD HL,WACT ; Addr of white attkrs/defenders LD DE,BACT ; Addr of black attkrs/defenders BIT 7,A ; Is piece white? JR Z,XC20-$ ; Yes - Jump EX DE,HL ; Swap list pointers XC20: LD B,(HL) ; Initialize list counts EX DE,HL LD C,(HL) EX DE,HL EXX ; Restore registers LD C,0 ; Init attacker/defender flag LD E,0 ; Init points lost count LD IX,(T3) ; Load piece value index LD D,(IX+PVALUE) ; Get attacked piece value SLA D ; Double it LD B,D ; Save CALL NEXTAD ; Retrieve first attacker RET Z ; Return if none XC10: LD L,A ; Save attacker value CALL NEXTAD ; Get next defender JR Z,XC18-$ ; Jump if none EX AF,AF' ; Save defender value LD A,B ; Get attacked value CP L ; Attacked less than attacker? JR NC,XC19-$ ; No - Jump EX AF,AF' ; Restore defender XC15: CP L ; Defender less than attacker? RET C ; Yes - Return CALL NEXTAD ; Retrieve next attacker value RET Z ; Return if none LD L,A ; Save attacker value CALL NEXTAD ; Retrieve next defender value JR NZ,XC15-$ ; Jump if none XC18: EX AF,AF' ; Save defender LD A,B ; Get value of attacked piece XC19: BIT 0,C ; Attacker or defender? JR Z,XC30-$ ; Jump if defender NEG ; Negate value for attacker XC30: ADD A,E ; Total points lost LD E,A ; Save total EX AF,AF' ; Restore previous defender RET Z ; Return if none LD B,L ; Prev attacker becomes defender JR XC10-$ ; Jump ;*************************************************************************** ; NEXT ATTACKER/DEFENDER ROUTINE ;*************************************************************************** ; FUNCTION To retrieve the next attacker or defender ; piece value from the attack list, and delete ; that piece from the list. ; ; CALLED BY: XCHNG ; ; CALLS: None ; ; ARGUMENTS: Attack list addresses ; Side flag ; Attack list counts ;**************************************************************************** NEXTAD: INC C ; Increment side flag EXX ; Swap registers LD A,B ; Swap list counts LD B,C LD C,A EX DE,HL ; Swap list pointers XOR A CP B ; At end of list? JR Z,NX6-$ ; Yes - Jump DEC B ; Decrement list count NX10: INC HL ; Increment list pointer CP (HL) ; Check next item in list JR Z,NX10-$ ; Jump if empty RRD ; Get value from list ADD A,A ; Double it DEC HL ; Decrement list pointer NX6: EXX ; Restore registers RET ; Return ;************************************************************************** ; POINT EVALUATION ROUTINE ;************************************************************************* ; FUNCTION To perform a static board evaluation and ; derive a score for a given board position ; ; CALLED BY: FNDMOV EVAL ; ; CALLS: ATTACK XCHNG LIMIT ; ; ARGUMNENTS: None ;*************************************************************************** POINTS: XOR A ; Zero out variables LD (MTRL),A LD (BRDC),A LD (PTSL),A LD (PTSW1),A LD (PTSW2),A LD (PTSCK),A LD HL,T1 ; Set attacker flag LD (HL),7 ; LD A,21 ; Init to first square on the board PT5: LD (M3),A ; Save as board index LD IX,(M3) ; Load board index LD A,(IX+BOARD) ; Get piece from board CP -1 ; Off board edge? JP Z,PT25 ; Yes - Jump LD HL,P1 ; Save piece, if any LD (HL),A AND 7 ; Save piece type, if any LD (T3),A CP KNIGHT ; Less than a Knight (Pawn)? JR C,PT6X-$ ; Yes - Jump CP ROOK ; Rook, Queen or King JR C,PT6B-$ ; No - Jump CP KING ; Is it a King? JR Z,PT6AA-$ ; Yes - Jump LD A,(MOVENO) ; Get move number CP 7 ; Less than 7? JR C,PT6A-$ ; Yes - Jump JR PT6X-$ ; Jump PT6AA: BIT 4,(HL) ; Castled yet? JR Z,PT6A-$ ; No - Jump LD A,6 ; Bonus for white castling BIT 7,(HL) ; Check piece color JR Z,PT6D-$ ; Jump if white LD A,-6 ; Bonus for black castling JR PT6D-$ ; Jump PT6A: BIT 3,(HL) ; Has piece moved yet? JR Z,PT6X-$ ; No - Jump JR PT6C-$ ; Jump PT6B: BIT 3,(HL) ; Has piece moved yet? JR NZ,PT6X-$ ; Jump PT6C: LD A,-2 ; Two points penalty for white BIT 7,(HL) ; Check piece color JR Z,PT6D-$ ; Jump if white LD A,2 ; Two points penalty for black PT6D: LD HL,BRDC ; Get address of board control ADD A,(HL) ; Add on penalty/bonus points LD (HL),A ; Save PT6X: XOR A ; Zero out attack list LD B,14 LD HL,ATKLST PT85: LD (HL),A INC HL DJNZ PT85-$ CALL ATTACK ; Build attack list for square LD HL,BACT ; Get black attacker count addr LD A,(WACT) ; Get white attacker count SUB (HL) ; Accumulate board control score LD HL,BRDC ; Address of board control ADD A,(HL) ; Accumulate board control score LD (HL),A ; Save LD A,(P1) ; Get piece on current square AND A ; Is it empty? JR Z,PT25-$ ; Yes - Jump CALL XCHNG ; Evaluate exchange, if any XOR A ; Check for a loss CP E ; Points lost? JR Z,PT23-$ ; No - Jump DEC D ; Deduct half a pawn value LD A,(P1) ; Get piece under attack LD HL,COLOR ; Color of side just moved XOR (HL) ; Compare with piece BIT 7,A ; Do colors match? LD A,E ; Points lost JR NZ,PT20-$ ; Jump if no match LD HL,PTSL ; Previous max points lost CP (HL) ; Compare to current value JR C,PT23-$ ; Jump if greater than LD (HL),E ; Store new value as max lost LD IX,(MLPTRJ) ; Load pointer to this move LD A,(M3) ; Get position of lost piece CP (IX+MLTOP) ; Is it the one moving? JR NZ,PT23-$ ; No - Jump LD (PTSCK),A ; Save position as a flag JR PT23-$ ; Jump PT20: LD HL,PTSW1 ; Previous maximum points won CP (HL) ; Compare to current value JR C,PT50-$ ; Jump if greater than LD A,(HL) ; Load previous maximum value LD (HL),E ; Store new value as maximum won PT50: LD HL,PTSW2 ; Previous 2nd max points won CP (HL) ; Compare to current value JR C,PT23-$ ; Jump if greater than LD (HL),A ; Store as new 2nd max lost PT23: LD HL,P1 ; Get piece BIT 7,(HL) ; Test color LD A,D ; Value of piece JR Z,PT55-$ ; Jump if white NEG ; Negate if black PT55: LD HL,MTRL ; Get addrs of material total ADD A,(HL) ; Add new value LD (HL),A ; Store PT25: LD A,(M3) ; Get current board position INC A ; Increment CP 99 ; At end of the board? JP NZ,PT5 ; No - Jump LD A,(PTSCK) ; Moving piece lost flag AND A ; Was it lost? JR Z,PT25A-$ ; No - Jump LD A,(PTSW2) ; 2nd max points won LD (PTSW1),A ; Store as max points won XOR A ; Zero out 2nd max points won LD (PTSW2),A PT25A: LD A,(PTSL) ; Get max points lost AND A ; Is it zero? JR Z,PT60-$ ; Yes - Jump DEC A ; Decrement it PT60: LD B,A ; Save it LD A,(PTSW1) ; Max points won AND A ; Is it zero? JR Z,PT65-$ ; Yes - Jump LD A,(PTSW2) ; 2nd max points won AND A ; Is it zero? JR Z,PT65-$ ; Yes - Jump DEC A ; Decrement it SRL A ; Divide it by 2 PT65: SUB B ; Subtract points lost LD HL,COLOR ; Color of side just moved BIT 7,(HL) ; Is it white? JR Z,PT70-$ ; Yes - Jump NEG ; Negate for black PT70: LD HL,MTRL ; Net material on board ADD A,(HL) ; Add exchange adjustments LD HL,MV0 ; Material at ply 0 SUB (HL) ; Subtract from current LD B,A ; Save LD A,30 ; Load material limit CALL LIMIT ; Limit to plus or minus value LD E,A ; Save limited value LD A,(BRDC) ; Get board control poinnts LD HL,BC0 ; Board control at ply 0 SUB (HL) ; Get difference LD B,A ; Save LD A,(PTSCK) ; Moving piece lost flag AND A ; Is it zero? JR Z,PT75-$ ; Yes - Jump LD B,0 ; Zero board control points PT75: LD A,6 ; Load board control limit CALL LIMIT ; Limit to plus or minus value LD D,A ; Save limited value LD A,E ; Get material points ADD A,A ; Multiply by 4 ADD A,A ADD A,D ; Add board control LD HL,COLOR ; Color of side just moved BIT 7,(HL) ; Is it white? JR NZ,PT80-$ ; No - Jump NEG ; Negate for white PT80: ADD A,80H ; Rescale score (neutral = 80H) LD (VALM),A ; Save score LD IX,(MLPTRJ) ; Load move list pointer LD (IX+MLVAL),A ; Save score in move list RET ; Return ;************************************************************************** ; LIMIT ROUTINE ;************************************************************************** ; FUNCTION: To limit the magnitude of a given value ; to another given value ; ; CALLED BY: POINTS ; ; CALLS: None ; ; ARGUMENTS: Input - Value to be limited in the B ; register. ; - Value to limit in the A register. ; Output - Limited value in the A register. ;*************************************************************************** LIMIT: BIT 7,B ; Is the value negative? JR Z,LIM10-$ ; No - Jump NEG ; Make positive CP B ; Compare to limit RET NC ; Return if outside limit LD A,B ; Output value as it is RET ; Return LIM10: CP B ; Compare to limit RET C ; Return if outside limit LD A,B ; Output value as is RET ; Return ;************************************************************************* ; MOVE ROUTINE ;************************************************************************* ; FUNCTION: To execute a move from the move list on the ; board array. ; ; CALLED BY: CPTRMV PLYRMV EVAL FNDMOV ; VALMOV ; ; CALLS: None ; ; ARGUMENTS: None ;************************************************************************ MOVE: LD HL,(MLPTRJ) ; Load move list pointer INC HL ; Increment past link bytes INC HL MV1: LD A,(HL) ; "From" position LD (M1),A ; Save INC HL ; Increment pointer LD A,(HL) ; "To" position LD (M2),A ; Save INC HL ; Increment pointer LD D,(HL) ; Get captured piece/flags LD IX,(M1) ; Load "from" position board index LD E,(IX+BOARD) ; Get piece moved BIT 5,D ; Test Pawn promotion flag JR NZ,MV15-$ ; Jump if set LD A,E ; Piece moved AND 7 ; Clear flag bits CP QUEEN ; Is it a Queen? JR Z,MV20-$ ; Yes - Jump CP KING ; Is it a King? JR Z,MV30-$ ; Yes - Jump MV5: LD IY,(M2) ; Load "to" position board index SET 3,E ; Set piece moved flag LD (IY+BOARD),E ; Insert piece at new position LD (IX+BOARD),0 ; Empty previous position BIT 6,D ; Double move? JR NZ,MV40-$ ; Yes - Jump LD A,D ; Get captured piece, if any AND 7 CP QUEEN ; Was it a Queen? RET NZ ; No - Return LD HL,POSQ ; Addr of saved Queen position BIT 7,D ; Is Queen white? JR Z,MV10-$ ; Yes - Jump INC HL ; Increment to black Queen position MV10: XOR A ; Set saved position to zero LD (HL),A RET ; Return MV15: SET 2,E ; Change Pawn to a Queen JR MV5-$ ; Jump MV20: LD HL,POSQ ; Addr of saved Queen position MV21: BIT 7,E ; Is Queen white? JR Z,MV22-$ ; Yes - Jump INC HL ; Increment to black Queen position MV22: LD A,(M2) ; Get new Queen position LD (HL),A ; Save JR MV5-$ ; Jump MV30: LD HL,POSK ; Get saved King position BIT 6,D ; Castling? JR Z,MV21-$ ; No - Jump SET 4,E ; Set King castled flag JR MV21-$ ; Jump MV40: LD HL,(MLPTRJ) ; Get move list pointer LD DE,8 ; Increment to next move ADD HL,DE JP MV1 ; Jump (2nd part of double move) ;*********************************************************************** ; UN-MOVE ROUTINE ;*********************************************************************** ; FUNCTION: To reverse the process of the move routine, ; thereby restoring the board array to its ; previous position. ; ; CALLED BY: VALMOV ; EVAL ; FNDMOV ; ASCEND ; ; CALLS: None ; ; ARGUMENTS: None ;*************************************************************************** UNMOVE: LD HL,(MLPTRJ) ; Load move list pointer INC HL ; Increment past the link bytes INC HL UM1: LD A,(HL) ; Get "from" position LD (M1),A ; Save INC HL ; Increment pointer LD A,(HL) ; Get "to" position LD (M2),A ; Save INC HL ; Increment pointer LD D,(HL) ; Get captured piece/flags LD IX,(M2) ; Load "to" position board index LD E,(IX+BOARD) ; Get piece moved BIT 5,D ; Was it a Pawn promotion? JR NZ,UM15-$ ; Yes - Jump LD A,E ; Get piece moved AND 7 ; Clear flag bits CP QUEEN ; Was it a Queen? JR Z,UM20-$ ; Yes - Jump CP KING ; Was it a King? JR Z,UM30-$ ; Yes - Jump UM5: BIT 4,D ; Is this the 1st move for this piece? JR NZ,UM16-$ ; Yes - Jump UM6: LD IY,(M1) ; Load "from" position board index LD (IY+BOARD),E ; Return to previous board position LD A,D ; Get captured piece, if any AND 8FH ; Clear flags LD (IX+BOARD),A ; Return to board BIT 6,D ; Was it a double move? JR NZ,UM40-$ ; Yes - Jump LD A,D ; Get captured piece, if any AND 7 ; Clear flag bits CP QUEEN ; Was it a Queen? RET NZ ; No - Return LD HL,POSQ ; Address of saved Queen position BIT 7,D ; Is Queen white? JR Z,UM10-$ ; Yes - Jump INC HL ; Increment to black Queen position UM10: LD A,(M2) ; Queen's previous position LD (HL),A ; Save RET ; Return UM15: RES 2,E ; Restore Queen to Pawn JR UM5-$ ; Jump UM16: RES 3,E ; Clear piece move flag JR UM6-$ ; Jump UM20: LD HL,POSQ ; Addr of saved Queen position UM21: BIT 7,E ; Is Queen white? JR Z,UM22-$ ; Yes - Jump INC HL ; Increment to black Queen position UM22: LD A,(M1) ; Get previous position LD (HL),A ; Save JP UM5 ; Jump UM30: LD HL,POSK ; Address of saved King position BIT 6,D ; Was it a castle? JR Z,UM21-$ ; No - Jump RES 4,E ; Clear castled flag JR UM21-$ ; Jump UM40: LD HL,(MLPTRJ) ; Load move list pointer LD DE,8 ; Increment to next move ADD HL,DE JP UM1 ; Jump (2nd part of double move) ;*************************************************************************** ; SORT ROUTINE ;*************************************************************************** ; FUNCTION: To sort the move list in order of ; increasing move value scores. ; ; CALLED BY: FNDMOV ; ; CALLS: EVAL ; ; ARGUMENTS: None ;*************************************************************************** SORTM: LD BC,(MLPTRI) ; Move list begin pointer LD DE,0 ; Initialize working pointers SR5: LD H,B LD L,C LD C,(HL) ; Link to next move INC HL LD B,(HL) LD (HL),D ; Store to link in list DEC HL LD (HL),E XOR A ; End of list? CP B RET Z ; Yes - Return SR10: LD (MLPTRJ),BC ; Save list pointer CALL EVAL ; Evaluate move LD HL,(MLPTRI) ; Beginning of move list LD BC,(MLPTRJ) ; Restore list pointer SR15: LD E,(HL) ; Next move for compare INC HL LD D,(HL) XOR A ; At end of list? CP D JR Z,SR25-$ ; Yes - Jump PUSH DE ; Transfer move pointer POP IX LD A,(VALM) ; Get new move value CP (IX+MLVAL) ; Less than list value? JR NC,SR30-$ ; No - Jump SR25: LD (HL),B ; Link new move into list DEC HL LD (HL),C JR SR5-$ ; Jump SR30 EX DE,HL ; Swap pointers JR SR15-$ ; Jump ;*************************************************************************** ; EVALUATION ROUTINE ;*************************************************************************** ; FUNCTION: To evaluate a given move in the move list. ; It first makes the move on the board, then if ; the move is legal, it evaluates it, and then ; restores the board position ; ; CALLED BY: SORT ; ; CALLS: MOVE INCHK PINFND POINTS ; UNMOVE ; ; ARGUMENTS: None ;************************************************************************** EVAL: CALL MOVE ; Make move on the board array CALL INCHK ; Determine if move is legal AND A ; Legal move? JR Z,EV5-$ ; Yes - Jump XOR A ; Score of zero LD (VALM),A ; For illegal move JR EV10-$ ; Jump EV5: CALL PINFND ; Compile pinned list CALL POINTS ; Assign points to move EV10: CALL UNMOVE ; Restore board array RET ; Return ;************************************************************************** ; FIND MOVE ROUTINE ;************************************************************************** ; FUNCTION: To determine the computer's best move by ; performing a depth first tree search using ; the techniques of alpha-beta pruning. ; ; CALLED BY: CPTRMV ; ; CALLS: PINFND POINTS GENMOV SORTM ; ASCEND UNMOVE MOVE ; ; ARGUMENTS: None ;************************************************************************** FNDMOV: LD A,(MOVENO) ; Current move number CP 1 ; First move? CALL Z,BOOK ; Yes - execute book opening XOR A ; Initialize ply number to zero LD (NPLY),A LD HL,0 ; Initialize best move to zero LD (BESTM),HL LD HL,MLIST ; Initialize ply list pointers LD (MLNXT),HL LD (MLPTRJ),HL LD HL,PLYIX-2 LD (MLPTRI),HL LD A,(KOLOR) ; Initialize color LD (COLOR),A LD HL,SCORE ; Initialize score index LD (SCRIX),HL LD A,(PLYMAX) ; Get max ply number ADD A,2 ; Add 2 LD B,A ; Save as counter XOR A ; Zero out score table FM41: LD (HL),A INC HL DJNZ FM41-$ LD (BC0),A ; Zero ply 0 board control LD (MV0),A ; Zero ply 0 material CALL PINFND ; Compile pin list CALL POINTS ; Evaluate board at ply 0 LD A,(BRDC) ; Get board control points LD (BC0),A ; Save LD A,(MTRL) ; Get material count LD (MV0),A ; Save FM5: LD HL,NPLY ; Address of ply counter INC (HL) ; Increment ply count XOR A ; Initialize mate flag LD (MATEF),A CALL GENMOV ; Generate list of moves LD A,(NPLY) ; Current ply counter LD HL,PLYMAX ; Address of maximum ply number CP (HL) ; At max ply? CALL C,SORTM ; No - Call SORTM LD HL,(MLPTRI) ; Load ply index pointer LD (MLPTRJ),HL ; Save as last move pointer FM15: LD HL,(MLPTRJ) ; Load last move pointer LD E,(HL) ; Get next move pointer INC HL LD D,(HL) LD A,D AND A ; End of move list? JR Z,FM25-$ ; Yes - Jump LD (MLPTRJ),DE ; Save current move pointer LD HL,(MLPTRI) ; Save in ply pointer list LD (HL),E INC HL LD (HL),D LD A,(NPLY) ; Current ply counter LD HL,PLYMAX ; Maximum ply counter? CP (HL) ; Compare JR C,FM18-$ ; Jump if not max CALL MOVE ; Execute move on board array CALL INCHK ; Check for legal move AND A ; Is move legal? JR Z,FM50-$ ; Yes - Jump CALL UNMOVE ; Restore board position JR FM15-$ ; Jump FM50: LD A,(NPLY) ; Get ply number LD HL,PLYMAX ; Max ply number CP (HL) ; Beyond max ply JR NZ,FM35-$ ; Yes - Jump LD A,(COLOR) ; Get current color XOR 80H ; Get opposite color CALL INCHK1 ; Determine if King is in check AND A ; In check? JR Z,FM35-$ ; No - Jump JR FM19-$ ; Jump (One more ply for check) FM18: LD IX,(MLPTRJ) ; Load move pointer LD A,(IX+MLVAL) ; Get move score AND A ; Is it zero (illegal move)? JR Z,FM15-$ ; Yes - Jump CALL MOVE ; Execute move on board array FM19: LD HL,COLOR ; Toggle color LD A,80H XOR (HL) LD (HL),A ; Save new color BIT 7,A ; Is it white? JR NZ,FM55-$ ; No - Jump LD HL,MOVENO ; Increment move counter INC (HL) FM55: LD HL,(SCRIX) ; Load score table pointer LD A,(HL) ; Get score two plys above INC HL ; Increment ply INC HL LD (HL),A ; Save score as initial value DEC HL ; Decrement pointer LD (SCRIX),HL ; Save it JP FM5 ; Jump FM25: LD A,(MATEF) ; Get mate flag AND A ; Checkmate or stalemate? JR NZ,FM30-$ ; No - Jump LD A,(CKFLG) ; Get check flag AND A ; Was King in check? LD A,80H ; Pre-set stalemate score JR Z,FM36-$ ; No - Jump (stalemate) LD A,(MOVENO) ; Get move number LD (PMATE),A ; Save LD A,0FFH ; Pre-set checkmate score JR FM36-$ ; Jump FM30: LD A,(NPLY) ; Get ply counter CP 1 ; At top of tree? RET Z ; Yes - return CALL ASCEND ; Ascend one ply in tree LD HL,(SCRIX) ; Load score table pointer INC HL ; Increment to current ply INC HL LD A,(HL) ; Get score DEC HL ; Restore pointer DEC HL JR FM37-$ ; Jump FM35: CALL PINFND ; Compile pin list CALL POINTS ; Evaluate move CALL UNMOVE ; Restore board position LD A,(VALM) ; Get value of move FM36: LD HL,MATEF ; Set mate flag SET 0,(HL) LD HL,(SCRIX) ; Load score table pointer FM37: CP (HL) ; Compare to score 2 ply above JR C,FM40-$ ; Jump if less JR Z,FM40-$ ; Jump if equal NEG ; Negate score INC HL ; Increment score table pointer CP (HL) ; Compare to score 1 ply above JP C,FM15 ; Jump if less than JP Z,FM15 ; Jump if equal LD (HL),A ; Save as new score 1 ply above LD A,(NPLY) ; Get current ply counter CP 1 ; At top of tree? JP NZ,FM15 ; No - Jump LD HL,(MLPTRJ) ; Load current move pointer LD (BESTM),HL ; Save as best move pointer LD A,(SCORE+1) ; Get best move score CP 0FFH ; Was it a checkmate? JP NZ,FM15 ; No - Jump LD HL,PLYMAX ; Get maximum ply number DEC (HL) ; Subtract 2 DEC (HL) LD A,(KOLOR) ; Get computer's color BIT 7,A ; Is it white? RET Z ; Yes - Return LD HL,PMATE ; Checkmate move number DEC (HL) ; Decrement RET ; Return FM40: CALL ASCEND ; Ascend one ply in tree JP FM15 ; Jump ;************************************************************************** ; ASCEND TREE ROUTINE ;************************************************************************** ; FUNCTION: To adjust all necessary parameters to ; ascend one ply in the tree. ; ; CALLED BY: FNDMOV ; ; CALLS: UNMOV ; ; ARGUMENTS: None ;************************************************************************** ASCEND: LD HL,COLOR ; Toggle color LD A,80H XOR (HL) LD (HL),A ; Save new color BIT 7,A ; Is it white? JR Z,ASC20-$ ; Yes - Jump LD HL,MOVENO ; Decrement move numbr DEC (HL) ASC20: LD HL,(SCRIX) ; Load score table index DEC HL ; Decrement LD (SCRIX),HL ; Save LD HL,NPLY ; Decrement ply counter DEC (HL) LD HL,(MLPTRI) ; Load ply list pointer DEC HL ; Load pointer to move list top LD D,(HL) DEC HL LD E,(HL) LD (MLNXT),DE ; Update move avail pointer DEC HL ; Get pointer to next move to undo LD D,(HL) DEC HL LD E,(HL) LD (MLPTRI),HL ; Save new ply counter LD (MLPTRJ),DE ; Save next move pointer CALL UNMOVE ; Restore board to previous ply RET ;************************************************************************** ; ONE MOVE BOOK OPENING ;************************************************************************** ; ; FUNCTION: To provide a book opening of a single move ; ; CALLED BY: FNDMOV ; ; CALLS: None ; ; ARGUMENTS: None ;*************************************************************************** BOOK: POP AF ; Abort return to FNDMOV LD HL,SCORE+1 ; Zero out score LD (HL),0 ; Zero out score table LD HL,BMOVES-2 ; Init best move ptr to book LD (BESTM),HL LD HL,BESTM ; Initialize address of pointer LD A,(KOLOR) ; Get computer's color AND A ; Is it white? JR NZ,BM5-$ ; No - Jump LD A,R ; Load refresh reg (random no) BIT 0,A ; Test random bit RET Z ; Return if zero (P-K4) INC (HL) ; P-Q4 INC (HL) INC (HL) RET BM5: INC (HL) ; Increment to black moves INC (HL) INC (HL) INC (HL) INC (HL) INC (HL) LD IX,(MLPTRJ) ; Pointer to opponent's 1st move LD A,(IX+MLFRP) ; Get "from" position CP 22 ; Is it a Queen Knight move? JR Z,BM9-$ ; Yes - Jump CP 27 ; Is it a King Knight move? JR Z,BM9-$ ; Yes - Jump CP 34 ; Is it a Queen Pawn? JR Z,BM9-$ ; Yes - Jump RET C ; If Queen side Pawn opening - ; return (P-K4) CP 35 ; Is it a King Pawn? RET Z ; Yes - Return (P-K4) BM9: INC (HL) ; (P-Q4) INC (HL) INC (HL) RET ; Return to CPTRMV ;*********************************************************************** ; COMPUTER MOVE ROUTINE ;*********************************************************************** ; FUNCTION: To control the search for the computers move ; and the display of that move on the board ; and in the move list ; ; CALLED BY: DRIVER ; ; CALLS: FNDMOV FCDMAT MOVE EXECMV ; BITASN INCHK LINOUT LINSET ; ; ARGUMENTS: None ;*********************************************************************** CPTRMV: LD BC,2047 LD HL,MLIST XOR A LD (HL),A LD DE,MLIST+1 LDIR CALL FNDMOV ; Select best move LD HL,(BESTM) ; Move list pointer variable LD (MLPTRJ),HL ; Pointer to move data LD A,(SCORE+1) ; To check for mates CP 1 ; Mate against computer JR NZ,CP0C-$ ; No - Jump LD C,1 ; Computer mate flag CALL FCDMAT ; Full checkmate? CP0C: CALL MOVE ; Produce move on board array LD E,1 LD D,7 ; Ring the bell CALL WRCHR LD BC,120 ; Store the board condition LD HL,BOARDA ; as a result ofthis move LD DE,BMOVE1 ; in array BMOVE1 LDIR CALL EXECMV ; Make move on graphics board ; and return info about it LD A,B ; Special move flags AND A ; Special? JR NZ,CP10-$ ; Yes - Jump LD D,E ; "To" position of the move CALL BITASN ; Convert to ASCII LD (MVEMSG+3),HL ; Put in move message LD D,C ; "From" position of the move CALL BITASN ; Convert to ASCII LD (MVEMSG),HL ; Put in move message LD HL,MVEMSG LD E,1 LD B,5 CALL LINOUT ; Output text of the move JR CP1C-$ CP10: BIT 1,B ; King side castle? JR Z,CP34-$ ; No - Jump LD E,1 LD B,5 LD HL,OO CALL LINOUT ; Output "O-O" JR CP1C-$ CP34: BIT 2,B ; Queen side castle? JR Z,CP28-$ ; No - Jump LD B,5 LD HL,OOO CALL LINOUT ; Output "O-O-O" JR CP1C-$ CP28: LD B,5 LD HL,PPEP CALL LINOUT ; Output "PxPep" - En passant CP1C: LD A,128 LD (XSET),A LD A,(COLOR) ; Should computer call check? LD B,A XOR 80H ; Toggle color LD (COLOR),A CALL INCHK ; Check for check AND A ; Is enemy in check? LD A,B ; Restore color LD (COLOR),A JR Z,CP24-$ ; No - Return LD A,(KOLOR) ; Bring in the computer's color AND A ; Is it white? JR NZ,CP50-$ ; No - Jump LD A,(MOVENO) CP 4 ; Is the move number < 4? JR C,CP50-$ ; Yes - Jump LD HL,LINECT DEC (HL) ; Decrement the line counter CP50: CALL LINSET ; Set the cursor LD A,(SCORE+1) ; Check for player mated CP 0FFH ; Forced mate? CALL NZ,TBCPMV ; No - Tab to computer column LD E,1 LD B,5 LD HL,CKMSG CALL LINOUT ; Output "CHECK" LD HL,LINECT INC (HL) CP24: LD A,(SCORE+1) ; Check again for mates CP 0FFH ; Player mated? RET NZ ; No - Return LD C,0 ; Set player mate flag CALL FCDMAT ; Full checkmate? RET ;*********************************************************************** ; FORCED MATE HANDLING ;*********************************************************************** ; FUNCTION: To examine situations where there exists ; a forced mate and determine whether or ; not the current move is checkmate. If it is, ; a losing player is offered another game, ; while a loss for the computer signals the ; King resignation signal. ; ; CALLED BY: CPTRMV ; ; CALLS: MATED CHARTR TBPLMV ; ; ARGUMENTS: The only value passed in a register is the ; flag which tells FCDMAT whether the computer ; or the player is mated. ;*********************************************************************** FCDMAT: LD A,(MOVENO) ; Current move number LD B,A ; Save LD A,(PMATE) ; Move number where mate occurs SUB B ; Number of moves till mate AND A ; Checkmate? JR NZ,FM0C-$ ; No - Jump BIT 0,C ; Check flag for who is mated JR Z,FM04-$ ; Jump if player CALL LINSET ; New line LD B,9 LD HL,CKMSG FM20: CALL LINOUT ; Print "CHECKMATE" CALL MATED ; RIP King LD A,128 LD (XSET),A CALL LINSET LD B,7 LD HL,UWIN FM22: CALL LINOUT ; Output "YOU WIN" JR FM08-$ ; Jump FM04: LD A,128 LD (XSET),A CALL LINSET LD B,4 LD HL,MTMSG CALL LINOUT ; Output "MATE" CALL LINSET LD B,5 LD HL,IWIN CALL LINOUT ; Output "I WIN" FM08: POP HL ; Remove return addresses POP HL CALL LINSET CALL CHARTR ; Input any character to play again FM09: LD B,2 LD HL,CLRSCR FM28: CALL LINOUT ; Blank screen LD B,23 LD HL,AGAIN CALL LINOUT ; Output "CARE FOR ANOTHER GAME?" JP DRIV01 ; Jump (Rest of game initialization) FM0C: BIT 0,C ; Who has forced mate? RET NZ ; Return if player PUSH AF ; Save the A register LD A,128 LD (XSET),A CALL LINSET ; New line POP AF ; Return the A register ADD A,30H ; Number of moves in ASCII LD (MTPL),A ; Place value in message LD B,9 LD HL,MTMSG CALL LINOUT ; Output "MATE IN x MOVES" CALL LINSET ; New line CALL TBPLMV ; Tab to player's column RET ; Return ;*********************************************************************** ; TAB TO PLAYER'S COLUMN ;*********************************************************************** ; FUNCTION: To space over in the move listing to the ; column in which the player's moves are being ; recorded. This routine also reprints the ; move number. ; ; CALLED BY: PLYRMV ; ; CALLS: None ; ; ARGUMENTS: None ;*********************************************************************** TBPLCL: LD B,3 LD HL,MVENUM CALL LINOUT ; Reproduce move number LD A,(KOLOR) ; Computer's color AND A ; Is computer white? RET NZ ; No - Return LD B,7 TBPL2: CALL SPACE ; Tab to next column DJNZ TBPL2-$ RET ; Return ;*********************************************************************** ; TAB TO COMPUTER'S COLUMN ;*********************************************************************** ; FUNCTION: To space over in the move listing to the ; column in which the computer's moves are being ; recorded. This routine also reprints the ; move number. ; ; CALLED BY: PLYRMV ; ; CALLS: None ; ; ARGUMENTS: None ;*********************************************************************** TBCPCL: LD B,3 LD HL,MVENUM CALL LINOUT ; Reproduce move number LD A,(KOLOR) ; Computer's color AND A ; Is computer white? RET Z ; No - Return LD B,7 TBCP2: CALL SPACE ; Tab to next column DJNZ TBCP2-$ RET ; Return ;*********************************************************************** ; TAB TO PLAYER'S W/O MOVE NO. ;*********************************************************************** ; FUNCTION: Like TBPLCL, except that the move number ; is not reprinted. ; ; CALLED BY: FCDMAT ;*********************************************************************** TBPLMV: LD B,3 TBPL3: CALL SPACE DJNZ TBPL3-$ LD A,(KOLOR) AND A RET NZ LD B,7 TBPL4: CALL SPACE DJNZ TBPL4-$ RET ;*********************************************************************** ; TAB TO COMPUTER'S W/O MOVE NO. ;*********************************************************************** ; FUNCTION: Like TBCPCL, except that the move number ; is not reprinted. ; ; CALLED BY: FCDMAT ;*********************************************************************** TBCPMV: LD B,3 TBCP3: CALL SPACE DJNZ TBCP3-$ LD A,(KOLOR) AND A RET Z LD B,7 TBCP4: CALL SPACE DJNZ TBCP4-$ RET ;*********************************************************************** ; BOARD INDEX TO ASCII SQUARE NAME ;*********************************************************************** ; FUNCTION: To translate a hexadecimal index in the ; board array into an ASCII description ; of the square in algebraic chess notation. ; ; CALLED BY: CPTRMV ; ; CALLS: DIVIDE ; ; ARGUMENTS: Board index inpur in register D and the ; ASCII square name is output in register ; pair HL. ;*********************************************************************** BITASN: SUB A ; Get ready for division LD E,10 CALL DIVIDE ; Divide DEC D ; Get rank on 1-8 basis ADD A,60H ; Convert file to ASCII (a-h) LD L,A ; Save LD A,D ; Rank ADD A,30H ; Convert rank to ASCII (1-8) LD H,A ; Save RET ; Return ;*********************************************************************** ; PLAYER'S MOVE ANALYSIS ;*********************************************************************** ; FUNCTION: To accept and validate the player's move ; and produce it on the graphics board. It ; allows player to resign the game by ; entering a Control-R. It allows the player ; to replay his last move by entering a Control-S. ; It allows the player to save the current board ; position in a floppy disc file by entering a ; Control-V. ; ; CALLED BY: DRIVER ; ; CALLS: CHARTR ASNTBI VALMOV EXECMV ; PGIFND TBPLCL ; ; ARGUMENTS: None ;*********************************************************************** PLYRMV: CALL CHARTR ; Accept "from" file letter CP 12H ; Is it instead a Control-R? JP Z,FM09 ; Yes - Jump CP 13H ; Is it instead a Control-S? JP Z,PL30 ; Yes - Jump CP 16H ; Is it instead a Control-V? JP NZ,PL70 ; No - Jump ;********************************************* ; OUTPUT THE BOARD POSITION TO THE DISKETTE ;********************************************* LD D,5 CALL RESET1 ; Call GETVEC LD HL,TEXT5 ; Request the name of the data file CALL PTXT CALL LINSET ; Carriage Return LD B,16 LD HL,VEHOLD BS35: CALL RDCHR ; Input the data set specification CALL CHART1 LD (HL),A INC HL CP 0DH ; Is the input a Carriage Return? JR Z,BS40-$ ; Yes - Jump DJNZ BS35-$ JP BS75 ; Jump to the error address BS40: LD HL,VEHOLD LD A,7 ; CALL CSISYN CALL JTASK CP 2 ; Error bit set? JP Z,BS75 ; Yes - Jump to the error address LD HL,VEHOLD LD A,6 CALL JTASK ; CALL CSISYN CP 0 ; Dataset found and parsed? JP NZ,BS75 ; No - Jump to error address ;********************************************* ; STUFF THE OUTPUT VECTOR AND PREPARE TO OPEN ; THE OUTPUT FILE FOR A WRITE ;********************************************* LD (IY+0),5 ; Set LUN = 5 LD (IY+1),'D' ; Set device to DK: LD (IY+2),'K' LD (IY+15),1 ; Request to open the file for a WRITE LD (IY+16),21H ; Format = Logical Buffer; 1 Rec buff LD (IY+19),0 ; Clear Error Return Address LD (IY+20),0 LD (IY+22),0 ; Clear status flags LD (IY+27),121 ; Set USIZE to 121 LD (IY+28),0 CALL JIOCS LD (IY+15),7 ; Erase the file CALL JIOCS LD (IY+15),1 ; Request to open the file for a WRITE CALL JIOCS LD A,(IY+23) ; Errors? AND A JR NZ,BS75-$ ; Yes - Jump to error address ;********************************************************* ; THIS SECTION OUTPUTS THE CONTENTS OF THE BOARD POSITION ; ARRAY TO THE DISKETTE ;********************************************************* BS99: LD HL,BOARDA LD (IY+25),L ; Store address of the buffer LD (IY+26),H ; BOARDA in UBFFR for writing LD (IY+15),4 CALL JIOCS ; Write data to the unit LD (IY+15),2 CALL JIOCS ; Close the output file BS75: LD A,128 LD (XSET),A CALL LINSET ; Carriage Return CALL TBPLCL ; Tab to player's column LD HL,LINECT INC (HL) JP PLYRMV ; Jump to PLYRMV ;********************************************* ; RESTORE THE PLAYER'S MOVE ;********************************************* PL30: LD BC,120 ; Restore board to the condition LD DE,BOARDA ; it was in three moves ago LD HL,BMOVE2 LDIR CALL DSPBRD ; Display board CALL TITLES ; Display titles LD A,(MOVENO) ; What is the present hexadecimal CP 1 ; move number? Is it 1? JP Z,BA25 ; Yes - Jump LD HL,MVENUM+2 ; Address of the 3rd move character LD A,20H CP (HL) ; Is the character a space? LD A,47 ; Set up test value JR Z,BA10-$ DEC HL ; Decrement value CP (HL) ; Under ASCII 0? JR NZ,BA14-$ LD (HL),32 ; Set 3rd character to a blank DEC HL LD (HL),57 ; Set 2nd character to 9 DEC HL LD (HL),57 ; Set 1st character to 9 JR BA14-$ BA10: DEC HL ; 2nd character of ASCII move DEC (HL) ; Decrement value CP (HL) ; Under ASCII 9? JR NZ,BA14-$ LD (HL),57 ; Set character to 9 DEC HL ; 1st character of ASCII move DEC (HL) ; Decrement value BA14: LD HL,MOVENO ; Decrement the hexadecimal move DEC HL ; number BA25: CALL TBPLCL LD HL,LINECT ; Increment the line counter INC (HL) CALL CHARTR ; Accept "from" file letter CP 12H ; Is it a Control-R? JP Z,FM09 JR PL35-$ PL70: PUSH AF ; Save the A register LD BC,120 ; Transfer the contents of the LD HL,BMOVE1 ; board array from the past move LD DE,BMOVE2 ; to the board array of the LDIR ; 2nd previous move POP AF ; Restore the A register PL35: LD H,A ; Save CALL CHARTR ; Accept "from" rank number LD L,A ; Save CALL ASNTBI ; Convert to a board index SUB B ; Gives board index, if valid JR Z,PL08-$ ; Jump if invalid LD (MVEMSG),A ; Move list "from" position CALL CHARTR ; Accept separator & ignore it CALL CHARTR ; Repeat for "to" position LD H,A CALL CHARTR LD L,A CALL ASNTBI SUB B JR Z,PL08-$ LD (MVEMSG+1),A ; Move list "to" position CALL VALMOV ; Determines if a legal move AND A ; Legal? JR NZ,PL08-$ ; No - Jump CALL EXECMV ; Make move on graphics board RET PL08: LD E,1 ; Adress to LUN #1 LD A,128 LD (XSET),A LD A,(KOLOR) ; Get the computer's color AND A ; Is it white? JR Z,PL25-$ ; Yes - Jump CALL LINSET ; New line JR PL20-$ PL25: CALL LIN1 PL20: LD HL,INVAL1 ; Output "INVALID MOVE -- TRY AGAIN" LD B,25 CALL LINOUT CALL LINSET CALL TBPLCL ; Tab to player's column LD A,(KOLOR) ; Get the computer's color AND A ; Is it white? JR NZ,PL10-$ ; No - Jump LD HL,LINECT INC (HL) PL10: JP PLYRMV ; Jump ;*********************************************************************** ; ASCII SQUARE NAME TO BOARD INDEX ;*********************************************************************** ; FUNCTION: To convert an algebraic square name in ; ASCII to a hexadecimal board index. ; This routine also checks for input validity/ ; ; CALLED BY: PLYRMV ; ; CALLS: MLTPLY ; ; ARGUMENTS: Accepts the square name in register pair HL ; and outputs the board indes in register A. ; Register B = 0 if ok. Register B = Register ; A if invalid. ;*********************************************************************** ASNTBI: LD A,L ; ASCII rank SUB 30H ; Rank 1 - 8 CP 1 ; Check lower bound JP M,AT04 ; Jump if invalid CP 9 JR NC,AT04-$ ; Jump if invalid INC A ; Rank 2 - 9 LD D,A ; Ready for multiplication LD E,10 CALL MLTPLY ; Multiply LD A,H ; ASCII file letter (a - h) SUB 40H ; File 1 - 8 CP 1 ; Check lower bound JP M,AT04 ; Jump if invalid CP 9 ; Check upper bound JR NC,AT04-$ ; Jump if invalid ADD A,D ; File+Rank (20-90) = Board Index LD B,0 ; Ok flag RET ; Return AT04: LD B,A ; Invalid flag RET ;*********************************************************************** ; VALIDATE MOVE SUBROUTINE ;*********************************************************************** ; FUNCTION: To check a player's move for validity. ; ; CALLED BY: PLYRMV ; ; CALLS: GENMOV MOVE INCHK UNMOVE ; ; ARGUMENTS: Returns flag in register A, 0 for valid ; and 1 for invalid move. ;*********************************************************************** VALMOV: LD BC,1023 LD HL,MLIST+1024 XOR A LD (HL),A LD DE,MLIST+1025 LDIR LD HL,(MLPTRJ) ; Save last move pointer PUSH HL ; Save register LD A,(KOLOR) ; Computer's color XOR 80H ; Toggle color LD (COLOR),A ; Store LD HL,PLYIX-2 ; Load move list index LD (MLPTRI),HL LD HL,MLIST+1024 ; Next available list pointer LD (MLNXT),HL CALL GENMOV ; Generate opponent's moves LD IX,MLIST+1024 ; Index to start of moves VA5: LD A,(MVEMSG) ; "From" position CP (IX+MLFRP) ; Is it in list? JR NZ,VA6-$ ; No - Jump LD A,(MVEMSG+1) ; "To" position CP (IX+MLTOP) ; Is it the list? JR Z,VA7-$ ; Yes - Jump VA6: LD E,(IX+MLPTR) ; Pointer to next move in the list LD D,(IX+MLPTR+1) XOR A ; At end of list? CP D JR Z,VA10-$ ; Yes - Jump PUSH DE POP IX JR VA5-$ ; Jump VA7: LD (MLPTRJ),IX ; Save opponent's move pointer CALL MOVE ; Make move on board array CALL INCHK ; Was it a legal move? AND A JR NZ,VA9-$ ; No - Jump VA8: POP HL ; Restore saved register RET ; Return VA9: CALL UNMOVE ; Un-do move on board array VA10: LD A,1 ; Set flag for invalid move POP HL ; Restore saved register LD (MLPTRJ),HL ; Save move pointer RET ; Return ;*********************************************************************** ; DISPLAY MATED KING ;*********************************************************************** ; FUNCTION: To let the computer's King RIP when ; mated. ; ; CALLED BY: FCDMAT ; ; CALLS: CONVRT ; BLNKER ; INSPCE (Abnormal Call to IP04) ; ; ARGUMENTS: None ;*********************************************************************** MATED: LD A,(KOLOR) ; Computer's color AND A ; Is computer white? LD HL,COLBIT ; JR Z,MA20-$ LD (HL),42H ; Color is black (B) LD A,(POSK+1) ; Position of black King JR MA08-$ MA20: LD (HL),57H ; Color is white (W) LD A,(POSK) ; Position of white King MA08: LD (BRDPOS),A ; Store King position LD (ANBDPS),A ; Again CALL CONVRT ; Convert to norm address LD A,6 ; Piece value of the King LD B,10 ; Blink parameter CALL BLNKER ; Blink King position LD IY,MA0C ; Prepare for abnormal call PUSH IY PUSH HL PUSH BC PUSH DE PUSH IX PUSH AF JP IP04 ; Call INSPCE ; Prepare to RIP the King MA0C: LD A,(YPOINT) ; Get Y norm pointer DEC A LD (YSET),A ; Set Y-vector for the cursor LD A,(XPOINT) ; Get X norm pointer INC A LD (XSET),A ; Set X-vector for the cursor CALL CURSOR ; Set the cursor LD E,1 LD HL,VIDBIT ; Set up for proper video LD D,(HL) CALL WRCHR LD B,3 LD HL,RIP MA30: CALL LINOUT ; Output RIP LD B,10 ; Blink again LD A,(ANBDPS) LD (BRDPOS),A CALL BLNKER RET ; Return ;*********************************************************************** ; SET UP POSITION FOR ANALYSIS ;*********************************************************************** ; FUNCTION: To enable user to set up any position ; for analysis, or to continue to play ; the game. The routine blinks the board ; squares in turn and the user has the option ; of leaving the contents unchanged by a ; carriage return, emptying the square by a 0, ; or inputting a piece of his choosing. To ; enter a piece, type in piece-code, color-code, ; moved-code. This subroutine also queries the ; the player if he wishes to analyse a position ; which is stored in a floppy disc file. ; ; Piece-code is a letter indicating ; Piece-code is a letter indicating the ; desired piece: ; K - King ; Q - Queen ; R - Rook ; B - Bishop ; N - Knight ; P - Pawn ; ; Color-code is a letter, W for white, or ; B for black. ; ; Moved-code is a number. 0 indicates that the ; piece has never moved. 1 indicates that the ; piece has moved. ; ; A backspace will back up inthe sequence of ; blinked squares. An Escape will terminate ; the link cycle and verify that the ; position is correct, then proceed with game ; initialization. ; ; CALLED BY: DRIVER ; ; CALLS: CHARTR DSPBRD BLNKER ROYALT ; PLYRMV CPTRMV JTASK ; ; ARGUMENTS: None ;*********************************************************************** ANALYS: LD A,0 LD (LINECT),A LD A,128 LD (XSET),A CALL LIN1 LD B,38 LD HL,ANAMSG AN30: CALL LINOUT ; "CARE TO ANALYSE A POSITION?" CALL CHARTR ; Accept answer PUSH AF ; Save the A register LD HL,LINECT ; Increment the line counter INC (HL) CALL LINSET ; New line POP AF ; Retrieve the A register CP 4EH ; Is the answer a "N"? JR NZ,AN04-$ ; No - Jump LD A,1 CALL JTASK ; Return to monitor AN04: LD HL,TEXT6 ; "DO YOU HAVE A BOARD POSITION" ; "STORED IN A FILE? " CALL PTXT CALL CHARTR ; Accept answer CP 89 ; Is it a "Y"? JP NZ,AN90 ; No - Jump LD D,4 CALL RESET1 ; CALL GETVEC CALL LINSET LD HL,TEXT7 ; "WHAT IS THE NAME OF YOUR BOARD" ; "POSITION DATA FILE? " CALL PTXT LD B,16 LD HL,VEHOLD AN80: CALL RDCHR ; Input the name of the board CALL CHART1 ; position file LD (HL),A INC HL CP 0DH ; Is the input a Carriage Return? JR Z,AN82-$ ; Yes - Jump DJNZ AN80-$ JR AN90-$ ; Jump to the error address AN82: LD HL,VEHOLD LD A,7 CALL JTASK ; CALL CSISYN CP 2 ; Error bit set? JR Z,AN90-$ ; Yes - Jump to the error address LD A,6 CALL JTASK ; CALL CSISYN CP 0 ; Dataset found and parsed? JP NZ,AN90 ; No - Jump to error address ;********************************************* ; STUFF THE INPUT VECTOR AND PREPARE TO OPEN ; THE INPUT FILE FOR A READ ;********************************************* LD (IY+0),4 ; Set LUN = 4 LD (IY+1),'D' ; Set device to DK: LD (IY+2),'K' LD (IY+15),0 ; Request to open for a WRITE LD (IY+16),21H ; Format = Logical Buffer; 1 Rec buff LD (IY+19),0 ; Clear Error Return Address LD (IY+20),0 LD (IY+22),0 ; Clear status flags LD (IY+27),120 ; Set USIZE to 120 LD (IY+28),0 CALL JIOCS ; Open output file LD A,(IY+23) ; Errors? AND A JR NZ,AN90-$ ; Yes - Jump to error address ;********************************************************* ; THIS SECTION INPUTS THE CONTENTS OF THE BOARD POSITION ; ARRAY FROM THE DISKETTE ;********************************************************* LD HL,BOARDA LD (IY+25),L ; Store address of the buffer LD (IY+26),H ; BOARDA in UBFFR for reading LD (IY+15),3 CALL JIOCS ; Read data from the unit LD (IY+15),2 CALL JIOCS ; Close the input file AN90: CALL DSPBRD ; Current board position LD A,21 ; First board index AN08: LD (ANBDPS),A ; Save LD (BRDPOS),A CALL CONVRT ; Determine norm address ; Store in RANK(Y) and FILE(X) LD (M1),A ; Set up board index LD IX,(M1) LD A,(IX+BOARD) ; Get board contents CP 0FFH ; Boarder square? JR Z,AN19-$ ; Yes - Jump AN35: LD B,4 ; Ready to blink square CALL BLNKER ; Blink LD E,1 ; Set cursor to home position LD D,30 CALL WRCHR CALL CHARTR ; Accept input CP 1BH ; Is it an escape? JR Z,AN1B-$ ; Yes - Jump CP 08H ; Is it a backspace? JR Z,AN1A-$ ; Yes - Jump CP 0DH ; Is it a carriage return? JR Z,AN19-$ ; Yes - Jump LD BC,7 ; Number of types of pieces + 1 LD HL,PCS ; Address of piece symbol table CPIR ; Search JR NZ,AN18-$ ; Jump if not found CALL CHARTR ; Accept and ignore separator CALL CHARTR ; Color of piece CP 42H ; Is it black? JR NZ,AN50-$ ; No - skip SET 7,C ; Black piece indicator AN50: CALL CHARTR ; Accept and ignore separator CALL CHARTR ; Moved flag CP 31H ; Has piece moved? JR NZ,AN18-$ ; No - Jump SET 3,C ; Set moved indicator AN18: LD IX,(M1) LD (IX+BOARD),C ; Insert piece into board array LD E,1 LD D,25 CALL WRCHR CALL DSPBRD ; Update graphics board AN19: LD A,(ANBDPS) ; Current board position INC A ; Next CP 99 ; Done? JR NZ,AN08-$ ; No - Jump JP AN04 ; Jump AN1A: LD A,(ANBDPS) ; Prepare to go back a square DEC A ; Decrement CP 20 ; Off the other end? JP NC,AN25 ; No - Jump LD A,98 ; Wrap around to top of screen AN0B: JP AN08 ; Jump AN25: LD (ANBDPS),A LD (BRDPOS),A CALL CONVRT LD (M1),A LD IX,(M1) LD A,(IX+BOARD) CP 0FFH JR Z,AN1A-$ JP AN35 AN1B: LD A,128 LD (XSET),A LD E,1 LD D,30 CALL WRCHR LD B,15 LD HL,CRTNES CALL LINOUT ; Ask if correct? CALL CHARTR ; Accept answer CP 4EH ; Is it "N"? JP Z,AN04 ; No - Jump CALL ROYALT ; Update positions of royalty LD B,2 LD HL,CLRSCR CALL LINOUT ; Blank screen LD A,-1 LD (LINECT),A CALL INTERR ; Accept color choice AN1C: CALL LINSET LD B,18 LD HL,WSMOVE CALL LINOUT ; Ask whose move it is CALL CHARTR ; Accept response PUSH AF ; Save the A register CALL DSPBRD ; Display graphics board LD D,30 ; Set the cursor CALL WRCHR LD B,15 LD HL,TITLE4 ; Put up titles CALL LINOUT LD A,-1 LD (LINECT),A CALL LIN1 LD B,15 LD HL,TITLE3 CALL LINOUT CALL LINSET ; Set the cursor POP AF ; Restore the A register CP 57H ; Is it white's move? JP Z,DRIV04 ; Yes - Jump LD B,3 LD HL,MVENUM CALL LINOUT ; Print move number LD B,7 AN46: CALL SPACE ; Tab to black's move DJNZ AN46-$ LD A,(KOLOR) ; Computer's color AND A ; Is computer white? JR NZ,AN20-$ ; No - Jump CALL PLYRMV ; Get player's move LD A,128 LD (XSET),A CALL LINSET ; New line JP DR0C ; Jump AN20: CALL CPTRMV ; Get computer's move LD A,128 LD (XSET),A CALL LINSET ; New line JP DR0C ; Jump ;*********************************************************************** ; UPDATE POSITIONS OF ROYALTY ;*********************************************************************** ; FUNCTION: To update the positions of the Kings and Queens ; after a change of board position in ANALYS. ; ; CALLED BY: ANALYS ; ; CALLS: None ; ; ARGUMENTS: None ;*********************************************************************** ROYALT: LD HL,POSK ; Start of Royalty array LD B,4 ; Clear all four positions RY60: LD (HL),0 INC HL DJNZ RY60-$ LD A,21 ; First board position RY04: LD (M1),A ; Set up board position LD HL,POSK ; Address of King position LD IX,(M1) LD A,(IX+BOARD) ; Fetch board contents BIT 7,A ; Test color bit JR Z,RY50-$ ; Jump if white INC HL ; Offset for black RY50: AND 7 ; Delete flags, leave piece CP KING ; King? JR Z,RY08-$ ; Yes - Jump CP QUEEN ; Queen JR NZ,RY0C-$ ; No - Jump INC HL ; Queen position INC HL ; Plus offset RY08: LD A,(M1) ; Index LD (HL),A ; Save RY0C: LD A,(M1) ; Current position INC A ; Next position CP 99 ; Done? JR NZ,RY04-$ ; No - Jump RET ; Return ;*********************************************************************** ; SQUARE BLINKER ;*********************************************************************** ; FUNCTION: To blink the graphics board square to signal ; a piece's intention to move, or to highlight ; the square as being alterable in ANALYS. ; ; CALLED BY: MAKEMV ANALYS MATED ; ; CALLS: None ; ; ARGUMENTS: Number of times to blink passed in register B. ;*********************************************************************** BLNKER: PUSH AF PUSH DE PUSH HL PUSH IX PUSH BC CALL RANFIL LD A,(XPOINT) ; Convert norm address to pointer LD (XSET),A ; address LD A,(YPOINT) LD (YSET),A CALL CURSOR ; Set the cursor LD B,5 LD HL,SQHOLD BL60: LD E,0 LD D,27 ; Read values of the upper half of CALL WRCHR ; the square and store them in PUSH IX ; SQHOLD POP IX PUSH IX POP IX LD D,41 CALL WRCHR PUSH IX POP IX PUSH IX POP IX CALL RDCHR LD (HL),A INC HL DJNZ BL60-$ LD A,(YPOINT) DEC A LD (YSET),A CALL CURSOR LD HL,SQHOLD+5 LD B,5 BL65: LD E,0 LD D,27 ; Read the values of the lower half CALL WRCHR ; of the square and store them in PUSH IX ; SQHOLD POP IX PUSH IX POP IX LD D,41 CALL WRCHR PUSH IX POP IX PUSH IX POP IX CALL RDCHR LD (HL),A INC HL DJNZ BL65-$ BL25: LD A,(VIDBI) LD D,A CALL WRCHR LD A,(YPOINT) LD (YSET),A LD A,(XPOINT) LD (XSET),A CALL CURSOR LD B,5 LD HL,SQHOLD BL30: LD D,(HL) CALL WRCHR INC HL DJNZ BL30-$ LD A,(YPOINT) DEC A LD (YSET),A CALL CURSOR LD B,5 LD HL,SQHOLD+5 BL35: LD D,(HL) CALL WRCHR INC HL DJNZ BL35-$ LD D,30 CALL WRCHR LD BC,3030H BL40: DEC BC LD A,B CP 0 JR NZ,BL40-$ LD A,C CP 0 JR NZ,BL40-$ LD A,(VIDBIT) LD D,A CALL WRCHR LD A,(YPOINT) LD (YSET),A LD A,(XPOINT) LD (XSET),A CALL CURSOR LD B,5 LD HL,SQHOLD BL80: LD D,(HL) CALL WRCHR INC HL DJNZ BL80-$ LD A,(YPOINT) DEC A LD (YSET),A CALL CURSOR LD B,5 LD HL,SQHOLD+5 BL85: LD D,(HL) CALL WRCHR INC HL DJNZ BL85-$ LD D,30 CALL WRCHR LD BC,3030H BL90: DEC BC LD A,B CP 0 JR NZ,BL90-$ LD A,C CP 0 JR NZ,BL90-$ POP BC ; Restore the B register DEC B PUSH BC ; Store the B register JP NZ,BL25 LD D,25 CALL WRCHR POP BC POP IX POP HL POP DE POP AF RET ;*********************************************************************** ; EXECUTE MOVE SUBROUTINE ;*********************************************************************** ; FUNCTION: This routine is the control routine for ; MAKEMV. It checks for double moves and ; sees that they are properly handled. It ; sets flags in the B register for double moves. ; En Passant -- Bit 0 ; O-O -- Bit 1 ; O-O-O -- Bit 2 ; ; CALLED BY: PLYRMV CPTRMV ; ; CALLS: MAKEMV ; ; ARGUMENTS: Flags set in the B register as described above. ;*********************************************************************** EXECMV: PUSH IX ; Save registers PUSH AF LD E,1 ; Save present cursor poition LD D,27 CALL WRCHR ; Output an "ESCAPE" and a "?" LD D,63 CALL WRCHR LD E,0 CALL RDCHR CALL RDCHR LD (YSETS),A ; Store the Y-position in YSETS CALL RDCHR LD (XSETS),A ; Store the X-position in XSETS LD IX,(MLPTRJ) ; Index into move list LD C,(IX+MLFRP) ; Move list "from" position LD E,(IX+MLTOP) ; Move list "to" position CALL MAKEMV ; Produce move LD D,(IX+MLFLG) ; Move list flags LD B,0 BIT 6,D ; Double move? JR Z,EX14-$ ; No - Jump LD DE,6 ; Move list entry width ADD IX,DE ; Increment MLPTRJ LD C,(IX+MLFRP) ; Second "from" position LD E,(IX+MLTOP) ; Second "to" position LD A,E ; Get "to" position CP C ; Same as "from" position? JR NZ,EX04-$ ; No - Jump INC B ; Set en passant flag JR EX10-$ ; Jump EX04: CP 1AH ; White O-O? JR NZ,EX08-$ ; No - Jump SET 1,B ; Set O-O flag JR EX10-$ ; Jump EX08: CP 60H ; Black O-O JR NZ,EX0C-$ ; No - Jump SET 1,B ; Set O-O flag JR EX10-$ ; Jump EX0C: SET 2,B ; Set move on board EX10: CALL MAKEMV EX14: PUSH DE LD E,1 ; Set normal video LD D,25 CALL WRCHR LD A,(YSETS) ; Set cursor to its proper position SUB 30H ; in the move list LD (YSET),A LD A,(XSETS) SUB 30H LD (XSET),A CALL CURSOR POP DE POP AF ; Restore registers POP IX RET ; Return ;*********************************************************************** ; MAKE MOVE SUBROUTINE ;*********************************************************************** ; FUNCTION: Moves the piece on the board when a move ; is made. It blinks both the "from" and ; "to" positions to give notice of the move. ; ; CALLED BY: EXECMV ; ; CALLS: CONVRT BLNKER INSPCE CURSOR ; ; ARGUMENTS: The "from" position is passed in register ; C, and the "to" position in Register E. ;*********************************************************************** MAKEMV: PUSH AF ; Save register PUSH BC PUSH HL PUSH DE LD A,C ; "From" position LD (BRDPOS),A ; Set up parameter CALL CONVRT ; Determine norm address LD B,10 ; Blink parameter CALL BLNKER ; Blink "from" square MK56: LD HL,YPOINT ; Convert norn address to pointer LD A,(HL) ; address LD (YSET),A LD HL,XPOINT LD A,(HL) ADD A,2 LD (XSET),A CALL CURSOR ; Set the cursor LD E,1 LD HL,VIDBIT LD D,(HL) CALL WRCHR ; Output video signal (inverse or LD D,32 ; normal video) CALL WRCHR ; Output 2 blanks LD D,32 CALL WRCHR POP DE ; Restore the E regoster PUSH DE LD A,E ; Get "to" position LD (BRDPOS),A ; Set up parameter CALL CONVRT ; Determine norm address LD B,10 ; Blink parameter CALL INSPCE ; Inserts the piece CALL BLNKER ; Blinks "to" square POP DE POP HL POP BC POP AF RET END r