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Copy pathFill Er Up.asm
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Fill Er Up.asm
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;
;FILL 'ER UP!
;
;BY TOM HUDSON
;A.N.A.L.O.G. COMPUTING #10
;
;
;ALPHABETIC CONSTANTS
;
CA = 'A'-$20
CB = 'B'-$20
CC = 'C'-$20
CD = 'D'-$20
CE = 'E'-$20
CF = 'F'-$20
CG = 'G'-$20
CH = 'H'-$20
CI = 'I'-$20
CJ = 'J'-$20
CK = 'K'-$20
CL = 'L'-$20
CM = 'M'-$20
CN = 'N'-$20
CO = 'O'-$20
CP = 'P'-$20
CQ = 'Q'-$20
CR = 'R'-$20
CS = 'S'-$20
CT = 'T'-$20
CU = 'U'-$20
CV = 'V'-$20
CW = 'W'-$20
CX = 'X'-$20
CY = 'Y'-$20
CZ = 'Z'-$20
CCOL = ':'-$20
;
;PAGE ZERO ITEMS
;
LO = $CB
HI = $CC
PLOTX = $CD
PLOTY = $CE
LOHLD = $CF
HIHLD = $D0
SMTIM = $D1
MOVTIM = $D2
TIMER = $D3
DEADFG = $D4
PX = $D5
PY = $D6
XI = $D7
YI = $D8
;
;MISCELLANEOUS MEMORY USAGE
;
PMAREA = $1000
MISSLS = PMAREA+384
PL0 = PMAREA+512
PL1 = PMAREA+640
PL2 = PMAREA+768
PL3 = PMAREA+896
DISP = $3000
;
;SYSTEM EQUATES
;
KEY = $2FC
CONSOL = $D01F
PMBASE = $D407
CHBASE = $02F4
RANDOM = $D20A
SETVBV = $E45C
XITVBV = $E45F
COLBK = $2C8
COLPF0 = $2C4
COLPF1 = $2C5
COLPF2 = $2C6
COLPF3 = $2C7
AUDC1 = $D201
AUDC2 = $D203
AUDC3 = $D205
AUDC4 = $D207
AUDF1 = $D200
AUDF2 = $D202
AUDF3 = $D204
AUDF4 = $D206
AUDCTL = $D208
PRIOR = $026F
ATTRACT = $4D
DMACTL = $22F
DLISTL = $230
GRACTL = $D01D
NMIEN = $D40E
PCOLR0 = $D012
COLPM0 = $2C0
COLPM1 = $2C1
COLPM2 = $2C2
COLPM3 = $2C3
HPOSP0 = $D000
HPOSP1 = $D001
HPOSP2 = $D002
HPOSP3 = $D003
HPOSM0 = $D004
HITCLR = $D01E
P0PF = $D004
P1PF = $D005
P2PF = $D006
P3PF = $D007
P0PL = $D00C
P3PL = $D00F
STICK = $278
STRIG = $284
ORG $6000 ;ASSEMBLER WILL
;PUT IT HERE
LOC $1400 ;PROGRAM START
;
;THIS CODE, WHEN CALLED BY BASIC, WILL
;MOVE THE 'FILL 'ER UP!' CODE TO ITS
;PROPER LOCATION ($1400) AND EXECUTE IT.
;
PROG PLA ;DISCARD
PLA ;PULL THE
STA $81 ;ADDRESS OF
PLA ;THE HOLDING
STA $80 ;STRING.
LDA #$00 ;SET UP
STA $82 ;DESTINATION
LDA #$14 ;ADDRESS ON
STA $83 ;PAGE ZERO.
LDY #0
COPYLP LDA ($80),Y ;COPY THE BLOCK
STA ($82),Y ;OF MEMORY.
LDA $80
CLC
ADC #1
STA $80
LDA $81
ADC #0
STA $81
LDA $82
CLC
ADC #1
STA $82
LDA $83
ADC #0
STA $83
CMP #DIR/256 ;AT END YET?
BNE COPYLP ;NO!
LDA $82 ;WELL, MAYBE...
CMP #DIR&255 ;AT END?
BNE COPYLP ;NOPE!
;
;MAIN PROGRAM STARTS HERE
;
START JSR $E465 ;INIT SOUNDS
LDA #$11 ;P/M PRIORITY
STA PRIOR
LDA #1 ;DON'T SHOW
STA SHOOFF ;PLAYER OR STAR
STA FILLON ;WE STILL MUST
JSR PMCLR ;CLEAR P/M AREA
LDA #64 ;AND SET UP THE
STA STRHGT ;STAR'S HEIGHT
LDA #128 ;AND
STA STRHOR ;HORIZONTAL POSITION
LDA #$D0 ;NOW LET'S
LDX #4 ;ZERO OUT
ZSCLP STA SCOLIN+4,X ;THE SCORE
STA SCOLIN+15,X ;AREAS!
DEX
BPL ZSCLP
LDX #5
ZSCLP2 STA SCOLN2+12,X
DEX
BPL ZSCLP2
LDA #0 ;THESE ITEMS
STA FILLON ;MUST BE SET
STA DEADFG ;TO ZERO ON
STA NOCCHG ;STARTUP OR
STA HITCLR ;ELSE WE'LL
STA DMACTL ;WIND UP WITH
STA NMIEN ;NASTY THINGS
STA HASDRN ;HAPPENING!
STA AUDCTL
LDX #5 ;LET'S ZERO
CMSLP STA SCORE,X ;OUT THE SCORE
DEX ;COUNTER...
BPL CMSLP
STA LEVEL ;AND LEVEL #!
LDA #3 ;WE START WITH
STA LIVES ;3 LIVES
ORA #$90 ;AND PUT THEM IN
STA SCOLN2+19 ;THE SCORE LINE
LDA #$0A ;NEXT WE SET UP
STA COLPF0 ;THE COLORS WE
LDA #$24 ;WANT TO USE.
STA COLPF1
LDA #$94
STA COLPF2
LDA #$C4
STA COLPF3
LDA #0
STA COLBK
LDA #$76
STA COLPM3
LDA #$34
STA COLPM0
LDA #DLIST&255 ;WE'D BETTER TELL
STA DLISTL ;THE COMPUTER WHERE
LDA #DLIST/256 ;OUR DISPLAY LIST
STA DLISTL+1 ;IS LOCATED!
LDY #INTRPT&255 ;TELL WHERE THE
LDX #INTRPT/256 ;VERTICAL BLANK
LDA #6 ;INTERRUPT IS
JSR SETVBV ;AND SET IT!
LDA #PMAREA/256 ;HERE'S OUR P/M
STA PMBASE ;GRAPHICS AREA!
LDA #$2E ;TURN ON THE
STA DMACTL ;DMA CONTROL
LDA #$3 ;AND
STA GRACTL ;GRAPHICS CONTROL!
LDA #$40 ;ENABLE VBI
STA NMIEN
JMP CLRDSP
PMCLR LDA #0 ;CLEAR OUT
LDX #127 ;THE P/M AREA:
PMICLR STA MISSLS,X ;MISSILES,
STA PL0,X ;PLAYER 0,
STA PL1,X ;PLAYER 1,
STA PL2,X ;PLAYER 2,
STA PL3,X ;AND PLAYER 3!
DEX
BNE PMICLR ;LOOP UNTIL DONE
RETURN RTS ;WE'RE DONE!
;
;PLOT ADDRESS CALCULATOR
;
;MULTIPLY PLOTY BY 40, THEN CALCULATE ADDRESS
;OF THE SCREEN MEMORY TO BE ALTERED.
;
PLOTCL LDA PLOTY
ASL A
STA LO
LDA #0
STA HI ;*2
ASL LO
ROL HI ;*4
ASL LO
LDA LO
STA LOHLD
ROL HI ;*8
LDA HI
STA HIHLD
ASL LO
ROL HI ;*16
ASL LO
ROL HI ;*32
LDA LO
CLC
ADC LOHLD
STA LO
LDA HI
ADC HIHLD
STA HI ;+*8=*40
LDA #DISP&255
CLC
ADC LO
STA LO
LDA #DISP/256
ADC HI
STA HI ;+DISPLAY START
LDA PLOTX ;MASK X POSITION
AND #3
TAX
LDA PLOTX
LSR A
LSR A
CLC
ADC LO
STA LO
LDA HI
ADC #0 ;LO & HI NOW HOLD
STA HI ;THE ADDRESS!
RTS ;EXIT!
;
;CLEAR THE DISPLAY MEMORY
;
CLRDSP LDX #0 ;THIS ROUTINE WILL
STX PLOTX ;CLEAR THE SCREEN RAM.
LDX #0 ;IT GETS THE ADDRESS
DLOOP2 STX PLOTY ;OF THE BEGINNING OF
JSR PLOTCL ;EACH GR.7 LINE
LDX PLOTY ;THEN ZEROES OUT
LDA #$00 ;EACH OF THE
LDY #39 ;40 BYTES (0-39)
DLOOP3 STA (LO),Y ;IN THE LINE.
DEY
BPL DLOOP3
INX
CPX #86
BNE DLOOP2
;
;DRAW THE COLOR 1 BORDER
;
LDA #3 ;THIS ROUTINE
STA BORNUM ;DRAWS THE 4 LINES
BORDER LDX BORNUM ;THAT MAKE UP THE
LDA BXSTRT,X ;WHITE GR.7 BORDER
STA PLOTX ;ON THE SCREEN.
LDA BYSTRT,X
STA PLOTY
LDA BXINC,X
STA BDINCX
LDA BYINC,X
STA BDINCY
LDA BORCNT,X
STA BDCNT
DRAWLN JSR PLOTCL
LDA COLOR1,X
LDY #0
ORA (LO),Y
STA (LO),Y
LDA PLOTX
CLC
ADC BDINCX
STA PLOTX
LDA PLOTY
CLC
ADC BDINCY
STA PLOTY
DEC BDCNT
BNE DRAWLN
DEC BORNUM
BPL BORDER
;
;THIS SECTION STARTS OFF EACH LEVEL
;
LDA #80 ;POSITION THE
STA PX ;PLAYER
LDA #84
STA PY
LDA LEVEL ;INCREMENT THE
CLC ;LEVEL NUMBER
ADC #1
STA LOWK
LDA #0 ;ZERO OUT
STA CURLO ;CURRENT TALLY
STA CURHI ;WORK AREA
STA HIWK
LDA #$FF ;TELL DECIMAL CONVERTER
STA SLLOC ;NOT TO PLACE RESULT
JSR CNVDEC ;CONVERT LEVEL #
LDA DECIMAL+1 ;GET DECIMAL LEVEL #
ORA #$90 ;ADD COLOR
STA SCOLN2+3 ;PUT IN SCORE LINE
LDA DECIMAL ;SAME FOR 2ND
ORA #$90 ;LEVEL #
STA SCOLN2+4 ;DIGIT
LDX LEVEL ;GET THIS LEVEL'S
LDA TGTLO,X ;PARAMETERS
STA LOWK
LDA TGTHI,X
STA HIWK
LDA STARSP,X
STA STRSPD
LDA #4
STA SLLOC
JSR CNVDEC ;SHOW TARGET AMOUNT
;
;CLEAR OUT THE TRACKING TABLE THAT
;REMEMBERS WHERE THE PLAYER MOVED
;
CLRTRK LDA #0
STA SHOOFF
TAX
CLRTLP STA DIR,X ;CLEAR DIRECTION
STA LGTH,X ;AND LENGTH ENTRIES
DEX
BNE CLRTLP
STA MOVIX ;CLEAR MOVEMENT INDEX
STA DRAWFG ;AND DRAW FLAG
GETSTK LDA PAUSE ;GAME PAUSED?
BNE GETSTK ;YES, LOOP AND WAIT.
LDA #$FD ;DO 'WARBLE' SOUND
STA AUDF1 ;USING SOUND
LDA #$FE ;CHANNELS 1-3
STA AUDF2
LDA #$FF
STA AUDF3
LDA #$A3
STA AUDC1
STA AUDC2
STA AUDC3
LDA #0 ;NO ATTRACT MODE!
STA ATTRACT
LDA DEADFG ;DID STAR HIT US?
BEQ ALIVE ;NO!
LDX LEVEL ;IT HIT US--
LDA KILLFG,X ;UNCONDITIONAL KILL?
BNE JCRSH ;YES! WE'RE DEAD!!!
LDA PX ;NO, IF WE'RE ON A
STA PLOTX ;WHITE LINE (COLOR 1)
LDA PY ;THEN WE'RE ALIVE!
STA PLOTY
JSR PLOTCL
LDY #0
LDA BITSON,X
AND (LO),Y
CMP COLOR1,X ;ON COLOR 1?
BEQ ALIVE ;YES (WHEW!)
JCRSH JMP CRASH ;GO KILL PLAYER.
ALIVE LDA MOVTIM ;PLAYER MOVING?
BEQ GOTSTK ;YES--GET STICK.
JMP MOVSTR ;NO, MOVE STAR.
JGSTK JMP GETSTK ;GO GET STICK
GOTSTK LDA #4 ;SET UP THE
STA MOVTIM ;MOVEMENT TIMER
LDA STICK ;GET THE STICK
STA STKHLD ;AND SAVE IT
TAX ;THEN LOOK UP
LDA XD,X ;X DIRECTION
CLC
ADC XD,X
STA XI ;AND
LDA YD,X ;Y DIRECTION
CLC
ADC YD,X
STA YI
ORA XI ;ANY MOVEMENT?
BEQ JGSTK ;NO, TRY AGAIN.
LDA PX ;INCREMENT
CLC ;PLAYER X
ADC XI ;POSITION AND
STA CKX ;HOLD IT...
CMP #159 ;OFFSCREEN?
BCS JGSTK ;YES!
STA PLOTX ;NO, SAVE IT
SEC
SBC XD,X
STA PXWC
LDA PY ;INCREMENT
CLC ;PLAYER Y
ADC YI ;POSITION AND
STA CKY ;HOLD IT...
CMP #85 ;OFFSCREEN?
BCS JGSTK ;YES!
STA PLOTY ;NO, SAVE IT
SEC
SBC YD,X
STA PYWC
JSR PLOTCL ;LOCATE NEW PLAYER
LDY #0 ;POSITION.
LDA BITSON,X
AND (LO),Y
STA CKV ;SAVE THE 'LOCATE'.
STX CKVX
LDA PXWC ;CHECK THE
STA PLOTX ;POSITION NEXT
LDA PYWC ;TO THE ONE WE'RE
STA PLOTY ;NOW IN...
JSR PLOTCL
LDY #0
LDA BITSON,X
AND (LO),Y
PHA ;AND SAVE IT!
LDA STRIG ;TRIGGER PRESSED?
BNE NOTDRN ;NO!
PLA ;OK TO DRAW?
BNE JGS ;NO!!
JMP DRAWIN ;YES, GO DRAW.
NOTDRN PLA ;NOT DRAWING--ARE WE
CMP COLOR1,X ;ON COLOR 1?
BNE JGS ;NO, TRY AGAIN
LDA CKV ;ARE WE MOVING
LDX CKVX ;ONTO ANOTHER
CMP COLOR1,X ;COLOR 1?
BNE JGS ;NO! TRY AGAIN.
LDA CKX ;ALL'S WELL...
STA PX ;UPDATE PX
LDA CKY ;AND
STA PY ;PY,
JGS JMP GETSTK ;GET STICK.
;
;THIS ROUTINE HANDLES THE DRAW FUNCTION.
;
DRAWIN LDA DRAWFG ;ALREADY DRAWING?
BNE DRAWOK ;YES!
STA MOVIX ;NO, THIS IS THE
LDA STKHLD ;FIRST TIME--SET UP
STA DIR ;INITIAL DRAWING
LDA #1 ;VARIABLES.
STA DRAWFG
STA HASDRN
LDA PX
STA INIX
STA MINX
STA MAXX
LDA PY
STA INIY
STA MINY
STA MAXY
DRAWOK LDA CKV ;DID WE
LDX CKVX ;RUN INTO ANOTHER
CMP COLOR2,X ;COLOR 2?
BNE NOCRSH ;NO, WE'RE OK.
JMP CRASH ;CRRAAASSSHHH!
NOCRSH LDX MOVIX ;UPDATE THE
LDA STKHLD ;TRACKING
CMP DIR,X ;TABLES WITH
BEQ SAMDIR ;DIRECTION
INC MOVIX ;INFORMATION.
INX
STA DIR,X
LDA #0
STA LGTH,X
SAMDIR INC LGTH,X
LDA #3
STA BDCNT
LDA PX ;NOW PLOT THE
STA PLOTX ;LINE WE'RE
LDA PY ;DRAWING...
STA PLOTY
CCLOOP JSR PLOTCL
LDY #0
LDA (LO),Y
AND BITOFF,X
ORA COLOR2,X ;IN COLOR 2.
STA (LO),Y
DEC BDCNT
BEQ CKCOLR
LDY MOVIX
LDX DIR,Y
LDA XD,X
CLC
ADC PLOTX
STA PLOTX
LDA YD,X
CLC
ADC PLOTY
STA PLOTY
JMP CCLOOP
CKCOLR LDA PLOTX ;UPDATE X POS.
STA PX
CMP MAXX ;CHECK MINIMUM
BCC TMINX ;AND MAXIMUM
STA MAXX ;X & Y VALUES
JMP CHKYMM ;AND UPDATE IF
TMINX CMP MINX ;NECESSARY
BCS CHKYMM
STA MINX
CHKYMM LDA PLOTY
STA PY
CMP MAXY
BCC TMINY
STA MAXY
JMP ENDMM
TMINY CMP MINY
BCS ENDMM
STA MINY
ENDMM LDX CKVX ;DID WE DRAW
LDA CKV ;INTO
CMP COLOR1,X ;COLOR 1?
BEQ ENDLIN ;YES! END OF LINE!
JMP GETSTK ;NO, GO GET STICK.
ENDLIN LDA #0 ;WE AREN'T
STA DRAWFG ;DRAWING ANYMORE
JSR SEARCH ;SEARCH AND FILL!!
LDA CURLO ;GET CURRENT VALUE
STA LOWK
LDA CURHI
STA HIWK
LDA #15 ;PUT AT 15TH
STA SLLOC ;POS. IN SCOLIN
JSR CNVDEC ;CONVERT TO DECIMAL
LDA #1 ;NOW REDRAW THE
STA RDRCOL ;PLAYER'S PATH IN
JSR REDRAW ;COLOR 1 (WHITE).
LDX LEVEL ;CHECK TO SEE
LDA CURLO ;IF WE'VE HIT
SEC ;THE TARGET.
SBC TGTLO,X
STA LOWK
LDA CURHI
SBC TGTHI,X
STA HIWK ;HIT TARGET?
BPL NEWLVL ;YES--NEW LEVEL!
JMP CLRTRK ;NO, GO CLEAR TRACK
NEWLVL LDA LEVEL ;IF LEVEL < 15
CMP #15 ;THEN
BEQ NOLINC ;INCREMENT
INC LEVEL ;LEVEL
;
;INCREASE SCORE HERE
;
NOLINC ASL LOWK ;SCORE INC =
ROL HIWK ;TGT-CUR * 2
LDA #$FF ;DON'T PLACE
STA SLLOC ;THE RESULT!
JSR CNVDEC ;CONVERT TO DECIMAL
LDX #5 ;AND ADD TO SCORE
LDY #0
SCOLP LDA DECIMAL,Y
CLC
ADC SCORE,X
CMP #10
BMI NOCARY
SEC
SBC #10
STA SCORE,X
INC SCORE-1,X
JMP NXSPOS
NOCARY STA SCORE,X
NXSPOS INY
DEX
BPL SCOLP
LDX #5 ;NOW PLACE THE
SHSLP LDA SCORE,X ;SCORE IN
ORA #$10 ;SCORE LINE #2
STA SCOLN2+12,X
DEX
BPL SHSLP
LDA #1 ;STOP VBI FOR
STA FILLON ;A MOMENT
STA SHOOFF
JSR PMCLR ;CLEAR P/M AREA
LDA #64 ;INITIALIZE
STA STRHGT ;THE
LDA #128 ;STAR
STA STRHOR ;POSITION
LDA #0 ;VBI ON AGAIN
STA FILLON
JMP CLRDSP ;GO CLEAR DISPLAY!
;
;THIS SECTION HANDLES PLAYER'S DEATH
;
CRASH LDA #0 ;NO WARBLE SOUND
STA AUDC1
STA AUDC2
STA AUDC3
LDA #1 ;NO PLAYER COLOR
STA NOCCHG ;CHANGE IN VBI
LDA #15 ;SET BRIGHTNESS OF
STA DEDBRT ;PLAYER DEATH.
TIMRST LDA #5 ;SET DEATH TIMER
STA TIMER ;TO 5 JIFFIES.
DEADCC LDA DEDBRT ;MOVE BRIGHTNESS
STA AUDC1 ;TO DEATH SOUND VOLUME
LDA RANDOM ;GET RANDOM
AND #$1F ;DEATH SOUND
STA AUDF1 ;FREQUENCY
LDA RANDOM ;GET RANDOM
AND #$F0 ;DEATH COLOR
ORA DEDBRT ;ADD BRITE
STA COLPF1 ;PUT IN LINE COLOR
STA COLPM3 ;AND PLAYER COLOR
LDA TIMER ;TIMER DONE YET?
BNE DEADCC ;NO, GO CHANGE COLOR.
DEC DEDBRT ;DECREMENT BRIGHTNESS
BPL TIMRST ;IF MORE, GO DO IT.
DEC LIVES ;1 LESS LIFE
LDA LIVES ;GET # LIVES
ORA #$90 ;ADD COLOR
STA SCOLN2+19 ;AND DISPLAY!
CMP #$90 ;ZERO LIVES?
BNE NOTDED ;NO!
LDA #GOMSG&255 ;WE'RE COMPLETELY
STA SCDL ;DEAD, SHOW
LDA #GOMSG/256 ;'GAME OVER'
STA SCDL+1 ;MESSAGE
CKSTRT LDA CONSOL ;WAIT FOR START
AND #1 ;KEY...
BNE CKSTRT ;NOT PRESSED--LOOP.
RELEAS LDA CONSOL ;KEY PRESSED, NOW
AND #1 ;WAIT FOR RELEASE!
BEQ RELEAS ;NOT RELEASED YET!
LDA #SCOLIN&255 ;PUT SCORE
STA SCDL ;LINE BACK
LDA #SCOLIN/256 ;IN DISPLAY
STA SCDL+1 ;LIST...
JMP START ;AND START GAME!
;
;THIS SECTION PLACES PLAYER AT A RANDOM
;LOCATION IF THERE ARE MORE LIVES LEFT.
;
NOTDED LDA #1 ;DON'T SHOW
STA SHOOFF ;PLAYER
NEWLOC LDA RANDOM ;GET RANDOM X
AND #$FE ;MUST BE EVEN
CMP #159 ;AND ON SCREEN
BCS NEWLOC
STA PLOTX
CSHY LDA RANDOM ;GET RANDOM Y
AND #$7E ;MUST BE EVEN
CMP #85 ;AND ON SCREEN
BCS CSHY
STA PLOTY
JSR PLOTCL
LDY #0
LDA BITSON,X
AND (LO),Y ;IS LOCATION ON
CMP COLOR1,X ;COLOR 1?
BNE NEWLOC ;NO, TRY AGAIN.
JSR PMCLR ;IT'S OK, CLEAR P/M
LDA PLOTX ;SAVE
STA PX ;THE PLAYER'S
LDA PLOTY ;NEW
STA PY ;COORDINATES.
LDA #0 ;REDRAW THE
STA RDRCOL ;PLAYER'S TRACK
LDA HASDRN ;IN COLOR 0
BEQ JCTRK
JSR REDRAW
LDA INIX ;THIS PART IS
STA PLOTX ;NEEDED TO PLOT
LDA INIY ;A COLOR 1 BLOCK
STA PLOTY ;AT THE START OF
JSR PLOTCL ;THE PLAYER'S TRACK
LDY #0 ;AFTER IT IS ERASED.
LDA BITOFF,X ;(NOBODY'S PERFECT!)
AND (LO),Y
ORA COLOR1,X
STA (LO),Y
JCTRK LDA #$24 ;RESTORE DRAW LINE
STA COLPF1 ;COLOR
LDA #0
STA NOCCHG
STA HITCLR
STA DEADFG
JMP CLRTRK ;AND GO START NEW TRACK.
;
;THIS ROUTINE USES THE TRACKING TABLES,
;DIR AND LGTH, TO REDRAW THE LINE THE
;PLAYER DREW. RDRCOL INDICATES THE COLOR
;DESIRED.
;
REDRAW LDA INIX
STA REX
LDA INIY
STA REY
LDA #0
STA X
REDXLP LDX X
LDA DIR,X
STA REDIR
LDA LGTH,X
STA LGTHY
LDA #1
STA Y
REDYLP LDA #3
STA TIMES
TIMES3 LDA REX
STA PLOTX
LDA REY
STA PLOTY
JSR PLOTCL
LDY #0
LDA RDRCOL
BNE RDC1
LDA BITOFF,X
AND (LO),Y
STA (LO),Y
JMP SETNRP
ENDRD LDA #0
STA DRAWFG
RTS
RDC1 LDA BITOFF,X
AND (LO),Y
ORA COLOR1,X
STA (LO),Y
SETNRP DEC TIMES
BEQ NXTY
LDX REDIR
LDA REX
CLC
ADC XD,X
STA REX
LDA REY
CLC
ADC YD,X
STA REY
JMP TIMES3
NXTY INC Y
LDA Y
CMP LGTHY
BEQ JNRD
BCS NXTX
JNRD JMP REDYLP
NXTX INC X
LDA X
CMP MOVIX
BEQ JRXLP
BCS ENDRD
JRXLP JMP REDXLP
;
;2-BYTE DECIMAL CONVERTER. CONVERTS
;A 2-BYTE BINARY NUMBER TO A 5-BYTE
;DECIMAL NUMBER. WILL PLACE THE
;DECIMAL NUMBER IN SCOLIN IF DESIRED
;(SLLOC DETERMINES POSITION).
;
CNVDEC LDX #4
LDA #0
CDLP STA DECIMAL,X
DEX
BPL CDLP
LDX #4
CKMAG LDA HIWK
CMP HIVALS,X
BEQ CKM2
BCS SUBEM
BCC NOSUB
CKM2 LDA LOWK
CMP LOVALS,X
BCS SUBEM
NOSUB DEX
BPL CKMAG
JMP SHOWIT
SUBEM LDA LOWK
SEC
SBC LOVALS,X
STA LOWK
LDA HIWK
SBC HIVALS,X
STA HIWK
INC DECIMAL,X
JMP CKMAG
SHOWIT LDX #$4
LDY SLLOC
BMI SHEND
SHOLP LDA DECIMAL,X
ORA #$D0
STA SCOLIN,Y
INY
DEX
BPL SHOLP
SHEND RTS
;
;THIS ROUTINE MOVES THE STAR AROUND ON
;THE PLAYFIELD. THE STAR IS ROTATED AND
;PLOTTED (IN A PLAYER) IN THE VBI.
;
MOVSTR LDA SMTIM ;TIME TO MOVE?
BEQ MSTR ;YES, GO DO IT
JMP GETSTK ;NO, GET STICK
MSTR LDA STRSPD ;SET MOVEMENT TIMER
STA SMTIM ;WITH STAR SPEED
LDA STRHGT ;ADJUST P/M
SEC ;COORDINATES TO
SBC #13 ;MATCH PLAYFIELD
STA STRLY ;PLOTTING
LDA STRHOR ;COORDINATES.
SEC
SBC #44
STA STRLX
LDA RANDOM ;WANT TO CHANGE
CMP #240 ;THE STAR'S DIRECTION?
BCC SAMSTD ;NO, USE SAME.
NEWDIR LDA RANDOM ;GET RANDOM
AND #7 ;DIRECTION
JMP DIRCHK
SAMSTD LDA STRDIR ;GET OLD DIRECTION.
DIRCHK TAX ;CHECK TO SEE
STA TMPDIR ;IF STAR WILL
LDA STRLX ;BUMP INTO ANY
CLC ;PLAYFIELD
ADC STRDTX,X ;OBJECT.
STA PLOTX
LDA STRLY
CLC
ADC STRDTY,X
STA PLOTY
JSR PLOTCL
LDY #0
LDA BITSON,X
AND (LO),Y ;ANY COLLISION?
BEQ WAYCLR ;NO, ALL CLEAR!
LDA #15 ;HIT SOMETHING,
STA BSCNT ;START BUMP SOUND AND
BNE NEWDIR ;GET NEW DIRECTION.
WAYCLR LDA PLOTX ;ADJUST STAR
CLC ;COORDINATES
ADC #44 ;BACK TO P/M
STA STRHOR ;COORDINATES
LDA PLOTY ;FROM PLAYFIELD.
CLC
ADC #13
STA STRHGT
LDA TMPDIR ;SET DIRECTION
STA STRDIR
JMP GETSTK ;AND LOOP
;
;SEARCH FOR FILLABLE AREA
;
;THIS SECTION SEARCHES FOR THE AREA TO
;BE FILLED. IT IS SO COMPLICATED THAT
;EXPLANATION OF ITS FINER DETAILS
;WOULD BE ALMOST IMPOSSIBLE WITHOUT
;WRITING ANOTHER COMPLETE ARTICLE. AT
;ANY RATE, IT WORKS. THOSE WITH ANY
;SPECIFIC QUESTIONS SHOULD WRITE ME,
;CARE OF A.N.A.L.O.G.
;
SEARCH LDA #1
STA FILLON
LDA #0
STA D
LDA STRHOR
SEC
SBC #44
STA SX
LDA STRHGT
SEC
SBC #13
STA SY
FINDCL LDX D
LDA SX
CLC
ADC SXD,X
STA SX
STA PLOTX
LDA SY
CLC
ADC SYD,X
STA SY
STA PLOTY
JSR PLOTCL
LDY #0
LDA (LO),Y
AND BITSON,X
CMP COLOR1,X
BEQ FINDC2
CMP COLOR2,X
BNE FINDCL
LDA #0
STA TD
JMP FOUND2
FINDC2 LDA D
STA TD
JSR DECD
FC2A JSR SRCHLC
CMP COLOR1,X
BNE FC2B
JSR GRABEM
JMP FINDC2
FC2B CMP COLOR2,X
BNE FC2C
JSR GRABEM
JMP OUTLIN
FC2C JSR INCD
JMP FC2A
FOUND2 LDA #0
STA TRIES
JSR DECD
FND2A JSR SRCHLC
CMP COLOR2,X
BNE FND2B
JSR GRABEM
JMP FOUND2
FND2B LDA TRIES
CLC
ADC #1
STA TRIES
CMP #3
BEQ FINDC1
JSR INCD
JMP FND2A
FINDC1 LDA D
STA TD
JSR DECD
FC1A JSR SRCHLC
CMP COLOR1,X
BNE FC1B
JSR GRABEM
JMP FINDC2
FC1B JSR INCD
JMP FC1A
OUTLIN JSR PLSXSY
LDA #0
STA TRIES
OUTLA JSR SRCHLC
CMP COLOR1,X
BNE OUTLB
JSR GRABEM
JMP OUTLIN
OUTLB LDA TRIES
CLC
ADC #1
STA TRIES
CMP #4
BEQ OUTLD
JSR INCD
JMP OUTLA
OUTLD JSR LOCTXY
OUTLD2 CMP COLOR2,X
BNE OUTLE