; *************************************************************************************** ; *** *** ; *** This code requires a modified DASM which was posted to [stella] at 02/19/2001 ! *** ; *** *** ; *************************************************************************************** ; *** DEATH DERBY *** ;FILENAME DATE WORKED ON BY ;DD_2LK_15 03/10/2003 (Glenn Saunders) ;--game reset code is just about done now. No color cycling yet. ;Now it's time to work on incrementing the player scores when gremlins wrap ;work on car movement routines ;DD_2LK_14 03/5/2003 (Glenn Saunders) ;--working on game reset debounce, not completely finished yet ;DD_2LK_13 02/24/2003 (Glenn Saunders) ;--Working timer countdown ;--fixed car glitch bug ;DD_2LK_12 02/24/2003 (Glenn Saunders/Thomas Jentzsch) ;--Thomas fixed the M1 glitch when crossing top boundary. ;--I re-integrated the fix he made to the new codebase. ;--I was then able to finish off the HMMx precompensation routine for M1. ;--Re-integrated stagger-step demo animation for gremlins. ;DD_2LK_10 02/21/2003 (Glenn Saunders) ;--score kernel functional ;--reverse gear indicators finished ;--controller reading code complete. Cars rotate again finally!! ;--Wrote first 'real' code ever for the Y-cable (for the reverse gear indicators). ;--reading triggers. Got the cars moving (just up for now). ;DD_2LK_07 02/20/2003 (Glenn Saunders) ;--started working on added reverse gear indicators ;--working on a fully functional score display ;--to do indirect y load of digits ;DD_2LK_06 02/17/2003 (Glenn Saunders) ; -fixed horizontal position of Gremlin0 when cut off at top of screen ; -Gremlin1 still a little messed up ; -got a static score up there, started work on score digit graphics ; -set up top and bottom borders, colors come from RAM ; -implemented color/BW switch. All colors switch to Greyscale ; -implemented typing scheme for border and grenade for game-state purposes ;DD_2LK_02 02/10/2003 (Glenn Saunders) ; -standardized labels ; -Removed random tombstone generator ; -created new title screen (not easy!) ; -added initial walkcycle animation for the zombies ; -added hardcoded zigzag movement of zombies (as a demo) ; 01/26/2003: (Thomas Jentzsch) ; - optimized kernel, *no* tearing of Gremlins and Cars ; - kernel initialisation code added, all four objects can be freely moved ; *everywhere* (DEBUG: use left, right joystick and left fire button) ; TODO: correct X-position if Gremlin enters at top of screen ; - reduced Gremlin RAM usage ; - halved tombstone RAM usge ; 01/19/2003 (later): (Thomas Jentzsch) ; - improved grenade code: ; - no safe zone colouring ; - taler ball ; - fullscreen ball mode switchable with right difficulty ; 01/19/2003: (Thomas Jentzsch) ; - first working 2LK demo version with preliminary grenade ;NAMING CONVENTION: ; CONSTANTS (all caps) ; variables (Mixed case) ; subroutines (Mixed case) ; please be verbose, avoid abbreviations and acronyms ; all should use underscores between logical words (i.e. Car0_X) processor 6502 include vcs.h ;=============================================================================== ; T I A - C O N S T A N T S ;=============================================================================== BM_SIZE_1 = %000000 BM_SIZE_2 = %010000 BM_SIZE_4 = %100000 BM_SIZE_8 = %110000 HMOVE_L7 = $70 HMOVE_L6 = $60 HMOVE_L5 = $50 HMOVE_L4 = $40 HMOVE_L3 = $30 HMOVE_L2 = $20 HMOVE_L1 = $10 HMOVE_0 = $00 HMOVE_R1 = $f0 HMOVE_R2 = $e0 HMOVE_R3 = $d0 HMOVE_R4 = $c0 HMOVE_R5 = $b0 HMOVE_R6 = $a0 HMOVE_R7 = $90 HMOVE_R8 = $80 ;JS1_LEFT = %00000000 ;JS1_RIGHT = %00000000 ;JS1_UP = %00000000 ;JS1_DOWN = %00000000 JS1_LEFT = %00001000 JS1_RIGHT = %00000100 JS1_DOWN = %00000010 JS1_UP = %00000001 JS1_UP_LEFT = JS1_UP | JS1_LEFT JS1_UP_RIGHT = JS1_UP | JS1_RIGHT JS1_DOWN_LEFT = JS1_DOWN | JS1_LEFT JS1_DOWN_RIGHT = JS1_DOWN | JS1_RIGHT DISABLE_BM = %00 ENABLE_BM = %10 ;=============================================================================== ; U S E R - C O N S T A N T S ;=============================================================================== BCD_0 = 0 BCD_1 = 1 BCD_2 = 2 BCD_3 = 3 BCD_4 = 4 BCD_5 = 5 BCD_6 = 6 BCD_7 = 7 BCD_8 = 8 BCD_9 = 9 BCD0_ = 0 << 4 BCD1_ = 1 << 4 BCD2_ = 2 << 4 BCD3_ = 3 << 4 BCD4_ = 4 << 4 BCD5_ = 5 << 4 BCD6_ = 6 << 4 BCD7_ = 7 << 4 BCD8_ = 8 << 4 BCD9_ = 9 << 4 GAME_TIMER_INITIAL = BCD0_|BCD_0 GAME_TIMER_START = BCD9_|BCD_9 ; constants that reference rotation index pointers PointUp = 0 PointRight = 4 PointDown = 8 PointLeft = 12 TurnOnSpriteReflect = %00001000 TurnOffSpriteReflect = 0 CarPage = $FF;00 CarDataAlign = $65 FlipThreshold = #9 GAME_STATE_START = 1 GAME_STATE_OVER = 0 GAME_STATE_INITIAL = GAME_STATE_OVER; game over SCREEN_WIDTH = 160 TOMBSTONE_HEIGHT = 8 ; 8*2 = 16 (single scanlines) high per tombstone TOMBSTONE_ROWS = 11 ; 11 rows of tombstones per screen CAR_HEIGHT = 8 ; 8 doubled scanlines (used as offset) GREMLIN_HEIGHT = 8 SCORE_HEIGHT = 5 KERNEL_HEIGHT = TOMBSTONE_ROWS*TOMBSTONE_HEIGHT+CAR_HEIGHT CAR_Y_INITIAL = KERNEL_HEIGHT/2+40 CAR0_X_INITIAL = 17 CAR1_X_INITIAL = 135 GREMLIN0_X_INITIAL = 0 GREMLIN1_X_INITIAL = 160 GREMLIN0_Y_INITIAL = 210 GREMLIN1_Y_INITIAL = 140 ;ANIMATION GREMLIN_SPEED = 2 GREMLIN_FRAMES = 5 ;INITIALIZATION CONSTANTS... ;INITIAL SETTINGS (COLOR) CAR0_COLOR_C = $36;Also colors Gremlin 0 CAR1_COLOR_C = $c6;Also colors Gremlin 1 FORCEFIELD_GENERATOR_COLOR_C = $93 TIMER_COLOR_C = $18 ;INITIAL SETTINGS (B&W) CAR0_COLOR_BW = $0F;Also colors Gremlin 0 CAR1_COLOR_BW = $06;Also colors Gremlin 1 FORCEFIELD_GENERATOR_COLOR_BW = $02 TIMER_COLOR_BW = $0F ;GAME OVER SETTINGS (COLOR) CAR0_COLOR_C_GO = $36;Also colors Gremlin 0 CAR1_COLOR_C_GO = $c6;Also colors Gremlin 1 FORCEFIELD_GENERATOR_COLOR_C_GO = $93 TIMER_COLOR_C_GO = $18 BACKGROUND_COLOR_GAME_OVER = $04 BACKGROUND_COLOR = 0 ;GAME OVER SETTINGS (B&W) CAR0_COLOR_BW_GO = $0F;Also colors Gremlin 0 CAR1_COLOR_BW_GO = $06;Also colors Gremlin 1 FORCEFIELD_GENERATOR_COLOR_BW_GO = $02 TIMER_COLOR_BW_GO = $0F ;STATE BORDER_STATE_INITIAL = 0;solid BALL_COLUMN_INITIAL = $58;This should be moved to RAM BALL_WIDTH = BM_SIZE_1/4 RAND_EOR_8 = $b2 FACING_LEFT = 0 FACING_RIGHT = GREMLIN_FRAMES; use as an +X offset to frames of graphics ;SCORE_PAGE = >Score_0 CAR0_GEAR_INDICATOR_FORWARD = %00000000 CAR1_GEAR_INDICATOR_FORWARD = %00000000 CAR0_GEAR_INDICATOR_REVERSE = %01110000 CAR1_GEAR_INDICATOR_REVERSE = %11100000 Y_BOUNDARY_BOTTOM = KERNEL_HEIGHT+80+(CAR_HEIGHT*2) ;=============================================================================== ; Z P - V A R I A B L E S ;=============================================================================== SEG.U variables ORG $80 Frame_Counter ds 1 Random ds 1 ;TEMP VARIABLE OVERLAYS Overlay0 ds 1 Overlay1 ds 1 Overlay2 ds 1 Car_Picker ds 1 OverlayDouble ds 2 Temp_Var = Overlay0 Gremlin_Pointer_Temp = Overlay0 P0_P1_PARAMETER = Overlay0 ;SWCHA_Nybble = Overlay1 Temp_PF_Left = Overlay1 Temp_PF_Right = Overlay2 Gremlin0_X_Save = Overlay1 Gremlin1_X_Save = Overlay2 SWCHB_Current ds 1 SWCHA0_FAKE ds 1 SWCHA1_FAKE ds 1 Car_Current_Delta = OverlayDouble SWCHA_Nybble ds 2 SWCHA_Previous ds 2 SWCHA_Current ds 1 SWCHB_Last ds 1 Gremlin_Direction_Counter ds 1 ;sprite graphics pointers P0_CurrentRotationSequence ds 1; 0-15 P1_CurrentRotationSequence ds 1; 0-15 ;these above reference addresses that get stored below P0_CurrentFramePtr ds 2; this will wind up being a constant $FF in the high byte P1_CurrentFramePtr ds 2; this will wind up being a constant $FF in the high byte ;Playfield Bitmap RAM Data_PF_Left ds TOMBSTONE_ROWS Data_PF_Right ds TOMBSTONE_ROWS Car0_Y ds 1 Car1_Y ds 1 Gremlin0_Y ds 1 Gremlin1_Y ds 1 Gremlin0_Y_Temp ds 1 Gremlin1_Y_Temp ds 1 Car0_X ds 1 Car1_X ds 1 Gremlin0_X ds 1 Gremlin1_X ds 1 Ball_X ds 1 Car0_YFullres ds 1 ; 0..KERNEL_HEIGHT*2-2 Car1_YFullres ds 1 Car0_Pointer ds 2 Car1_Pointer ds 2 Gremlin0_Pointer ds 2 Gremlin1_Pointer ds 2 Gremlin0_ID ds 1 Gremlin1_ID ds 1 Gremlin0_Anim_Counter ds 1 Gremlin1_Anim_Counter ds 1 Gremlin0_Direction_Counter ds 1 Gremlin1_Direction_Toggle ds 1 Gremlin0_Facing ds 1 Gremlin1_Facing ds 1 Gremlin0_Overscan_Count ds 1 Gremlin1_Overscan_Count ds 1 Gremlin0_SubDirection_A ds 1 Gremlin1_SubDirection_A ds 1 Gremlin0_SubDirection_B ds 1 Gremlin1_SubDirection_B ds 1 Border_State ds 1 Border_Top_Color ds 1 Border_Bottom_Color ds 1 Grenade_Column ds 1 ;these two can probably be merged Ball_Type ds 1 ;identifies the mode of the ball Ball_Size ds 1 Ball_Row ds 1 Ball_Control ds 1 ; dual purpose - ;since bit 0 is insignificant for color, use it to determine mode. ;bit 0 = 1 -> full screen Forcefield_Generator_Color ds 1 ;use these in order to "go greyscale" for Color/BW mode P0_Color ds 1 P1_Color ds 1 Timer_Color ds 1 Background_Color ds 1 Car0_Score ds 1;bcd Car1_Score ds 1;bcd Game_Timer ds 1 Game_State ds 1; determines when game is running or game over Car0_Gear ds 1 Car1_Gear ds 1 Car0_Score_Pointer_0X ds 2 Car0_Score_Pointer_X0 ds 2 Car1_Score_Pointer_0X ds 2 Car1_Score_Pointer_X0 ds 2 Timer_Pointer_0X ds 2 Timer_Pointer_X0 ds 2 Seconds_Counter ds 1 ; CURRENT RAM STATISTICS: ;DESC BYTES ;---------------------- ------- ;PLAYFIELD BITMAP 22 ; big savings due to interleave technique ;OTHER 53 ;TOTAL RAM USED 75 ;FREE RAM 53 ; plenty left for game state, AI, anim/sound ;=============================================================================== ; M A C R O S ;=============================================================================== MAC BIT_B .byte $24 ENDM MAC BIT_W .byte $2c ENDM MAC SLEEP IF {1} = 1 ECHO "ERROR: SLEEP 1 not allowed !" END ENDIF IF {1} & 1 nop $00 REPEAT ({1}-3)/2 nop REPEND ELSE REPEAT ({1})/2 nop REPEND ENDIF ENDM ;=============================================================================== ; R O M - C O D E ;=============================================================================== SEG Bank0 ORG $f000 Start SUBROUTINE sei ; Disable interrupts, if there are any. cld ; Clear BCD math bit. ldx #0 txs pha ; Set stack to beginning. txa .clearLoop: pha dex bne .clearLoop ;GAME INIT ;GAME INIT ;GAME INIT ;GAME INIT ;GAME INIT .Game_Boot ; RUNS ONLY ONCE WHEN THE MACHINE BOOTS UP lda SWCHB sta SWCHB_Last ;sta SWCHB_Current ;lda #GAME_STATE_INITIAL ;sta Game_State lda #GAME_TIMER_INITIAL sta Game_Timer lda #60 sta Seconds_Counter lda #0 sta Car0_Score sta Car1_Score lda #0 sta Game_State lda #JS1_RIGHT sta Gremlin0_SubDirection_A lda #JS1_UP sta Gremlin0_SubDirection_B lda #JS1_LEFT sta Gremlin1_SubDirection_A lda #JS1_UP sta Gremlin1_SubDirection_B lda #CAR0_GEAR_INDICATOR_REVERSE sta Car0_Gear lda #CAR1_GEAR_INDICATOR_REVERSE sta Car1_Gear lda #0 sta SWCHA0_FAKE sta SWCHA1_FAKE lda #BALL_COLUMN_INITIAL sta Grenade_Column ;load in the title graphics ldx #TOMBSTONE_ROWS-1 .titleLoader lda Title_PF_L,X sta Data_PF_Left,X lda Title_PF_R,X sta Data_PF_Right,X dex bpl .titleLoader ; initialize animation counters lda #GREMLIN_SPEED sta Gremlin0_Anim_Counter sta Gremlin1_Anim_Counter lda #1 sta Gremlin1_Direction_Toggle lda #FACING_RIGHT sta Gremlin0_Facing lda #FACING_LEFT sta Gremlin1_Facing ;update ball state .updateBallState ; lda #BM_SIZE_2|1 ; sta CTRLPF .updateCarColors ;lda #$00 ;sta COLUBK ;lda #CAR0_COLOR ;$36 ;sta COLUP0 ; lda #CAR1_COLOR ;$c6 ;sta COLUP1 .updateCarPositions lda #CAR_Y_INITIAL;16 ;KERNEL_HEIGHT*2-2;16 sta Car0_YFullres lda #CAR_Y_INITIAL;16 sta Car1_YFullres lda #CAR0_X_INITIAL sta Car0_X lda #CAR1_X_INITIAL sta Car1_X .updateGremlinPositions lda #GREMLIN0_Y_INITIAL sta Gremlin0_Y lda #GREMLIN1_Y_INITIAL sta Gremlin1_Y lda #GREMLIN0_X_INITIAL sta Gremlin0_X lda #GREMLIN1_X_INITIAL sta Gremlin1_X .updateBallPosition lda #50 sta Ball_X lda #6 sta Ball_Row lda #1 sta VDELBL .updateCarPointers lda #>Car_Rotation_Frame0 sta Car0_Pointer+1 sta Car1_Pointer+1 ldx #0 stx P0_CurrentRotationSequence ldx #8 stx P1_CurrentRotationSequence .updateGremlinPointers lda #>Gremlin_Frame0_Left; take care of the high order byte (should all be on the same page of ROM) sta Gremlin0_Pointer+1 sta Gremlin1_Pointer+1 ldx #1 stx Gremlin0_ID ldx #3 stx Gremlin1_ID .updateScorePointers ;take care of the high byte (the page) lda #>Score_0 sta Car0_Score_Pointer_0X+1 sta Car1_Score_Pointer_0X+1 sta Car0_Score_Pointer_X0+1 sta Car1_Score_Pointer_X0+1 sta Timer_Pointer_X0+1 sta Timer_Pointer_0X+1 jsr Update_Score_Pointers ;here we want to have 3 mainloops .mainLoop: jsr VerticalBlank jsr GameCalc jsr Setup_Player_Missile_Graphics jsr Draw_Screen jsr OverScan jmp .mainLoop Update_Score_Pointers SUBROUTINE ;cld ;extract BCD timer into pointer variables lda Game_Timer and #%00001111 tax lda Score1_Digit_Table,X sta Timer_Pointer_0X lda Game_Timer lsr lsr lsr lsr tax lda Score1_Digit_Table,X sta Timer_Pointer_X0 ;CAR0 SCORE lda Car0_Score and #%00001111 tax lda Score0_Digit_Table,X sta Car0_Score_Pointer_0X lda Car0_Score lsr lsr lsr lsr tax lda Score0_Digit_Table,X sta Car0_Score_Pointer_X0 ;CAR1 SCORE lda Car1_Score and #%00001111 tax lda Score1_Digit_Table,X sta Car1_Score_Pointer_0X lda Car1_Score lsr lsr lsr lsr tax lda Score0_Digit_Table,X sta Car1_Score_Pointer_X0 rts VerticalBlank SUBROUTINE lda #2 sta WSYNC sta VSYNC sta WSYNC sta WSYNC lsr ldx #44 sta WSYNC sta VSYNC stx TIM64T rts Stagger_Step_Animation SUBROUTINE lda Frame_Counter and #$5 ; determines speed beq .do_Gremlin_Move lda #0 sta SWCHA0_FAKE sta SWCHA0_FAKE+1 rts .do_Gremlin_Move lda Gremlin_Direction_Counter bne .keep_going lda #GREMLIN_SPEED sta Gremlin_Direction_Counter .keep_going cmp #GREMLIN_SPEED/2 bmi .do_SubDirection_B .do_SubDirection_A lda Gremlin0_SubDirection_A sta SWCHA0_FAKE lda Gremlin0_SubDirection_A+1 sta SWCHA0_FAKE+1 rts .do_SubDirection_B lda Gremlin0_SubDirection_B sta SWCHA0_FAKE lda Gremlin0_SubDirection_B+1 sta SWCHA0_FAKE+1 lda #GREMLIN_SPEED sta Gremlin_Direction_Counter rts Game_Reset SUBROUTINE ;lda #$4b ;sta COLUBK lda #GAME_STATE_START sta Game_State lda #GAME_TIMER_START sta Game_Timer lda #60 sta Seconds_Counter lda #0 sta Car0_Score sta Car1_Score ;reset frame timers ;.clear title graphics or any leftover tombstones lda #0 ldx #TOMBSTONE_ROWS-1 .Clear_Tombstones sta Data_PF_Left,X sta Data_PF_Right,X dex bpl .Clear_Tombstones .ResetCarPositions lda #CAR_Y_INITIAL;16 ;KERNEL_HEIGHT*2-2;16 sta Car0_YFullres sta Car1_YFullres lda #CAR0_X_INITIAL sta Car0_X lda #CAR1_X_INITIAL sta Car1_X .ResetGremlinPositions lda #GREMLIN0_Y_INITIAL sta Gremlin0_Y lda #GREMLIN1_Y_INITIAL sta Gremlin1_Y lda #GREMLIN0_X_INITIAL sta Gremlin0_X lda #GREMLIN1_X_INITIAL sta Gremlin1_X .ResetScore ;zero out the scores lda Score0_Digit_Table sta Car0_Score_Pointer_X0 sta Car0_Score_Pointer_0X sta Car1_Score_Pointer_X0 sta Car1_Score_Pointer_0X jsr Update_Score_Pointers ;lda #0 ;sta SWCHB_Current rts ; this has to branch off depending on game mode GameCalc SUBROUTINE inc Frame_Counter lda SWCHB and %00000001 sta SWCHB_Current ;IF current state eq 1 (reset not depressed) bne .bind_ON_RESET_TOGGLE;we have to check for ON_RESET_TOGGLE event ;lda #$CF ;sta COLUBK ;ELSE if current state eq 0 (reset depressed) ;we do NOT have to check for ON_RESET_TOGGLE event lda #0 sta Game_State;freeze the game jmp .finish_timer; just skip ahead ;figure out if this is the ON_RESET_DOWN event or not ;IF (current state eq 0 ... (reset not depressed) .bind_ON_RESET_TOGGLE ;brk ;lda #$F4 ;sta COLUBK lda SWCHB_Last and %00000001 ;...and previous state eq 0) (reset previously depressed) beq .ON_RESET_TOGGLE; THEN perform game reset ;ELSE just skip ahead jmp .skip_game_reset; just skip ahead .ON_RESET_TOGGLE; previous was 1 and current is 0 so do reset jsr Game_Reset jmp .SetColors .skip_game_reset ;inc Frame_Counter lda Game_State beq .finish_timer ;if game_state = 0 (game over) then do not decrement timer lda Frame_Counter dec Seconds_Counter bne .SetColors .Decrement_Timer lda #60 ; reset counter sta Seconds_Counter ;testing score increment ;lda Car0_Score ;sed ;adc #1 ;cld ;sta Car0_Score ;lda Car1_Score ;sed ;adc #1 ;cld ;sta Car1_Score ;/testing score increment sed lda Game_Timer sbc #0 cld sta Game_Timer beq .end_Game jsr Update_Score_Pointers jmp .finish_timer .end_Game jsr Update_Score_Pointers ;lda #GAME_STATE_OVER; end game due to timer running out ;sta Game_State ; there is a bug here, so disable game over .finish_timer ;this block should always execute except when colors are cycling .SetColors lda SWCHB_Current sta SWCHB_Last lda Game_State beq .Game_Over_Colors lda #BACKGROUND_COLOR; set to black sta Background_Color jmp .continue_SetColors .Game_Over_Colors lda #BACKGROUND_COLOR_GAME_OVER; set to grey sta Background_Color .continue_SetColors ;finish the rest of the score graphics later lda SWCHB and %00001000 beq .SetColors_Black_and_White ;COLOR ;BORDER lda #BORDER_STATE_INITIAL sta Border_State ;set border colors based on Border_State ldx Border_State lda Border_Type_Table,X sta Border_Top_Color sta Border_Bottom_Color lda #FORCEFIELD_GENERATOR_COLOR_C sta Forcefield_Generator_Color ;GRENADE ldx Ball_Type lda Grenade_Color_Table,x sta Ball_Control ;TIMER lda #TIMER_COLOR_C sta Timer_Color ;P0/P1 lda #CAR0_COLOR_C sta COLUP0 sta P0_Color; this is only used in the score display lda #CAR1_COLOR_C sta COLUP1 sta P1_Color; this is only used in the score display jmp .SetColors_Done ;B&W .SetColors_Black_and_White ;BORDER ldx Border_State lda Border_Type_Table+3,X sta Border_Top_Color sta Border_Bottom_Color lda #FORCEFIELD_GENERATOR_COLOR_BW sta Forcefield_Generator_Color ;GRENADE ldx Ball_Type lda Grenade_Color_Table+4,x sta Ball_Control ;TIMER lda #TIMER_COLOR_BW sta Timer_Color ;P0/P1 lda #CAR0_COLOR_BW sta COLUP0 sta P0_Color lda #CAR1_COLOR_BW sta COLUP1 sta P1_Color .SetColors_Done ;set ball config based on Ball_Type variable ldx Ball_Type cpx #3 bne .ClearBarrier .SetBarrier lda #1 ; brk ;ora Ball_Control sta Ball_Control .ClearBarrier lda Ball_Control and %11111110 sta Ball_Control ldx Ball_Type lda Grenade_Size_Table,x sta Ball_Size .skipRandom: ; move the ball: lda Frame_Counter and #$03 bne .skipMoveBL ldx Ball_X dex cpx #17 bcs .okBall_X ldx #143 .okBall_X: stx Ball_X .skipMoveBL: ;this chunk should always execute regardless of game state ;update zombie walkcycles .walkCycler0 ;first, update counters and determine whether or not to update ;the walk cycle on this frame dec Gremlin0_Anim_Counter bne .walkCycler1 ; don't update until timer reaches 0 .walkCycle0Reset ldy #GREMLIN_SPEED; this should be based on zombie speed, variable sty Gremlin0_Anim_Counter ;animate zombie dec Gremlin0_ID bne .walkCycler1 .walkCycle0Repeat ldy #GREMLIN_FRAMES sty Gremlin0_ID ;update zombie walkcycles .walkCycler1 ;first, update counters and determine whether or not to update ;the walk cycle on this frame dec Gremlin1_Anim_Counter bne .exitWalkCycle ; don't update until timer reaches 0 .walkCycle1Reset ldy #GREMLIN_SPEED; this should be based on zombie speed, variable sty Gremlin1_Anim_Counter ;animate zombie1 ;ldx #1 lda Game_State jsr Stagger_Step_Animation ;jsr moveGremlin1 dec Gremlin_Direction_Counter dec Gremlin1_ID bne .exitWalkCycle .walkCycle1Repeat ldy #GREMLIN_FRAMES sty Gremlin1_ID .exitWalkCycle rts Setup_Player_Missile_Graphics SUBROUTINE ; *** calculate kernel variables: *** ; calculate pointer to Car #0 graphics: lda Car0_YFullres sta VDELP0 lsr sta Car0_Y ldy P0_CurrentRotationSequence lda Car_Rotation_Sequence,y clc adc Car0_Y sta Car0_Pointer ; calculate pointer to Car #1 graphics: lda Car1_YFullres eor #1 sta VDELP1 eor #1 lsr adc #0 sta Car1_Y ldy P1_CurrentRotationSequence lda Car_Rotation_Sequence,y clc adc Car1_Y sta Car1_Pointer ; calculate pointer to missile #0 graphics: lda Gremlin0_Y and #~$80 clc adc #GREMLIN_HEIGHT-1 sta Gremlin0_Y_Temp tay lda Gremlin0_ID adc Gremlin0_Facing tax lda Gremlin_Table,x sec sbc Gremlin0_Y_Temp sta Gremlin0_Pointer ;fix cpy #KERNEL_HEIGHT-1 bmi .skipWrap0 ldy #KERNEL_HEIGHT ;/end Fix .skipWrap0: lda (Gremlin0_Pointer),y asl asl sta NUSIZ0 ; calculate pointer to missile #1 graphics: lda Gremlin1_Y and #~$80 clc adc #GREMLIN_HEIGHT-1 sta Gremlin1_Y_Temp tay lda Gremlin1_ID adc Gremlin1_Facing tax lda Gremlin_Table,x sec sbc Gremlin1_Y_Temp sta Gremlin1_Pointer ;fix cpy #KERNEL_HEIGHT bmi .skipWrap1 ldy #KERNEL_HEIGHT-1 .skipWrap1: ;/end fix lda (Gremlin1_Pointer),y asl asl sta NUSIZ1 ;BEGIN PRECOMPENSATION ;The missiles rely on the cumulative effect of relative position changes. ;When the missiles are at the top of the screen, however, their starting horizontal ;position needs to be absolutely defined. So what we have to do is add up ;all the relative changes up to the first visible missile row and apply this ;as precompensation before the screen starts. That way the horizontal position ;will match what it would be if the zombie were not at the top of the screen. ;the first thing we need to do is figure out which zombie may be at the top of the screen. ;then we need to figure out how many rows of the zombie are being cut off. ;we then take this number and loop over it, aggregating the HMMx values ;as we go along. This simulates what the kernel would have done had the ;zombie been completely in the screen. The final aggregate value is converted ;back into the proper HMMx constant and stored in HMMx and applied with an HMOVE. ;save off Gremlin X position lda Gremlin1_X sta Gremlin1_X_Save lda Gremlin0_X sta Gremlin0_X_Save ;loop through this 8 times ;FROM: KERNEL_HEIGHT-1+GREMLIN_HEIGHT (maximum extent of gremlin, off screenn at top) ;TO: KERNEL_HEIGHT-1 (minimum extent of gremlin, collision with top) ldy #KERNEL_HEIGHT-1+GREMLIN_HEIGHT .do_adjustments jsr HMMx_Aggregate_Line dey cpy #KERNEL_HEIGHT-1 bpl .do_adjustments ; perform initial horizontal positioning updates for all objects ldx #4 .loopPos: lda Car0_X,x jsr SetPosX dex bpl .loopPos sta WSYNC sta HMOVE sta WSYNC sta HMCLR ;restore Gremlin X position lda Gremlin1_X_Save sta Gremlin1_X lda Gremlin0_X_Save sta Gremlin0_X rts ;LOAD Y with SCANLINE BEFORE CALLING THIS FUNCTION HMMx_Aggregate_Line SUBROUTINE .isM0atTop ; determine whether to draw Gremlin #0: cpy Gremlin0_Y_Temp bpl .Gremlin1_Compensation_Start; no gremlin1, so go to g0 routine ;.drawM1: iny ; this is necessary because of the interleaved nature of M0 vs. M1 lda (Gremlin0_Pointer),y dey ; this is necessary because of the interleaved nature of M0 vs. M1 tax ;this is really only necessary on the top line ;this is wasting a fair amount of cycles asl asl sta NUSIZ0 txa lsr lsr lsr lsr sta Gremlin_Pointer_Temp clc ; if the offset is less than 12, then it's either zero or a positive offset cmp #12 bcc .Gremlin0_Compensation_Positive_to_Negative .Gremlin0_Compensation_Negative_to_Positive ;brk sbc #12; brings the numbers back down to a 0-3 range tax lda HMMx_Compensation_Table,X; look up the conversion index based on the table adc Gremlin0_X; Gremlin1_X = Gremlin1_X + A sta Gremlin0_X jmp .Gremlin1_Compensation_Start .Gremlin0_Compensation_Positive_to_Negative ;just use the accumulator as is to subtract from Gremlin1_X lda Gremlin0_X adc #1; I don't know why this hack is necessary sbc Gremlin_Pointer_Temp; Gremlin1_X = Gremlin1_X - A sta Gremlin0_X .Gremlin1_Compensation_Start ; determine whether to draw Gremlin #1: ldx Gremlin1_Y_Temp cpy Gremlin1_Y_Temp bpl .Gremlin1_Compensation_End; no gremlin1 ;.drawM1: ;this dey/iny thing is a hack. ;dey lda (Gremlin1_Pointer),y ;iny tax ;this is really only necessary on the top line ;this is wasting a fair amount of cycles asl asl ;this might be the wrong value sta NUSIZ1 txa lsr lsr lsr lsr sta Gremlin_Pointer_Temp clc ; if the offset is less than 12, then it's either zero or a positive offset cmp #12 bcc .Gremlin1_Compensation_Positive_to_Negative .Gremlin1_Compensation_Negative_to_Positive ;brk sbc #12; brings the numbers back down to a 0-3 range tax lda HMMx_Compensation_Table,X; look up the conversion index based on the table adc Gremlin1_X; Gremlin1_X = Gremlin1_X + A sta Gremlin1_X rts .Gremlin1_Compensation_Positive_to_Negative ;just use the accumulator as is to subtract from Gremlin1_X lda Gremlin1_X adc #1; I don't know why this hack is necessary sbc Gremlin_Pointer_Temp; Gremlin1_X = Gremlin1_X - A sta Gremlin1_X .Gremlin1_Compensation_End ;END PRECOMPENSATION rts NextRandom SUBROUTINE ; lda Random ; 3 ; lsr ; 2 ; bcc .skipEor ; 2³ ; eor #RAND_EOR_8 ; 2 ;.skipEor: ; = 11/12 (~11.5) ; sta Random ; 3 lda Random ; 3 asl ; 2 eor Random ; 3 asl ; 2 eor Random ; 3 asl ; 2 asl ; 2 eor Random ; 3 asl ; 2 rol Random ; 5 rts ; 6 ;NextRandom END align 256 Draw_Screen SUBROUTINE lda #%00010010 ora Ball_Size; important sta CTRLPF lda Forcefield_Generator_Color sta COLUPF ; lda #$02 ; use this for a custom background color for the score ; sta COLUBK ; setting up a timer to make experimenting inside the kernel easier ; (the final code shouldm't need this): ldx #228 .waitTim: lda INTIM bne .waitTim sta WSYNC sta VBLANK stx TIM64T STA WSYNC ldy #SCORE_HEIGHT ldx #0 ;This whole score section required some very careful timing, but naturally, I did ;it mostly though trial and error, rather than calculating the cycle times. :) ;sleep 3 .Draw_Score ;SLEEP 4 stx PF0;blank out PF0, or set it to GEAR graphic (on next line) stx.w PF2 lda (Car0_Score_Pointer_X0),y; CAR0 - TENS DIGIT and #%11100000 sta PF1 ; get the write over with ASAP to buy us time lda (Car0_Score_Pointer_0X),y; CAR0 - ONES DIGIT and #%00001111 sta PF1 SLEEP 6 lda (Car1_Score_Pointer_X0),y; CAR1 - TENS DIGIT and #%00001111 lsr sta.w PF1 lda (Car1_Score_Pointer_0X),y; CAR1 - ONES DIGIT and #%00001111 sta PF2 stx PF0 stx PF1 stx PF2 ; ------------------------------------ lda Car0_Gear and %11100000 sta PF0 SLEEP 15 ;toggle in and out of PF modes lda Timer_Color STA.W COLUP1 sta COLUP0 lda (Timer_Pointer_X0),y;TIMER - TENS DIGIT and #%11110000 sta PF2 ;INSERT TIMER CODE HERE lda (Timer_Pointer_0X),y;TIMER - ONES DIGIT and #%11110000 sta PF0; write in PF0 ;SLEEP 9 lda Car1_Gear; gear indicator and #%11100000 sta PF2 lda P1_Color sta COLUP1 ;lda Car0_Gear; gear indicator ;and #%11101111 ;sta PF0 SLEEP 2 lda P0_Color sta COLUP0 sta WSYNC ; end of scanline pair dey bne .Draw_Score lda Background_Color sta COLUBK sty PF0 sty PF1 sty PF2 ; reset playfield/ball settings lda Ball_Size ora #1 ; and Ball_Size; important sta CTRLPF ldx Border_Top_Color lda #$FF; top border sta WSYNC stx COLUPF sta PF0 sta PF1 sta PF2 ; sta WSYNC ; *** initialize the kernel loop: *** ; From here on in to .ExitKernel this is all Thomas Jentzsch and it's a complete work of art. ; ; lda MaskTbl+TOMBSTONE_ROWS-1 ; 4 lda #%01010101 and Data_PF_Left+TOMBSTONE_ROWS-1 ; 4 sta Temp_PF_Left ; 3 lda Data_PF_Right+TOMBSTONE_ROWS-1 ; 4 sta Temp_PF_Right ; 3 = 18 ;lda #0 ; 2 ;sta COLUP0 ; 3 ;sta COLUP1 ; 3 = 8 nop nop nop nop ;BEGIN FIX ldy #KERNEL_HEIGHT-2 ; 2 = 4 cpy Gremlin1_Y_Temp ; 3 bpl .skipEnableM1 ; 2³ lda Gremlin1_Y ; 3 sta Gremlin1_Y_Temp ; 3 iny cpy Gremlin1_Y_Temp ; 3 bpl .skipEnableM1a ; 2³ lda #2 ; 2 ; lda #0 sta ENAM1 ; 3 .skipEnableM1a dey .skipEnableM1: iny cpy Gremlin0_Y_Temp ; 3 bpl .skipEnableM0 ; 2³ lda Gremlin0_Y ; 3 sta Gremlin0_Y_Temp ; 3 lda #2 ; 2 sta ENAM0 ; 3 .skipEnableM0: ;END OF FIX iny ; 2 ldx #TOMBSTONE_ROWS-1 ; 2 = 4 ; draw Car #1: lda #CAR_HEIGHT-1 ; 2 cmp Car1_Y ; 3 bcs .doDraw1 ; 2³ lda #0 ; 2 BIT_W ;-1 .doDraw1: lda (Car1_Pointer),y ; 5 sta GRP1 ; 3 = 16 lda #CAR_HEIGHT-1 ; 2 cmp Car0_Y ; 3 bcs .doDraw0 ; 2³ lda #0 ; 2 BIT_W ;-1 .doDraw0: lda (Car0_Pointer),y ; 5 sta GRP0 ; 3 = 16 dey ; 2 = 2 ; draw Car #1: lda #CAR_HEIGHT-1 ; 2 dcp Car1_Y ; 5 bcs .doDraw1_a ; 2³ lda #0 ; 2 BIT_W ;-1 .doDraw1_a: lda (Car1_Pointer),y ; 5 sta GRP1 ; 3 = 18 lda Ball_Control ; 3 asl ; 2 = 5 ;end border sta ENABL ; 3 = 3 VDELed lda #$0F sta WSYNC sta COLUPF ;--------------------------------------- ; lda #CAR1_COLOR ; 2 ;sta COLUP1 ; 3 ;lda #CAR0_COLOR ; 2 ; sta COLUP0 ; 3 nop nop nop nop nop lda #$90 ; 2 enable left and right borders sta PF0 ; 3 jmp EnterKernel ; 3 = 18 @21 ;*************************************** align 256 ; wasting some bytes to avoid page penalties: ds $74, 0 Kernel SUBROUTINE .disableM1: ; 9 SLEEP 2 ; 2 waste two cycles for constant timing lda #DISABLE_BM ; 2 beq .continueM1a ;10 .checkM1: ; 6 bne .disableM1 ; 2³ ;.enableM1: lda Gremlin1_Y ; 3 sta Gremlin1_Y_Temp ; 3 lda #ENABLE_BM ; 2 .continueM1a: sta.w ENAM1 ; 4 @00 (>= @00) bpl .continueM1 ; 3 .disableM0: ; 8 SLEEP 2 ; 5 waste two cycles for constant timing lda #DISABLE_BM ; 2 beq .continueM0a ; 9 .checkM0: ; 6 bne .disableM0 ; 2³ ;.enableM0: lda Gremlin0_Y ; 3 sta Gremlin0_Y_Temp ; 3 lda #ENABLE_BM ; 2 .continueM0a: sta.w ENAM0 ; 4 @01 (>= @00) bpl .continueM0 ; 3 ;*************************************** ; cycle count (tombstone row): ; - loop overhead 9 ; - COLUPF 5 = 5 ; - playfield 29+8 = 37 ; - players 18*2 = 36 ; - missiles/HMOVE 23*2 = 46 ; - HMCLR 3*2 = 6 ; - free 4+9 = 13 ; ---------------- ; Total 76*2 = 152 :-) .contBlock: ; @42 SLEEP 9 ; 9 asl ; 2 = 11 .nextBlock: sta COLUPF ; 3 = 3 @56 too early for 2nd row of ball ; draw Gremlin #1: cpy Gremlin1_Y_Temp ; 3 bpl .checkM1 ; 2³ ;.drawM1: lda (Gremlin1_Pointer),y ; 5 sta HMM1 ; 3 asl ; 2 asl ; 2 sta HMOVE ; 3 @00 three cycles too early, ok ;--------------------------------------- sta NUSIZ1 ; 3 @03 (>= @00) .continueM1: ; = 23 timing is constant! ; draw Car #1: lda #CAR_HEIGHT-1 ; 2 dcp Car1_Y ; 5 bcs .doDraw1 ; 2³ lda #0 ; 2 BIT_W ;-1 .doDraw1: lda (Car1_Pointer),y ; 5 sta GRP1 ; 3 = 18 @21 EnterKernel: ; ; draw tomstones (part 1/2): lda Temp_PF_Left ; 3 sta PF1 ; 3 @27 (<= @27) eor Data_PF_Left,x ; 4 sta PF2 ; 3 @34 (<= @38) SLEEP 4 ; 4 ; draw tomstones (part 2/2): lda MaskTbl,x ; 4 and Temp_PF_Right ; 3 sta PF2 ; 3 @48 (== @48) eor Temp_PF_Right ; 3 sta PF1 ; 3 @54 (<= @54) ; clear all hmov registers: sta HMCLR ; 3 = 3 @57 ; draw Gremlin #0: cpy Gremlin0_Y_Temp ; 3 bpl .checkM0 ; 2³ ;.drawM0: lda (Gremlin0_Pointer),y ; 5 sta HMM0 ; 3 asl ; 2 asl ; 2 ;--------------------------------------- sta HMOVE ; 3 @01 two cycles too early, ok sta NUSIZ0 ; 3 @04 (>= @00) .continueM0: ; = 23 timing is constant! ; draw Car #0: lda #CAR_HEIGHT-1 ; 2 dcp Car0_Y ; 5 bcs .doDraw0 ; 2³ lda #0 ; 2 BIT_W ;-1 .doDraw0: lda (Car0_Pointer),y ; 5 sta GRP0 ; 3 = 18 @22 ; disable playfield: lda #0 ; 2 sta PF1 ; 3 @27 (<= @27) sta PF2 ; 3 = 8 @30 (<= @38) ; clear all hmov registers: sta HMCLR ; 3 = 3 @33 ; tombstone indexer routine (part 1/2): dey ; 2 tya ; 2 and #7 ; 2 bne .contBlock ; 2³= 8 SLEEP 5 ; 5 = 5 ; draw grenade: lda #ENABLE_BM ; 2 cpx Ball_Row ; 3 beq .enableBL ; 2³ BIT_W ; 1 .enableBL: sta ENABL ; 3 = 11 @57 VDELed! ; draw Gremlin #1: cpy Gremlin1_Y_Temp ; 3 bpl .checkGremlin1_a ; 2³ ;.drawGremlin1_a: lda (Gremlin1_Pointer),y ; 5 sta HMM1 ; 3 asl ; 2 asl ; 2 ;--------------------------------------- sta HMOVE ; 3 @01 two cycles too early, ok sta NUSIZ1 ; 3 @04 (>= @00) .continueGremlin1_a: ; = 23 timing is constant! ; draw Car #1: lda #CAR_HEIGHT-1 ; 2 dcp Car1_Y ; 5 bcs .doDraw1_a ; 2³ lda #0 ; 2 BIT_W ;-1 .doDraw1_a: lda (Car1_Pointer),y ; 5 sta GRP1 ; 3 = 18 @22 ; set grenade color and clear PF0: lda Ball_Control ; 3 sta COLUPF ; 3 @28 stx PF0 ; 3 = 9 @31 clear PF0 (bits 0..3: don't Care) ; prepare tombstone row: lda MaskTbl-1,x ; 4 and Data_PF_Left-1,x ; 4 sta Temp_PF_Left ; 3 lda Data_PF_Right-1,x ; 4 sta Temp_PF_Right ; 3 = 18 SLEEP 4 ; 4 = 4 ; clear all hmov registers: sta HMCLR ; 3 = 3 @56 ; draw Gremlin #0: cpy Gremlin0_Y_Temp ; 3 bpl .checkGremlin0_a ; 2³ ;.drawGremlin0_a: lda (Gremlin0_Pointer),y ; 5 sta HMM0 ; 3 asl ; 2 asl ; 2 sta HMOVE ; 3 @75 four cycles too early, (just!) ok ;--------------------------------------- sta NUSIZ0 ; 3 @03 (>= @00) .continueGremlin0_a: ; = 23 timing is constant! ; draw Car #0: lda #CAR_HEIGHT-1 ; 2 dcp Car0_Y ; 5 bcs .doDraw0_a ; 2³ lda #0 ; 2 BIT_W ;-1 .doDraw0_a: lda (Car0_Pointer),y ; 5 sta GRP0 ; 3 = 18 @21 ; set color for second ball row: lda #$0e ; 2 sta COLUPF ; 3 = 5 @26 (<= @27) ; tombstone indexer routine (part 2/2): dex ; 2 bmi .exitLoop ; 2³= 4 ; disable grenade: lda Ball_Control ; 3 asl ; 2 sta ENABL ; 3 @38 VDELed! lda #$90 ; 2 sta PF0 ; 3 = 13 @43 ; clear all hmov registers: sta HMCLR ; 3 = 3 @46 ; TombstoneIndexer routine: dey ; 2 lda #$0e ; 2 jmp .nextBlock ; 3 = 7 .exitLoop: jmp ExitKernel ;*************************************** .disableGremlin1_a: ; 9 SLEEP 2 ; 2 waste two cycles for constant timing lda #DISABLE_BM ; 2 beq .continueM1a_a ;10 .checkGremlin1_a: ; 6 bne .disableGremlin1_a ; 2³ ;.enableGremlin1_a: lda Gremlin1_Y ; 3 sta Gremlin1_Y_Temp ; 3 lda #ENABLE_BM ; 2 .continueM1a_a: ;--------------------------------------- sta.w ENAM1 ; 4 @01 (>= @00) bpl .continueGremlin1_a ; 3 .disableGremlin0_a: ; 8 SLEEP 2 ; 5 waste two cycles for constant timing lda #DISABLE_BM ; 2 beq .continueM0a_a ; 9 .checkGremlin0_a: ; 6 bne .disableGremlin0_a ; 2³ ;.enableGremlin0_a: lda Gremlin0_Y ; 3 sta Gremlin0_Y_Temp ; 3 lda #ENABLE_BM ; 2 .continueM0a_a: ;--------------------------------------- sta.w ENAM0 ; 4 @02 (>= @00) bpl .continueGremlin0_a ; 3 ;*************************************** ;end of Thomas Jentzsch's miracle kernel ExitKernel: ldx #$FF lda #0 ldy Border_Bottom_Color sta WSYNC sta ENAM0 sta ENAM1 sta GRP0 sta GRP1 sta GRP0; this is necessary due to VDEL ;--------------------------------------- sty COLUPF stx PF0 ; already 0 stx PF1 stx PF2 ldx #0 sta WSYNC; do 2nd line of border ldx Forcefield_Generator_Color ; sta WSYNC sta PF0 sta PF1 sta PF2 stx COLUPF sta WSYNC ldx #2 .waitScreen0: lda INTIM bne .waitScreen0 sta WSYNC stx VBLANK rts ;check boundaries Rotation_Check_Boundaries SUBROUTINE lda P0_CurrentRotationSequence,X cmp #$FF beq .Rotation_Wrap_Left cmp #16 beq .Rotation_Wrap_Right rts ; no boundary crossed .Rotation_Wrap_Left lda #15 sta P0_CurrentRotationSequence,X rts .Rotation_Wrap_Right lda #0 sta P0_CurrentRotationSequence,X rts Player_Reflect_Check SUBROUTINE ;this will have been modified by the controller routines ldy #TurnOffSpriteReflect; initialize to no flip ;this will load either P0 or P1 depending on P0_P1_PARAMETER lda P0_CurrentRotationSequence,X;0-15 cmp #FlipThreshold bmi .Continue0 ; if A < 9 then sigN will be 1 ; so do not flip, just .Continue .FlipSprite0 ldy #TurnOnSpriteReflect .Continue0 sty REFP0,X RTS ;DRIVING CONTROLLER CODE Read_Driving_Controller SUBROUTINE ; ldy SWCHA_Previous lda SWCHA_Previous,X tay lda SWCHA_Nybble,X and #%00000011 sta SWCHA_Previous,X; this might have to move lda SWCHA_Nybble,X and #%00000011 eor NextDCTab,y ; works like cmp for beq beq .leftTurn eor #%00000011 beq .rightTurn RTS .leftTurn: dec P0_CurrentRotationSequence,X RTS .rightTurn: inc P0_CurrentRotationSequence,X RTS ;/DRIVING CONTROLLER CODE Transmission SUBROUTINE stx Car_Picker lda SWCHA_Nybble,X and #%00001100 cmp #%00000100 beq .CarReverseGear cmp #%00001000 beq .CarForwardGear RTS ;bcs .Car1Transmission .CarForwardGear lda #0 sta Car0_Gear,X RTS .CarReverseGear lda #$FF sta Car0_Gear,X RTS Gas_Pedal SUBROUTINE ;do gas pedal ldx Car_Picker txa ;read the fire button beq .other_button lda INPT5;INPT,X bpl .Accelerate jmp .Decelerate .other_button lda INPT4;INPT,X bpl .Accelerate .Decelerate rts .Accelerate ;rts jmp .Process_Acceleration lda Car_Vector_Sequence_Forward sta Overlay2 jmp .odd_frame; disable below for now lda Frame_Counter clc lsr bcs .odd_frame .even_frame lda Overlay2 lsr lsr lsr lsr sta Overlay2 .odd_frame ;WORK ON THIS AREA!! ;jmp .VL_Check0 .Process_Acceleration ldx Car_Picker ;ldx #1 lda Car0_Gear,X beq .do_forward_acceleration lda P0_CurrentRotationSequence,X tax lda Car_Vector_Sequence_Reverse,X jmp .continue_acceleration .do_forward_acceleration lda P0_CurrentRotationSequence,X tax lda Car_Vector_Sequence_Forward,X .continue_acceleration ldx Car_Picker ldy Car0_YFullres,X lsr bcs .skipUpCar .doDownCar: iny ; Car0_Y++ cpy #Y_BOUNDARY_BOTTOM;#KERNEL_HEIGHT+1|$80 bne .skipUpCar ldy #1;|$80 .skipUpCar: lsr bcs .skipDownCar .doUpCar: dey ;bounds check for top of screen cpy #0 bne .skipDownCar ;brk ldy #Y_BOUNDARY_BOTTOM;|$80; reset to bottom of screen .skipDownCar: sty Car0_YFullres,X lsr ldy Car0_X,X bcs .skipLeftCar bne .doLeftCar ldy #SCREEN_WIDTH .doLeftCar: dey; Car0_X-- .skipLeftCar: lsr bcs .skipRightCar .doRightCar: iny ; Car0_X++ cpy #SCREEN_WIDTH bne .skipRightCar ldy #0 .skipRightCar: sty Car0_X,X rts OverScan SUBROUTINE lda #36 sta TIM64T bit SWCHB bmi .set_Barrier; difficulty switch was toggled lda #0; powerup jmp .store_Ball_type .set_Barrier lda #3; barrier .store_Ball_type sta Ball_Type ;COLLISION DETECTION ldx #1 .collision_detection lda CXM0P,X bpl .no_killings ;testing score increment lda Car0_Score,X sed clc adc #1 cld sta Car0_Score,X lda #0 sta Gremlin0_X,X .no_killings dex bpl .collision_detection sta CXCLR ;BEGIN USER INPUT SEGMENT ;BEGIN USER INPUT SEGMENT ;BEGIN USER INPUT SEGMENT ;BEGIN USER INPUT SEGMENT ;this should be the only sample of SWCHA for the frame lda SWCHA sta SWCHA_Current ;SPLIT OFF THE DATA INTO TWO BYTES WITH THE BITS ALIGNED THE SAME ;THAT WAY THE Read_Driving_Controller CAN BE GENERAL-PURPOSE sta SWCHA_Nybble+1 LSR LSR lSR lSR sta SWCHA_Nybble ;if game is over, freeze the cars wherever they last were lda Game_State beq .skip_Car_Engine ldx #2 .Read_Controllers dex stx Temp_Var jsr Read_Driving_Controller jsr Rotation_Check_Boundaries jsr Player_Reflect_Check jsr Transmission jsr Gas_Pedal ldx Temp_Var bne .Read_Controllers .skip_Car_Engine ldx #1 ;GREMLIN ANIMATION ; turn this into a bounds-checking-only routine .moveGremlins: ;lda Frame_Counter ;and #$02 ; determines speed ;bne .skipJoystick .loopMoveGremlins: lda SWCHA0_FAKE,X ;lda SWCHA_Nybble,X ldy Gremlin0_Y,x lsr bcs .skipUpGremlin iny cpy #KERNEL_HEIGHT+1|$80 bne .skipUpGremlin ldy #1|$80 .skipUpGremlin:;SWCHA0_FAKE = %00000001 lsr bcs .skipDownGremlin dey cpy #0|$80 bne .skipDownGremlin ldy #KERNEL_HEIGHT|$80 .skipDownGremlin:;SWCHA0_FAKE = %00000010 sty Gremlin0_Y,x lsr ldy Gremlin0_X,x bcs .skipLeftGremlin bne .skipResetLeftGremlin ldy #SCREEN_WIDTH .skipResetLeftGremlin:;SWCHA0_FAKE = %00000100 dey .skipLeftGremlin: lsr bcs .skipRightGremlin iny cpy #SCREEN_WIDTH bne .skipRightGremlin ldy #0 ;cpx #0 ;bne .skipRightGremlin .skipRightGremlin: sty Gremlin0_X,x dex bpl .loopMoveGremlins .skipJoystick: .waitTim: lda INTIM bne .waitTim rts SetPosX SUBROUTINE ; TODO: use new Fatal Run method discovered by Manuel ; calculates the values and positions objects: ; Input: ; - a = x-position tay ; 2 iny ; 2 tya ; 2 and #$0F ; 2 sta Temp_Var ; 3 tya ; 2 lsr ; 2 lsr ; 2 lsr ; 2 lsr ; 2 tay ; 2 clc ; 2 adc Temp_Var ; 3 cmp #$0F ; 2 bcc .skipIny ; 2 sbc #$0F ; 2 iny ; 2 .skipIny: sta WSYNC ; 3 eor #$07 ; 2 asl ; 2 asl ; 2 asl ; 2 asl ; 2 sta.wx HMP0,x ; 5 @15 .waitPos: dey ; 2 bpl .waitPos ; 2³ .bankCheck: sta RESP0,X ; 4 rts ; 6 ;SetPosX END ;=============================================================================== ; R O M - T A B L E S (Bank 0) ;=============================================================================== org $fA00 Title_PF_L ; 76543210 .byte %00000000 | %00000000 ;%00000000 .byte %00000000 | %00000000 .byte %00000000 | %00000000 .byte %00000000 | %00101111 .byte %00011000 | %00000000 .byte %00011000 | %00000000 .byte %00100100 | %00000000 .byte %01000010 | %00000000 .byte %10000001 | %00000000 .byte %01000000 | %00011111 .byte %00000000 | %00000000 .byte 0 Title_PF_R ; 01234567 .byte %00000000 | %00000000 .byte %00000000 | %00000000 .byte %01010111 | %00000000 .byte %00000100 | %00100000 .byte %00001000 | %00010000 .byte %00010000 | %00001000 .byte %00100000 | %00000100 .byte %01000000 | %00000010 .byte %00111111 | %00000000 .byte %00000000 | %00000000 .byte %00000000 | %00000000 .byte 0 Car_Rotation_Sequence: ;NO FLIP BIT - FACE RIGHT .byte