Routines
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28253: Handler: Car Type 1 (Driving Right)
Used by the routine at Handler_Cars.
Handles a car driving right across the screen. The car is made up of two sprites (16 pixels apart) representing the front and back.
When the car reaches the right edge it is reinitialised from a random position.
Handler_Car_Type1 28253 LD IX,56008 IX=Sprite02_3Wide_X_Position.
28257 LD A,(24507) Call InitialiseCar if *RespawnFlag is set/ the room is being initialised.
28260 OR A
28261 CALL NZ,InitialiseCar
If the car crash timer is active, handle the crash animation.
28264 LD A,(29192) A=*CarCrashTimer.
28267 OR A Jump to Handler_CarType1_Drive if the crash timer is zero (car is driving normally).
28268 JR Z,Handler_CarType1_Drive
This entry point is used by the routines at Handler_CarType2 and Handler_CarType3.
Handler_Car_Type1_0 28270 CP 1 Jump to Handler_CarType1_CrashEnd if the crash timer has reached 1 (crash ending).
28272 JR Z,Handler_CarType1_CrashEnd
Car is crashing — decrement the timer and cycle through crash animation frames.
28274 DEC A Decrement the crash timer.
28275 LD (29192),A Write A to *CarCrashTimer.
28278 AND %00000010 Keep only bit 1 (alternates between 0 and 2).
28280 ADD A,32 A+=32 (crash frame base).
28282 EX AF,AF' Stash the frame in shadow AF.
If the car is on the lower road (Y=160), use a different frame set.
28283 LD A,(IX+1) Load A with the car's Y position (from *IX+1).
28286 CP 160 Jump to Handler_CarType1_SetCrashFrame if the car is not on the lower road.
28288 JR NZ,Handler_CarType1_SetCrashFrame
28290 EX AF,AF' Retrieve the crash frame from shadow AF.
28291 ADD A,2 A+=2 (offset to left-facing crash frames).
28293 JR Handler_CarType1_StoreCrashFrame Jump to Handler_CarType1_StoreCrashFrame.
Handler_CarType1_SetCrashFrame 28295 EX AF,AF' Retrieve the crash frame from shadow AF.
Handler_CarType1_StoreCrashFrame 28296 LD (IX+3),A Write A to *IX+3 (front sprite frame).
28299 INC A Increment A for the rear sprite.
28300 LD (IX+7),A Write A to *IX+7 (rear sprite frame).
28303 JR Handler_CarCheckPercyCollision Jump to Handler_CarCheckPercyCollision.
Crash animation finished — clear the timer.
Handler_CarType1_CrashEnd 28305 XOR A Write 0 to *CarCrashTimer.
28306 LD (29192),A
28309 JR Handler_CarCheckPercyCollision Jump to Handler_CarCheckPercyCollision.
Car is driving normally — move it to the right.
Handler_CarType1_Drive 28311 LD HL,29196 HL=CarSpeed2 (car speed).
28314 LD A,(IX+0) A=*IX+0 (car X position).
28317 ADD A,(HL) A+=*HL (add speed).
28318 CP 222 Call InitialiseCar to reinitialise the car if it's at the right edge.
28320 CALL NC,InitialiseCar
Update both sprite X positions (16 apart).
28323 LD (IX+0),A Write A to *IX+0 (front X).
28326 ADD A,16 A+=16.
28328 LD (IX+4),A Write A to *IX+4 (rear X).
Set the driving right frames.
28331 LD (IX+3),28 Write 28 to *IX+3 (front frame: driving right).
28335 LD (IX+7),29 Write 29 to *IX+7 (rear frame: driving right).
Set the car colour for both sprites.
28339 LD A,(29194) Write *CarColour to;
  • *IX+2 (front colour)
  • *IX+6 (rear colour)
28342 LD (IX+2),A
28345 LD (IX+6),A
This entry point is used by the routine at Handler_CarType2.
Set the Y positions for the wheels/underside sprites.
Handler_Car_Type1_1 28348 LD (IX+33),160 Write 160 to *IX+33 (front underside Y).
28352 LD (IX+37),160 Write 160 to *IX+37 (rear underside Y).
Set the X positions for the underside sprites (offset by 3 and 24 from the car's X).
28356 LD A,(IX+0) A=*IX+0.
28359 ADD A,3 A+=3.
28361 LD (IX+32),A Write A to *IX+32 (front underside X).
28364 ADD A,21 A+=21.
28366 LD (IX+36),A Write A to *IX+36 (rear underside X).
Animate the wheels — cycle through frames 16-19.
28369 LD HL,29197 HL=CarWheelAnimation (wheel animation counter).
28372 LD A,(HL) A=*HL.
28373 INC A Increment the counter.
28374 AND %00000011 Keep only bits 0-1 (cycle 0-3).
28376 LD (HL),A Write back to *HL.
28377 ADD A,16 A+=16 (wheel frame base).
28379 LD (IX+35),A Write A to *IX+35 (front wheel frame).
Offset the rear wheel animation by 2 for visual variety.
28382 LD A,(HL) A=*HL.
28383 ADD A,2 A+=2.
28385 AND %00000011 Keep only bits 0-1.
28387 ADD A,16 A+=16 (wheel frame base).
28389 LD (IX+39),A Write A to *IX+39 (rear wheel frame).
This entry point is used by the routine at Handler_CarType2.
Check if Percy's egg has hit the car.
Handler_Car_Type1_2 28392 LD A,(24489) A=*EggDropFlag.
28395 OR A Call CheckCarEggCollision if the egg is active.
28396 CALL NZ,CheckCarEggCollision
Check if the car has collided with Percy.
Handler_CarCheckPercyCollision 28399 LD IX,56000 IX=Percy_X_Position.
28403 LD IY,56012 IY=Sprite03_3Wide_X_Position.
This entry point is used by the routine at Handler_Cars.
Handler_CarCheckPercyCollision_Test 28407 CALL CheckSpriteCollision Call CheckSpriteCollision.
28410 RET C Return if no collision.
Car hit Percy — knock him backward.
Handler_CarKnockBackPercy 28411 LD HL,56000 HL=Percy_X_Position (Percy's X position).
28414 LD A,(HL) A=*HL.
28415 SUB 20 A-=20 (knock back distance).
28417 JR C,Handler_CarKnockBackPercy_LeftEdge Jump to Handler_CarKnockBackPercy_LeftEdge if the result underflowed (Percy at the left edge).
Handler_Car_Type1_3 28419 LD (HL),A Write the new X position to *HL.
28420 INC HL Advance to Percy's Y position.
28421 LD (HL),120 Write 120 to *HL (set Percy's Y position after knockback).
28423 LD (24487),A Write A to *FallingState (set the falling state).
28426 RET Return.
Percy was too close to the left edge — adjust position rightward.
Handler_CarKnockBackPercy_LeftEdge 28427 LD A,(HL) A=*HL.
28428 ADD A,10 A+=10.
28430 JR Handler_Car_Type1_3 Jump to Handler_Car_Type1_3.
Alternate entry point for car initialisation.
InitialiseCar_Alternate 28432 CALL InitialiseCar Call InitialiseCar.
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