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Routines |
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Used by the routine at Handler_Cars.
Handles a car driving left across the screen. When it reaches the left boundary it turns around and drives right at ground level until reaching the right edge, then reinitialises.
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| Handler_CarType2 | 6F8D | LD IX,$DAC8 | IX=Sprite02_3Wide_X_Position. | |||||
| 6F91 | LD HL,$720B | HL=CarSpeed (car speed). | ||||||
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If the room is being initialised, set up the car.
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| 6F94 | LD A,($5FBB) | Jump to Handler_CarType2_Initialise if *RespawnFlag is set. | ||||||
| 6F97 | OR A | |||||||
| 6F98 | JR NZ,Handler_CarType2_Initialise | |||||||
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If the car crash timer is active, handle the crash animation.
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| 6F9A | LD A,($7208) | Jump to Handler_Car_Type1_0 if *CarCrashTimer is active. | ||||||
| 6F9D | OR A | |||||||
| 6F9E | JP NZ,Handler_Car_Type1_0 | |||||||
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Check which road the car is on.
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| 6FA1 | LD A,(IX+$01) | A=*IX+01 (car Y position). | ||||||
| 6FA4 | CP $90 | Jump to Handler_CarType2_DriveRight if on the upper road. | ||||||
| 6FA6 | JR Z,Handler_CarType2_DriveRight | |||||||
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Car is on the lower road (Y=A0) — driving left.
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| 6FA8 | LD A,(IX+$00) | A=*IX+00 (car X position). | ||||||
| 6FAB | SUB (HL) | A-=*HL (subtract speed). | ||||||
| 6FAC | CP $68 | Jump to Handler_CarType2_TurnAround if at the left boundary (turn around). | ||||||
| 6FAE | JR C,Handler_CarType2_TurnAround | |||||||
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This entry point is used by the routine at Handler_CarType3.
Update positions and set driving left frames.
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| Handler_CarType2_UpdateLeft | 6FB0 | LD (IX+$00),A | Write A to *IX+00 (front X). | |||||
| 6FB3 | ADD A,$10 | A+=10. | ||||||
| 6FB5 | LD (IX+$04),A | Write A to *IX+04 (rear X). | ||||||
| 6FB8 | LD (IX+$01),$A0 | Write A0 to *IX+01 (front Y: lower road). | ||||||
| 6FBC | LD (IX+$05),$A0 | Write A0 to *IX+05 (rear Y: lower road). | ||||||
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| 6FC0 | LD (IX+$03),$1E | Write 1E to *IX+03 (front frame: driving left). | ||||||
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| 6FC4 | LD (IX+$07),$1F | Write 1F to *IX+07 (rear frame: driving left). | ||||||
| 6FC8 | JP Handler_Car_Type1_2 | Jump to Handler_Car_Type1_2. | ||||||
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Car is on the upper road (Y=90) — driving right.
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| Handler_CarType2_DriveRight | 6FCB | LD A,(IX+$00) | A=*IX+00 (car X position). | |||||
| 6FCE | ADD A,(HL) | A+=*HL (add speed). | ||||||
| 6FCF | CP $DE | Jump to Handler_CarType2_Initialise if at the right edge (reinitialise). | ||||||
| 6FD1 | JR NC,Handler_CarType2_Initialise | |||||||
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This entry point is used by the routine at Handler_CarType3.
Update positions and set driving right frames.
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| Handler_CarType2_UpdateRight | 6FD3 | LD (IX+$00),A | Write A to *IX+00 (front X). | |||||
| 6FD6 | ADD A,$10 | A+=10. | ||||||
| 6FD8 | LD (IX+$04),A | Write A to *IX+04 (rear X). | ||||||
| 6FDB | LD (IX+$01),$90 | Write 90 to *IX+01 (front Y: upper road). | ||||||
| 6FDF | LD (IX+$05),$90 | Write 90 to *IX+05 (rear Y: upper road). | ||||||
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| 6FE3 | LD (IX+$03),$1C | Write 1C to *IX+03 (front frame: driving right). | ||||||
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| 6FE7 | LD (IX+$07),$1D | Write 1D to *IX+07 (rear frame: driving right). | ||||||
| 6FEB | JP Handler_Car_Type1_1 | Jump to Handler_Car_Type1_1. | ||||||
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Car reached the left boundary — turn around. Pick a new random speed and colour, then start driving right from the left boundary.
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| Handler_CarType2_TurnAround | 6FEE | PUSH HL | Stash HL on the stack. | |||||
| 6FEF | CALL GenerateRandomNumber | Call GenerateRandomNumber. | ||||||
| 6FF2 | POP HL | Restore HL from the stack. | ||||||
| 6FF3 | AND %00000011 | Keep only bits 0-1 (random speed 00-03). | ||||||
| 6FF5 | INC A | Increment the random number by one (speed 01-04). | ||||||
| 6FF6 | LD (HL),A | Write the new speed to *HL. | ||||||
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Pick a new colour, rejecting BLUE.
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| PickCarColour | 6FF7 | PUSH HL | Stash HL on the stack. | |||||
| 6FF8 | CALL GenerateRandomNumber | Call GenerateRandomNumber. | ||||||
| 6FFB | POP HL | Restore HL from the stack. | ||||||
| 6FFC | AND %00000011 | Keep only bits 0-1 (random colour from BLACK,BLUE,RED,MAGENTA). | ||||||
| 6FFE | CP $01 | Jump to PickCarColour if the colour is BLUE (pick again). | ||||||
| 7000 | JR Z,PickCarColour | |||||||
| 7002 | LD (IX+$02),A | Write A to *IX+02 (front colour). | ||||||
| 7005 | LD (IX+$06),A | Write A to *IX+06 (rear colour). | ||||||
| 7008 | LD A,$68 | A=68 (left boundary X position). | ||||||
| 700A | JR Handler_CarType2_UpdateRight | Jump to Handler_CarType2_UpdateRight. | ||||||
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Initialise car type 2 — start from the right edge driving left with a random speed and colour.
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| Handler_CarType2_Initialise | 700C | PUSH HL | Stash HL on the stack. | |||||
| 700D | CALL GenerateRandomNumber | Call GenerateRandomNumber. | ||||||
| 7010 | POP HL | Restore HL from the stack. | ||||||
| 7011 | AND %00000011 | Keep only bits 0-1 (random speed 00-03). | ||||||
| 7013 | INC A | Increment the random speed by one (speed 01-04). | ||||||
| 7014 | LD (HL),A | Write the new speed to *HL. | ||||||
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Pick a colour, using the range 04-07 (bright colours).
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| 7015 | PUSH HL | Stash HL on the stack. | ||||||
| 7016 | CALL GenerateRandomNumber | Call GenerateRandomNumber. | ||||||
| 7019 | POP HL | Restore HL from the stack. | ||||||
| 701A | AND %00000011 | Keep only bits 0-1. | ||||||
| 701C | ADD A,$04 | A+=04 (bright colour range). | ||||||
| 701E | LD (IX+$02),A | Write A to *IX+02 (front colour). | ||||||
| 7021 | LD (IX+$06),A | Write A to *IX+06 (rear colour). | ||||||
| 7024 | LD A,$DE | A=DE (right edge X position). | ||||||
| 7026 | JR Handler_CarType2_UpdateLeft | Jump to Handler_CarType2_UpdateLeft. | ||||||
| Prev: 6F54 | Up: Map | Next: 7028 |
