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Routines |
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Moves a light one cell to the left, along the frame of the screen, if the cell on the left is part of the frame. If it is not then the light turns. A light that gets back to the top left of the frame after its delay has run out is finished.
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| MoveLightLeft | AFAE | LD L,E | Point HL at the cell on the left. | |||||||
| AFAF | LD H,D | |||||||||
| AFB0 | DEC L | |||||||||
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This entry point is used by the routine at MoveLightRight.
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| MoveLightLeft_Move | AFB1 | LD A,(HL) | Fetch the attribute of the cell. | |||||||
| AFB2 | CP $48 | Jump to turn the light if it is not part of the frame. | ||||||||
| AFB4 | JR NZ,TurnLightVertically | |||||||||
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This entry point is used by the routines at MoveLightUp and SetLightUp.
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| MoveLight_Move | AFB6 | LD A,$48 | Restore the attribute of the frame in the cell that the light is leaving. | |||||||
| AFB8 | LD (DE),A | |||||||||
| AFB9 | EX DE,HL | Put the address of the new cell in DE. | ||||||||
| AFBA | LD A,(IX+$01) | Fetch the delay of the light. | ||||||||
| AFBD | AND A | Jump to show the light if the delay has not run out. | ||||||||
| AFBE | JR NZ,MoveLight_Show | |||||||||
| AFC0 | LD HL,$5821 | Point HL at the top left of the frame. | ||||||||
| AFC3 | AND A | Jump to show the light if it has not got there. | ||||||||
| AFC4 | SBC HL,DE | |||||||||
| AFC6 | JR NZ,MoveLight_Show | |||||||||
| AFC8 | LD (IX+$00),$00 | Otherwise the light has finished, so free its slot... | ||||||||
| AFCC | RET | ...and return. | ||||||||
| MoveLight_Show | AFCD | LD A,(IX+$00) | Fetch the type of the light. | |||||||
| AFD0 | AND $07 | Keep the colour... | ||||||||
| AFD2 | OR $48 | ...and add the attribute of the frame. | ||||||||
| AFD4 | LD (DE),A | Show the light in the new cell. | ||||||||
| AFD5 | LD (IX+$02),E | Store the address of the cell... | ||||||||
| AFD8 | LD (IX+$03),D | ...in the light. | ||||||||
| AFDB | RET | Return. | ||||||||
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