Routines
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BCC0: Move Crosshair Down
Used by the routine at HandleCrosshair.
Part of the handler for the crosshair, which is entered when the down control is pressed. Moves the crosshair down, but not past the lower limit.
Input
E The speed of the crosshair
H The vertical position of the crosshair
MoveCrosshairDown BCC0 LD A,H Fetch the vertical position.
BCC1 SUB E Subtract the speed.
BCC2 CP $54 Jump to HandleCrosshair_SetVertical if the crosshair is not past it.
BCC4 JR NC,HandleCrosshair_SetVertical
BCC6 LD A,$54 Stop at the lower limit.
BCC8 JR HandleCrosshair_SetVertical Jump to set the position.
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