Routines
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CD9E: Limit Distance
Used by the routine at UpdateEndingGhost.
Subtracts a position from a target and limits the difference to four pixels in either direction.
Input
A Target position
IX Object
Output
A The distance to move, from FC to 04
LimitDistance CD9E SUB (IX+$0A) Work out how far the object is from the target along the X axis, and jump to LimitDistance_Negative if the target is on the left.
CDA1 JR C,LimitDistance_Negative
CDA3 CP $04 Return if the distance is less than four.
CDA5 RET C
CDA6 LD A,$04 Limit the distance to four and return.
CDA8 RET
LimitDistance_Negative CDA9 CP $FC Return if the distance is FC or more, which means it is less than four to the left.
CDAB RET NC
CDAC LD A,$FC Limit the distance to minus four and return.
CDAE RET
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