Routines
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51140: Nudge Object North South
Sets the adjustment of the speed in X of an object, to bring it a step closer to the middle line of an arch that goes north and south.
Input
IX Address of the arch object
IY Address of the object
Step the object towards the north-south middle line.
NudgeObjectNorthSouth 51140 LD A,(IX+9) Fetch the X coordinate of the middle of the doorway.
51143 CP (IY+1) Compare it with the X coordinate of the object.
51146 JR Z,NudgeObjectsToArch_Restore Jump to NudgeObjectsToArch_Restore if the object is in the middle.
51148 LD A,1 Set the adjustment to 1.
51150 JR NC,NudgeObjectNorthSouth_Set Jump to NudgeObjectNorthSouth_Set if the object is west of the middle.
51152 NEG Make the adjustment negative.
NudgeObjectNorthSouth_Set 51154 LD (IY+14),A Set the adjustment of the speed in X of the object.
This entry point is used by the routine at NudgeObjectEastWest.
NudgeObjectsToArch_Restore 51157 POP BC Restore the number of objects left from the stack.
This entry point is used by the routine at NudgeObjectsToArch.
NudgeObjectsToArch_Advance 51158 ADD IY,DE Point IY at the next object.
51160 DJNZ NudgeObjectsToArch_Next Jump to NudgeObjectsToArch_Next until all of the objects have been done.
51162 RET Return.
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