Routines
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8880: Fall, after a frame's grace
Used by the routine at MOVE_OBJECT.
On the first frame with nothing underneath, an object can still walk -- off a ledge, say -- and only after that does it drop a block a frame.
Nothing sets bit 3 of the flags -- not the BASIC's DATA, not the code -- so the three instructions of its "never falls" branch never run. These are the only instructions in the game not seen to run.
FALL 8880 BIT 3,(IX+$07) Bit 3: never falls.
8884 JR Z,FALL_0
8886 XOR A
8887 LD (IX+$05),A
888A JP MOVE_OBJECT_0
FALL_0 888D LD A,(IX+$05) Count the frame; the first one, walk.
8890 INC A
8891 LD (IX+$05),A
8894 DEC A
8895 JP Z,MOVE_OBJECT_1
8898 DEC C Then drop a block.
8899 LD (IX+$02),C
889C RET
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