Routines
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BF85: Select Mirrored Erase
Used by the routine at RunFrame.
Used when the ship is erased. If it is facing left (bit 7 of C8FD or of A if entered at SelectMirroredErase_Entry) the horizontal position is moved to the other side of the sprite by its width in ScratchQuad and IY is pointed at the routine for the width in the table at EraseMirroredRowDirectly, which erases a mirrored sprite.
Input
HL' Position (if entered at SelectMirroredErase_Entry)
Output
IY Address of the routine
SelectMirroredErase BF85 LD A,($C8FD) The ship's facing.
This entry point is used by the routine at DrawPiece.
SelectMirroredErase_Entry BF88 LD HL,($BF83) Fetch the word at BF83 into HL.
BF8B BIT 7,A Return if bit 7 of A is clear.
BF8D RET Z
BF8E LD B,$F9 B=F9.
BF90 LD A,($5C28) The sprite width in bytes.
BF93 DEC A Step A back.
BF94 ADD A,A Double A.
BF95 ADD A,A Double A.
BF96 ADD A,A Double A.
BF97 ADD A,L A gains L.
BF98 LD ($BF83),A The column on the other side of the sprite.
BF9B LD A,($5C28) The sprite width in bytes.
BF9E LD IY,$A7A4 The erase mirrored row directly.
BFA2 CP $06 Return if A is 06.
BFA4 RET Z
BFA5 LD IY,$A7AC The second mirrored-row erase.
BFA9 CP $05 Return if A is 05.
BFAB RET Z
BFAC LD IY,$A7B4 The third mirrored-row erase.
BFB0 CP $04 Return if A is 04.
BFB2 RET Z
BFB3 LD IY,$A7BC The fourth mirrored-row erase.
BFB7 RET Return.
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