Routines
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B946: Find Tile Record
Used by the routine at FindTilesOverlapped.
Looks for the record of the tile at a position of the planet, in the four records that are kept at GameEntry and then every 25 bytes, which are for the tile at the map position in MapPosition and the ones next to it. If none of them match, the address of an empty record is returned.
Input
B Map zone
D Map column
Output
IX Address of the record of the tile
F The zero flag is set if the tile was found
FindTileRecord B946 LD E,B E=B.
B947 LD IX,$5B80 The decryption routine.
B94B LD BC,($CE57) Fetch the word at MapPosition into BC.
B94F CALL CompareTilePosition Call CompareTilePosition.
B952 RET Z Return if the zero flag is set.
B953 LD IX,$5BA5 Use 5BA5.
B957 INC B Advance B.
B958 CALL CompareTilePosition Call CompareTilePosition.
B95B RET Z Return if the zero flag is set.
B95C LD IX,$5BEF Use 5BEF.
B960 INC C Advance C.
B961 LD A,C A=C.
B962 CP $60 Jump to FindTileRecord_Column if A is not 60.
B964 JR NZ,FindTileRecord_Column
B966 LD C,$00 Clear C.
FindTileRecord_Column B968 CALL CompareTilePosition Call CompareTilePosition.
B96B RET Z Return if the zero flag is set.
B96C DEC B Step B back.
B96D LD IX,$5BCA Use 5BCA.
B971 CALL CompareTilePosition Call CompareTilePosition.
B974 RET Z Return if the zero flag is set.
B975 LD IX,$B944 The shot frame records.
B979 RET Return.
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