Routines
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27097: Find the data structure which represents the row of aliens
_ALIEN_ROWS_DATA holds the data for the alien rows. Each row is 706 bytes, and there's 5 of them.
Used by the routines at generate_alien_bullets, bullet_alien_coll_yaxis, move_aliens and init_draw_aliens.
Input
A Row number
Output
IX Start of row data
find_alien_row_data 27097 LD IX,_ALIEN_ROWS_DATA Row data block starts here
27101 OR A For row zero we already have the answer
27102 RET Z
27103 PUSH BC Go into a loop adding the row data size (706 bytes) to IX.
27104 LD BC,706
find_alien_row_data_0 27107 ADD IX,BC
27109 DEC A
27110 JR NZ,find_alien_row_data_0
27112 POP BC
27113 RET That's the address of that row's data
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