Routines
Prev: B863 Up: Map Next: B899
B881: Count Rooms Visited
Used by the routine at GameOver.
Counts the bits which are set in RoomsVisitedBitmap.
Output
A The number of rooms visited, less one
Count every set bit.
CountRoomsVisited B881 LD E,$00 Set the count to 00.
B883 LD BC,$0820 Set a counter of 08 bits and 20 bytes.
B886 LD HL,$5B58 Point HL at RoomsVisitedBitmap.
CountRoomsVisited_NextByte B889 PUSH BC Stash the counters on the stack.
B88A LD A,(HL) Fetch a byte of the table.
B88B INC HL Move on.
CountRoomsVisited_NextBit B88C RRCA Move a bit into the carry flag.
B88D JR NC,CountRoomsVisited_CountBits Jump to CountRoomsVisited_CountBits if the bit is not set.
B88F INC E Count the room.
CountRoomsVisited_CountBits B890 DJNZ CountRoomsVisited_NextBit Jump to CountRoomsVisited_NextBit until all of the bits have been done.
B892 POP BC Restore the counters from the stack.
B893 DEC C Count down the bytes.
B894 JR NZ,CountRoomsVisited_NextByte Jump to CountRoomsVisited_NextByte until all of the bytes have been done.
B896 LD A,E Copy the count to A.
B897 DEC A Subtract one from it.
B898 RET Return.
Prev: B863 Up: Map Next: B899