Routines
Prev: 54097 Up: Map Next: 54148
54132: Move virtual cursor (bitmap) to display file for coordinates x=C, y=B and load address into HL
Used by the routines at 28833, 32694, 34990, 35123, 52596, 52635, 52717, 52820, 54598 and 54647.
Input
B y-coordinate (characters)
C x-coordinate (characters)
Output
HL Virtual cursor (bitmap) display file address
54132 LD A,B Load y-coordinate into A
54133 AND 24 AND 24 to determine which third of the bitmap memory we are in (A = 0, 8 or 16)
54135 ADD A,64 Load HL with display file address of start of appropriate third of display...
54137 LD H,A ...(16,384, 18,432 or 20,480)
54138 LD A,B Load y-coordinate back into A
54139 AND 7 AND 7 to determine which of the 8 character rows within the third we are interested in
54141 RRCA Multiply by 8 to get pixel row required...
54142 RRCA ...
54143 RRCA ...
54144 ADD A,C Add x-coordinate
54145 LD L,A Add to value currently in HL
54146 JR 54188 Store the updated address of bitmap virtual text cursor and return
Prev: 54097 Up: Map Next: 54148