Routines
Prev: 36510 Up: Map Next: 36569
36551: Move bitmap virtual cursor to display file address for coordinates x=C, y=B
Used by the routines at 29356, 36987, 37147, 37333, 37552 and 38417.
Input
B y-coordinate (characters)
C x-coordinate (characters)
Output
HL Virtual bitmap cursor display file address
36551 LD A,B Load y-coordinate into A
36552 AND 24 AND 24 to determine which third of the bitmap memory we are in (A = 0, 8 or 16)
36554 ADD A,64 Load HL with display file address of start of appropriate third of display...
36556 LD H,A ...(16,384, 18,432 or 20,480)
36557 LD A,B Load y-coordinate back into A
36558 AND 7 AND 7 to determine which of the 8 character rows within the third we are interested in
36560 RRCA Multiply by 8 to get pixel row required...
36561 RRCA ...
36562 RRCA ...
36563 ADD A,C Add x-coordinate
36564 LD L,A Add to value currently in HL
36565 LD (36488),HL Set (video) memory location to start printing character
36568 RET Return
Prev: 36510 Up: Map Next: 36569