Routines
Prev: 85D9 Up: Map Next: 8606
85F6: Screen Address One Pixel Above
Used by the routines at 858E, 8606, 87B9, 8BA5 and A993.
Input
HL Current position
Output
HL Address for new position
Calculates the new address for writing a sprite pixel, in an upward direction, taking into consideration the screen memory layout.
ScreenPos1PixelAbove 85F6 DEC H Decrement H by one to move up one pixel on screen.
85F7 LD A,H Store the inverted result in A.
85F8 CPL
85F9 AND %00000111 Keep only bits 0-2.
85FB RET NZ If a screen bank boundary has not been crossed then return.
85FC LD A,L Else subtract 20 from L.
85FD SUB $20
85FF LD L,A
8600 RET C If there is any carry then return.
8601 LD A,H Else add 08 to H and return.
8602 ADD A,$08
8604 LD H,A
8605 RET Return.
Prev: 85D9 Up: Map Next: 8606