Prev: ACFB Up: Map Next: AE6A
AE59: Copy Display Data If Zero
Used by the routine at ACFB.
Conditionally copies a 2-byte display data value from DE to HL if the destination is currently zero. Used to initialise display data only when it hasn't been set yet.
Input
HL Destination pointer (2-byte display data)
DE Source pointer (2-byte display data)
CopyDisplayDataIfZero AE59 LD A,(HL)
AE5A INC HL
AE5B OR (HL)
AE5C DEC HL
AE5D JR NZ,CopyDisplayDataIfZero_0
AE5F LD A,(DE)
AE60 LD (HL),A
CopyDisplayDataIfZero_0 AE61 INC HL
AE62 INC DE
AE63 JR NZ,CopyDisplayDataIfZero_1
AE65 LD A,(DE)
AE66 LD (HL),A
CopyDisplayDataIfZero_1 AE67 INC HL
AE68 INC DE
AE69 RET
Prev: ACFB Up: Map Next: AE6A