Programming:Next / previous line calculation
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Next line
This routines calculate the next line from the given address.
Firmware
Input: HL=Address
Output: HL=Address of the next line
Destroyed: AF
SCR_NEXT_LINE equ #BC26 call SCR_NEXT_LINE
Without Firmware
Input: HL=Address
Output: HL=Address of the next line
Destroyed: AF,BC
; Richard Fairhurst ; October 1997 ; ;*** Next line down from HL *** .nline ld a,8 add h ld h,a ret nc ld bc,#c050 add hl,bc ret
Previous line
This routines calculate the previous line from the given address.
Firmware
Input: HL=Address
Output: HL=Address of the previous line
Destroyed: AF
SCR_PREV_LINE equ #BC29 call SCR_PREV_LINE