Programming:Next / previous line calculation
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Revision as of 06:45, 28 December 2010 by Octoate (Talk | contribs) (Created page with "= Next line = This routines calculate the next line from the given address. == Firmware == '''Input:''' HL=Address '''Output:''' HL=Address of the next line '''Destroyed:'''...")
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
; Richard Fairhurst
; October 1997
;
;*** Next line down from HL ***
.nline ld a,8
add h
ld h,a
and 64
ret nz
ld bc,16304
sbc 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
