Changes

Programming:Next / previous line calculation

850 bytes added, 11:45, 28 December 2010
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

<pre>
SCR_NEXT_LINE equ #BC26

call SCR_NEXT_LINE
</pre>

== Without Firmware ==

'''Input:''' HL=Address

'''Output:''' HL=Address of the next line

'''Destroyed:''' AF

<pre>
; 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
</pre>

= 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

<pre>
SCR_PREV_LINE equ #BC29

call SCR_PREV_LINE
</pre>

[[Category:Programming]]
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