mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-12-26 11:30:12 +00:00
68 lines
1.1 KiB
ArmAsm
68 lines
1.1 KiB
ArmAsm
scroll_row1 = $800
|
|
scroll_row2 = $900
|
|
scroll_row3 = $A00
|
|
scroll_row4 = $B00
|
|
|
|
SCROLL_LENGTH = $63
|
|
;OFFSET = $62
|
|
|
|
|
|
; 5 + (45*40) +4 + 13 + 7 + 6 = 1835
|
|
|
|
scroll_loop:
|
|
|
|
ldx #0 ; 2
|
|
ldy OFFSET ; 3
|
|
|
|
draw_loop:
|
|
|
|
lda scroll_row1,Y ; 4
|
|
sta $650,X ; 5
|
|
lda scroll_row2,Y ; 4
|
|
sta $6d0,X ; 5
|
|
lda scroll_row3,Y ; 4
|
|
sta $750,X ; 5
|
|
lda scroll_row4,Y ; 4
|
|
sta $7d0,X ; 5
|
|
|
|
iny ; 2
|
|
inx ; 2
|
|
cpx #40 ; 2
|
|
bne draw_loop ; 2nt/3
|
|
;===============
|
|
; 45
|
|
|
|
|
|
; -1
|
|
inc OFFSET ; 5
|
|
;============
|
|
; 4
|
|
;==================
|
|
; wrap scrolltext
|
|
;==================
|
|
clc ; 2
|
|
lda OFFSET ; 3
|
|
adc #40 ; 2
|
|
cmp SCROLL_LENGTH ; 3
|
|
|
|
bne no_wrap ; 3
|
|
;============
|
|
; 13
|
|
|
|
; -1
|
|
lda #0 ; 2
|
|
sta OFFSET ; 3
|
|
jmp done_wrap ; 3
|
|
no_wrap:
|
|
lda $0 ; 3
|
|
nop ; 2
|
|
nop ; 2
|
|
;===========
|
|
; 7
|
|
|
|
done_wrap:
|
|
rts ; 6
|
|
|
|
|
|
.assert >scroll_loop = >done_wrap, error, "gr_scroll crosses page"
|