mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-07-04 08:29:30 +00:00
59 lines
725 B
ArmAsm
59 lines
725 B
ArmAsm
;================================
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;================================
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;================================
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;================================
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scroll_screen:
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ldx #8
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stx INL
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ldx #0
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stx OUTL
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scroll_yloop:
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ldx INL
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lda hposn_low,X
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sta xloop_smc1+1
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lda hposn_high,X
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sta xloop_smc1+2
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ldx OUTL
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lda hposn_low,X
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sta xloop_smc2+1
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lda hposn_high,X
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sta xloop_smc2+2
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ldy #39
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scroll_xloop:
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xloop_smc1:
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lda $2000,Y
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xloop_smc2:
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sta $2000,Y
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dey
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bpl scroll_xloop
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inc INL
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inc OUTL
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lda INL
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cmp #192
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bne scroll_yloop
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; blank bottom line
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lda #$00
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ldy #39
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scroll_hline_xloop:
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sta $23D0,Y
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sta $27D0,Y
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sta $2BD0,Y
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sta $2FD0,Y
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sta $33D0,Y
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sta $37D0,Y
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sta $3BD0,Y
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sta $3FD0,Y
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dey
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bpl scroll_hline_xloop
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rts
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