49 lines
1.0 KiB
ArmAsm
49 lines
1.0 KiB
ArmAsm
;==================================
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; HLINE
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;==================================
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; Color in A
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; Y has which line
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; takes 435 cycles
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hline:
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pha ; 3
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ldx gr_offsets,y ; 4+
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stx hline_loop+1 ; self-modify code ; 4
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lda gr_offsets+1,y ; 4+
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clc ; 2
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adc DRAW_PAGE ; 3
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sta hline_loop+2 ; self-modify code ; 4
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pla ; 4
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ldx #39 ; 2
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;===========
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; 30
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hline_loop:
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sta $5d0,X ; 38 ; 5
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dex ; 2
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bpl hline_loop ; 2nt/3
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;===========
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; 40*(10)=400
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; -1
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rts ; 6
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;==========================
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; Clear gr screen
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;==========================
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; Color in A, Clears 0 to and including Y
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; clear_gr: takes 2+(48/2)*(6+435+7)+5 = 10759
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; cpl: takes (Y/2)*(6+435+7)+5 = ?
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clear_gr:
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ldy #46 ; 2
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clear_page_loop:
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jsr hline ; 6+435
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dey ; 2
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dey ; 2
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bpl clear_page_loop ; 2/3
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rts ; 6
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gr_offsets:
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.word $400,$480,$500,$580,$600,$680,$700,$780
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.word $428,$4a8,$528,$5a8,$628,$6a8,$728,$7a8
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.word $450,$4d0,$550,$5d0,$650,$6d0,$750,$7d0
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