82 lines
983 B
ArmAsm
82 lines
983 B
ArmAsm
; nyan
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; by Vince `deater` Weaver <vince@deater.net> / dSr
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; zero page
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H2 = $2C
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COLOR = $30
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X0 = $F0
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XX = $F1
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FRAME = $F2
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Y1 = $F3
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Y0 = $F4
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X1 = $F5
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; soft-switches
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FULLGR = $C052
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; ROM routines
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PLOT = $F800 ;; PLOT AT Y,A
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PLOT1 = $F80E ;; PLOT at (GBASL),Y (need MASK to be $0f or $f0)
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HLINE = $F819 ;; HLINE Y,$2C at A
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SETCOL = $F864 ;; COLOR=A
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SETGR = $FB40 ;; init lores and clear screen
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WAIT = $FCA8 ;; delay 1/2(26+27A+5A^2) us
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;================================
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; Clear screen and setup graphics
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;================================
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boxes:
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jsr SETGR ; set lo-res 40x40 mode
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lda #0
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sta COLOR
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sta X0 ; X0
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tax
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lda #39
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sta H2 ; X1
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sta Y1
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draw_box_loop:
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stx Y0
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inner_loop:
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;; HLINE Y,H2 at A
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;; X left alone, carry set on exit
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;; H2 left alone
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;; Y and A trashed
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ldy X0
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txa
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jsr HLINE ; y, H2 at A
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cpx Y1
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inx
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bcc inner_loop
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inc COLOR
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ldx Y0
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inx ; Y0
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inx
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dec Y1
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dec Y1
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inc X0
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dec H2
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cpx #20
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bne draw_box_loop
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end:
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jmp end
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