311 lines
5.2 KiB
ArmAsm
311 lines
5.2 KiB
ArmAsm
; Display a 40x96 lo-res image
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; Uses the 40x96 page1/page2 every-2-scanline pageflip mode
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; as shown in my kfest18 hackfest demo
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; by deater (Vince Weaver) <vince@deater.net>
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; Zero Page
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FRAMEBUFFER = $00 ; $00 - $0F
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YPOS = $10
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YPOS_SIN = $11
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CH = $24
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CV = $25
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GBASL = $26
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GBASH = $27
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BASL = $28
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BASH = $29
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FRAME = $60
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BLARGH = $69
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DRAW_PAGE = $EE
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LASTKEY = $F1
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PADDLE_STATUS = $F2
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TEMP = $FA
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WHICH = $FB
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; Soft Switches
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KEYPRESS= $C000
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KEYRESET= $C010
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SET_GR = $C050 ; Enable graphics
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FULLGR = $C052 ; Full screen, no text
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PAGE0 = $C054 ; Page0
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PAGE1 = $C055 ; Page1
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LORES = $C056 ; Enable LORES graphics
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PADDLE_BUTTON0 = $C061
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PADDL0 = $C064
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PTRIG = $C070
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; ROM routines
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TEXT = $FB36 ;; Set text mode
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HOME = $FC58 ;; Clear the text screen
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WAIT = $FCA8 ;; delay 1/2(26+27A+5A^2) us
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MAX = 4
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lda #$ff
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sta WHICH
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start_over:
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inc WHICH
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lda WHICH
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cmp #MAX
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bne in_range
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lda #0
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sta WHICH
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in_range:
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;===================
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; init screen
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jsr TEXT
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jsr HOME
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bit KEYRESET
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;===================
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; init vars
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lda #0
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sta DRAW_PAGE
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;=============================
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; Load graphic page0
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lda #$0c
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sta BASH
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lda #$00
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sta BASL ; load image to $c00
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lda WHICH
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asl
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asl ; which*4
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tay
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lda pictures,Y
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sta GBASL
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lda pictures+1,Y
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sta GBASH
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jsr load_rle_gr
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lda #4
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sta DRAW_PAGE
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jsr gr_copy_to_current ; copy to page1
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; GR part
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bit PAGE1
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bit LORES ; 4
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bit SET_GR ; 4
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bit FULLGR ; 4
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jsr wait_until_keypressed
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;=============================
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; Load graphic page1
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lda #$0c
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sta BASH
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lda #$00
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sta BASL ; load image to $c00
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lda WHICH
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asl
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asl ; which*4
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tay
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lda pictures+2,Y
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sta GBASL
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lda pictures+3,Y
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sta GBASH
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jsr load_rle_gr
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lda #0
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sta DRAW_PAGE
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jsr gr_copy_to_current
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; GR part
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bit PAGE0
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jsr wait_until_keypressed
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;==============================
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; setup graphics for vapor lock
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;==============================
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jsr vapor_lock ; 6+
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; vapor lock returns with us at beginning of hsync in line
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; 114 (7410 cycles), so with 5070 lines to go
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; GR part
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bit LORES ; 4
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bit SET_GR ; 4
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bit FULLGR ; 4
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jsr gr_copy_to_current ; 6+ 9292
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; now we have 322 left
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; 322 - 12 = 310
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; - 3 for jmp
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; 307
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; Try X=9 Y=6 cycles=307
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ldy #6 ; 2
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loopA: ldx #9 ; 2
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loopB: dex ; 2
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bne loopB ; 2nt/3
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dey ; 2
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bne loopA ; 2nt/3
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jmp display_loop ; 3
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.align $100
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;================================================
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; Display Loop
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;================================================
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; each scan line 65 cycles
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; 1 cycle each byte (40cycles) + 25 for horizontal
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; Total of 12480 cycles to draw screen
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; Vertical blank = 4550 cycles (70 scan lines)
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; Total of 17030 cycles to get back to where was
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; We want to alternate between page1 and page2 every 65 cycles
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; vblank = 4550 cycles to do scrolling
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; 2 + 48*( (4+2+25*(2+3)) + (4+2+23*(2+3)+4+5)) + 9)
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; 48*[(6+125)-1] + [(6+115+10)-1]
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display_loop:
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ldy #48 ; 2
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outer_loop:
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bit PAGE0 ; 4
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ldx #25 ; 130 cycles with PAGE0 ; 2
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page0_loop: ; delay 126+bit
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dex ; 2
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bne page0_loop ; 2/3
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bit PAGE1 ; 4
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ldx #23 ; 130 cycles with PAGE1 ; 2
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page1_loop: ; delay 115+(7 loop)+4 (bit)+4(extra)
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dex ; 2
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bne page1_loop ; 2/3
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nop ; 2
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lda DRAW_PAGE ; 3
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dey ; 2
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bne outer_loop ; 2/3
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;======================================================
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; We have 4550 cycles in the vblank, use them wisely
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;======================================================
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; do_nothing should be 4550+1 -2-9 -7= 4533
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jsr do_nothing ; 6
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lda KEYPRESS ; 4
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bpl no_keypress ; 3
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jmp start_over
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no_keypress:
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jmp display_loop ; 3
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;=================================
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; do nothing
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;=================================
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; and take 4533-6 = 4527 cycles to do it
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do_nothing:
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; Try X=4 Y=174 cycles=4525 R2
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nop ; 2
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ldy #174 ; 2
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loop1:
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ldx #4 ; 2
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loop2:
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dex ; 2
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bne loop2 ; 2nt/3
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dey ; 2
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bne loop1 ; 2nt/3
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rts ; 6
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;==================================
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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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hline:
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pha ; 3
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ldx gr_offsets,y ; 4+
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stx hline_loop+1 ; 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 ; 4
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pla ; 4
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ldx #39 ; 2
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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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rts ; 6
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;==========================
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; Clear gr screen
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;==========================
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; Color in A
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clear_gr:
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ldy #46
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clear_page_loop:
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jsr hline
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dey
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dey
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bpl clear_page_loop
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rts
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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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.include "../../asm_routines/gr_unrle.s"
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.include "../../asm_routines/keypress.s"
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.include "gr_copy.s"
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.include "vapor_lock.s"
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.include "delay_a.s"
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pictures:
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.word apple_low,apple_high
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.word katahdin_low,katahdin_high
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.word df_girl_low,df_girl_high
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.word df_girl2_low,df_girl2_high
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.include "apple_40_96.inc"
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.include "katahdin_40_96.inc"
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.include "df_girl_40_96.inc"
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.include "df_girl2_40_96.inc"
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