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47 lines
1.1 KiB
ArmAsm
47 lines
1.1 KiB
ArmAsm
; Tiny Gr
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; by Vince `deater` Weaver, vince@deater.net --- d e s i r e ---
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; trying to make small graphics in 8 bytes for Apple II
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; drops into the middle of the CHRGET get next token routine
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; that the Applesoft interpreter copies to $B1 - $C8 on boot
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; zero page locations
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; ROM calls
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SETGR = $FB40 ; set lo-res graphics code, clear screen
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PRHEX = $FDE3 ; print hex digit
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COUT = $FDED ; output A to screen
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COUT1 = $FDF0 ; output A to screen
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tiny_gr:
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;chrget B1: E6 B8 inc txtptrl
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; B3: D0 02 bne chrgot
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; B5: E6 B9 inc txtptrh
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;chrgot B7: AD 00 08 lda $800 txtprtrl/txtptrh
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; BA: C9 3A cmp #$3A
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; BC: B0 0A bcs end
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; BE: C9 20 cmp #$20
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; C0: F0 EF beq chrget
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; C2: 38 sec
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; C3: E9 30 sbc #$30
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; C5: 38 sec
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; C6: E9 D0 sbc #$D0
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; C8: 60 rts
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; we drop this at B9
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;chrget B1: E6 B8 inc txtptrl
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; B3: D0 02 bne chrgot
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; B5: E6 B9 inc txtptrh
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;chrgot B7: AD 00 08 lda $800
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tiny_loop:
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; lda $7800
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.byte $78 ; sei ; B9
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bit $C050 ; BA BB BC set LORES
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jsr COUT1 ; BD BE BF output A to stdout, with scroll
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.byte $50 ; bvc (bra we hope) ; C0
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; chrget
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