mirror of https://github.com/digarok/gslib.git
65 lines
1.4 KiB
ArmAsm
65 lines
1.4 KiB
ArmAsm
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* SHR1 *
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* *
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* Dagen Brock <dagenbrock@gmail.com> *
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* 2013-07-17 *
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****************************************
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rel ; Compile
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dsk SHR1.l ; Save Name
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mx %00 ; Program starts in 16-bit mode
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phk ; Set Data Bank to Program Bank
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plb ; Always do this first!
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GraphicsOn sep #$30 ; 8-bit mode
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lda #$81
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stal $00C029 ; Turn on SHR mode
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rep #$30 ; back to 16-bit mode
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jsr WaitKey ; pause
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ClearNaive ldx #$0000 ; Start at first pixel
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lda #$0000 ; store zeros
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:clearloop stal $E12000,x ; screen location
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inx
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inx
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cpx #$8000 ; see if we've filled entire frame/colors/scbs
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bne :clearloop ; pause
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jsr WaitKey
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ClearFaster ldx #$7FFE ; start at top this time
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lda #$0000 ; store zeros
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:clearloop stal $E12000,x ; screen location
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dex
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dex
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; avoid 16K "compare X's" for 80K cycle savings
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bne :clearloop ; loop until we've worked our way down to 0
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jsr WaitKey
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jsl $E100A8 ; Prodos 16 entry point
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da $29 ; Quit code
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adrl QuitParm ; address of parameter table
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bcs Error ; never taken
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Error brk ; should never get here
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QuitParm adrl $0000 ; pointer to pathname (not used here)
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da $00 ; quit type (absolute quite)
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WaitKey sep #$30 ; good old apple ii key wait routine
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:wait ldal $00C000 ; but called using long addressing modes
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bpl :wait ; in 8-bit mode
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stal $00C010
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rep #$30
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rts
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