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https://github.com/deater/dos33fsprogs.git
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99 lines
1.6 KiB
ArmAsm
99 lines
1.6 KiB
ArmAsm
; Solaris scrolling code
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; 235 bytes = direct port
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; 162 bytes = updated version
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; 158 bytes = offset in X
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; 156 bytes = bit trick
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; 153 bytes = eliminate count
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; 151 bytes = questionably init count to value in Y
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; 150 bytes = remove unnecessary init
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; zero page
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GBASL = $26
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GBASH = $27
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HGR_X = $E0
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HGR_XH = $E1
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HGR_Y = $E2
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HGR_COLOR = $E4
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HGR_PAGE = $E6
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; soft-switches
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FULLGR = $C052
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PAGE1 = $C054
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; ROM routines
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HGR2 = $F3D8
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HPOSN = $F411 ; (Y,X),(A) (values stores in HGRX,XH,Y)
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; put in GBASL/GBASH
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WAIT = $FCA8 ;; delay 1/2(26+27A+5A^2) us
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COUNT = $FE
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FRAME = $FF
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solaris2:
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jsr HGR2
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outer_loop:
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sty COUNT ; reset count to 0 (first) or FF (from loop)
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dex ; decrement offset
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txa
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and #$f ; make sure stays less than 16
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tax
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inner_loop:
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sec
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lda #160
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sbc COUNT ; YY = 160-COUNT
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jsr HPOSN ; calculate line addr in GBASL/H, trashes all
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ldx HGR_X ; restore offset
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lda lookup,X ; see if match count
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cmp COUNT
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bne skip_color
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clc ; needed?
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txa
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adc #16
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tax
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lda #$00 ; draw black
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.byte $2C
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; jmp no_color
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skip_color:
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lda #$FF
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no_color:
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ldy #39 ; draw horizontal line at GBASL
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inner_inner_loop:
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sta (GBASL),Y
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dey
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bpl inner_inner_loop
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; Y is FF here
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inc COUNT
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lda COUNT
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cmp #83
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bne inner_loop
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beq outer_loop
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lookup:
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.byte 2, 5, 8,11,14,16,19,21,23,25,27,29,31,32,34,36
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.byte 37,39,40,41,43,44,45,46,47,48,49,50,51,52,53,54
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.byte 55,56,57,57,58,59,60,60,61,62,62,63,64,64,65,65
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.byte 66,66,67,67,68,68,69,69,70,70,71,71,71,72,72,73
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.byte 73,73,74,74,75,75,75,76,76,76,77,77,77,77,78,78
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.byte 78,79,79,79,79,80,80,80,80,81,81,81,81,82,82,82
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