mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-05-28 17:41:29 +00:00
231 lines
4.1 KiB
ArmAsm
231 lines
4.1 KiB
ArmAsm
; wires
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; 159 -- initial
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; 158 -- jmp to branch
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; 152 -- special case dark blue
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; 151 -- another jmp to branch
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; 148 -- use $10 instead of $ff for black color
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; 147 -- optimize color code
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; 143 -- use 15x15 grid instead of 7x7
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; 138 -- re-wrote clear screen code
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; 144 -- back to original layout
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; 142 -- jump to earlier BGND entry point
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; 141 -- start at $FF even though it misses upper left
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; this makes noticable glitches though
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; goal=141
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.include "zp.inc"
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.include "hardware.inc"
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CTEMP = $FC
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;================================
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; Clear screen and setup graphics
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;================================
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plasma:
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jsr $F3D8 ; HGR2 (and full screen), set HGRPAGE to $40
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; after, A is #$60
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lda #$10 ; write $10 to the 8k starting at $4000
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jsr $F3F4 ; does the store, is this allowed?
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; stores to HGR.BITS and then runs BKGND
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bit LORES ; switch to lo-res
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;================================
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; create texture
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;================================
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; we create a 16x16 texture, which we pattern across 40x48 screen
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ldx #15
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; store at 15,x 8,x and x,15 x,8
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; 240+x, (x*16),15
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write_loop:
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txa ; write 0123456789ABCDEF pattern horizontally
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sta lookup+64,X ; line at Y=4
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sta lookup+192,X ; line at Y=12
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asl ; draw vertical line
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asl
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asl
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asl
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tay
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txa
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sta lookup+4,Y ; line at X=4
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sta lookup+12,Y ; line at X=12
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dex
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bpl write_loop
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create_lookup_done:
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; X is $FF
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; Y is $00?
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;=========================
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; cycle colors
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;=========================
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cycle_colors:
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; can't do palette rotate on Apple II so faking it here
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; just incrementing every entry in texture by 1
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; for this one we wrap at $f
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; and we don't touch color $10 which maps to zero (black)
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; X is $FF when arriving here
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; both from init and from end loop
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; we should start at 0, starting at FF means we never
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; cycle pixel 0. We worked around this by arranging the texture
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; so pixel 0 is always black
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; ldx #0
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; inx ; make X 0
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;cycle_loop:
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; ldy lookup,X
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; cpy #$10 ; $10 is black background, don't rotate it
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; beq skip_zero
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; dey
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; tya
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; and #$f
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; sta lookup,X
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;skip_zero:
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; dex
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; bne cycle_loop
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cycle_loop:
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lda lookup,X
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cmp #$10 ; $10 is black background, don't rotate it
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; carry set if >=10
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bcs skip_zero
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sbc #0
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and #$f
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sta lookup,X
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skip_zero:
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dex
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bne cycle_loop
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;=========================
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; set/flip pages
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;=========================
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; we want to flip pages and then draw to the offscreen one
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flip_pages:
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; ldx #0 ; x already 0
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lda draw_page_smc+1 ; DRAW_PAGE
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beq done_page
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inx
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done_page:
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ldy PAGE1,X ; set display page to PAGE1 or PAGE2
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eor #$4 ; flip draw page between $400/$800
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sta draw_page_smc+1 ; DRAW_PAGE
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;===================================
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; plot current frame
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;===================================
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; scan whole 40x48 screen and plot each point based on
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; lookup table colors
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plot_frame:
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ldx #47 ; YY=47 (count backwards)
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plot_yloop:
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txa ; get (y&0xf)<<4
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pha ; save YY / SAVEX
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asl
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asl
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asl
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asl
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sta CTEMP ; save for later
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txa ; get YY in accumulator
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lsr ; call actually wants Ycoord/2
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ldy #$0f ; setup mask for odd/even line
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bcc plot_mask ; set by the lsr
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ldy #$f0
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plot_mask:
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sty MASK
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jsr GBASCALC ; point GBASL/H to address in (A is ycoord/2)
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; after, A is GBASL, C is clear
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lda GBASH ; adjust to be PAGE1/PAGE2 ($400 or $800)
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draw_page_smc:
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adc #0
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sta GBASH
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;==========
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ldy #39 ; XX = 39 (countdown)
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plot_xloop:
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tya ; get x&0xf
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and #$f
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ora CTEMP ; combine with val from earlier
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; get ((y&0xf)*16)+x
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tax
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plot_lookup:
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lda lookup,X ; load lookup, (y*16)+x
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cmp #11
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bcc color_blue ; if < 11, blue
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color_notblue:
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tax
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lda colorlookup-11,X ; lookup color
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.byte $2C ; BIT trick
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color_blue:
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lda #$22 ; load color blue (skipped if bit trick)
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sta COLOR ; each nibble should be same
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jsr PLOT1 ; plot at GBASL,Y (x co-ord goes in Y)
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dey ; XX--
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bpl plot_xloop ; loop if >=0
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pla ; restore YY
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tax
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dex ; YY--
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bpl plot_yloop ; loop if >=0
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bmi cycle_colors ; move to next frame
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colorlookup:
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.byte $66,$77,$ff,$77,$66,$00
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; want this to be at 3f5
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; Length is 141 so start at $3f4 -
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; 1013 - 141 + 3 = 875 = $36B
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jmp plasma
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; make lookup happen at page boundary
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.org $4000
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lookup:
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