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dos33fsprogs/graphics/hgr/flood_fill/flood.s
Vince Weaver dc2601d020 flood_fill: update
2023-02-15 00:43:41 -05:00

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;*******************************************************************************
;* Micro-Painter, by Bob Bishop *
;* Copyright 1980 Datasoft, Inc. All Rights Reserved. *
;* *
;* Disassembly of "PAINT" routines. *
;*******************************************************************************
;* Disassembly by Andy McFadden, using 6502bench SourceGen v1.4. *
;* Last updated 2019/10/25. *
;*******************************************************************************
color_black = 0
color_purple = 1
color_green = 2
color_blue = 3
color_orange = 4
color_white = 5
work_buffer = $7000 ; work data area,$ from $7000-7fff
pageflg = $00
xc = $01
yc = $02
back = $03
evenc = $04
oddc = $05
screen_bit = $06
hptr = $07
cflag = $09
match_color = $10
add_coord_lo = $12
plot_coord_lo = $13
add_coord_ptr = $14 ; new coords are added at this point
plot_coord_ptr = $16 ; coords are read from this pointer and plotted
tmp = $18
HGR2 = $F3D8
HGR = $F3E2
flood_test:
jsr HGR2
lda #100
sta xc
sta yc
lda #color_blue
sta evenc
lda #color_white
sta oddc
jsr FILL
done:
jmp done
.align $100
;*******************************************************************************
;* FILL - flood fill with dither pattern. *
;* *
;* Uses a circular buffer at $7000-7fff to hold X/Y coordinates. The color of *
;* the pixel at the initial X/Y is used as the to-fill color. *
;* *
;* Start by adding the initial X/Y to the work buffer. We then loop, removing *
;* the first coordinate from the buffer and testing the color at that location.*
;* If it matches, we draw the pixel, and then add the four adjacent pixels to *
;* the list. Repeat until the list is empty. *
;* *
;* Warning: filling with the same color, e.g. filling a white area with white,*
;* will likely hang. *
;* *
;* On entry: *
;* $01 - X-coord *
;* $02 - Y-coord *
;* $04 - even color (0-5) *
;* $05 - odd color (0-5) *
;* *
;* Preserves X/Y registers. *
;*******************************************************************************
FILL:
txa
pha
tya
pha
lda #$80
sta back
jsr PLT ; get current color at X,Y
lda back
sta match_color ; this is the color we're replacing
lda #<work_buffer
sta add_coord_ptr
sta plot_coord_ptr
lda #>work_buffer
sta add_coord_ptr+1
sta plot_coord_ptr+1
lda xc ; put first point into work buffer
sta work_buffer
lda yc
sta work_buffer+1
ldy #$02 ; point next output past the X,Y we just added
sty add_coord_lo
ldy #$00
sty plot_coord_lo
; Get the next candidate coordinate.
FillLoop:
lda (plot_coord_ptr),Y
sta xc
iny
lda (plot_coord_ptr),Y
sta yc
iny
bne L6845 ; still on same page, branch
inc plot_coord_ptr+1 ; move to next page
lda plot_coord_ptr+1
cmp #$80 ;did we reach the end of the buffer?
bne L6845 ; no, keep going
lda #>work_buffer ; yes, reset it
sta plot_coord_ptr+1
L6845:
sty plot_coord_lo
lda #$80
sta back
jsr PLT ; get screen pixel color
lda back
cmp match_color ; matching color?
bne L6873 ; no, don't plot
; The current pixel matches the color we want to replace. Plot a pixel and add
; the four adjacent pixels to the work list.
jsr DITHER ; plot pixel with dither colors
inc xc
jsr AddCoord ; X+1,Y
dec xc
inc yc
jsr AddCoord ; X,Y+1
dec xc
dec yc
jsr AddCoord ; X-1,Y
inc xc
dec yc
jsr AddCoord ; X-1,Y-1
inc yc
L6873:
ldy plot_coord_lo ; have we reached the end?
cpy add_coord_lo
bne FillLoop ; low part differs, continue
lda plot_coord_ptr+1
cmp add_coord_ptr+1
bne FillLoop ; high part differs, continue
pla ; done!
tay
pla
tax
rts
AddCoord:
lda yc ; check Y-coord
cmp #255 ; off top of screen?
beq L68CA ; yes, ignore
cmp #192 ; off bottom of screen?
beq L68CA ; yes, ignore
lda xc ; check X-coord
cmp #$ff ; off left of screen?
beq L68CA ; yes, ignore
cmp #140 ; off right of screen?
beq L68CA ; yes, ignore
; Looks good, add X,Y to list.
; Note add_coord_ptr is always $xx00; the low byte is in add_coord_lo.
ldy add_coord_lo
sta (add_coord_ptr),Y
iny
lda yc
sta (add_coord_ptr),Y
iny
sty add_coord_lo
lda add_coord_ptr+1
sta tmp
cpy #$00 ; did we advance to next page?
bne L68B8 ; no, continue
inc add_coord_ptr+1 ; yes, advance
lda add_coord_ptr+1
cmp #(>work_buffer)+16 ; did we reach end of work area?
bne L68B8 ; no, still good
lda #>work_buffer ; yes, wrap around
sta add_coord_ptr+1
L68B8:
cpy plot_coord_lo ; did we run into the "write" ptr?
bne L68CA ; no
lda plot_coord_ptr+1 ; check the high byte
cmp add_coord_ptr+1
bne L68CA ;still no
dec add_coord_lo ; whoops; back up, discarding what we just added
dec add_coord_lo
lda tmp ; restore previous high byte
sta add_coord_ptr+1
L68CA:
rts
.align $100
DITHER:
jmp DITHER1
PLT:
jmp PLT1 ; external entry point
;*******************************************************************************
;* DITHER - plot a point with dithered colors. *
;* *
;* On entry: *
;* *
;* $00 - hi-res page (zero for page 1, nonzero for page 2) *
;* $01 - X coordinate [0,139] *
;* $02 - Y coordinate [0,191] *
;* $04 - even color value *
;* $05 - odd color value *
;* *
;* Preserves X/Y registers. *
;*******************************************************************************
;Clear variables
DITHER1:
txa
pha
lda yc ; start with the Y-coord
ldx evenc ; check the even color
beq L691A ; black, use checkerboard
cpx #color_white ; white
beq L691A ; yes, use checkerboard pattern
ldx oddc ; check the odd color
beq L691A ; black, use checkerboard
cpx #color_white ; white?
bne L691C ; yes, use checkerboard
L691A:
eor xc ; factor in the X coord to get checkerboard
L691C:
and #$01 ; only low bit matters
tax ; X=0 or 1
lda evenc,X ; load evenc or oddc
sta back ; set as color to draw
jmp Plt2
;*******************************************************************************
;* PLT - plot a point and return the current color. *
;* *
;* On entry: *
;* *
;* $00 = hi-res page (zero for page 1, nonzero for page 2) *
;* $01 = X-coord [0,139] *
;* $02 = Y-coord [0,191] *
;* $03 = $80=no plot, 0-5=color to draw *
;* *
;* On exit: *
;* $03 = screen color (0-5) (will be the new color if we're in draw mode) *
;* *
;* Preserves X/Y registers. *
;*******************************************************************************
PLT1:
txa
pha
Plt2:
tya
pha
jsr SetRowBase ; set $07-08 as hi-res pointer
ldx back ; get color
bmi L693B ; not drawing, branch
lda color_flag_0,X ; get color flags for the two bits
sta cflag
lda color_flag_1,X
sta cflag+1
L693B:
ldx xc
ldy div7_tab,X ; get byte offset
lda bit_tab,X ; get bit offset (low bit of pair)
sta screen_bit
; We want to read/write two hi-res bits, so we loop through here twice.
ldx #$00 ; first bit
BitLoop:
lda screen_bit
bit back ; are we writing?
bpl PlotWrite ; yes, branch
; Just reading the screen.
and (hptr),Y ; test screen bit
beq BitLoopBottom ; not set
txa ; 0 or 1
sec ; will add +1 or +2
adc back ; so this sets bit 0 or bit 1
sta back
lda (hptr),Y ; check hi bit
bpl BitLoopBottom ; not set, branch
lda back ; set bit 2 if the hi-res pixel's high bit was set
ora #$04
sta back
bne BitLoopBottom
; Draw the pixel.
PlotWrite:
eor #$ff ; reverse screen bit to form mask
and (hptr),Y ; AND with screen data
sta (hptr),Y ; store, clearing previous value at that bit
lda cflag,X ; get color flag 0 or 1
beq BitLoopBottom ; zero, don't need to set pixel or high bit
lda screen_bit ; nonzero, set the appropriate bit in the pixel
ora (hptr),Y
sta (hptr),Y
lda cflag ; is it black or white?
cmp cflag+1 ; (want black/white to match hi bit of adjacent color)
beq BitLoopBottom ; yes, leave high bit alone
lda (hptr),Y ; not black or white, so we need to set high bit
and #$7f ; clear whatever's there now
sta (hptr),Y
lda cflag,X ; get high bit from color flag
and #$80
ora (hptr),Y
sta (hptr),Y ; set that on the screen
BitLoopBottom:
inx
cpx #$02 ; have we done it twice?
beq BitLoopDone ; yes, bail
asl screen_bit ; no, shift screen bit to next position
bpl BitLoop ; didn't shift into high bit, loop
iny ; shifted into high bit, move on to next byte
lda #$01 ; and reset bit to low bit
sta screen_bit
bne BitLoop ; (always)
BitLoopDone:
lda back ; were we writing?
bpl L69A3 ; yes, bail
and #$07 ; no, do a color lookup
tax
lda bits_to_color,X ; convert 00000HBA to 0-5
sta back
L69A3:
pla
tay
pla
tax
rts
;
; Sets $07-08 as the hi-res base pointer for the row in "yc".
;
SetRowBase:
ldy yc
lda ytable_lo,Y
sta hptr
lda pageflg ; 0 for page 1, nonzero for page 2
beq L69D2
lda #$60 ; configure for page 2
L69D2:
eor ytable_hi,Y
sta hptr+1
rts
; These bytes have three possible values. They're used by PLT to figure out
; which bits to set on the hi-res screen for a given color (0-5).
;
; $00 = don't set this bit
; $7f = set this bit, clear high bit of byte
; $ff = set this bit, set high bit of byte
;
; Each hi-res color (in our 140x192 screen) requires two bits per pixel. One
; bit comes from each table.
color_flag_0:
.byte $00,$7f,$00,$ff,$00,$ff
color_flag_1:
.byte $00,$00,$7f,$00,$ff,$ff
;
; Converts a bit pattern to a color, 0-5.
;
; Index is a 3-bit value 00000HBA, where A is set if the first bit of the hi-res
; pixel was set, B is set if the second bit of the hi-res pixel was set, and H
; is set if the high bit of at least one of the bytes with a pixel was set.
; (Remember that we're treating the screen as being 140 pixels across, so it's
; two bits per pixel.)
bits_to_color:
.byte color_black
.byte color_purple
.byte color_green
.byte color_white
.byte color_black
.byte color_blue
.byte color_orange
.byte color_white
.align $100
; Hi-res row base address, low byte.
ytable_lo:
.byte $00,$00,$00,$00,$00,$00,$00,$00,$80,$80,$80,$80,$80,$80,$80,$80
.byte $00,$00,$00,$00,$00,$00,$00,$00,$80,$80,$80,$80,$80,$80,$80,$80
.byte $00,$00,$00,$00,$00,$00,$00,$00,$80,$80,$80,$80,$80,$80,$80,$80
.byte $00,$00,$00,$00,$00,$00,$00,$00,$80,$80,$80,$80,$80,$80,$80,$80
.byte $28,$28,$28,$28,$28,$28,$28,$28,$a8,$a8,$a8,$a8,$a8,$a8,$a8,$a8
.byte $28,$28,$28,$28,$28,$28,$28,$28,$a8,$a8,$a8,$a8,$a8,$a8,$a8,$a8
.byte $28,$28,$28,$28,$28,$28,$28,$28,$a8,$a8,$a8,$a8,$a8,$a8,$a8,$a8
.byte $28,$28,$28,$28,$28,$28,$28,$28,$a8,$a8,$a8,$a8,$a8,$a8,$a8,$a8
.byte $50,$50,$50,$50,$50,$50,$50,$50,$d0,$d0,$d0,$d0,$d0,$d0,$d0,$d0
.byte $50,$50,$50,$50,$50,$50,$50,$50,$d0,$d0,$d0,$d0,$d0,$d0,$d0,$d0
.byte $50,$50,$50,$50,$50,$50,$50,$50,$d0,$d0,$d0,$d0,$d0,$d0,$d0,$d0
.byte $50,$50,$50,$50,$50,$50,$50,$50,$d0,$d0,$d0,$d0,$d0,$d0,$d0,$d0
.align $100
; Hi-res row base address, high byte.
ytable_hi:
.byte $20,$24,$28,$2c,$30,$34,$38,$3c,$20,$24,$28,$2c,$30,$34,$38,$3c
.byte $21,$25,$29,$2d,$31,$35,$39,$3d,$21,$25,$29,$2d,$31,$35,$39,$3d
.byte $22,$26,$2a,$2e,$32,$36,$3a,$3e,$22,$26,$2a,$2e,$32,$36,$3a,$3e
.byte $23,$27,$2b,$2f,$33,$37,$3b,$3f,$23,$27,$2b,$2f,$33,$37,$3b,$3f
.byte $20,$24,$28,$2c,$30,$34,$38,$3c,$20,$24,$28,$2c,$30,$34,$38,$3c
.byte $21,$25,$29,$2d,$31,$35,$39,$3d,$21,$25,$29,$2d,$31,$35,$39,$3d
.byte $22,$26,$2a,$2e,$32,$36,$3a,$3e,$22,$26,$2a,$2e,$32,$36,$3a,$3e
.byte $23,$27,$2b,$2f,$33,$37,$3b,$3f,$23,$27,$2b,$2f,$33,$37,$3b,$3f
.byte $20,$24,$28,$2c,$30,$34,$38,$3c,$20,$24,$28,$2c,$30,$34,$38,$3c
.byte $21,$25,$29,$2d,$31,$35,$39,$3d,$21,$25,$29,$2d,$31,$35,$39,$3d
.byte $22,$26,$2a,$2e,$32,$36,$3a,$3e,$22,$26,$2a,$2e,$32,$36,$3a,$3e
.byte $23,$27,$2b,$2f,$33,$37,$3b,$3f,$23,$27,$2b,$2f,$33,$37,$3b,$3f
.align $100
; Maps X coordinate [0,139] to bit.
bit_tab:
.byte $01,$04,$10,$40,$02,$08,$20,$01,$04,$10,$40,$02,$08,$20,$01,$04
.byte $10,$40,$02,$08,$20,$01,$04,$10,$40,$02,$08,$20,$01,$04,$10,$40
.byte $02,$08,$20,$01,$04,$10,$40,$02,$08,$20,$01,$04,$10,$40,$02,$08
.byte $20,$01,$04,$10,$40,$02,$08,$20,$01,$04,$10,$40,$02,$08,$20,$01
.byte $04,$10,$40,$02,$08,$20,$01,$04,$10,$40,$02,$08,$20,$01,$04,$10
.byte $40,$02,$08,$20,$01,$04,$10,$40,$02,$08,$20,$01,$04,$10,$40,$02
.byte $08,$20,$01,$04,$10,$40,$02,$08,$20,$01,$04,$10,$40,$02,$08,$20
.byte $01,$04,$10,$40,$02,$08,$20,$01,$04,$10,$40,$02,$08,$20,$01,$04
.byte $10,$40,$02,$08,$20,$01,$04,$10,$40,$02,$08,$20
.align $100
; Maps X coordinate [0,$139] to byte [0,$39].
div7_tab:
.byte $00,$00,$00,$00,$01,$01,$01,$02,$02,$02,$02,$03,$03,$03,$04,$04
.byte $04,$04,$05,$05,$05,$06,$06,$06,$06,$07,$07,$07,$08,$08,$08,$08
.byte $09,$09,$09,$0a,$0a,$0a,$0a,$0b,$0b,$0b,$0c,$0c,$0c,$0c,$0d,$0d
.byte $0d,$0e,$0e,$0e,$0e,$0f,$0f,$0f,$10,$10,$10,$10,$11,$11,$11,$12
.byte $12,$12,$12,$13,$13,$13,$14,$14,$14,$14,$15,$15,$15,$16,$16,$16
.byte $16,$17,$17,$17,$18,$18,$18,$18,$19,$19,$19,$1a,$1a,$1a,$1a,$1b
.byte $1b,$1b,$1c,$1c,$1c,$1c,$1d,$1d,$1d,$1e,$1e,$1e,$1e,$1f,$1f,$1f
.byte $20,$20,$20,$20,$21,$21,$21,$22,$22,$22,$22,$23,$23,$23,$24,$24
.byte $24,$24,$25,$25,$25,$26,$26,$26,$26,$27,$27,$27
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