Re: 6502 assembler for 6502?
Posted: Tue Aug 29, 2023 2:30 am
https://github.com/pebmeister/Pasm
my opensource Assembler.
supports labels, local labels, -+ labels, macros
example basic graphics wedge I wrote using it
my opensource Assembler.
supports labels, local labels, -+ labels, macros
example basic graphics wedge I wrote using it
Code: Select all
; written by Paul Baxter
.inc "macros.asm"
.inc "pagezero.asm"
.inc "basic.asm"
.inc "kernal.asm"
;********************************************
BITMAPBASE = 4096 * 2
COLORBASE = 1024
; Some zero page has multiple uses
XCOORD = LINNUM ; DO NOT CHANGE set by basic parse routine
LOC = UNUSED2
DX = BITTS
DY = BITCI
XS = RIDATA
YS = RIPRTY + 1
K1 = OLDLIN
K2 = FREKZP
_D = FREKZP + 2
_X = LINNUM
_Y = RESHO
_CMD = FREKZP
TMP = UNUSED2 + 2
CMDTABLE = UNUSED2
BASICTEXT = RESHO
CMDJUMP = UNUSED2
WEDGE_TMP = LINNUM
CURLOC = BITTS
CURLOCB = BITCI
COUNTER = UNUSED2
MASKB = RESHO
MASKE = FREKZP
YCOUNT = FREKZP + 2
YCOL = PTR1
XD = PTR1
COLORPTR = TMPDATA
X0 = FORPNT
X1 = OPPTR
Y0 = PRTY
Y1 = MSGFLG
R = FREKZP
PK = OLDLIN
CURX = BITCI
CURY = FREKZP + 2
CX = RIDATA
CY = RIPRTY + 1
XDIST = INDEX
YDIST = INDEX + 2
StartX = DSCPNT
YMAX = OLDLIN
XMAX = BLNCT
SRCM = BSOUR
;************************************
; The values below are globals must
; not be modified by basic
; The values below will work if you do
; not use tape
;************************************
CIRJUMP = CNTDN
IGONE_SV = BSOUR
COLOR = CMP0
.org $C000
;********************************************
;* *
;* INSTALL *
;* *
;* Installs Basic Wedge *
;* *
;********************************************
INSTALL
php
cli
;
; install wedge
;
MOVE16 IGONE, IGONE_SV
MOVE16I IGONE, WEDGE
; fix basic pointers
MOVE16I TXTTAB,2049
MOVE16I STREND,2051
; clear first 5 bytes of BASIC
; same as doing a NEW
lda #0
ldy #5
-
sta (TXTTAB),y
dey
bne -
sta SRCM
lda #3
sta COLOR
plp
jmp WARM
;********************************************
;* *
;* WEDGE *
;* *
;* TXTPTR - pointer to BASIC text *
;* IGONE - jump vector back to BASIC *
;* *
;********************************************
WEDGE
; move the address of the table to pagezero
MOVE16I CMDTABLE, _Commands
MOVE16 TXTPTR, BASICTEXT
; init _cmd INDEX TO 0
; also init y to 1
ldy #0
sty _CMD
iny
@SkipSpace
lda (BASICTEXT),y
cmp #' '
bne @MatchCmd
INC16 BASICTEXT
jmp @SkipSpace
@MatchCmd
lda (BASICTEXT),y
; if it's a null then its the end of a command
beq @NextCmd
; if its a colon let basic handle it
cmp #':'
beq @NextCmd
; compare to the table entry
cmp (CMDTABLE),y
bne @NextCmd
; get the next char
iny
jmp @MatchCmd
; -------------------------------------
@NextCmd
lda (CMDTABLE),y
beq @ExecuteCmd
inc _CMD
ldy #0
@CmdTableInc
INC16 CMDTABLE
lda (CMDTABLE),y
bne @CmdTableInc
iny
lda (CMDTABLE),y
beq @ExitToBasic
INC16 CMDTABLE
iny
jmp @MatchCmd
; -------------------------------------
@ExecuteCmd
dey
sty WEDGE_TMP
lda #0
sta WEDGE_TMP + 1
ADD16 BASICTEXT, WEDGE_TMP, BASICTEXT
MOVE16 BASICTEXT, TXTPTR
; multiply _CMD by two to get jump offset
lda _CMD
asl
; move offset to x
; move jump entry to
; pagezero jump
tax
lda _Jump,x
sta CMDJUMP
lda _jump + 1,x
sta CMDJUMP + 1
jsr @Jump
@Cleanup
jsr CHRGOT
beq @Exit2
jsr CHRGET
jmp @Cleanup
@Exit2
DEC16 TXTPTR
@ExitToBasic
jmp (IGONE_SV)
@Jump
; execute the command
jmp (CMDJUMP)
; -------------------------------------
; each command
; 1st byte space or 0 for end of table
; 0 terminates the string entry
; -------------------------------------
_Commands
.byte " H", FRE_TOK, "CT", 0
.byte " HLINE", 0
.byte " HPLOT", 0
.byte " HRECT", 0
.byte " HGROFF", 0
.byte " HFCOL", 0
.byte " HBCOL", 0
.byte " HCLS", 0
.byte " HGR", 0
.byte " HCIR", 0
.byte " HFCIR", 0
.byte " HSRCMODE", 0
.byte 0
; offsets to commands
_Jump
.word HGRFillRect
.word HGRLine
.word HGRPlot
.word HGRRect
.word HGROff
.word HGRFColor
.word HGRBColor
.word HGRCls
.word HGROn
.word HGRCircle
.word HGRFillCircle
.word HSourceMode
;********************************************
;* *
;* HGROn *
;* *
;* Enter HGR Mode *
;* *
;********************************************
HGROn
; hires on
lda $D018
ora #%00001000
sta $D018
lda $D011
ora #%00100000
sta $D011
rts
;********************************************
;* *
;* HGRCls *
;* *
;* Clear graphics bitmap and colors *
;* *
;********************************************
HGRCls
ldx #0
lda #0
@_ClrLoop
sta BITMAPBASE + ($0100 * 0),x
sta BITMAPBASE + ($0100 * 1),x
sta BITMAPBASE + ($0100 * 2),x
sta BITMAPBASE + ($0100 * 3),x
sta BITMAPBASE + ($0100 * 4),x
sta BITMAPBASE + ($0100 * 5),x
sta BITMAPBASE + ($0100 * 6),x
sta BITMAPBASE + ($0100 * 7),x
sta BITMAPBASE + ($0100 * 8),x
sta BITMAPBASE + ($0100 * 9),x
sta BITMAPBASE + ($0100 * 10),x
sta BITMAPBASE + ($0100 * 11),x
sta BITMAPBASE + ($0100 * 12),x
sta BITMAPBASE + ($0100 * 13),x
sta BITMAPBASE + ($0100 * 14),x
sta BITMAPBASE + ($0100 * 15),x
sta BITMAPBASE + ($0100 * 16),x
sta BITMAPBASE + ($0100 * 17),x
sta BITMAPBASE + ($0100 * 18),x
sta BITMAPBASE + ($0100 * 19),x
sta BITMAPBASE + ($0100 * 20),x
sta BITMAPBASE + ($0100 * 21),x
sta BITMAPBASE + ($0100 * 22),x
sta BITMAPBASE + ($0100 * 23),x
sta BITMAPBASE + ($0100 * 24),x
sta BITMAPBASE + ($0100 * 25),x
sta BITMAPBASE + ($0100 * 26),x
sta BITMAPBASE + ($0100 * 27),x
sta BITMAPBASE + ($0100 * 28),x
sta BITMAPBASE + ($0100 * 29),x
sta BITMAPBASE + ($0100 * 30),x
inx
bne @_ClrLoop
@_ClrLoop2
sta BITMAPBASE + ($0100 * 31),x
inx
cpx #8000-31*255
bne @_ClrLoop2
jmp ClearColor
;********************************************
;
; HGRBColor
; Set HGR Background COLOR
;
;********************************************
HGRBColor
jsr GETBYTC
txa
and #$0F
sta TMP
lda COLOR
and #$F0
ora TMP
sta COLOR
rts
;********************************************
;
; HGRFColor
; Set HGR Forground COLOR
;
;********************************************
HGRFColor
jsr GETBYTC
txa
and #$0F
asl
asl
asl
asl
sta TMP
lda COLOR
and #$0F
ora TMP
sta COLOR
rts
;********************************************
;
; ClearColor
; clear Color memory
;
;********************************************
ClearColor
lda COLOR
ldx #0
@Clear3
sta COLORBASE + ($0100 * 0),x
sta COLORBASE + ($0100 * 1),x
sta COLORBASE + ($0100 * 2),x
inx
bne @Clear3
@Clear4
sta COLORBASE + ($0100 * 3),x
inx
cpx #1000-3*255
bne @Clear4
rts
;********************************************
;
; HGROff
;
;********************************************
HGROff
; hires off
lda $D018
and #~ %00001000
sta $D018
lda $D011
and #~ %00100000
sta $D011
rts
;********************************************
;
; HGRPlot
;
; Parses Basic Text and plot a point
;
; Calls
; GETNUM $B7EB
; _Plot
;
; HGRPlot x,y
;
;********************************************
HGRPlot
INC16 TXTPTR
jsr GETNUM ; get address in $14/$15 y next integer at X
jsr RangeCheckXY
;********************************************
;
; _Plot
; XCOORD IN 2 byte x coordinate
; X register IN y coordinate
;
; Plot a single point
; Must not be called Plot because it collides with Kernal
; PLOT = $E50A
;
; Calls
; CalcPlot
;
;********************************************
_Plot
stx YCOL
MOVE16 XCOORD, COLORPTR
; Calc Bitmap location
jsr CalcPlot
ldy #0
lda (LOC),y
ora MaskStart,x
sta (LOC),y
; Calc color map location
jsr CalcColorByte
lda COLOR
ldy #0
sta (COLORPTR),y
rts
;********************************************
;
; CalcColorByte
;
; COLORPTR = x location
; YCOL = y location
;
; Warning:
; Destroys both COLORPTR and YCOL
;********************************************
CalcColorByte
lda #0
sta YCOL + 1
RSHIFT16 COLORPTR, 3 ; COLORPTR = x / 8
RSHIFT16 YCOL, 3 ; ycol int(y/8)*40
MULT40 YCOL
ADD16 COLORPTR, YCOL, COLORPTR ; COLORPTR = COLORPTR + ycol
ADD16I COLORPTR, COLORBASE, COLORPTR ; COLORPTR = COLORPTR + COLORBASE
rts
;********************************************
;
; CalcPlot
; XCOORD IN 2 byte x coordinate
; X reg IN y coordinate
;
; LOC OUT byte of bitemap
; X reg OUT bit of bitmap
;
;********************************************
CalcPlot
; 320*int(y/8)=32*[8*int(y/8)] + 8*[8*int(y/8)]
lda #0
sta LOC
txa ;X register has Y coordinate
lsr
lsr
lsr
sta LOC + 1 ; high-byte of 32*8*int(y/8)
;-------------------------------------------------
lsr
ror LOC
lsr
ror LOC ; low byte of 8*[8*int(y/8)]
;-------------------------------------------------
adc LOC + 1
adc #>BITMAPBASE
sta LOC+1 ; high byte of memory=BITMAPBASE + 320*int(y/8)
;-------------------------------------------------
lda XCOORD
and #%11111000 ; 8*int(x/8)
adc LOC
sta LOC ; set address memory block of bytes
;-----------------------------------------------
lda XCOORD + 1
adc LOC + 1
sta LOC + 1
;-----------------------------------------------
txa
and #%00000111 ; int(y/7), byte offset inside bLOCk
tay
;-----------------------------------------------
lda XCOORD
and #%00000111 ; int(x/7), bit inside byte
tax
; add y to LOC
sty TMP
lda #0
sta TMP + 1
ADD16 TMP, LOC, LOC
;-----------------------------------------------
; given: x (0 - 7)
; x = 7 - x
MOVE8I TMP, 7
stx TMP + 1
SUB8 TMP, TMP + 1, TMP
ldx TMP
rts
;********************************************
;
; HGRLine
;
; This routine draws a line
;
; Calls:
; GETNUM
; _Line
;
;********************************************
HGRLine
INC16 TXTPTR
jsr GETNUM ; get address in LINNUM $14/$15 y next integer at X
jsr RangeCheckXY
stx Y0
MOVE16 XCOORD, X0
jsr CHKCOM
jsr GETNUM ; get address in LINNUM $14/$15 y next integer at X
jsr RangeCheckXY
stx Y1
MOVE16 XCOORD, X1
;********************************************
;
; _Line
;
; XO - start X
; Y0 - start Y
; X1 - end X
; Y1 - end Y
;
; optimized for horizontal lines
;********************************************
_Line
ldx Y0
cpx Y1
bne NotHorizontal
;---------------------------------------
lda X0 + 1
cmp X1 + 1
bcc _Line2
;---------------------------------------
lda X0
cmp X1
bcc _Line2
;---------------------------------------
MOVE16 X1, XCOORD
SUB16 X0, X1, XDIST
jmp CalcPlotHLine
;********************************************
;* *
;* _Line2 *
;* Draw Horizontal line *
;* X0 must be less than X1 *
;* *
;* XO - start X *
;* Y0 - start Y *
;* X1 - end X *
;* Y1 - end Y *
;* *
;********************************************
_Line2
MOVE16 X0,XCOORD
SUB16 X1, X0, XDIST
;---------------------------------------
CalcPlotHLine
MOVE16 XCOORD, COLORPTR
MOVE8 Y0, YCOL
ldx Y0
; Calculate 1st byte and bit of BitMap
jsr CalcPlot
MOVE16 LOC, CURLOC
; Draw the horizontal Line
jsr HGRHorizontalLine
; Set the Lines color memory
jmp HCPlotLine
;---------------------------------------
NotHorizontal
MOVE8I DY+1, 0
; DX% = abs(x0%-x1%)
; set XS to add or substract
;
lda X0 + 1
cmp X1 + 1
bcc @X1_larger
lda X0
cmp X1
bcc @X1_larger
;-------------------------------------------
SUB16 X0, X1, DX
lda #1
bne @Calc_DY
@X1_larger
SUB16 X1, X0, DX
lda #0
@Calc_DY
sta XS
;-------------------------------------------
; DY = abs(y0% - y1%)
; set YS to add or subtract
lda Y0
cmp Y1
bcc @Y1_larger
SUB8 Y0, Y1, DY
lda #1
bne @Done_calc
@Y1_larger
SUB8 Y1, Y0, DY
lda #0
@Done_calc
sta YS
;-------------------------------------------
; y is 8 bit so if this is not 0 its larger
lda DX + 1
; using reverse logic because branch is > 128
beq @DX_DY_compare
jmp @DX_larger
@DX_DY_compare
lda DX
cmp DY
; using reverse logic because branch is > 128
bcc @DY_larger
jmp @DX_larger
@DY_larger
; K1 = 2 * DX
MOVE16 DX, K1
LSHIFT16 K1, 1
; K2%=2*(DX%-DY%)
SUB16 DX, DY, K2
LSHIFT16 K2, 1
; d%=K1%-DY
SUB16 K1, DY, _D
;-------------------------------------------
; y=y0%
lda Y0
sta _Y
; x = x0
MOVE16 X0, _X
;-------------------------------------------
; for y=y0% to y1% step YS%
@Y_loop_start
lda _Y
cmp Y1
bne @Y_loop_continue
jmp @Exitline
@Y_loop_continue
; plot
ldx _Y
jsr _Plot
; -------------------------------------------
; if d%<0 then y_loop_d0_minus
lda _D + 1
bmi @Y_loop_d0_minus
; x = x + XS
lda XS
beq @Y_loop_X_inc
DEC16 _X
jmp @Y_loop_add_d
@Y_loop_X_inc
INC16 _X
@Y_loop_add_d
; d% = d% + K2%
ADD16 _D, K2, _D
jmp @Y_loop_next
; -------------------------------------------
@y_loop_d0_minus
; d%=d%+K1%
ADD16 _D, K1, _D
; -------------------------------------------
@y_loop_next
; y = y + YS
lda YS
beq @Y_loop_next_inc
DEC8 _Y
jmp @Y_loop_start
@Y_loop_next_inc
inc _Y
jmp @Y_loop_start
; -------------------------------------------
@DX_larger
; K1 = 2 * DY
MOVE16 DY, K1
LSHIFT16 K1, 1
; K2%=2*(DY%-DX%)
SUB16 DY, DX, K2
LSHIFT16 K2, 1
; d%=K1%-DX
SUB16 K1, DX, _D
; -------------------------------------------
; y=y0%
lda Y0
sta _Y
; x = x0
MOVE16 X0, _X
;-------------------------------------------
; for x=x0% to x1% step XS%
@X_loop_start
lda _X + 1
cmp X1 + 1
bne @X_loop_continue
lda _X
cmp X1
bne @X_loop_continue
jmp @Exitline
@X_loop_continue
; plot
ldx _Y
jsr _Plot
; -------------------------------------------
; if d%<0 then x_loop_d0_minus
lda _D + 1
bmi @X_loop_d0_minus
; y = y + YS
lda YS
beq @X_loop_Y_inc
DEC8 _Y
jmp @X_loop_add_d
@X_loop_Y_inc
inc _Y
@X_loop_add_d
; d% = d% + K2%
ADD16 _D, K2, _D
jmp @X_loop_next
@X_loop_d0_minus
; d%=d%+K1%
ADD16 _D, K1, _D
; -------------------------------------------
@X_loop_next
; x = x + XS
lda XS
beq @x_loop_next_inc
DEC16 _X
jmp @X_loop_start
@X_loop_next_inc
INC16 _X
jmp @X_loop_start
; -------------------------------------------
@Exitline
ldx _Y
jmp _Plot
;********************************************
;
; HCPlotLine
;
; COLORPTR - X start
; XDIST - X Distance
; YCOL - Y Location
;
; Plot color memory line
;
;********************************************
HCPlotLine
; Save start, distance and end
MOVE16 COLORPTR, StartX
; get the start byte
jsr CalcColorByte
MOVE16 XDIST, XD
INC16 XD
lda StartX
and #%00000111
beq @InitLoop
; -------------------------------------------
; subtract 8 - N from XD
sta TMP
sec
lda #8
sbc TMP
sta TMP
SUB168 XD, TMP, XD
; -------------------------------------------
; set color Memory
ldy #0
lda COLOR
sta (COLORPTR),y
INC16 COLORPTR
; -------------------------------------------
; set y to 0
@InitLoop
ldy #0
@Loop
lda XD + 1 ; check that there is more to process
; check high byte first
bne @LoopContinue
lda XD ; check low byte is at least 8 pixels
cmp #08
bcc @LoopExit
; -------------------------------------------
@LoopContinue
; set color Memory
lda COLOR
sta (COLORPTR),y
INC16 COLORPTR
; subtract 8 from distance
SUB16I XD, 8, XD
jmp @Loop
; -------------------------------------------
@LoopExit
; check for last byte
lda XD
beq @Exit
; set color Memory
lda COLOR
sta (COLORPTR),y
@Exit
rts
;********************************************
;
; HGRHorizontalLine
;
; CURLOC IN POINTER to bitmap byte
; XDIST IN x distance
; X register IN bit in first byte of bitmap
;
;********************************************
HGRHorizontalLine
; If there are 8 bits to set then we can use bytes
; instead of using bits
;
; set the first potentially partial byte
; set x to number of bits in first byte
lda XDIST + 1 ; load HI byte
bne @HFirstByte ; if its not 0 then it > 8 bits
cpx XDIST ; see if bit is within distance
bcc @HFirstByte ; yes so we leave x unmodified
ldx XDIST ; set x to XDIST
jmp @HLastByte
;----------------------------------------------
@HFirstByte
stx COUNTER ; save in counter
lda #0 ; zero out high byte
sta COUNTER + 1
;----------------------------------------------
; substract COUNTER from distance of first byte
; and save in COUNTER
SUB16 XDIST, COUNTER, COUNTER
;----------------------------------------------
; Plot the first byte
ldy #0
lda (CURLOC),y
ora MaskData,x
sta (CURLOC),y
;----------------------------------------------
; Horizontal Line - Loop
; here we plot bytes instead of bits
;----------------------------------------------
@HLoop1
; test that there are at least 8 bits to plot
lda COUNTER + 1 ; get the high byte
bne @HLoop_Cont ; if its set there are more than 8 bits left
lda COUNTER ; load lo byte
cmp #8 ; compare it to 8
beq @HLoop1End ; if it is equal then go to the last byte
bcs @HLoop_Cont ; continue if > 8
jmp @HLoop1End ; less than 8 go to last byte
; -------------------------------------------
@HLoop_Cont ; add 8 to current pointer
ADD16I CURLOC, 8, CURLOC
lda #$FF ; load a with FF
sta (CURLOC),y ; store the byte
; Increrment COUNTER by 8
SUB16I COUNTER, 8, COUNTER
jmp @HLoop1 ; goto to byte loop
; -------------------------------------------
@HLoop1End
ldx COUNTER ; see if there are bits left
beq @HLoop1EXIT ; if no then exit
;----------------------------------------------
; Horizontal Lines Last Byte
;----------------------------------------------
ADD16I CURLOC, 8, CURLOC
@HLastByte
lda (CURLOC),y
ora MaskDataEnd,x
sta (CURLOC),y
@HLoop1EXIT
rts
;********************************************
;
; HGRFillRect
;
;********************************************
HGRFillRect
INC16 TXTPTR ; advance basic textptr
; get the start position, xdistance and ydistance
jsr GETNUM ; get address in $14/$15 y next integer at X
jsr RangeCheckXY
stx Y0
MOVE16 XCOORD, X0
jsr CHKCOM
jsr GETNUM ; get address in $14/$15 y next integer at X
jsr RangeCheckXY
stx YDIST
MOVE16 XCOORD, XDIST
;********************************************
;
; HFillRect
;
; X0 - xstart
; Y0 - ystart
; XDIST - xdistance
; YDIST - ydistance
;
;********************************************
HFillRect
ADD8 Y0, YDIST, YMAX
ADD16 X0, XDIST, X1
lda Y0
; -------------------------------------------
@YLOOP
sta Y1
jsr _Line2
ldy Y0
cpy YMAX
beq @Exit
iny
sty Y0
jmp @YLOOP
@Exit
rts
;********************************************
;
; HGRRect
;
; Parse Basic text for
; x, y, xdist, ydist
;
; Call HRect for to draw rectangle
;
;********************************************
HGRRect
INC16 TXTPTR ; advance basic textptr
; get the start position, xdistance and ydistance
jsr GETNUM ; get address in $14/$15 y next integer at X
jsr RangeCheckXY
stx Y0
MOVE16 XCOORD, X0
jsr CHKCOM
jsr GETNUM ; get address in $14/$15 y next integer at X
jsr RangeCheckXY
stx YDIST
MOVE16 XCOORD, XDIST
;********************************************
;
; HRect
;
; X0 - x start
; Y0 - y start
; XDIST - x distance
; YDIST - y distance
;********************************************
HRect
ADD16 X0, XDIST, XMAX
ADD8 Y0, YDIST, YMAX
; ------------------------------
;
; Top Horizontal Line
;
; ------------------------------
MOVE16 XMAX, X1
MOVE8 Y0, Y1
pha
jsr _Line2
; ------------------------------
;
; Bottom Horizontal Line
;
; ------------------------------
lda YMAX
sta Y0
sta Y1
jsr _Line2
; ------------------------------
;
; Left Vertical Line
;
; ------------------------------
MOVE16 X0, X1
pla
sta Y0
jsr _Line
; ------------------------------
;
; Right Vertical Line
;
; ------------------------------
MOVE16 XMAX, X0
MOVE16 X0, X1
jsr _Line
rts
;********************************************
;
; SetCircleJump
;
; set routine for circle to plot or fill
;
;********************************************
SetCircleJump
asl
tax
lda JumpTable, x
sta CIRJUMP
inx
lda JumpTable, x
sta CIRJUMP + 1
rts
;********************************************
;
; JumpCircle
;
; SetCircleJump MUST be called first
; This will fill or plot for circles
;
;********************************************
JumpCircle
jmp (CIRJUMP)
JumpTable
.word PlotCirclePixels
.word PlotFillCircle
;********************************************
;
; HGRFillCircle
;
; Fill a circle from BASIC
; x, y, radius
;
; Bresenham's algorithm
;
;*******************************************
HGRFillCircle
lda #1
jsr SetCircleJump
jmp HGRCircle2
;********************************************
;
; HGRFillCircle
;
; Fill a circle from asm
;
;*******************************************
HGRFillCircle2
lda #1
jsr SetCircleJump
jmp HGRCircle3
;********************************************
;
; HGRCircle
;
; Parse Basic text for
; x, y, radius
;
; Bresenham's algorithm
;
;********************************************
HGRCircle
lda #0
jsr SetCircleJump
HGRCircle2
INC16 TXTPTR ; advance basic textptr
; get the start position, xdistance and ydistance
jsr GETNUM ; get address in $14/$15 y next integer at X
stx CY
MOVE16 XCOORD, CX
jsr GETBYTC
stx R
jsr RangeCheckCircle
HGRCircle3
; pk = 3 - 2 * r;
lda #0
sta PK + 1
MOVE8 R, PK ; pk = r
LSHIFT16 PK,1 ; pk = r * 2
MOVE16I TMP, 3; ; tmp = 3
SUB16 TMP, PK, PK ; pk = tmp - pk
MOVE16I CURX, 0 ; x = 0
MOVE8 R, CURY ; y = r
; PlotPixels(x, y, xc, yc);
jsr JumpCircle
@StartWhile
; while (x < y)
lda CURX + 1
bne @ContinueWhile
lda CURX
cmp CURY
bcs @Exit
@ContinueWhile
; if (pk <= 0)
lda PK+1
bmi @PKLessEqualZero
bne @PKGreaterZero
lda PK
bne @PKGreaterZero
@PKLessEqualZero
; pk = pk + (4 * x) + 6;
MOVE16 CURX, TMP
LSHIFT16 TMP, 2
ADD16 PK, TMP, PK
ADD16I PK, 6, PK
;++x;
INC16 CURX
jmp @EndWhile
@PKGreaterZero
; pk = pk + (4 * (x - y)) + 10;
SUB168 CURX, CURY, TMP
LSHIFT16 TMP, 2
ADD16I TMP, 10, TMP
ADD16 PK, TMP, PK
; ++x;
INC16 CURX
; --y;
DEC8 CURY
@EndWhile
; PlotPixels(x, y, xc, yc);
jsr JumpCircle
jmp @StartWhile
@Exit
rts
;********************************************
;
; PlotCirclePixels
;
; plot circle pixels
;
;*******************************************
PlotCirclePixels
; PutPixel(CX - CURX, CY + CURY);
SUB16 CX, CURX, XCOORD
ADD8 CY, CURY, Y1
tax
jsr _Plot
;----------------------------------------------
; PutPixel(CX + CURX, CY + CURY);
ADD16 CX, CURX, XCOORD
ldx Y1
jsr _Plot
;----------------------------------------------
; PutPixel(CX - CURX, CY - CURY);
SUB16 CX, CURX, XCOORD
SUB8 CY, CURY, Y1
tax
jsr _Plot
;----------------------------------------------
; PutPixel(CX + CURX, CY - CURY);
ADD16 CX, CURX, XCOORD
ldx Y1
jsr _Plot
;----------------------------------------------
; PutPixel(CX - CURY, CY + CURX);
SUB168 CX, CURY, XCOORD
ADD8 CY, CURX, Y1
tax
jsr _Plot
;----------------------------------------------
; PutPixel(CX + CURY, CY + CURX);
ADD168 CX, CURY, XCOORD
ldx Y1
jsr _Plot
;----------------------------------------------
; PutPixel(CX - CURY, CY - CURX);
SUB168 CX, CURY, XCOORD
SUB8 CY, CURX, Y1
tax
jsr _Plot
;----------------------------------------------
; PutPixel(CX + CURY, CY - CURX);
ADD168 CX, CURY, XCOORD
ldx Y1
jmp _Plot
;********************************************
;
; PlotFillCircle
;
; fill circle pixels
;
;*******************************************
PlotFillCircle
; Line(CX - CURY, CY + CURX) to (CX + CURY, CY + CURX)
SUB168 CX, CURY, X0
ADD8 CY, CURX, Y0
ADD168 CX, CURY, X1
MOVE8 Y0, Y1
jsr _Line2
;----------------------------------------------
; Line (CX - CURY, CY - CURX) to (CX + CURY, CY - CURX)
SUB168 CX, CURY, X0
SUB8 CY, CURX, Y0
ADD168 CX, CURY, X1
MOVE8 Y0, Y1
jsr _Line2
;----------------------------------------------
; Line(CX - CURX, CY + CURY) to (CX + CURX, CY + CURY)
SUB16 CX, CURX, X0
ADD8 CY, CURY, Y0
ADD16 CX, CURX, X1
MOVE8 Y0, Y1
jsr _Line2
;----------------------------------------------
; Line(CX - CURX, CY - CURY) to (CX + CURX, CY - CURY)
SUB16 CX, CURX, X0
SUB8 CY, CURY, Y0
ADD16 CX, CURX, X1
MOVE8 Y0, Y1
jmp _Line2
;********************************************
;
; RangeCheckXY
;
; Check XCOORD and x range
;
;*******************************************
RangeCheckXY
cpx # 200
bcs RangeError
lda XCOORD + 1
beq @Exit
lda XCOORD
cmp # 320 - 256
bcs RangeError
@Exit
rts
RangeError
ldx # ILLEGALQUANITY
jmp ERROR
;********************************************
;
; RangeCheckCircle
;
; Range check Circle parameters
;
;*******************************************
RangeCheckCircle
lda CY
cmp R
bcc RangeError
adc R
tax
lda CX + 1
bne @CheckMax
lda CX
cmp R
bcc RangeError
@CheckMax
ADD168 CX,R,XCOORD
jmp RangeCheckXY
;********************************************
;
; HSourceMode
;
; Set source plotmode
;
;*******************************************
HSourceMode
jsr GETBYTC
stx SRCM
rts
;----------------------------------------------
MaskStart
.byte %00000001 ; 0
.byte %00000010 ; 1
.byte %00000100 ; 2
.byte %00001000 ; 3
.byte %00010000 ; 4
.byte %00100000 ; 5
.byte %01000000 ; 6
.byte %10000000 ; 7
MaskData
.byte %00000001 ; 0
.byte %00000011 ; 1
.byte %00000111 ; 2
.byte %00001111 ; 3
.byte %00011111 ; 4
.byte %00111111 ; 5
.byte %01111111 ; 6
.byte %11111111 ; 7
MaskDataEnd
.byte %00000000 ; 0
.byte %10000000 ; 1
.byte %11000000 ; 2
.byte %11100000 ; 3
.byte %11110000 ; 4
.byte %11111000 ; 5
.byte %11111100 ; 6
.byte %11111110 ; 7
.byte %11111111 ; 8