.byte 1 ; Number of screens available
.byte 8 ; System font X size
.byte 8 ; System font Y size
- .res 4, $00 ; Reserved for future extensions
-
-; Next comes the jump table. Currently all entries must be valid and may point
-; to an RTS for test versions (function not implemented). A future version may
-; allow for emulation: In this case the vector will be zero. Emulation means
-; that the graphics kernel will emulate the function by using lower level
-; primitives - for example ploting a line by using calls to SETPIXEL.
-
- .word INSTALL
- .word UNINSTALL
- .word INIT
- .word DONE
- .word GETERROR
- .word CONTROL
- .word CLEAR
- .word SETVIEWPAGE
- .word SETDRAWPAGE
- .word SETCOLOR
- .word SETPALETTE
- .word GETPALETTE
- .word GETDEFPALETTE
- .word SETPIXEL
- .word GETPIXEL
- .word LINE
- .word BAR
- .word CIRCLE
- .word TEXTSTYLE
- .word OUTTEXT
+ .word $100 ; Aspect ratio
+
+; Next comes the jump table. With the exception of IRQ, all entries must be
+; valid and may point to an RTS for test versions (function not implemented).
+
+ .addr INSTALL
+ .addr UNINSTALL
+ .addr INIT
+ .addr DONE
+ .addr GETERROR
+ .addr CONTROL
+ .addr CLEAR
+ .addr SETVIEWPAGE
+ .addr SETDRAWPAGE
+ .addr SETCOLOR
+ .addr SETPALETTE
+ .addr GETPALETTE
+ .addr GETDEFPALETTE
+ .addr SETPIXEL
+ .addr GETPIXEL
+ .addr LINE
+ .addr BAR
+ .addr TEXTSTYLE
+ .addr OUTTEXT
+ .addr 0 ; IRQ entry is unused
; ------------------------------------------------------------------------
; Data.
Y1 := ptr2
X2 := ptr3
Y2 := ptr4
-RADIUS := tmp1
ROW := tmp2 ; Bitmap row...
COL := tmp3 ; ...and column, both set by PLOT
DX: .res 2
DY: .res 2
-; Circle routine stuff, overlaid by BAR variables
-X1SAVE:
-CURX: .res 1
-CURY: .res 1
-Y1SAVE:
-BROW: .res 1 ; Bottom row
-TROW: .res 1 ; Top row
-X2SAVE:
-LCOL: .res 1 ; Left column
-RCOL: .res 1 ; Right column
-Y2SAVE:
-CHUNK1: .res 1
-OLDCH1: .res 1
-CHUNK2: .res 1
-OLDCH2: .res 1
+; BAR variables
+X1SAVE: .res 2
+Y1SAVE: .res 2
+X2SAVE: .res 2
+Y2SAVE: .res 2
; Text output stuff
TEXTMAGX: .res 1
@L4: rts
-; ------------------------------------------------------------------------
-; CIRCLE: Draw a circle around the center X1/Y1 (= ptr1/ptr2) with the
-; radius in tmp1 and the current drawing color.
-;
-; Must set an error code: NO
-;
-
-CIRCLE: lda RADIUS
- sta CURY
- bne @L1
- jmp SETPIXEL ; Plot as a point
-
-@L1: clc
- adc Y1
- sta Y1
- bcc @L2
- inc Y1+1
-@L2: jsr CALC ; Compute XC, YC+R
-
- lda ROW
- sta BROW
- lda COL
- sta LCOL
- sta RCOL
-
- sty Y2 ; Y AND 07
- lda BITCHUNK,X
- sta CHUNK1 ; Forwards chunk
- sta OLDCH1
- lsr
- eor #$FF
- sta CHUNK2 ; Backwards chunk
- sta OLDCH2
- lda POINT
- sta TEMP2 ; TEMP2 = forwards high pointer
- sta X2 ; X2 = backwards high pointer
- lda POINT+1
- sta TEMP2+1
- sta X2+1
-
-; Next compute CY-R
-
- lda Y1
- sec
- sbc RADIUS
- bcs @C3
- dec Y1+1
- sec
-@C3: sbc RADIUS
- bcs @C4
- dec Y1+1
-@C4: sta Y1
-
- jsr CALC ; Compute new coords
- sty Y1
- lda POINT
- sta X1 ; X1 will be the backwards
- lda POINT+1 ; low-pointer
- sta X1+1 ; POINT will be forwards
- lda ROW
- sta TROW
-
- sei ; Get underneath ROM
- lda #$34
- sta $01
-
- lda RADIUS
- lsr ; A=r/2
- ldx #00
- stx CURX ; y=0
-
-; Main loop
-
-@LOOP: inc CURX ; x=x+1
-
- lsr CHUNK1 ; Right chunk
- bne @CONT1
- jsr UPCHUNK1 ; Update if we move past a column
-@CONT1: asl CHUNK2
- bne @CONT2
- jsr UPCHUNK2
-@CONT2: sec
- sbc CURX ; a=a-x
- bcs @LOOP
-
- adc CURY ;if a<0 then a=a+y; y=y-1
- tax
- jsr PCHUNK1
- jsr PCHUNK2
- lda CHUNK1
- sta OLDCH1
- lda CHUNK2
- sta OLDCH2
- txa
-
- dec CURY ;(y=y-1)
-
- dec Y2 ;Decrement y-offest for upper
- bpl @CONT3 ;points
- jsr DECYOFF
-@CONT3: ldy Y1
- iny
- sty Y1
- cpy #8
- bcc @CONT4
- jsr INCYOFF
-@CONT4: ldy CURX
- cpy CURY ;if y<=x then punt
- bcc @LOOP ;Now draw the other half
-;
-; Draw the other half of the circle by exactly reversing
-; the above!
-;
-NEXTHALF:
- lsr OLDCH1 ;Only plot a bit at a time
- asl OLDCH2
- lda RADIUS ;A=-R/2-1
- lsr
- eor #$FF
-@LOOP:
- tax
- jsr PCHUNK1 ;Plot points
- jsr PCHUNK2
- txa
- dec Y2 ;Y2=bottom
- bpl @CONT1
- jsr DECYOFF
-@CONT1: inc Y1
- ldy Y1
- cpy #8
- bcc @CONT2
- jsr INCYOFF
-@CONT2: ldx CURY
- beq @DONE
- clc
- adc CURY ;a=a+y
- dec CURY ;y=y-1
- bcc @LOOP
-
- inc CURX
- sbc CURX ;if a<0 then x=x+1; a=a+x
- lsr CHUNK1
- bne @CONT3
- tax
- jsr UPCH1 ;Upchunk, but no plot
-@CONT3: lsr OLDCH1 ;Only the bits...
- asl CHUNK2 ;Fix chunks
- bne @CONT4
- tax
- jsr UPCH2
-@CONT4: asl OLDCH2
- bcs @LOOP
-@DONE:
-CIRCEXIT: ;Restore interrupts
- lda #$37
- sta $01
- cli
- rts
-;
-; Decrement lower pointers
-;
-DECYOFF:
- tay
- lda #7
- sta Y2
-
- lda X2 ;If we pass through zero, then
- sec
- sbc #<320 ;subtract 320
- sta X2
- lda X2+1
- sbc #>320
- sta X2+1
- lda TEMP2
- sec
- sbc #<320
- sta TEMP2
- lda TEMP2+1
- sbc #>320
- sta TEMP2+1
-
- tya
- dec BROW
- bmi EXIT2
- rts
-EXIT2: pla ;Grab return address
- pla
- jmp CIRCEXIT ;Restore interrupts, etc.
-
-; Increment upper pointers
-INCYOFF:
- tay
- lda #00
- sta Y1
- lda X1
- clc
- adc #<320
- sta X1
- lda X1+1
- adc #>320
- sta X1+1
- lda POINT
- clc
- adc #<320
- sta POINT
- lda POINT+1
- adc #>320
- sta POINT+1
-@ISKIP: inc TROW
- bmi @DONE
- lda TROW
- cmp #25
- bcs EXIT2
-@DONE: tya
- rts
-
-;
-; UPCHUNK1 -- Update right-moving chunk pointers
-; Due to passing through a column
-;
-UPCHUNK1:
- tax
- jsr PCHUNK1
-UPCH1: lda #$FF ;Alternative entry point
- sta CHUNK1
- sta OLDCH1
- lda TEMP2
- clc
- adc #8
- sta TEMP2
- bcc @CONT
- inc TEMP2+1
- clc
-@CONT: lda POINT
- adc #8
- sta POINT
- bcc @DONE
- inc POINT+1
-@DONE: txa
- inc RCOL
- rts
-
-;
-; UPCHUNK2 -- Update left-moving chunk pointers
-;
-UPCHUNK2:
- tax
- jsr PCHUNK2
-UPCH2: lda #$FF
- sta CHUNK2
- sta OLDCH2
- lda X2
- sec
- sbc #8
- sta X2
- bcs @CONT
- dec X2+1
- sec
-@CONT: lda X1
- sbc #8
- sta X1
- bcs @DONE
- dec X1+1
-@DONE: txa
- dec LCOL
- rts
-;
-; Plot right-moving chunk pairs for circle routine
-;
-PCHUNK1:
-
- lda RCOL ;Make sure we're in range
- cmp #40
- bcs @SKIP2
- lda CHUNK1 ;Otherwise plot
- eor OLDCH1
- sta TEMP
- lda TROW ;Check for underflow
- bmi @SKIP
- ldy Y1
- lda (POINT),y
- eor BITMASK
- and TEMP
- eor (POINT),y
- sta (POINT),y
-
-@SKIP: lda BROW ;If CY+Y >= 200...
- cmp #25
- bcs @SKIP2
- ldy Y2
- lda (TEMP2),y
- eor BITMASK
- and TEMP
- eor (TEMP2),y
- sta (TEMP2),y
-@SKIP2: rts
-
-;
-; Plot left-moving chunk pairs for circle routine
-;
-
-PCHUNK2:
- lda LCOL ;Range check in X
- cmp #40
- bcs EXIT3
- lda CHUNK2 ;Otherwise plot
- eor OLDCH2
- sta TEMP
- lda TROW ;Check for underflow
- bmi @SKIP
- ldy Y1
- lda (X1),y
- eor BITMASK
- and TEMP
- eor (X1),y
- sta (X1),y
-
-@SKIP: lda BROW ;If CY+Y >= 200...
- cmp #25
- bcs EXIT3
- ldy Y2
- lda (X2),y
- eor BITMASK
- and TEMP
- eor (X2),y
- sta (X2),y
-EXIT3: rts
-
; ------------------------------------------------------------------------
; TEXTSTYLE: Set the style used when calling OUTTEXT. Text scaling in X and Y
; direction is passend in X/Y, the text direction is passed in A.
projects / cc65 / blobdiff