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C64 TGI: LINE: Optimization: Don't check boundaries; LINE always is called by tgi_clippedline().
Submitted in Pull Request #611 by Sven Michael Klose.
This commit is contained in:
Greg King
parent
d869368679
commit
155f3ade41
@ -4,6 +4,7 @@
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; Based on Stephen L. Judd's GRLIB code.
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;
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; 2017-01-13, Greg King
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; 2018-03-13, Sven Klose
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;
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.include "zeropage.inc"
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@ -70,12 +71,9 @@ X2 := ptr3
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Y2 := ptr4
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TEXT := ptr3
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ROW := tmp2 ; Bitmap row...
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COL := tmp3 ; ...and column, both set by PLOT
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TEMP := tmp4
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TEMP2 := sreg
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POINT := regsave
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INRANGE := regsave+2 ; PLOT variable, $00 = coordinates in range
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CHUNK := X2 ; Used in the line routine
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OLDCHUNK := X2+1 ; Dito
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@ -454,11 +452,6 @@ GETPIXEL:
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; LINE: Draw a line from X1/Y1 to X2/Y2, where X1/Y1 = ptr1/ptr2 and
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; X2/Y2 = ptr3/ptr4 using the current drawing color.
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;
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; To deal with off-screen coordinates, the current row
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; and column (40x25) is kept track of. These are set
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; negative when the point is off the screen, and made
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; positive when the point is within the visible screen.
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;
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; X1,X2 etc. are set up above (x2=LINNUM in particular)
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; Format is LINE x2,y2,x1,y1
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;
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@ -513,7 +506,7 @@ LINE:
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stx YINCDEC
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stx XINCDEC
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jsr CALC ; Set up .X,.Y,POINT, and INRANGE
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jsr CALC ; Set up .X, .Y, and POINT
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lda BITCHUNK,X
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sta OLDCHUNK
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sta CHUNK
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@ -556,15 +549,11 @@ STEPINY:
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;
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YLOOP: sta TEMP
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lda INRANGE ;Range check
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bne @SKIP
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lda (POINT),y ;Otherwise plot
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lda (POINT),y
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eor BITMASK
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and CHUNK
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eor (POINT),y
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sta (POINT),y
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@SKIP:
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YINCDEC:
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iny ;Advance Y coordinate
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cpy #8
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@ -581,7 +570,7 @@ YCONT2: lda (POINT),y ;Plot endpoint
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and CHUNK
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eor (POINT),y
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sta (POINT),y
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YDONE: lda #$36
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lda #$36
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sta $01
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cli
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rts
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@ -592,23 +581,12 @@ YFIXX: ;x=x+1
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bne YCONT ;If we pass a column boundary...
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ror CHUNK ;then reset CHUNK to $80
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sta TEMP2
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lda COL
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bmi @C1 ;Skip if column is negative
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cmp #39 ;End if move past end of screen
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bcs YDONE
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@C1: lda POINT ;And add 8 to POINT
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lda POINT ;And add 8 to POINT
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adc #8
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sta POINT
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bcc @CONT
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inc POINT+1
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@CONT: inc COL ;Increment column
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bne @C2
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lda ROW ;Range check
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cmp #25
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bcs @C2
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lda #00 ;Passed into col 0
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sta INRANGE
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@C2: lda TEMP2
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@CONT: lda TEMP2
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dex
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bne YLOOP
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beq YCONT2
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@ -647,7 +625,7 @@ XCONT2: dex
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dec COUNTHI ;High bits set?
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bpl XLOOP
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XDONE: lsr CHUNK ;Advance to last point
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lsr CHUNK ;Advance to last point
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jsr LINEPLOT ;Plot the last chunk
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EXIT: lda #$36
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sta $01
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@ -662,25 +640,14 @@ XFIXC: sta TEMP
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lda #$FF
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sta CHUNK
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sta OLDCHUNK
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lda COL
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bmi @C1 ;Skip if column is negative
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cmp #39 ;End if move past end of screen
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bcs EXIT
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@C1: lda POINT
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lda POINT
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clc
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adc #8
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sta POINT
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bcc @CONT
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lda TEMP
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bcc XCONT1
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inc POINT+1
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@CONT: inc COL
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bne @C2
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lda ROW
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cmp #25
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bcs @C2
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lda #00
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sta INRANGE
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@C2: lda TEMP
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sec
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bcs XCONT1
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jmp XCONT1
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;
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; Check to make sure there isn't a high bit, plot chunk,
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; and update Y-coordinate.
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@ -712,17 +679,14 @@ XINCDEC:
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; room, gray hair, etc.)
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;
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LINEPLOT: ; Plot the line chunk
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lda INRANGE
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bne @SKIP
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lda (POINT),Y ; Otherwise plot
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lda (POINT),Y
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eor BITMASK
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ora CHUNK
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and OLDCHUNK
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eor CHUNK
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eor (POINT),Y
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sta (POINT),Y
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@SKIP: rts
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rts
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;
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; Subroutine to fix up pointer when Y decreases through
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@ -730,23 +694,16 @@ LINEPLOT: ; Plot the line chunk
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;
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FIXY: cpy #255 ;Y=255 or Y=8
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beq @DECPTR
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@INCPTR: ;Add 320 to pointer
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ldy #0 ;Y increased through 7
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lda ROW
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bmi @C1 ;If negative, then don't update
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cmp #24
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bcs @TOAST ;If at bottom of screen then quit
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@C1: lda POINT
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lda POINT
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adc #<320
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sta POINT
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lda POINT+1
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adc #>320
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sta POINT+1
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@CONT1: inc ROW
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bne @DONE
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lda COL
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bpl @CLEAR
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@DONE: rts
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rts
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@DECPTR: ;Okay, subtract 320 then
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ldy #7 ;Y decreased through 0
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@ -757,21 +714,8 @@ FIXY: cpy #255 ;Y=255 or Y=8
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lda POINT+1
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sbc #>320
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sta POINT+1
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@CONT2: dec ROW
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bmi @TOAST
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lda ROW
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cmp #24
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bne @DONE
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lda COL
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bmi @DONE
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@CLEAR: lda #00
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sta INRANGE
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rts
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@TOAST: pla ;Remove old return address
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pla
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jmp EXIT ;Restore interrupts, etc.
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; ------------------------------------------------------------------------
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; BAR: Draw a filled rectangle with the corners X1/Y1, X2/Y2, where
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; X1/Y1 = ptr1/ptr2 and X2/Y2 = ptr3/ptr4 using the current drawing color.
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@ -896,48 +840,36 @@ OUTTEXT:
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rts
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; ------------------------------------------------------------------------
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; Calculate all variables to plot the pixel at X1/Y1. If the point is out
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; of range, a carry is returned and INRANGE is set to a value !0 zero. If
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; the coordinates are valid, INRANGE is zero and the carry clear.
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; Calculate all variables to plot the pixel at X1/Y1.
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CALC: lda Y1
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sta ROW
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sta TEMP2
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and #7
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tay
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lda Y1+1
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lsr ; Neg is possible
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ror ROW
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ror TEMP2
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lsr
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ror ROW
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ror TEMP2
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lsr
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ror ROW
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ror TEMP2
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lda #00
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sta POINT
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lda ROW
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lda TEMP2
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cmp #$80
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ror
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ror POINT
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cmp #$80
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ror
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ror POINT ; row*64
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adc ROW ; +row*256
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adc TEMP2 ; +row*256
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clc
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adc #>VBASE ; +bitmap base
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sta POINT+1
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lda X1
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tax
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sta COL
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lda X1+1
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lsr
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ror COL
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lsr
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ror COL
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lsr
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ror COL
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txa
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and #$F8
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clc
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adc POINT ; +(X AND #$F8)
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@ -948,13 +880,4 @@ CALC: lda Y1
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txa
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and #7
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tax
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lda ROW
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cmp #25
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bcs @L9
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lda COL
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cmp #40
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bcs @L9
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lda #00
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@L9: sta INRANGE
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rts
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