Posted By
rudis
on 2012-04-20
14:43:37
 |  Re: plot a dot at x,y
found a formula to calculate the byte in wich the dot plots
xh * 256 + ( xl and 248 ) + ( y and 7 ) + ( 40 * ( y and 248 ) )
edit 19.04. 20:22..
edit 20.04..
wrote something so far. calculate byte-adress of dot to print at.
zeilenlaenge = 352
wspalte = (zeilenlaenge/2)-20
.setcpu "6502"
.org $1001-2
.word $1001
.word link
.word 2012 ; Zeilennummer
.byte $9e ; sys-token
.byte "4109" ; adresse
.byte $00 ; zeilenende
link:
.byte $00,$00
lda #00
sta ylow
lda #$20
sta yhigh
ldy #0
loopy:
ldx #8
iloopy:
lda ylow,y
clc
adc #$1
sta ylow+1,y
lda yhigh,y
adc #0
sta yhigh+1,y
iny
dex
cpx #0
bne iloopy
clc
lda ylow,y
adc #<$138
sta ylow,y
lda yhigh,y
adc #>$138
sta yhigh,y
cpy #200
bne loopy
; Merke: Zeilen und Spalten beginnen mit 0 !!
clc ;
lda xcord+1 ;\
ror ; \
lda xcord ; |
ror ; |> X geteilt durch 8 ohne rest *g*
lsr ; |
lsr ; /
sta temp1 ;/
ldy ycord ; 199
lda ylow,y
clc
adc temp1
sta temp2
lda yhigh,y
sta temp2+1
brk
xcord:
.word 319
ycord:
.byte 199
temp1:
.word $0000
temp2:
.word $0000
xybasis:
.word $2000
ylow:
.repeat 200
.byte $0
.endrep
yhigh:
.repeat 200
.byte $0
.endrep
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