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Re: applesoft basic : how to poke hires screen

From	aiiadict@gmail.com
Newsgroups	comp.sys.apple2.programmer
Subject	Re: applesoft basic : how to poke hires screen
Date	2012-05-26 09:21 -0700
Organization	http://groups.google.com
Message-ID	<e4e1e0a4-03ab-464a-af41-4996a46e0b00@googlegroups.com> (permalink)
References	<4f966e32$0$12520$ba4acef3@reader.news.orange.fr>

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On Tuesday, April 24, 2012 2:11:11 AM UTC-7, andré lozano wrote:
> hello from France
> 
> I'm coding some basic code.
> 
> I want to know, if it's possible, how to change the state of a pixel in 
> hires screen with a poke instruction.
> 
> for example in a graphic lcd screen you can modify the graphics by 
> loading bytes directly in the memory
> 
> friendly
> 
> andres lozano









*******************************
*
* HPLOT XLOC,YLOC FROM ASSEMBLY
*
* INPUT : XLOC  X COORD
*         YLOC  Y COORD
*
*  requires:  lookup table at TLO, 192X2 byte table
*
* OUTPUT: OR'D WITH SCREEN
*
*****************************


XBIT     DFB   #00
XBYTE    DFB   #00


MASKTEMP DFB   #00
                          ;-----------------------------



HPLOT    LDA   #00
         STA   FOUNDLIT

         LDY   YLOC
         LDA   TLO,Y
         STA   SLO
         LDA   THI,Y
         STA   SHI


         LDA   XLOC
         LDY   #00
         CLC
DLOOPSV  CMP   #7         ;DIVIDE X COORDINATE BY 7
         BCC   DDONESV
         SEC
         SBC   #7
         INY
         CLC
         JMP   DLOOPSV


DDONESV


         TAX              ;Division done, now get the proper bit value
         LDA   MASK,X

         STA   MASKTEMP   ;GETS DESTROYED IN ISLIT
         AND   (SHI),Y    ;AND THE MASK WITH THE SCREEN, TO TEST IF BIT SET

         BEQ   NOTLIT

ISLIT    NOP              ;PIXEL IS LIT
         INC   FOUNDLIT

NOTLIT

         LDA   MODE
         BEQ   MODE0D
         JMP   MODE1D

MODE0D   TYA
         CLC
         ADC   #18        ;ADD 18 TO XBYTE
         TAY

MODE1D   LDA   MASKTEMP   ;GET MASK AGAIN
         ORA   (SHI),Y    ;
         STA   (SHI),Y    ;PUT ON SCREEN


         JSR   ADDPT      ;ADD PT TO TABLE (IN SCANCONVERT)

         RTS

MASK     DFB   #$01,#$02,#$04,#$08,#$10,#$20,#$40,#$80

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applesoft basic : how to poke hires screen andré lozano <nws@provsoire.com> - 2012-04-24 11:11 +0200
  Re: applesoft basic : how to poke hires screen dempson@actrix.gen.nz (David Empson) - 2012-04-24 23:07 +1200
    Re: applesoft basic : how to poke hires screen andré lozano <nws@provsoire.com> - 2012-04-24 14:23 +0200
  Re: applesoft basic : how to poke hires screen mmphosis@macgui.com ( mmphosis) - 2012-04-27 23:08 +0000
    Re: applesoft basic : how to poke hires screen Michael J. Mahon <mjmahon@aol.com> - 2012-04-27 20:40 -0500
      Re: applesoft basic : how to poke hires screen mmphosis@macgui.com ( mmphosis) - 2012-04-29 01:35 +0000
        Re: applesoft basic : how to poke hires screen "Bill Garber" <willy46pa@comcast.net> - 2012-04-28 23:58 -0400
        Re: applesoft basic : how to poke hires screen andré lozano <nws@provsoire.com> - 2012-05-02 19:54 +0200
    Re: applesoft basic : how to poke hires screen mmphosis@macgui.com ( mmphosis) - 2012-05-01 23:20 +0000
  Re: applesoft basic : how to poke hires screen aiiadict@gmail.com - 2012-05-26 09:21 -0700
    Re: applesoft basic : how to poke hires screen aiiadict@gmail.com - 2012-05-26 09:25 -0700
      Re: applesoft basic : how to poke hires screen "Michael J. Mahon" <mjmahon@aol.com> - 2012-05-26 23:42 -0700

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