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Atari coding BBS
Re: ST: Screen Pointer Update glit
Posted by: evil Jun,30.2017-12:16 

Do the actual hardware register write very early in vbl and swap the buffers in the main loop.
It doesn't hurt if the vbl set the same address several vbl in a row.

To do your own vbl routine isn't hard:

move.l $70.w,save_vbl
move.l #myvbl,$70.w

move.l d0,-(sp)
move.l scraddr,d0
lsr.w #8,d0
move.l d0,$ffff8200.w
move.l (sp)+,d0

move.l save_vbl,$70.w

However, if your main loop suddenly need less than 1 vbl in some cases, you need to wait for vbl so you don't swap around all buffers and end up on the visible one.

Anders Eriksson

[All messages in this thread]

Topic Posted by  Date 
ST: Screen Pointer Update glit Orion_ Jun,29.2017-20:41
  Re: ST: Screen Pointer Update glit evil Jun,30.2017-12:16
    Re: ST: Screen Pointer Update glit Orion_ Jun,30.2017-13:43

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