Subject: RE: [stella] bzoneRepos question From: "Fred Quimby" <c9r@xxxxxxxxxxx> Date: Wed, 8 Jun 2005 05:36:56 -0400 |
Sorry to post yet again, but a question for the experts could be: Is the problem be due to hitting RESPx too early? It seems to be happening in the HBLANK region (cycle 21) when the value is less than 15. >Adding a "nop" to it seems to fix it. So the new routine looks like >this: > >bzoneRepos > sta WSYNC ; 00 Sync to start of scanline. > sec ; 02 Set the carry flag so no borrow >will be applied during the division. > > NOP ;THIS NOP SEEMS TO PREVENT A STUTTER AT 15 PIXELS > >.divideby15 > sbc #15 ; 04 Waste the necessary amount of >time dividing X-pos by 15! > bcs .divideby15 ; 06/07 >11/16/21/26/31/36/41/46/51/56/61/66 > > tay > lda fineAdjustTable,y ; 13 -> Consume 5 cycles by guaranteeing >we cross a page boundary > sta HMP0,x > > sta RESP0,x ; 21/ 26/31/36/41/46/51/56/61/66/71 - Set >the rough position. > rts > > It does it in both Stella and z26. Does the problem that I'm seeing >exist on real hardware, too? Or am I "fixing" something to run in the >emulators that will break on hardware? I searched the archive for >"bzoneRepos", but I didn't find any discussions on this routine. > >Thanks! > >-Rich > >Archives (includes files) at http://www.biglist.com/lists/stella/archives/ >Unsub & more at http://stella.biglist.com > Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://stella.biglist.com
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