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Old 08 December 2013, 11:06   #427
Toni Wilen
WinUAE developer
Join Date: Aug 2001
Location: Hämeenlinna/Finland
Age: 43
Posts: 20,650
Most vertical copper bar glitches are now fixed. (not all, remaining are caused by real timing issues)

It is time to wear brown paper bag again (it has been quite long since last time!).

Blitter and bitplane DMA was emulated in separate passes during the time CPU was doing "nothing" (waiting for memory, doing internal calculations) which of course won't work that well if there are tiny blits started mid-scanline are blitter is really "racing the beam" (safety margin is only few clocks!)

If blitter writes to same addresses that bitplane dma fetches in same scanline, blitted data was visible on screen, even if blitter writes should have happened after bitplane dma fetched them.

(This is yet another performance optimization, used in non-ce modes)

Note that this only caused visual glitches in some quite rare situations, it didn't have any effect on emulation timing or compatibility (from running program point of view of course).

EDIT: It can increase CPU requirements in some demos, even if they didn't have any glitches. There is no way around it.
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