Deunan wrote:
Source: Deunan's blogI've also devised a tweak to GD-DMA code for that accursed MPEG library. It interferes with SH4 main loop, effectively causing a temporary slowdown. This should not be a problem and is only visible during CD boot sequence, as BIOS decrypts the executable on the fly using thousands of 32-byte reads. As a side effect it fixes (or so it seems) those MIL-CDs that required SH4 speed to be reduced in order to load properly. One of these days I'll have to try and verify that on hardware, to see just how much of a slowdown G1 bus DMA transfer in background really is.
However, this is not yet the final solution to the problem. Sofdec library still expects some reads to start in close to zero time and I can't figure out why - still not conviced any code could be that braindead, so I'm not ruling out a bug on my side. For the time being I try to detect situations where DMA is started before GD buffer has anything in it, but every now and then this too fails. It looks awfully suspicious so I'll be investigating this next.
In the meantime, all Dream Preview GDs from Yuki boot now and here's a proof:
