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View Full Version : RSP recompiler MMX optimization bug



themind
October 14th, 2004, 17:41
The RSP recompiler is very fast and nearly perfect and I'm very greatful for that, but I've found a bug in v1.4 which I'm fairly sure is in v1.5 as well. It is most noticeable with the bass in Legend of Zelda: Majora's Mask, it appears as a clicking during the decay. It can also be heard in a small way in the piano in the title theme of LOZ:OOT and in the ocarina in Wonder Project J2. I found that switching the RSP to interpreter mode fixed this, but it became unbearably slow. LaC suggested that it might be caused by the MMX optimizations, so I disabled that and indeed it turned out to fix the problem while retaining a good speed. I was able to leave MMX2 and SSE enabled without problems. The problem is that if MMX is supported by the processor the plugin will automatically enable all these optimizations.
I don't know enough about MMX to debug this section of the plugin, and I know PJ64 isn't in development anymore, but I thought it would be worthwhile reporting. If I figure out specifically what the bug is I'll let y'all know.

-hcs

olivieryuyu
October 14th, 2004, 18:00
why don't you PM Jabo ? i think it would be the best idea to get the bug fixed. May be he will help you a bit. :)

Azimer is also may be able to help you for that bug but i 'm quite unsure of that.

themind
October 14th, 2004, 19:33
Correction, it turns out the problem is the enabling of RSP section detection. I can disable that and leave MMX active for <strike>no noticeable</strike> a smaller performance penalty.

Hacktarux
October 14th, 2004, 20:43
You're right, i think i already had problem with this option while trying to do lle graphic emulation. Some graphic ucodes simply fails with this option.