Daedalus n64 for PSP "Source updated"

June 7th, 2006, 12:13 Posted By: mameuser

To who want to try it.
Source code http://daedalus-n64.cvs.sourceforge.net/daedalus-n64/

Earlier this evening I updated the project CVS repository with the latest version of the code. Normally I only do this when I release a new build, but I know people have been playing with the code and have expressed an interest in seeing the latest developments.

I'm not quite ready to release a new binary yet (still a few more optimisations I want to make and various bugs to fix first), but I'll try and do this within the coming week.

Incidentally, updating the source normally only takes 20 minutes or so, but it took a good couple of hours tonight. Sourceforge updated their CVS service recently (May 12th) and as a result I had to spend a couple of hours updating WinCVS, generating new SSH keys and the like. Hopefully it won't be so painful next time around, or I might just lose the will to live.

As a more general update, I cleared a couple of things from my TODO list sorted this weekend. I'm caching floating point registers for most of the single-precision Cop1 instructions, which are now implemented directly in the dynarec code. I've not timed this in depth yet, but it's shaving 10-20ms/frame off the intro to Mario 64 (Mario's Head), which is particularly FPU heavy (i.e. I'm getting ~160ms/frame rather than ~180ms)

Finally I need to have a good think about how to go about optimising the double-precision floating point performance. As the PSP doesn't have hardware support for double precision floating point this is currently very expensive (i.e. adding 2 doubles on the n64 takes just one instruction - on the psp this balloons to several hundred as it all has to be done in software).

Currently I cheat and cast all the double-precision floats to single-precision values before performing the calculations. Although this is much faster it obviously loses a lot of precision, so I need to be careful it's not going to break any roms. Also even the float->double/double->float conversions are pretty expensive so it's still not an ideal solution. Fortunately not many roms seem to use double-precision maths extensively (presumably because it was relatively expensive on the n64), and where they do use it they don't seem to be too sensitive to the fact that I'm throwing most of their mantissa away


From http://strmnnrmn.blogspot.com/

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