Q3:A(ltivec) Status Check
9:18 AM | Andy Largent | Comment on this story
A new post from id Software's Graeme Devine to the Quake3World
forums appeared last night, explaining the current delay on the G4 Velocity Engine -
enhanced version of Quake 3: Arena he has been working on. It seems the latest
stall is not from himself, but instead the Metroworks compiler, which won't play
nice with his new Altivec code. It will compile under Mac OS X, though there are many
issues (input, etc) still present with that version, due to the development status of that public beta. Here's Devine on the project's status:
A lot of you have been asking about the status of the Altivec build of Mac Quake 3 Arena.The comments about the G4 and above being supported are certainly interesting
I've run into a small hitch, and it's hard to get around. The Metrowerks 6.0 compiler does not generate something called the "VSRAVE" instruction correctly when generating Altivec code. This leads to a crash in the product whenever an Alitvec register is loaded (in certain situations). Metrowerks is aware of the problem and promises a fix, however, no time frame was available from them.
I had previously used the Altivec for optimized versions of the memory copies and sets. Moving 16bytes at a time compared to the 8 on the MMX. John was interested in this, and so I started to look a little more at how much we could push the Altivec by converting our floating point code to use the "vector float" data type.
This leaves OS X as the only platform available that correctly compiles Altivec code. OS X PB of course has it's own set of issues, so it takes a little longer to get everything together here. OS X Q3A and ongoing id products will certainly be G4 and above only builds.
Considering Apple's pride in the Altivec, it's somewhat frustrating to not be able to show it off!
I'll see what comes up tomorrow and go from there on releasing what I have so far.
for G3 owners, though it would certainly be best to wait for some clarification
on this point before panicking about OSX support. We'll be sure to keep you
updated as this story progresses.
Graeme Devine Forum Thread on Q3 Status
IMG News: Update on Q3 and Altivec
Quake III Arena
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