[vorbis-dev] Optimisations

[Jason Hecker]

>   It seems like we should have a general framework for this.  That is, 
> say that we have a routine foo() that can be optimized various ways.  It 
> would be good to have a runtime switch to enable different optimizations 
> for testing.  For example, you might have foo_ppc() and foo_ppc_altivec() 
> where the 'ppc' only takes advantage of instructions on all ppc machines 
> while the ppc_altivec version uses PPC7440 specific instructions.

etc etc etc

These are my sentiments exactly.

Have the base C version which is known to work (albeit slowly) for 
everything and through the use of compile time options be able to build the 
optimised version for the machine in question.

I don't think this will be too hard at all to set up.  Leave the function 
names the same, no need for blah_mmx() or blah_3dnow(), rather have 
directories for each CPU with the equivalent functions in them and have the 
linker link the right *.o files.

I think this might be easier than farting about with macros, or tables that 
register the functions with pointers at runtime and so on.

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