[cairo] [PATCH] Added MIPS32R2 and MIPS DSP ASE optimized functions

[Soeren Sandmann]

> The DSP ASE version uses the MIPS32R2 version of
> pixman_fill32(). Initially the plan was to develop separate versions
> of each function for each target instruction set (and DSP ASE Rev 2
> was also on the list) but the DSP ASE version of fill32 was
> eventually dropped. There are no MIPS processors that implement DSP
> ASE but are not MIPS32R2-compatible. It is convenient to be able to
> fall back to MIPS32R2 implementation if the DSP ASE code does not
> provide enough speedup to justify its use.

Right, I'm not complaining about the fact that it falls back. I'm
saying that the MIPS32R2 code should be added in one patch, followed
by another patch that adds the DSP ASE code.

> > - Is there a reason to not do runtime checking? I realize that most
> >  people using MIPS will likely do so on an embedded system where they
> >  know ahead of time what the CPU supports, but we do have runtime
> >  checking for the other CPU specific implementations.
> 
> Yes, at the present time this isn't very easy to do on MIPS Linux --
> checking if DSP ASE is implemented requires the use of privileged
> instructions. MIPS is aware of this problem and will push an update
> to the kernel that enables the use of AT_HWCAP for this purpose.

OK.

> Thanks for the all the comments! I'll update the code per your
> comments and submit another patch. Should I mail it just to the
> pixman list or CC both cairo and pixman?

Usually for pixman patches, it's fine to just mail the pixman lists,
although if a patch has implications for X or cairo, then those lists
should be CC'd as well.

One other thing: We need a copyright statement for the new files. The
canonical copyright text can be found in the pixman/COPYING file.


Soren