> > Danny Backx wrote:
> > iwmmxt is the xscale cpu that has wmmx instruction set support (which
> > resembles mmx from i386). Initially I thought that -mcpu=xscale is
> > enough but then I found out that I had to use -mcpu=iwmmxt. I have some
> > code that uses wmmx and I'm trying to compile it.
> > Here's reference for ms compiler for wmmx:
> > http://lmgtfy.com/?q=WMMX+Intrinsic+Functions
> Very interesting stuff. Oddly enough, my iPAQ 214 contains a PXA 310
> which should have this :-)
> I'm not sure whether this is a cegcc issue, I've just asked for info on
> the gcc mailing list.
> Danny
It should, here's the test code with ms compiler:
#include <mmintrin.h>
__m64 c;
BOOL res = IsProcessorFeaturePresent(PF_ARM_INTEL_WMMX);
if (res)
{
c = _mm_set_pi16(4, 4, 4, 4);
}
I'll try to force cegcc to compile my wmmx code; as far as I know there is a
switch to make it compile all asm even if it's not supported by target
-mcpu=xxx. I always thought that -mcpu=xscale was compiling my code, but
because of ifdefs it was silently skipped by preprocessor and I never knew that
my code was never used for the last year :)
For corrupted binary:
I wrote amr (voice codec, not arm cpu :)) encoder/decoder and it doesn't depend
on anything (like stdio, memory etc). The lib has both microsoft intrinsics for
arm cpu and gnu inline asm. Since with cegcc I could use more optimizations
(and because ms compiler exposes limited amount of useful dsp and other
instructions) I wanted to compare what would be performance difference. So, I
simply compiled my amr code to a single amr-nb.o and used it to link by the ms
compiler. The resulting binary also had to be compressed by upx otherwise it
didn't load. The library uses a lot of const tables and it's written in c++ (a
bit of templates, constructors/destructors), but exposes only c interface.
After I got it running performace differences were minimal (within 2-3%, so I
didn't even bother with that stuff anymore).
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