[mythtv] [PATCH] dtk libsoundtouch bug

Mark Spieth mark at dclabs.com.au
Sat Jan 29 17:54:48 EST 2005

> ]also dont need the -fPIC
> ]options. so I removed them too. static lib after all.
> Isn't this getting statically linked into a dynamic lib?
> Is it safe to get rid of -fPIC then?

no idea. defer to the judgement of others. I only know it works

> ]also the "new" intrisics are much slower. I had a look at the assembly
> ]produced and its quite inefficient at optimising the registers
> ]Id keep the older macros for now for performance reasons.
> Yep. But icc and newer gcc's like them. And those compilers may even
> clobber the old intrinsics in certain situations.

true. thus need an auto way of determining whether to use them or not.
configure would do it. perhaps a mini script in the libmythsoundtouch.pro
file to test for the presence of mmintrin.h


unix {
MMINTRINS = $$system( echo -e '\x23include <mmintrin.h>\nint main() {__m64
m0; m0 = _mm_setzero_si64(); return 0; }' > ___test.cpp; g++ -O3 -mmmx -o
___test.o ___test.cpp >/dev/null 2>&1 && echo 1 || echo 0; rm -f ___test.o
___test.cpp1 )
equals(MMINTRINS,1) {
    :message("looks like gcc supports mmx intrinsics")

note the system command must be all on one line. seems to work.


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