On Thu, 2010-04-01 at 04:33 -0700, Micha?? Kr??l wrote: > Module: Mesa > Branch: master > Commit: 3ff175d6de89ad92d167362355501f99d06f0f97 > URL: > http://cgit.freedesktop.org/mesa/mesa/commit/?id=3ff175d6de89ad92d167362355501f99d06f0f97 > > Author: Luca Barbieri <l...@luca-barbieri.com> > Date: Wed Mar 24 18:12:45 2010 +0100 > > gallium/util: add fast half float conversion functions > > This adds a fast half float conversion facility to Gallium. > > Mesa already contains such a facility, but using a much worse algorithm. > > This one is an implementation of > www.fox-toolkit.org/ftp/fasthalffloatconversion.pdf > and uses a branch-less algorithm with some lookup tables small enough > to fit in the L1 cache. > > Ideally, Mesa should start using these functions too, but I'm not sure > how to arrange that with the current build system. > > A new "u_gctors.cpp" is added that defines a global C++ constructor > allowing to initialize to conversion lookup tables at library init. > > --- > > src/gallium/auxiliary/Makefile | 4 + > src/gallium/auxiliary/util/u_gctors.cpp | 17 ++++ > src/gallium/auxiliary/util/u_half.c | 123 > +++++++++++++++++++++++++++++++ > src/gallium/auxiliary/util/u_half.h | 55 ++++++++++++++ > 4 files changed, 199 insertions(+), 0 deletions(-) [..] > diff --git a/src/gallium/auxiliary/util/u_gctors.cpp > b/src/gallium/auxiliary/util/u_gctors.cpp > new file mode 100644 > index 0000000..9ea9819 > --- /dev/null > +++ b/src/gallium/auxiliary/util/u_gctors.cpp > @@ -0,0 +1,17 @@ > +/* this file uses the C++ global constructor mechanism to automatically > + initialize global data > + > + __attribute__((constructor)) allows to do this in C, but is GCC-only > +*/ > + > +extern "C" void util_half_init_tables(void); > + > +struct util_gctor_t > +{ > + util_gctor_t() > + { > + util_half_init_tables(); > + } > +}; > + > +static struct util_gctor_t util_gctor;
This constructor scheme is not working for me. I think that's because there isn't any symbol here that's used elsewhere, hence the linker is not linking this file. > diff --git a/src/gallium/auxiliary/util/u_half.c > b/src/gallium/auxiliary/util/u_half.c > new file mode 100644 > index 0000000..8865acb > --- /dev/null > +++ b/src/gallium/auxiliary/util/u_half.c > @@ -0,0 +1,123 @@ > +#include "util/u_half.h" > + > +/* see www.fox-toolkit.org/ftp/fasthalffloatconversion.pdf > + * "Fast Half Float Conversions" by Jeroen van der Zijp, Nov 2008 > + */ > + > +/* Note that using a 64K * 4 table is a terrible idea since it will not fit > + * in the L1 cache and will massively pollute the L2 cache as well > + * > + * These should instead fit in the L1 cache. > + * > + * TODO: we could use a denormal bias table instead of the mantissa/offset > + * tables: this would reduce the L1 cache usage from 8704 to 2304 bytes > + * but would involve more computation > + * > + * Note however that if denormals are never encountered, the L1 cache usage > + * is only about 4608 bytes anyway. > + */ Please put copyright headers. *Especially* when basing your work from external references, as it gives the impression that this code was copied, and not your own creation. Jose ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Mesa3d-dev mailing list Mesa3d-dev@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mesa3d-dev
