Re: [Boost-users] Re: mpl related question

From: Istvan Buki (istvan.buki_at_[hidden])
Date: 2004-08-06 15:24:54

On Friday 06 August 2004 13:06, Aleksey Gurtovoy wrote:
> Istvan Buki writes:
> > I modified my sample code to take advantage of your suggestion to
> > calculate the index at compile time. It works perfectly well and the code
> > generated is faster than my previous version but I still have questions:
> >
> > 1) I'm not sure if this is the right place to ask, if not somebody will
> > certainly be able to point me into the right direction.
> > In the assembly code generated (file attached to this mail), there are
> > two 'call' instructions that seem useless to me. Why not inline the
> > single 'movl' instruction executed as the result of the call?
> > I'm using g++ 3.3.3 with O2 optimization flag and it is probably a very
> > compiler-specific question but perhaps I'm missing something obvious
> > here.
> >
> > 2) By now you probably guessed that my goal is to produce code for
> > embedded use. In this environment standard libraries would not be
> > available. Could you give me some idea how hard it would be to modify the
> > mpl library not to rely on any standard include and lib?
>
> Should be trivial -- the library has very little dependencies on the
> standard headers. In fact, 'std::size_t' and LONG_MAX are likely to be the
> only ones. You'd need to replace the default Boost config headers with your
> own, though, because those do depend on the presence of various std
> headers. Please see
> http://www.boost.org/libs/config/config.htm#advanced_config for the
> instructions on how to do that.
>
Indeed it was easy to do. I first created my own setup as described on the web 
site, starting from existing config files and then removing a couple of 
unknown header files in my environment.
After that, the only remaining problem was the type_traits library that 
include the <cstddef> header in several places to have access to the 
definition of std::size_t. I simply created my own version of the cstddef 
header with the appropriate definition for std::size_t and now everything 
compiles.

Thanks for your help,
Istvan