> I agree with the last, but IMHO asm offers a very weak environment for
> re-useable code, because there is no automatic
> - removal of un-used code

The librarian and linker do that, independent of language.

> - static-stack-like variable allocation

I'm not sure what you mean here.  I don't know how to envision a static
variable that is stack-like.

However, I have a method of RAM useage on PICs that has worked very nicely
accross dozens of projects and is easy to implement.  It works well in
assembler, but could just as easily be applied to a higher level language
(for all I know it has been).

I reserve part of the global RAM as "general registers", much like the
general registers of other machines.  13 of these (REG0 - REG12) are
usually allocated on the 16 family in the 70h - 7Fh global region.  They
are used as call and return arguments to subroutines, and for temporary
scratch inside a subroutine.  By convention, subroutines preserve all
these registers to the caller except those that are explicitly documented
to hold return values.  A software stack is used to save/restore those
general registers used by a subroutine on entry and return.  All this is
automated with the GLBSUB subroutine entry macro, and the LEAVEREST
subroutine end macro.  These and others can be found in STD.INS.ASPIC at
http://www.embedinc.com/pic.

The general registers are usually more than enough for all the temporary
local storage of a subroutine.  Therefore, the only RAM reserved by each
module is the persistant state it needs to maintain.  This scheme makes
very efficient use of RAM, and effective use of the limited global memory.
Of course one size doesn't fit all, so on relatively rare occasions a
subroutine may define a static variable that is really local, use an
overlay, trash some general registers on return, or whatever.  Fortunately
in assembler you can break the rules and do what you need to when you need
to.  But again, this happens quite rarely and of course is well documented
when it does.


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