How to find the size of physical memory?

[Ken Turkowski]

In our compression kafeeklatsch, we have determined a need for a
program which can determine the size of physical memory.  This is
needed to optimize the speed of the algorithm by allocating as big a
table as possible, with minimum liklihood of swapping.

Is there any way that this might be done?  It looks like there may be
some way of doing this with some fancy 4.2 system calls, but I'd like
it to be portable.  Any ideas will be entertained.
-- 
Ken Turkowski @ CADLINC, Palo Alto, CA
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