Functions and memory usage

[John Donovan <JohnD@...>]

Hi,
I'm new to the list, and normally I'd just lurk for a couple of weeks
getting the feel for the list. However, time is of the essence at the
moment.
We're developing a game on a couple of well-known games consoles, and I've
been given the task of implementing a scripting system. After looking at
various options, I picked Lua. Now I'm trying to convince my boss that Lua
is A Good Thing. He's worried about memory fragmentation.
As most of you will be aware, consoles have a very limited amount of memory,
and I'm going to be given as small a piece of that as possible, so I've got
to make every byte count. After looking at the code, and how it allocates
and deallocates memory, we noticed that when it loads up a function (with
LoadFunction()) it loads locals, lines, constants, and code in that order.
However when it comes to free the function (with luaF_freeproto()) it does
it in a different order. My question is, if I shuffle the deallocation of
the memory LoadFunction() allocates so it does it in reverse order, could we
implement a second memory allocator that uses a simple stack? So when
LoadFunction() pushes locals, lines, constants, and code, we could safely
free it in reverse order without worrying if something else has realloc'd or
otherwise messed around with our function's memory?
A search of the archives turned up nothing on this specific question, but I
have noticed that fragmentation is a reported problem that some people have
managed to keep to a minimum.

-John Donovan
Programmer - Magenta Software Ltd.


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