lecture 21 -- memory manager code walkthru

we looked at fred's sample code in files/memmgr.c.

simple, procedural (non-object-oriented) approach that uses globals to
store relevant data.

command line parser makes sure that user provides policy choice, pool
size, and command file.

command file parser reads in lines one at a time, and sets globals for
operation type (allocate or free), reference number, and size (size is
reference number in the case of free).

then it calls appropriate policy function.

we looked at data structure definition of node, which holds ref
number, address, size, and next-ptr.

then we wrote the code to do free, by searching through the list of
nodes and unlinking the one with a matching refnum.

we started on code for alloc, dealing with the case of allocating for
the first time.

we left it where students have to implement the rest of first-fit
allocation.