demo_ptr.m

%% Pointers Toolbox
% This demo file shows how one might use the Pointers Toolbox.
%
% The Pointers Toolbox emulates the behaviour of pointers in languages such
% as C/C++.
%
% Pointers are variables that point to slots in memory.  Here the "memory"
% or virtual memory is implemented as a large cell array and the pointers
% are integers that index into that array.  An important difference with C
% is that the size of the memory slot and the type of variables stored in
% each slot are irrelevant (within system constraints).
%
% The tools I've provided are fairly basic but should be enough to create
% virtually any dynamic data structure.  The demo below shows how to create
% a stack as a linked list.
%
% Author: Ben Petschel  31/8/2009

%% Basic use of pointers
% assign a slot in virtual memory
x = 10;
ptr = malloc(x)
%%
% read the value of the pointer:
mread(ptr)
%%
% rewrite the value of slot in virtual memory:
mwrite(ptr,11)
mread(ptr)
%%
% clear the memory used by ptr
mfree(ptr)
%%
% clear the virtual memory
mwipe
%% Creating a linked list (stack)
% pointer to top of stack
topptr = [];
%%
% add to the stack
for i=1:3
  top.value = i;
  top.next = topptr;
  topptr = malloc(top);
end;
%%
% read back the values of the stack and free the virtual memory, beginning at the top
while ~isempty(topptr)
  top = mfree(topptr);
  i = top.value
  topptr = top.next;
end;