regs.erl

-module(regs).
-export([create/1, set/3, get/2, regs/1, start/0]).

%%% Create a list of registers.
create(N) ->
	create([], 0, N).
create(R, _, 0) ->
	R;
create(R, C, N) ->
	create(R ++ [{C, 0}], C+1, N-1).

%%% Set data in register N.
set(R, N, Data) ->
	lists:keystore(N, 1, R, {N, Data}).

%%% Get data in register N.
get(R, N) ->
	{_, Data} = lists:keyfind(N, 1, R),
	Data.

%%% Main state machine.
regs(R) ->
	receive
		{From, get, {N}} ->
			From ! {self(), response, {get, get(R, N)}},
			regs(R);
		{_From, set, {N, Data}} ->
			regs(set(R, N, Data));
		terminate ->
			ok
	end.

%%% Starts a process with N registers.
start(N) ->
	spawn(regs, regs, [create(N)]).