Added missing example file msg.erl

Makefile

@@ -34,6 +34,7 @@ adocs = book.asciidoc \
 	code/memory_chapter/src/lb.erl \
 	code/memory_chapter/src/send.erl \
 	code/memory_chapter/src/share.erl \
+	code/processes_chapter/src/msg.erl \
 	images/observer_applications.png \
 	images/observer_code_server.png \
 	images/observer_load.jpg \

chapters/ap-code_listings.asciidoc

@@ -27,6 +27,12 @@ include::../code/compiler_chapter/src/json_parser.erl[]
 include::../code/compiler_chapter/src/json_test.erl[]
 ----
 
+[source,erlang]
+----
+include::../code/processes_chapter/src/msg.erl[]
+----
+
+
 [source,erlang]
 ----
 include::../code/beam_chapter/src/stack_machine_compiler.erl[]

chapters/processes.asciidoc

@@ -956,7 +956,10 @@ As mentioned we can force the message to end up in the in queue by
 setting the flag _message_queue_data_. We can try this with the following
  program:
 
-<embed file= "code/msg.erl"/>
+[source,erlang]
+----
+include::../code/processes_chapter/src/msg.erl[]
+----
 
 With this program we can try sending a message on heap and off heap and
 look at the PCB after each send. With on heap we get the same result

code/processes_chapter/src/msg.erl

@@ -0,0 +1,36 @@
+-module(msg).
+
+-export([send_on_heap/0
+        ,send_off_heap/0]).
+
+send_on_heap() -> send(on_heap).
+send_off_heap() -> send(off_heap).
+
+send(How) ->
+  %% Spawn a function that loops for a while
+  P2 = spawn(fun () -> receiver(How) end),
+  %% spawn a sending process
+  P1 = spawn(fun () -> sender(P2) end),
+  P1.
+
+sender(P2) ->
+  %% Send a message that ends up on the heap
+  %%  {_,S} = erlang:process_info(P2, heap_size),
+  M = loop(0),
+  P2 ! self(),
+  receive ready -> ok end,
+  P2 ! M,
+  %% Print the PCB of P2
+  hipe_bifs:show_pcb(P2),
+  ok.
+
+receiver(How) ->
+  erlang:process_flag(message_queue_data,How),
+  receive P -> P ! ready end,
+  %%  loop(100000),
+  receive x -> ok end,
+  P.
+
+
+loop(0) -> [done];
+loop(N) -> [loop(N-1)].