%% ``The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved via the world wide web at http://www.erlang.org/.
%% 
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%% 
%% The Initial Developer of the Original Code is Ericsson Utvecklings AB.
%% Portions created by Ericsson are Copyright 1999, Ericsson Utvecklings
%% AB. All Rights Reserved.''
%% 
%%     $Id$
%%

-module(seq_trace).
-define(SEQ_TRACE_SEND, 1).     %(1 << 0)
-define(SEQ_TRACE_RECEIVE, 2).  %(1 << 1)
-define(SEQ_TRACE_PRINT, 4).    %(1 << 2)
-define(SEQ_TRACE_TIMESTAMP, 8).    %(1 << 3)

-export([
	 set_token/1,
	 set_token/2,
	 get_token/0,
	 get_token/1,
	 print/1,
	 print/2,
	 reset_trace/0,
	 set_system_tracer/1,
	 get_system_tracer/0]).


set_token([]) ->
	erlang:seq_trace(sequential_trace_token,[]);
set_token({Flags,Label,Serial,_From,Lastcnt}) ->
    F = decode_flags(Flags),
    set_token2([{label,Label},{serial,{Lastcnt, Serial}} | F]).

% We limit the label type to always be a small integer because erl_interface
% expects that, the BIF can however "unofficially" handle atoms as well , and
% atoms can be used if only Erlang nodes are involved

set_token(Type,Val) ->
    erlang:seq_trace(Type,Val).

get_token() ->
    element(2,process_info(self(),sequential_trace_token)).

get_token(Type) ->
    erlang:seq_trace_info(Type).

print(Term) ->
    erlang:seq_trace_print(Term).

print(Label,Term) when is_atom(Label) ->
    erlang:error(badarg, [Label, Term]);
print(Label,Term) ->
    erlang:seq_trace_print(Label,Term).

reset_trace() ->
    erlang:system_flag(1,0).

%reset_trace(Pid) -> % this might be a useful function too


set_system_tracer(Pid) ->
    erlang:system_flag(sequential_tracer,Pid).

get_system_tracer() ->
    element(2,erlang:system_info(sequential_tracer)).


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% internal help functions 
%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

set_token2([{Type,Val}|T]) ->
    erlang:seq_trace(Type,Val),
    set_token2(T);
set_token2([]) ->
    ok.

decode_flags(Flags) ->
    Print = (Flags band ?SEQ_TRACE_PRINT) > 0,
    Send = (Flags band ?SEQ_TRACE_SEND) > 0,
    Rec = (Flags band ?SEQ_TRACE_RECEIVE) > 0,
    Ts = (Flags band ?SEQ_TRACE_TIMESTAMP) > 0,
    [{print,Print},{send,Send},{'receive',Rec},{timestamp,Ts}].