path: root/erts/preloaded/src/erlang.erl

%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1996-2011. All Rights Reserved.
%%
%% 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 online 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.
%%
%% %CopyrightEnd%
%%
-module(erlang).

-export([apply/2,apply/3,spawn/4,spawn_link/4,
	 spawn_monitor/1,spawn_monitor/3,
	 spawn_opt/2,spawn_opt/3,spawn_opt/4,spawn_opt/5,
	 disconnect_node/1]).
-export([spawn/1, spawn_link/1, spawn/2, spawn_link/2]).
-export([yield/0]).
-export([crasher/6]).
-export([fun_info/1]).
-export([send_nosuspend/2, send_nosuspend/3]).
-export([localtime_to_universaltime/1]).
-export([suspend_process/1]).
-export([min/2, max/2]).
-export([dlink/1, dunlink/1, dsend/2, dsend/3, dgroup_leader/2,
	 dexit/2, dmonitor_node/3, dmonitor_p/2]).
-export([delay_trap/2]).
-export([set_cookie/2, get_cookie/0]).
-export([nodes/0]).
-export([concat_binary/1]).
-export([list_to_integer/2,integer_to_list/2]).
-export([flush_monitor_message/2]).
-export([set_cpu_topology/1, format_cpu_topology/1]).
-export([await_proc_exit/3]).

-deprecated([hash/2]).
-deprecated([concat_binary/1]).

% Get rid of autoimports of spawn to avoid clashes with ourselves.
-compile({no_auto_import,[spawn/1]}).
-compile({no_auto_import,[spawn/4]}).
-compile({no_auto_import,[spawn_link/1]}).
-compile({no_auto_import,[spawn_link/4]}).
-compile({no_auto_import,[spawn_opt/2]}).
-compile({no_auto_import,[spawn_opt/4]}).
-compile({no_auto_import,[spawn_opt/5]}).

-export_type([timestamp/0]).

-type timestamp() :: {MegaSecs :: non_neg_integer(),
                      Secs :: non_neg_integer(),
                      MicroSecs :: non_neg_integer()}.

%%--------------------------------------------------------------------------

-spec apply(Fun, Args) -> term() when
      Fun :: function(),
      Args :: [term()].
apply(Fun, Args) ->
    erlang:apply(Fun, Args).

-spec apply(Module, Function, Args) -> term() when
      Module :: module(),
      Function :: atom(),
      Args :: [term()].
apply(Mod, Name, Args) ->
    erlang:apply(Mod, Name, Args).

%% Spawns with a fun

-spec spawn(Fun) -> pid() when
      Fun :: function().
spawn(F) when is_function(F) ->
    spawn(erlang, apply, [F, []]);
spawn({M,F}=MF) when is_atom(M), is_atom(F) ->
    spawn(erlang, apply, [MF, []]);
spawn(F) ->
    erlang:error(badarg, [F]).

-spec spawn(Node, Fun) -> pid() when
      Node :: node(),
      Fun :: function().
spawn(N, F) when N =:= node() ->
    spawn(F);
spawn(N, F) when is_function(F) ->
    spawn(N, erlang, apply, [F, []]);
spawn(N, {M,F}=MF) when is_atom(M), is_atom(F) ->
    spawn(N, erlang, apply, [MF, []]);
spawn(N, F) ->
    erlang:error(badarg, [N, F]).

-spec spawn_link(Fun) -> pid() when
      Fun :: function().
spawn_link(F) when is_function(F) ->
    spawn_link(erlang, apply, [F, []]);
spawn_link({M,F}=MF) when is_atom(M), is_atom(F) ->
    spawn_link(erlang, apply, [MF, []]);
spawn_link(F) ->
    erlang:error(badarg, [F]).

-spec spawn_link(Node, Fun) -> pid() when
      Node :: node(),
      Fun :: function().
spawn_link(N, F) when N =:= node() ->
    spawn_link(F);
spawn_link(N, F) when is_function(F) ->
    spawn_link(N, erlang, apply, [F, []]);
spawn_link(N, {M,F}=MF) when is_atom(M), is_atom(F) ->
    spawn_link(N, erlang, apply, [MF, []]);
spawn_link(N, F) ->
    erlang:error(badarg, [N, F]).

%% Spawn and atomically set up a monitor.

-spec spawn_monitor(Fun) -> {pid(), reference()} when
      Fun :: function().
spawn_monitor(F) when is_function(F, 0) ->
    erlang:spawn_opt({erlang,apply,[F,[]],[monitor]});
spawn_monitor(F) ->
    erlang:error(badarg, [F]).

-spec spawn_monitor(Module, Function, Args) -> {pid(), reference()} when
      Module :: module(),
      Function :: atom(),
      Args :: [term()].
spawn_monitor(M, F, A) when is_atom(M), is_atom(F), is_list(A) ->
    erlang:spawn_opt({M,F,A,[monitor]});
spawn_monitor(M, F, A) ->
    erlang:error(badarg, [M,F,A]).

-spec spawn_opt(Fun, Options) -> pid() | {pid(), reference()} when
      Fun :: function(),
      Options :: [Option],
      Option :: link | monitor | {priority, Level}
              | {fullsweep_after, Number :: non_neg_integer()}
              | {min_heap_size, Size :: non_neg_integer()}
              | {min_bin_vheap_size, VSize :: non_neg_integer()},
      Level :: low | normal | high.
spawn_opt(F, O) when is_function(F) ->
    spawn_opt(erlang, apply, [F, []], O);
spawn_opt({M,F}=MF, O) when is_atom(M), is_atom(F) ->
    spawn_opt(erlang, apply, [MF, []], O);
spawn_opt({M,F,A}, O) -> % For (undocumented) backward compatibility
    spawn_opt(M, F, A, O);
spawn_opt(F, O) ->
    erlang:error(badarg, [F, O]).

-spec spawn_opt(Node, Fun, Options) -> pid() | {pid(), reference()} when
      Node :: node(),
      Fun :: function(),
      Options :: [Option],
      Option :: link | monitor | {priority, Level}
              | {fullsweep_after, Number :: non_neg_integer()}
              | {min_heap_size, Size :: non_neg_integer()}
              | {min_bin_vheap_size, VSize :: non_neg_integer()},
      Level :: low | normal | high.
spawn_opt(N, F, O) when N =:= node() ->
    spawn_opt(F, O);
spawn_opt(N, F, O) when is_function(F) ->
    spawn_opt(N, erlang, apply, [F, []], O);
spawn_opt(N, {M,F}=MF, O) when is_atom(M), is_atom(F) ->
    spawn_opt(N, erlang, apply, [MF, []], O);
spawn_opt(N, F, O) ->
    erlang:error(badarg, [N, F, O]).

%% Spawns with MFA

-spec spawn(Node, Module, Function, Args) -> pid() when
      Node :: node(),
      Module :: module(),
      Function :: atom(),
      Args :: [term()].
spawn(N,M,F,A) when N =:= node(), is_atom(M), is_atom(F), is_list(A) ->
    spawn(M,F,A);
spawn(N,M,F,A) when is_atom(N), is_atom(M), is_atom(F) ->
    case is_well_formed_list(A) of
	true ->
	    ok;
	false ->
	    erlang:error(badarg, [N, M, F, A])
    end,
    case catch gen_server:call({net_kernel,N},
			       {spawn,M,F,A,group_leader()},
			       infinity) of
	Pid when is_pid(Pid) ->
	    Pid;
	Error ->
	    case remote_spawn_error(Error, {no_link, N, M, F, A, []}) of
		{fault, Fault} ->
		    erlang:error(Fault, [N, M, F, A]);
		Pid ->
		    Pid
	    end
    end;
spawn(N,M,F,A) ->
    erlang:error(badarg, [N, M, F, A]).

-spec spawn_link(Node, Module, Function, Args) -> pid() when
      Node :: node(),
      Module :: module(),
      Function :: atom(),
      Args :: [term()].
spawn_link(N,M,F,A) when N =:= node(), is_atom(M), is_atom(F), is_list(A) ->
    spawn_link(M,F,A);
spawn_link(N,M,F,A) when is_atom(N), is_atom(M), is_atom(F) ->
    case is_well_formed_list(A) of
	true ->
	    ok;
	_ ->
	    erlang:error(badarg, [N, M, F, A])
    end,
    case catch gen_server:call({net_kernel,N},
			       {spawn_link,M,F,A,group_leader()},
			       infinity) of
	Pid when is_pid(Pid) ->
	    Pid;
	Error ->
	    case remote_spawn_error(Error, {link, N, M, F, A, []}) of
		{fault, Fault} ->
		    erlang:error(Fault, [N, M, F, A]);
		Pid ->
		    Pid
	    end
    end;
spawn_link(N,M,F,A) ->
    erlang:error(badarg, [N, M, F, A]).

-spec spawn_opt(Module, Function, Args, Options) ->
                       pid() | {pid(), reference()} when
      Module :: module(),
      Function :: atom(),
      Args :: [term()],
      Options :: [Option],
      Option :: link | monitor | {priority, Level}
              | {fullsweep_after, Number :: non_neg_integer()}
              | {min_heap_size, Size :: non_neg_integer()}
              | {min_bin_vheap_size, VSize :: non_neg_integer()},
      Level :: low | normal | high.
spawn_opt(M, F, A, Opts) ->
    case catch erlang:spawn_opt({M,F,A,Opts}) of
	{'EXIT',{Reason,_}} ->
	    erlang:error(Reason, [M,F,A,Opts]);
	Res ->
	    Res
    end.

-spec spawn_opt(Node, Module, Function, Args, Options) ->
                       pid() | {pid(), reference()} when
      Node :: node(),
      Module :: module(),
      Function :: atom(),
      Args :: [term()],
      Options :: [Option],
      Option :: link | monitor | {priority, Level}
              | {fullsweep_after, Number :: non_neg_integer()}
              | {min_heap_size, Size :: non_neg_integer()}
              | {min_bin_vheap_size, VSize :: non_neg_integer()},
      Level :: low | normal | high.
spawn_opt(N, M, F, A, O) when N =:= node(),
			      is_atom(M), is_atom(F), is_list(A),
			      is_list(O) ->
    spawn_opt(M, F, A, O);
spawn_opt(N, M, F, A, O) when is_atom(N), is_atom(M), is_atom(F) ->
    case {is_well_formed_list(A), is_well_formed_list(O)} of
	{true, true} ->
	    ok;
	_ ->
	    erlang:error(badarg, [N, M, F, A, O])
    end,
    case lists:member(monitor, O) of
	false -> ok;
	true -> erlang:error(badarg, [N, M, F, A, O])
    end,
    {L,NO} = lists:foldl(fun (link, {_, NewOpts}) ->
				 {link, NewOpts};
			     (Opt, {LO, NewOpts}) ->
				 {LO, [Opt|NewOpts]}
			 end,
			 {no_link,[]},
			 O),
    case catch gen_server:call({net_kernel,N},
			       {spawn_opt,M,F,A,NO,L,group_leader()},
			       infinity) of
	Pid when is_pid(Pid) ->
	    Pid;
	Error ->
	    case remote_spawn_error(Error, {L, N, M, F, A, NO}) of
		{fault, Fault} ->
		    erlang:error(Fault, [N, M, F, A, O]);
		Pid ->
		    Pid
	    end
    end;
spawn_opt(N,M,F,A,O) ->
    erlang:error(badarg, [N,M,F,A,O]).

remote_spawn_error({'EXIT', {{nodedown,N}, _}}, {L, N, M, F, A, O}) ->
    {Opts, LL} = case L =:= link of
		     true ->
			 {[link|O], [link]};
		     false ->
			 {O, []}
		 end,
    spawn_opt(erlang,crasher,[N,M,F,A,Opts,noconnection], LL);
remote_spawn_error({'EXIT', {Reason, _}}, _) ->
    {fault, Reason};
remote_spawn_error({'EXIT', Reason}, _) ->
    {fault, Reason};
remote_spawn_error(Other, _) ->
    {fault, Other}.
    
is_well_formed_list([]) ->
    true;
is_well_formed_list([_|Rest]) ->
    is_well_formed_list(Rest);
is_well_formed_list(_) ->
    false.

crasher(Node,Mod,Fun,Args,[],Reason) ->
    error_logger:warning_msg("** Can not start ~w:~w,~w on ~w **~n",
			     [Mod,Fun,Args,Node]),
    exit(Reason);
crasher(Node,Mod,Fun,Args,Opts,Reason) ->
    error_logger:warning_msg("** Can not start ~w:~w,~w (~w) on ~w **~n",
			     [Mod,Fun,Args,Opts,Node]),
    exit(Reason).

-spec erlang:yield() -> 'true'.
yield() ->
    erlang:yield().

-spec nodes() -> Nodes when
      Nodes :: [node()].
nodes() ->
    erlang:nodes(visible).

-spec disconnect_node(Node) -> boolean() | ignored when
      Node :: node().
disconnect_node(Node) ->
    net_kernel:disconnect(Node).

-spec erlang:fun_info(Fun) -> [{Item, Info}] when
      Fun :: function(),
      Item :: arity | env | index | name
            | module | new_index | new_uniq | pid | type | uniq,
      Info :: term().
fun_info(Fun) when is_function(Fun) ->
    Keys = [type,env,arity,name,uniq,index,new_uniq,new_index,module,pid],
    fun_info_1(Keys, Fun, []).

fun_info_1([K|Ks], Fun, A) ->
    case erlang:fun_info(Fun, K) of
	{K,undefined} -> fun_info_1(Ks, Fun, A);
	{K,_}=P -> fun_info_1(Ks, Fun, [P|A])
    end;
fun_info_1([], _, A) -> A.

-type dst() :: pid()
             | port()
             | (RegName :: atom())
             | {RegName :: atom(), Node :: node()}.

-spec erlang:send_nosuspend(Dest, Msg) -> boolean() when
      Dest :: dst(),
      Msg :: term().
send_nosuspend(Pid, Msg) ->
    send_nosuspend(Pid, Msg, []).

-spec erlang:send_nosuspend(Dest, Msg, Options) -> boolean() when
      Dest :: dst(),
      Msg :: term(),
      Options :: [noconnect].
send_nosuspend(Pid, Msg, Opts) ->
    case erlang:send(Pid, Msg, [nosuspend|Opts]) of
	ok -> true;
	_  -> false
    end.

-spec erlang:localtime_to_universaltime({Date1, Time1}) -> {Date2, Time2} when
      Date1 :: calendar:date(),
      Date2 :: calendar:date(),
      Time1 :: calendar:time(),
      Time2 :: calendar:time().
localtime_to_universaltime(Localtime) ->
    erlang:localtime_to_universaltime(Localtime, undefined).

-spec erlang:suspend_process(Suspendee) -> 'true' when
      Suspendee :: pid().
suspend_process(P) ->
    case catch erlang:suspend_process(P, []) of
	{'EXIT', {Reason, _}} -> erlang:error(Reason, [P]);
	{'EXIT', Reason} -> erlang:error(Reason, [P]);
	Res -> Res
    end.

%%
%% If the emulator wants to perform a distributed command and
%% a connection is not established to the actual node the following 
%% functions are called in order to set up the connection and then
%% reactivate the command.
%%

-spec dlink(pid() | port()) -> 'true'.
dlink(Pid) ->
    case net_kernel:connect(node(Pid)) of
	true -> link(Pid);
	false -> erlang:dist_exit(self(), noconnection, Pid), true
    end.

%% Can this ever happen?
-spec dunlink(identifier()) -> 'true'.
dunlink(Pid) ->
    case net_kernel:connect(node(Pid)) of
	true -> unlink(Pid);
	false -> true
    end.

dmonitor_node(Node, Flag, []) ->
    case net_kernel:connect(Node) of
	true -> erlang:monitor_node(Node, Flag, []);
	false -> self() ! {nodedown, Node}, true
    end;

dmonitor_node(Node, Flag, Opts) ->
    case lists:member(allow_passive_connect, Opts) of
	true ->
	    case net_kernel:passive_cnct(Node) of
		true -> erlang:monitor_node(Node, Flag, Opts);
		false -> self() ! {nodedown, Node}, true
	    end;
	_ ->
	    dmonitor_node(Node,Flag,[])
    end.

dgroup_leader(Leader, Pid) ->
    case net_kernel:connect(node(Pid)) of
	true -> group_leader(Leader, Pid);
	false -> true  %% bad arg ?
    end.

dexit(Pid, Reason) -> 
    case net_kernel:connect(node(Pid)) of
	true -> exit(Pid, Reason);
	false -> true
    end.

dsend(Pid, Msg) when is_pid(Pid) ->
    case net_kernel:connect(node(Pid)) of
	true -> erlang:send(Pid, Msg);
	false -> Msg
    end;
dsend(Port, Msg) when is_port(Port) ->
    case net_kernel:connect(node(Port)) of
	true -> erlang:send(Port, Msg);
	false -> Msg
    end;
dsend({Name, Node}, Msg) ->
    case net_kernel:connect(Node) of
	true -> erlang:send({Name,Node}, Msg);
	false -> Msg;
	ignored -> Msg				% Not distributed.
    end.

dsend(Pid, Msg, Opts) when is_pid(Pid) ->
    case net_kernel:connect(node(Pid)) of
	true -> erlang:send(Pid, Msg, Opts);
	false -> ok
    end;
dsend(Port, Msg, Opts) when is_port(Port) ->
    case net_kernel:connect(node(Port)) of
	true -> erlang:send(Port, Msg, Opts);
	false -> ok
    end;
dsend({Name, Node}, Msg, Opts) ->
    case net_kernel:connect(Node) of
	true -> erlang:send({Name,Node}, Msg, Opts);
	false -> ok;
	ignored -> ok				% Not distributed.
    end.

-spec dmonitor_p('process', pid() | {atom(),atom()}) -> reference().
dmonitor_p(process, ProcSpec) ->
    %% ProcSpec = pid() | {atom(),atom()}
    %% ProcSpec CANNOT be an atom because a locally registered process
    %% is never handled here.
    Node = case ProcSpec of
	       {S,N} when is_atom(S), is_atom(N), N =/= node() -> N;
	       _ when is_pid(ProcSpec) -> node(ProcSpec)
	   end,
    case net_kernel:connect(Node) of
	true ->
	    erlang:monitor(process, ProcSpec);
	false ->
	    Ref = make_ref(),
	    self() ! {'DOWN', Ref, process, ProcSpec, noconnection},
	    Ref
    end.

%%
%% Trap function used when modified timing has been enabled.
%%

-spec delay_trap(Result, timeout()) -> Result.
delay_trap(Result, 0) -> erlang:yield(), Result;
delay_trap(Result, Timeout) -> receive after Timeout -> Result end.

%%
%% The business with different in and out cookies represented
%% everywhere is discarded.
%% A node has a cookie, connections/messages to that node use that cookie.
%% Messages to us use our cookie. IF we change our cookie, other nodes 
%% have to reflect that, which we cannot forsee.
%%
-spec erlang:set_cookie(Node, Cookie) -> true when
      Node :: node(),
      Cookie :: atom().
set_cookie(Node, C) when Node =/= nonode@nohost, is_atom(Node) ->
    case is_atom(C) of
	true ->
	    auth:set_cookie(Node, C);
	false ->
	    error(badarg)
    end.

-spec erlang:get_cookie() -> Cookie | nocookie when
      Cookie :: atom().
get_cookie() ->
    auth:get_cookie().

-spec concat_binary(ListOfBinaries) -> binary() when
      ListOfBinaries :: iolist().
concat_binary(List) ->
    list_to_binary(List).

-spec integer_to_list(Integer, Base) -> string() when
      Integer :: integer(),
      Base :: 2..36.
integer_to_list(I, 10) ->
    erlang:integer_to_list(I);
integer_to_list(I, Base) 
  when is_integer(I), is_integer(Base), Base >= 2, Base =< 1+$Z-$A+10 ->
    if I < 0 ->
	    [$-|integer_to_list(-I, Base, [])];
       true ->
	    integer_to_list(I, Base, [])
    end;
integer_to_list(I, Base) ->
    erlang:error(badarg, [I, Base]).

integer_to_list(I0, Base, R0) ->
    D = I0 rem Base,
    I1 = I0 div Base,
    R1 = if D >= 10 ->
		 [D-10+$A|R0];
	    true ->
		 [D+$0|R0]
	 end,
    if I1 =:= 0 ->
	    R1;
       true ->
	    integer_to_list(I1, Base, R1)
    end.


-spec list_to_integer(String, Base) -> integer() when
      String :: string(),
      Base :: 2..36.
list_to_integer(L, 10) ->
    erlang:list_to_integer(L);
list_to_integer(L, Base)
  when is_list(L), is_integer(Base), Base >= 2, Base =< 1+$Z-$A+10 ->
    case list_to_integer_sign(L, Base) of 
	I when is_integer(I) ->
	    I;
	Fault ->
	    erlang:error(Fault, [L,Base])
    end;
list_to_integer(L, Base) ->
    erlang:error(badarg, [L,Base]).

list_to_integer_sign([$-|[_|_]=L], Base) ->
    case list_to_integer(L, Base, 0) of
	I when is_integer(I) ->
	    -I;
	I ->
	    I
    end;
list_to_integer_sign([$+|[_|_]=L], Base) ->
    list_to_integer(L, Base, 0);
list_to_integer_sign([_|_]=L, Base) ->
    list_to_integer(L, Base, 0);
list_to_integer_sign(_, _) ->
    badarg.

list_to_integer([D|L], Base, I) 
  when is_integer(D), D >= $0, D =< $9, D < Base+$0 ->
    list_to_integer(L, Base, I*Base + D-$0);
list_to_integer([D|L], Base, I) 
  when is_integer(D), D >= $A, D < Base+$A-10 ->
    list_to_integer(L, Base, I*Base + D-$A+10);
list_to_integer([D|L], Base, I) 
  when is_integer(D), D >= $a, D < Base+$a-10 ->
    list_to_integer(L, Base, I*Base + D-$a+10);
list_to_integer([], _, I) ->
    I;
list_to_integer(_, _, _) ->
    badarg.

%% erlang:flush_monitor_message/2 is for internal use only!
%%
%% erlang:demonitor(Ref, [flush]) traps to
%% erlang:flush_monitor_message(Ref, Res) when
%% it needs to flush a monitor message.
flush_monitor_message(Ref, Res) when is_reference(Ref), is_atom(Res) ->
    receive {_, Ref, _, _, _} -> ok after 0 -> ok end,
    Res.

-record(cpu, {node = -1,
	      processor = -1,
	      processor_node = -1,
	      core = -1,
	      thread = -1,
	      logical = -1}).

%% erlang:set_cpu_topology/1 is for internal use only!
%%
%% erlang:system_flag(cpu_topology, CpuTopology) traps to 
%% erlang:set_cpu_topology(CpuTopology).
set_cpu_topology(CpuTopology) ->
    try format_cpu_topology(erlang:system_flag(internal_cpu_topology,
					       cput_e2i(CpuTopology)))
    catch
	Class:Exception when Class =/= error; Exception =/= internal_error -> 
	    erlang:error(badarg, [CpuTopology])
    end.

cput_e2i_clvl({logical, _}, _PLvl) ->
    #cpu.logical;
cput_e2i_clvl([E | _], PLvl) ->
    case element(1, E) of
	node -> case PLvl of
		    0 -> #cpu.node;
		    #cpu.processor -> #cpu.processor_node
		end;
	processor -> case PLvl of
			 0 -> #cpu.node;
			 #cpu.node -> #cpu.processor
		     end;
	core -> #cpu.core;
	thread -> #cpu.thread
    end.

cput_e2i(undefined) ->
    undefined;
cput_e2i(E) ->
    rvrs(cput_e2i(E, -1, -1, #cpu{}, 0, cput_e2i_clvl(E, 0), [])).

cput_e2i([], _NId, _PId, _IS, _PLvl, _Lvl, Res) -> 
    Res;
cput_e2i([E|Es], NId0, PId, IS, PLvl, Lvl, Res0) -> 
    case cput_e2i(E, NId0, PId, IS, PLvl, Lvl, Res0) of
	[] ->
	    cput_e2i(Es, NId0, PId, IS, PLvl, Lvl, Res0);
	[#cpu{node = N,
	      processor = P,
	      processor_node = PN} = CPU|_] = Res1 ->
	    NId1 = case N > PN of
			 true -> N;
			 false -> PN
		     end,
	    cput_e2i(Es, NId1, P, CPU, PLvl, Lvl, Res1)
    end;
cput_e2i({Tag, [], TagList}, Nid, PId, CPU, PLvl, Lvl, Res) ->
    %% Currently [] is the only valid InfoList
    cput_e2i({Tag, TagList}, Nid, PId, CPU, PLvl, Lvl, Res);
cput_e2i({node, NL}, Nid0, PId, _CPU, 0, #cpu.node, Res) ->
    Nid1 = Nid0+1,
    Lvl = cput_e2i_clvl(NL, #cpu.node),
    cput_e2i(NL, Nid1, PId, #cpu{node = Nid1}, #cpu.node, Lvl, Res);
cput_e2i({processor, PL}, Nid, PId0, _CPU, 0, #cpu.node, Res) ->
    PId1 = PId0+1,
    Lvl = cput_e2i_clvl(PL, #cpu.processor),
    cput_e2i(PL, Nid, PId1, #cpu{processor = PId1}, #cpu.processor, Lvl, Res);
cput_e2i({processor, PL}, Nid, PId0, CPU, PLvl, CLvl, Res)
  when PLvl < #cpu.processor, CLvl =< #cpu.processor ->
    PId1 = PId0+1,
    Lvl = cput_e2i_clvl(PL, #cpu.processor),
    cput_e2i(PL, Nid, PId1, CPU#cpu{processor = PId1,
				    processor_node = -1,
				    core = -1,
				    thread = -1}, #cpu.processor, Lvl, Res);
cput_e2i({node, NL}, Nid0, PId, CPU, #cpu.processor, #cpu.processor_node,
	 Res) ->
    Nid1 = Nid0+1,
    Lvl = cput_e2i_clvl(NL, #cpu.processor_node),
    cput_e2i(NL, Nid1, PId, CPU#cpu{processor_node = Nid1},
	     #cpu.processor_node, Lvl, Res);
cput_e2i({core, CL}, Nid, PId, #cpu{core = C0} = CPU, PLvl, #cpu.core, Res)
  when PLvl < #cpu.core ->
    Lvl = cput_e2i_clvl(CL, #cpu.core),
    cput_e2i(CL, Nid, PId, CPU#cpu{core = C0+1, thread = -1}, #cpu.core, Lvl,
	     Res);
cput_e2i({thread, TL}, Nid, PId, #cpu{thread = T0} = CPU, PLvl, #cpu.thread,
	 Res) when PLvl < #cpu.thread ->
    Lvl = cput_e2i_clvl(TL, #cpu.thread),
    cput_e2i(TL, Nid, PId, CPU#cpu{thread = T0+1}, #cpu.thread, Lvl, Res);
cput_e2i({logical, ID}, _Nid, PId, #cpu{processor=P, core=C, thread=T} = CPU,
	 PLvl, #cpu.logical, Res)
  when PLvl < #cpu.logical, is_integer(ID), 0 =< ID, ID < 65536 ->
    [CPU#cpu{processor = case P of -1 -> PId+1; _ -> P end,
	     core = case C of -1 -> 0; _ -> C end,
	     thread = case T of -1 -> 0; _ -> T end,
	     logical = ID} | Res].

%% erlang:format_cpu_topology/1 is for internal use only!
%%
%% erlang:system_info(cpu_topology),
%% and erlang:system_info({cpu_topology, Which}) traps to
%% erlang:format_cpu_topology(InternalCpuTopology).
format_cpu_topology(InternalCpuTopology) ->
    try cput_i2e(InternalCpuTopology)
    catch _ : _ -> erlang:error(internal_error, [InternalCpuTopology])
    end.


cput_i2e(undefined) -> undefined;
cput_i2e(Is) -> cput_i2e(Is, true, #cpu.node, cput_i2e_tag_map()).

cput_i2e([], _Frst, _Lvl, _TM) ->
    [];
cput_i2e([#cpu{logical = LID}| _], _Frst, Lvl, _TM) when Lvl == #cpu.logical ->
    {logical, LID};
cput_i2e([#cpu{} = I | Is], Frst, Lvl, TM) ->
    cput_i2e(element(Lvl, I), Frst, Is, [I], Lvl, TM).

cput_i2e(V, Frst, [I | Is], SameV, Lvl, TM) when V =:= element(Lvl, I) ->
    cput_i2e(V, Frst, Is, [I | SameV], Lvl, TM);
cput_i2e(-1, true, [], SameV, Lvl, TM) ->
    cput_i2e(rvrs(SameV), true, Lvl+1, TM);
cput_i2e(_V, true, [], SameV, Lvl, TM) when Lvl =/= #cpu.processor,
                                            Lvl =/= #cpu.processor_node ->
    cput_i2e(rvrs(SameV), true, Lvl+1, TM);
cput_i2e(-1, _Frst, Is, SameV, #cpu.node, TM) ->
    cput_i2e(rvrs(SameV), true, #cpu.processor, TM)
	++ cput_i2e(Is, false, #cpu.node, TM);
cput_i2e(_V, _Frst, Is, SameV, Lvl, TM) ->
    [{cput_i2e_tag(Lvl, TM), cput_i2e(rvrs(SameV), true, Lvl+1, TM)}
     | cput_i2e(Is, false, Lvl, TM)].

cput_i2e_tag_map() -> list_to_tuple([cpu | record_info(fields, cpu)]).

cput_i2e_tag(Lvl, TM) ->
    case element(Lvl, TM) of processor_node -> node; Other -> Other end.

rvrs([_] = L) -> L;
rvrs(Xs) -> rvrs(Xs, []).

rvrs([],Ys) -> Ys;
rvrs([X|Xs],Ys) -> rvrs(Xs, [X|Ys]).

%% erlang:await_proc_exit/3 is for internal use only!
%%
%% BIFs that need to await a specific process exit before
%% returning traps to erlang:await_proc_exit/3.
%%
%% NOTE: This function is tightly coupled to
%%       the implementation of the
%%       erts_bif_prep_await_proc_exit_*()
%%       functions in bif.c. Do not make
%%       any changes to it without reading
%%       the comment about them in bif.c!
-spec await_proc_exit(dst(), 'apply' | 'data' | 'reason', term()) -> term().
await_proc_exit(Proc, Op, Data) ->
    Mon = erlang:monitor(process, Proc),
    receive
	{'DOWN', Mon, process, _Proc, Reason} ->
	    case Op of
		apply ->
		    {M, F, A} = Data,
		    erlang:apply(M, F, A);
		data ->
		    Data;
		reason ->
		    Reason
	    end
    end.

-spec min(Term1, Term2) -> Minimum when
      Term1 :: term(),
      Term2 :: term(),
      Minimum :: term().
min(A, B) when A > B -> B;
min(A, _) -> A.

-spec max(Term1, Term2) -> Maximum when
      Term1 :: term(),
      Term2 :: term(),
      Maximum :: term().
max(A, B) when A < B -> B;
max(A, _) -> A.