anchor.diff:      pack_map_(Tail, << Acc/binary, (pack(Key))/binary, (pack(Value))/binary>>).
   
   % FIXME: write test for unpack_map/1
  --spec unpack_map_(binary(), non_neg_integer(), [{term(), msgpack_term()}]) ->
  -    {more, non_neg_integer()} | {any(), binary()}.
  +-spec unpack_map_(binary(), non_neg_integer(), [{msgpack_term(), msgpack_term()}]) -> {more, undefined} | {any(), binary()} | {error, reason()}.
   unpack_map_(Bin,  0,  Acc) -> {{lists:reverse(Acc)}, Bin};
   unpack_map_(Bin, Len, Acc) ->
       case unpack(Bin) of
  -	{ more, MoreLen } -> { more, MoreLen+Len-1 };
  -	{ Key, Rest } ->
  +	{more, undefined} -> {more, undefined};
  +	{Key, Rest} ->
   	    case unpack(Rest) of
  -		{more, MoreLen} -> { more, MoreLen+Len-1 };
  -		{ Value, Rest2 } ->
  +		{more, undefined} -> {more, undefined};
  +		{Value, Rest2} ->
   		    unpack_map_(Rest2,Len-1,[{Key,Value}|Acc])
   	    end
       end.
   
   
  --spec unpack_(Payload::binary()) -> {more, pos_integer()} | {msgpack_term(), binary()} | {error, reason()}.
  -unpack_(<<16#C0, Rest/binary>>) ->
  -    {nil, Rest};
  -unpack_(<<16#C2, Rest/binary>>) ->
  -    {false, Rest};
  -unpack_(<<16#C3, Rest/binary>>) ->
  -    {true, Rest};
  -
  -unpack_(<<16#CA, Return:32/float-unit:1, Rest/binary>>) -> % 32bit float
  -    {Return, Rest};
  -unpack_(<<16#CA, Rest/binary>>) ->
  -    {more, 4-byte_size(Rest)};
  -unpack_(<<16#CB, Return:64/float-unit:1, Rest/binary>>) -> % 64bit float
  -    {Return, Rest};
  -unpack_(<<16#CB, Rest/binary>>) ->
  -    {more, 8-byte_size(Rest)};
  -
  -unpack_(<<16#CC, Int:8/unsigned-integer, Rest/binary>>) -> % uint 8
  -    {Int, Rest};
  -unpack_(<<16#CC>>) ->
  -    {more, 1};
  -unpack_(<<16#CD, Int:16/big-unsigned-integer-unit:1, Rest/binary>>) -> % uint 16
  -    {Int, Rest};
  -unpack_(<<16#CD, Rest/binary>>) ->
  -    {more, 2-byte_size(Rest)};
  -unpack_(<<16#CE, Int:32/big-unsigned-integer-unit:1, Rest/binary>>) -> % uint 32
  -    {Int, Rest};
  -unpack_(<<16#CE, Rest/binary>>) ->
  -    {more, 4-byte_size(Rest)};
  -unpack_(<<16#CF, Int:64/big-unsigned-integer-unit:1, Rest/binary>>) -> % uint 64
  -    {Int, Rest};
  -unpack_(<<16#CF, Rest/binary>>) ->
  -    {more, 8-byte_size(Rest)};
  -
  -unpack_(<<16#D0, Int:8/signed-integer, Rest/binary>>) -> % int 8
  -    {Int, Rest};
  -unpack_(<<16#D0>>) ->
  -    {more, 1};
  -unpack_(<<16#D1, Int:16/big-signed-integer-unit:1, Rest/binary>>) -> % int 16
  -    {Int, Rest};
  -unpack_(<<16#D1, Rest/binary>>) ->
  -    {more, 2-byte_size(Rest)};
  -unpack_(<<16#D2, Int:32/big-signed-integer-unit:1, Rest/binary>>) -> % int 32
  -    {Int, Rest};
  -unpack_(<<16#D2, Rest/binary>>) ->
  -    {more, 4-byte_size(Rest)};
  -unpack_(<<16#D3, Int:64/big-signed-integer-unit:1, Rest/binary>>) -> % int 64
  -    {Int, Rest};
  -unpack_(<<16#D3, Rest/binary>>) ->
  -    {more, 8-byte_size(Rest)};
  -
  -unpack_(<<16#DA, Len:16/unsigned-integer-unit:1, Val:Len/binary, Rest/binary>>) -> % raw 16
  -    {Val, Rest};
  -unpack_(<<16#DA, Rest/binary>>) ->
  -    {more, 16-byte_size(Rest)};
  -unpack_(<<16#DB, Len:32/unsigned-integer-unit:1, Val:Len/binary, Rest/binary>>) -> % raw 32
  -    {Val, Rest};
  -unpack_(<<16#DB, Rest/binary>>) ->
  -    {more, 32-byte_size(Rest)};
  -
  -unpack_(<<16#DC, Len:16/big-unsigned-integer-unit:1, Rest/binary>>) -> % array 16
  -    unpack_array_(Rest, Len, []);
  -unpack_(<<16#DC, Rest/binary>>) ->
  -    {more, 2-byte_size(Rest)};
  -unpack_(<<16#DD, Len:32/big-unsigned-integer-unit:1, Rest/binary>>) -> % array 32
  -    unpack_array_(Rest, Len, []);
  -unpack_(<<16#DD, Rest/binary>>) ->
  -    {more, 4-byte_size(Rest)};
  -
  -unpack_(<<16#DE, Len:16/big-unsigned-integer-unit:1, Rest/binary>>) -> % map 16
  -    unpack_map_(Rest, Len, []);
  -unpack_(<<16#DE, Rest/binary>>) ->
  -    {more, 2-byte_size(Rest)};
  -unpack_(<<16#DF, Len:32/big-unsigned-integer-unit:1, Rest/binary>>) -> % map 32
  -    unpack_map_(Rest, Len, []);
  -unpack_(<<16#DF, Rest/binary>>) ->
  -    {more, 4-byte_size(Rest)};
  -
  -unpack_(<<0:1, Value:7, Rest/binary>>) -> % positive fixnum
  -    {Value, Rest};
  -unpack_(<<2#111:3, Value:5, Rest/binary>>) -> % negative fixnum
  -    {Value - 2#100000, Rest};
  -unpack_(<<2#101:3, Len:5, Value:Len/binary, Rest/binary>>) -> % fixraw
  -    {Value, Rest};
  -unpack_(<<2#101:3, Len:5, Rest/binary>>) ->
  -    {more, Len-byte_size(Rest)};
  -unpack_(<<2#1001:4, Len:4, Rest/binary>>) -> % fixarray
  -    unpack_array_(Rest, Len, []);
  -unpack_(<<2#1000:4, Len:4, Rest/binary>>) -> % fixmap
  -    unpack_map_(Rest, Len, []);
  -
  -%unpack_(<<F:8, Rest/binary>>) when F==16#C1; F==16#C4; F==16#C5; F==16#C6; F==16#C7; F==16#C8; F==16#C9; F==16#D5; F==16#D6; F==16#D7; F==16#D8; F==16#D9->
  -%    {error, {badarg, <<F, Rest/binary>>}}.
  -%unpack_(Other) when is_binary(Bin) ->
  -%    {more, 1}.
  -unpack_(<<>>) ->
  -    {more, 1}.
  -unpack_(Other) ->
  -    {error, {badarg, Other}}.
  +-spec unpack_(Payload::binary()) -> {more, undefined} | {msgpack_term(), binary()} | {error, reason()}.
  +% Atoms
  +unpack_(<<16#C0, Rest/binary>>) -> {nil, Rest};
  +unpack_(<<16#C2, Rest/binary>>) -> {false, Rest};
  +unpack_(<<16#C3, Rest/binary>>) -> {true, Rest};
  +
  +% Floats
  +unpack_(<<16#CA, Val:32/float-unit:1, Rest/binary>>) -> {Val, Rest};
  +unpack_(<<16#CB, Val:64/float-unit:1, Rest/binary>>) -> {Val, Rest};
  +
  +% Unsigned integers
  +unpack_(<<16#CC, Val:8/unsigned-integer, Rest/binary>>) ->             {Val, Rest};
  +unpack_(<<16#CD, Val:16/big-unsigned-integer-unit:1, Rest/binary>>) -> {Val, Rest};
  +unpack_(<<16#CE, Val:32/big-unsigned-integer-unit:1, Rest/binary>>) -> {Val, Rest};
  +unpack_(<<16#CF, Val:64/big-unsigned-integer-unit:1, Rest/binary>>) -> {Val, Rest};
  +
  +% Signed integers
  +unpack_(<<16#D0, Val:8/signed-integer, Rest/binary>>) ->             {Val, Rest};
  +unpack_(<<16#D1, Val:16/big-signed-integer-unit:1, Rest/binary>>) -> {Val, Rest};
  +unpack_(<<16#D2, Val:32/big-signed-integer-unit:1, Rest/binary>>) -> {Val, Rest};
  +unpack_(<<16#D3, Val:64/big-signed-integer-unit:1, Rest/binary>>) -> {Val, Rest};
  +
  +% Raw bytes
  +unpack_(<<16#DA, Len:16/unsigned-integer-unit:1, Val:Len/binary, Rest/binary>>) -> {Val, Rest};
  +unpack_(<<16#DB, Len:32/unsigned-integer-unit:1, Val:Len/binary, Rest/binary>>) -> {Val, Rest};
  +
  +% Arrays
  +unpack_(<<16#DC, Len:16/big-unsigned-integer-unit:1, Rest/binary>>) -> unpack_array_(Rest, Len, []);
  +unpack_(<<16#DD, Len:32/big-unsigned-integer-unit:1, Rest/binary>>) -> unpack_array_(Rest, Len, []);
  +
  +% Maps
  +unpack_(<<16#DE, Len:16/big-unsigned-integer-unit:1, Rest/binary>>) -> unpack_map_(Rest, Len, []);
  +unpack_(<<16#DF, Len:32/big-unsigned-integer-unit:1, Rest/binary>>) -> unpack_map_(Rest, Len, []);
  +
  +% Tag-encoded lengths (kept last, for speed)
  +unpack_(<<0:1, Val:7, Rest/binary>>) ->                      {Val, Rest};                  % pos fixnum
  +unpack_(<<2#111:3, Val:5, Rest/binary>>) ->                  {Val - 2#100000, Rest};       % neg fixnum
  +unpack_(<<2#101:3, Len:5, Val:Len/binary, Rest/binary>>) ->  {Val, Rest};                  % fixraw
  +unpack_(<<2#1001:4, Len:4, Rest/binary>>) ->                 unpack_array_(Rest, Len, []); % fixarray
  +unpack_(<<2#1000:4, Len:4, Rest/binary>>) ->                 unpack_map_(Rest, Len, []);   % fixmap
  +
  +% Incomplete / invalid data
  +unpack_(<<F:8, Rest/binary>>) when F==16#C1; F==16#C4; F==16#C5; F==16#C6; F==16#C7; F==16#C8; F==16#C9; F==16#D5; F==16#D6; F==16#D7; F==16#D8; F==16#D9->
  +    {error, {badarg, <<F, Rest/binary>>}};
  +unpack_(_Bin) ->
  +    {more, undefined}.
   
   
   % ===== test codes ===== %
  
positive.code:     pack_map(Map);
  pack(Map) when is_tuple(Map), element(1,Map)=:=dict ->
      pack_map(dict:from_list(Map));
  pack(_O) ->
      {error, undefined}.
  
  % unpacking.
  % if failed in decoding and not end, get more data
  % and feed more Bin into this function.
  % TODO: error case for imcomplete format when short for any type formats.
  -spec unpack( binary() )->
      {msgpack_term(), binary()} | {more, non_neg_integer()} | {error, reason()}.
  unpack(Bin) ->
      unpack_(Bin).
  
  -spec unpack_all( binary() ) -> [msgpack_term()].
  unpack_all(Data)->
  
negative.code: 	    << 16#DB:8, Len:32/big-unsigned-integer-unit:1, Bin/binary >>
      end.
  
  % list
  pack_array(L) ->
      case length(L) of
   	Len when Len < 16 ->
  