anchor.diff:  	NextStep = Step div 2,
   	btree_search(Log, Start, NextStep, Cont, element(1, R), disk_log:chunk_step(Log, Cont, NextStep));
   btree_search(Log, Start, Step, _PrevCont, _PrevChunkStart, Cont, {_NextCont, [R]})
  -		when Step > 0, element(1, R) > Start ->
  +		when Step > 0, element(1, R) >= Start ->
   	NextStep = -(Step div 2),
   	btree_search(Log, Start, NextStep, Cont, element(1, R), disk_log:chunk_step(Log, Cont, NextStep));
   btree_search(Log, Start, Step, _PrevCont, _PrevChunkStart, Cont, {_NextCont, [R]})
  -		when Step < -2, element(1, R) > Start, (Step rem 2) == 0 ->
  +		when Step < -2, element(1, R) >= Start, (Step rem 2) == 0 ->
   	NextStep = (Step div 2) - 1,
   	btree_search(Log, Start, NextStep, Cont, element(1, R), disk_log:chunk_step(Log, Cont, NextStep));
   btree_search(Log, Start, Step, _PrevCont, _PrevChunkStart, Cont, {_NextCont, [R]})
  -		when Step < 0, element(1, R) > Start ->
  +		when Step < 0, element(1, R) >= Start ->
   	NextStep = Step div 2,
   	btree_search(Log, Start, NextStep, Cont, element(1, R), disk_log:chunk_step(Log, Cont, NextStep));
   btree_search(Log, Start, Step, _PrevCont, _PrevChunkStart, Cont, {_NextCont, [R]})
  
positive.code: 	PrevCont;
  btree_search(Log, Start, _Step, PrevCont, PrevChunkStart, {error, end_of_log}) ->
  	LogInfo = disk_log:info(Log),
  	Step1 = case lists:keyfind(current_file, 1, LogInfo) of
  		{current_file, CurrentFile} when (CurrentFile rem 2) == 0, CurrentFile > 2 ->
  			(CurrentFile div 2) - 1;
  		{current_file, CurrentFile} ->
  			CurrentFile div 2
  	end,
  	btree_search(Log, Start, Step1, PrevCont, PrevChunkStart, disk_log:chunk_step(Log, PrevCont, Step1));
  btree_search(_Log, _Start, _Step, _PrevCont, _PrevChunkStart, {error, Reason}) ->
  	{error, Reason}.
  %% @hidden
  btree_search(_Log, Start, 1, PrevCont, _PrevChunkStart, _Cont, {_NextCont, [R]})
  		when element(1, R) > Start ->
  	PrevCont;
  btree_search(_Log, _Start, Step, _PrevCont, PrevChunkStart, Cont, {_NextCont, [R]})
  		when Step < 0, element(1, R) > PrevChunkStart ->
  
negative.code: 		Reason :: term().
  %% @doc Binary tree search of multi file wrap disk_log.
  %% @private
  btree_search(Log, Start) ->
  	btree_search(Log, Start, disk_log:chunk(Log, start, 1)).
  %% @hidden
  