hex.erl

%%%-------------------------------------------------------------------
%%% @author zhongwencool@gmail.com
%%% @copyright (C) 2016, <COMPANY>
%%% @doc
%%%
%%% @end
%%% Created : 06. 一月 2016 18:30
%%%-------------------------------------------------------------------
-module(hex).

%% API
-compile(export_all).

-define(RUN_TIMES, 100000).

hexstr_to_bin(S) ->
  hexstr_to_bin(S, []).
hexstr_to_bin([], Acc) ->
  list_to_binary(lists:reverse(Acc));
hexstr_to_bin([$ |T], Acc) ->
  hexstr_to_bin(T, Acc);
hexstr_to_bin([X, Y|T], Acc) ->
  {ok, [V], []} = io_lib:fread("~16u", [X, Y]),
  hexstr_to_bin(T, [V | Acc]).

hexbin_to_bin(S) ->
  hexbin_to_bin(S, <<>>).


hexbin_to_bin(<<>>, Acc) -> Acc;
hexbin_to_bin(<<$ , Rest/binary>>, Acc) -> hexbin_to_bin(Rest, Acc);
hexbin_to_bin(<<X, Y, Rest/binary>>, Acc) ->
  {ok, [V], []} = io_lib:fread("~16u", [X, Y]),
  hexbin_to_bin(Rest, <<Acc/binary, V>>).

test() ->
  Bin = <<"349906e74209e823228f0025ae99f0d9d2c406a523d6415d1087ae313c3d7539">>,
  Str = "349906e74209e823228f0025ae99f0d9d2c406a523d6415d1087ae313c3d7539",
  io:format("~p~n", [hexbin_to_bin(Bin) == hexstr_to_bin(Str)]),

  {TimeBin,_} = timer:tc(fun() -> hexstr_to_bin_test(?RUN_TIMES) end),
  {TimeStr,_} = timer:tc(fun() -> hexbin_to_bin_test(?RUN_TIMES) end),

  io:format("BinTime:~p StrTime:~p Diff:~p~n",[TimeBin, TimeStr, TimeBin- TimeStr]).

hexstr_to_bin_test(0) -> ok;
hexstr_to_bin_test(N) ->
  hexstr_to_bin("349906e74209e823228f0025ae99f0d9d2c406a523d6415d1087ae313c3d7539"),
  hexstr_to_bin_test(N-1).

hexbin_to_bin_test(0) -> ok;
hexbin_to_bin_test(N) ->
  hexbin_to_bin(<<"349906e74209e823228f0025ae99f0d9d2c406a523d6415d1087ae313c3d7539">>),
  hexbin_to_bin_test(N-1).

(zhongwencool@zhongwen)1> hex:test().
true
BinTime:1927792 StrTime:2175268 Diff:-247476
ok