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katana

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Erlang grab bag of useful functions. It should have been called swiss army knife but katanas are deadlier

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katana src ktn_base16.erl
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src/ktn_base16.erl 

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%% ktn_base16: encoding and decoding Base16 binaries

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

-module(ktn_base16).



-export([ encode/1

        , decode/1

        ]).



%% @doc Encodes a binary in base 16.

-spec encode(binary()) -> binary().

encode(Bin) ->

    << <<(encode_char(A)):8/unsigned-integer,

         (encode_char(B)):8/unsigned-integer>> ||

       <<A:4/unsigned-integer, B:4/unsigned-integer>> <= Bin>>.



%% @doc Decodes a base 16 binary.

-spec decode(binary()) -> binary().

decode(Bin) ->

    << <<(decode_char(A)):4/unsigned-integer,

         (decode_char(B)):4/unsigned-integer>> ||

       <<A:8/unsigned-integer, B:8/unsigned-integer>> <= Bin>>.



encode_char(C) when C > 9 ->

    C + $A - 10;

encode_char(C) ->

    C + $0.



decode_char(C) when C >= $A ->

    C - $A + 10;

decode_char(C) when C >= $a ->

    C - $a + 10;

decode_char(C) ->

    C - $0.