/src/mochihex.erl
Erlang | 106 lines | 52 code | 19 blank | 35 comment | 0 complexity | 2eb1299a4c911114fe3dd41ac4b1c736 MD5 | raw file
Possible License(s): MIT
- %% @author Bob Ippolito <bob@mochimedia.com>
- %% @copyright 2006 Mochi Media, Inc.
- %%
- %% Permission is hereby granted, free of charge, to any person obtaining a
- %% copy of this software and associated documentation files (the "Software"),
- %% to deal in the Software without restriction, including without limitation
- %% the rights to use, copy, modify, merge, publish, distribute, sublicense,
- %% and/or sell copies of the Software, and to permit persons to whom the
- %% Software is furnished to do so, subject to the following conditions:
- %%
- %% The above copyright notice and this permission notice shall be included in
- %% all copies or substantial portions of the Software.
- %%
- %% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- %% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- %% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
- %% THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- %% LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
- %% FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
- %% DEALINGS IN THE SOFTWARE.
- %% @doc Utilities for working with hexadecimal strings.
- -module(mochihex).
- -author('bob@mochimedia.com').
- -export([to_hex/1, to_bin/1, to_int/1, dehex/1, hexdigit/1]).
- %% @spec to_hex(integer | iolist()) -> string()
- %% @doc Convert an iolist to a hexadecimal string.
- to_hex(0) ->
- "0";
- to_hex(I) when is_integer(I), I > 0 ->
- to_hex_int(I, []);
- to_hex(B) ->
- to_hex(iolist_to_binary(B), []).
- %% @spec to_bin(string()) -> binary()
- %% @doc Convert a hexadecimal string to a binary.
- to_bin(L) ->
- to_bin(L, []).
- %% @spec to_int(string()) -> integer()
- %% @doc Convert a hexadecimal string to an integer.
- to_int(L) ->
- erlang:list_to_integer(L, 16).
- %% @spec dehex(char()) -> integer()
- %% @doc Convert a hex digit to its integer value.
- dehex(C) when C >= $0, C =< $9 ->
- C - $0;
- dehex(C) when C >= $a, C =< $f ->
- C - $a + 10;
- dehex(C) when C >= $A, C =< $F ->
- C - $A + 10.
- %% @spec hexdigit(integer()) -> char()
- %% @doc Convert an integer less than 16 to a hex digit.
- hexdigit(C) when C >= 0, C =< 9 ->
- C + $0;
- hexdigit(C) when C =< 15 ->
- C + $a - 10.
- %% Internal API
- to_hex(<<>>, Acc) ->
- lists:reverse(Acc);
- to_hex(<<C1:4, C2:4, Rest/binary>>, Acc) ->
- to_hex(Rest, [hexdigit(C2), hexdigit(C1) | Acc]).
- to_hex_int(0, Acc) ->
- Acc;
- to_hex_int(I, Acc) ->
- to_hex_int(I bsr 4, [hexdigit(I band 15) | Acc]).
- to_bin([], Acc) ->
- iolist_to_binary(lists:reverse(Acc));
- to_bin([C1, C2 | Rest], Acc) ->
- to_bin(Rest, [(dehex(C1) bsl 4) bor dehex(C2) | Acc]).
- %%
- %% Tests
- %%
- -ifdef(TEST).
- -include_lib("eunit/include/eunit.hrl").
- to_hex_test() ->
- "ff000ff1" = to_hex([255, 0, 15, 241]),
- "ff000ff1" = to_hex(16#ff000ff1),
- "0" = to_hex(16#0),
- ok.
- to_bin_test() ->
- <<255, 0, 15, 241>> = to_bin("ff000ff1"),
- <<255, 0, 10, 161>> = to_bin("Ff000aA1"),
- ok.
- to_int_test() ->
- 16#ff000ff1 = to_int("ff000ff1"),
- 16#ff000aa1 = to_int("FF000Aa1"),
- 16#0 = to_int("0"),
- ok.
- -endif.