| %% @author Bob Ippolito <bob@mochimedia.com> |
| %% @copyright 2006 Mochi Media, Inc. |
| |
| %% @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]). |
| |
| %% @type iolist() = [char() | binary() | iolist()] |
| %% @type iodata() = iolist() | binary() |
| |
| %% @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 |
| %% |
| -include_lib("eunit/include/eunit.hrl"). |
| -ifdef(TEST). |
| |
| 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. |