92 lines
2.7 KiB
Erlang
92 lines
2.7 KiB
Erlang
%%%----------------------------------------------------------------------
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%%% File : randoms.erl
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%%% Author : Alexey Shchepin <alexey@process-one.net>
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%%% Purpose : Random generation number wrapper
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%%% Created : 13 Dec 2002 by Alexey Shchepin <alexey@process-one.net>
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%%%
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%%%
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%%% ejabberd, Copyright (C) 2002-2018 ProcessOne
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%%%
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%%% This program is free software; you can redistribute it and/or
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%%% modify it under the terms of the GNU General Public License as
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%%% published by the Free Software Foundation; either version 2 of the
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%%% License, or (at your option) any later version.
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%%%
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%%% This program is distributed in the hope that it will be useful,
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%%% but WITHOUT ANY WARRANTY; without even the implied warranty of
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%%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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%%% General Public License for more details.
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%%%
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%%% You should have received a copy of the GNU General Public License along
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%%% with this program; if not, write to the Free Software Foundation, Inc.,
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%%% 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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%%%
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%%%----------------------------------------------------------------------
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-module(randoms).
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-author('alexey@process-one.net').
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-export([get_string/0, uniform/0, uniform/1, uniform/2, bytes/1,
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round_robin/1, get_alphanum_string/1]).
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-define(THRESHOLD, 16#10000000000000000).
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-ifdef(RAND_UNIFORM).
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get_string() ->
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R = rand:uniform(?THRESHOLD),
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integer_to_binary(R).
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uniform() ->
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rand:uniform().
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uniform(N) ->
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rand:uniform(N).
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uniform(N, M) ->
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rand:uniform(M-N+1) + N-1.
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-else.
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get_string() ->
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R = crypto:rand_uniform(0, ?THRESHOLD),
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integer_to_binary(R).
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uniform() ->
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crypto:rand_uniform(0, ?THRESHOLD)/?THRESHOLD.
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uniform(N) ->
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crypto:rand_uniform(1, N+1).
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uniform(N, M) ->
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crypto:rand_uniform(N, M+1).
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-endif.
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-ifdef(STRONG_RAND_BYTES).
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bytes(N) ->
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crypto:strong_rand_bytes(N).
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-else.
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bytes(N) ->
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crypto:rand_bytes(N).
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-endif.
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-spec round_robin(pos_integer()) -> non_neg_integer().
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round_robin(N) ->
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p1_time_compat:unique_integer([monotonic, positive]) rem N.
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-spec get_alphanum_string(non_neg_integer()) -> binary().
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get_alphanum_string(Length) ->
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list_to_binary(get_alphanum_string([], Length)).
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-spec get_alphanum_string(string(), non_neg_integer()) -> string().
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get_alphanum_string(S, 0) -> S;
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get_alphanum_string(S, N) ->
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get_alphanum_string([make_rand_char() | S], N - 1).
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-spec make_rand_char() -> char().
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make_rand_char() ->
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map_int_to_char(uniform(0, 61)).
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-spec map_int_to_char(0..61) -> char().
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map_int_to_char(N) when N =< 9 -> N + 48; % Digit.
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map_int_to_char(N) when N =< 35 -> N + 55; % Upper-case character.
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map_int_to_char(N) when N =< 61 -> N + 61. % Lower-case character.
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