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+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2019. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%% http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+%%
+-module(small_SUITE).
+
+-export([all/0, suite/0]).
+-export([edge_cases/1]).
+
+-include_lib("common_test/include/ct.hrl").
+
+suite() ->
+ [{ct_hooks,[ts_install_cth]},
+ {timetrap, {minutes, 1}}].
+
+all() ->
+ [edge_cases].
+
+edge_cases(Config) when is_list(Config) ->
+ {MinSmall, MaxSmall} = Limits = determine_small_limits(0),
+ ct:pal("Limits = ~p", [Limits]),
+
+ true = (MaxSmall + 1) =:= MaxSmall + id(1),
+ true = (MinSmall - 1) =:= MinSmall - id(1),
+ true = (MaxSmall + 1) > id(MaxSmall),
+ true = (MinSmall - 1) < id(MinSmall),
+ -1 = MinSmall + id(MaxSmall),
+ -1 = MaxSmall + id(MinSmall),
+
+ false = is_small(MinSmall * -1),
+ false = is_small(MinSmall - id(1)),
+ false = is_small(MinSmall - 1),
+ false = is_small(MaxSmall + id(1)),
+
+ Lower = lists:seq(MinSmall, MinSmall + 128),
+ Upper = lists:seq(MaxSmall, MaxSmall - 128, -1),
+ Pow2 = seq_pow2(MinSmall, MaxSmall),
+ NearZero = lists:seq(-128, 128),
+
+ ok = test_combinations([Lower, Upper, Pow2, NearZero], MinSmall, MaxSmall),
+
+ ok.
+
+test_combinations([As | Rest]=TestVectors, MinS, MaxS) ->
+ [begin
+ _ = [arith_test(A, B, MinS, MaxS) || B <- Bs]
+ end || A <- As, Bs <- TestVectors],
+ test_combinations(Rest, MinS, MaxS);
+test_combinations([], _MinS, _MaxS) ->
+ ok.
+
+%% Builds a sequence of all powers of 2 between MinSmall and MaxSmall
+seq_pow2(MinSmall, MaxSmall) ->
+ sp2_1(MinSmall, MinSmall, MaxSmall).
+
+sp2_1(N, _MinS, MaxS) when N >= MaxS ->
+ [];
+sp2_1(-1, MinS, MaxS) ->
+ [-1 | sp2_1(1, MinS, MaxS)];
+sp2_1(N, MinS, MaxS) when N < 0 ->
+ [N | sp2_1(N bsr 1, MinS, MaxS)];
+sp2_1(N, MinS, MaxS) when N > 0 ->
+ [N | sp2_1(N bsl 1, MinS, MaxS)].
+
+arith_test(A, B, MinS, MaxS) ->
+ verify_kind(A + B, MinS, MaxS),
+ verify_kind(B + A, MinS, MaxS),
+ verify_kind(A - B, MinS, MaxS),
+ verify_kind(B - A, MinS, MaxS),
+ verify_kind(A * B, MinS, MaxS),
+ verify_kind(B * A, MinS, MaxS),
+
+ true = A + B =:= apply(erlang, id('+'), [A, B]),
+ true = A - B =:= apply(erlang, id('-'), [A, B]),
+ true = A * B =:= apply(erlang, id('*'), [A, B]),
+
+ true = A + B =:= B + id(A),
+ true = A - B =:= A + id(-B),
+ true = B - A =:= B + id(-A),
+ true = A * B =:= B * id(A),
+
+ true = B =:= 0 orelse ((A * B) div id(B) =:= A),
+ true = A =:= 0 orelse ((B * A) div id(A) =:= B),
+
+ ok.
+
+%% Verifies that N is a small when it should be
+verify_kind(N, MinS, MaxS) ->
+ true = is_small(N) =:= (N >= MinS andalso N =< MaxS).
+
+is_small(N) when is_integer(N) ->
+ 0 =:= erts_debug:flat_size(N).
+
+determine_small_limits(N) ->
+ case is_small(-1 bsl N) of
+ true -> determine_small_limits(N + 1);
+ false -> {-1 bsl (N - 1), (1 bsl (N - 1)) - 1}
+ end.
+
+id(I) -> I.