Merge pull request #1389 from pguyot/w49/add-split_binary

Add erlang:split_binary/2

These changes are made under both the "Apache 2.0" and the "GNU Lesser General
Public License 2.1 or later" license terms (dual license).

SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 - Added a limited implementation of the OTP `ets` interface
 - Added `code:all_loaded/0` and `code:all_available/0`
+- Added `erlang:split_binary/2`
 
 ## [0.6.6] - Unreleased
 

libs/estdlib/src/erlang.erl

@@ -105,6 +105,7 @@
     garbage_collect/1,
     binary_to_term/1,
     term_to_binary/1,
+    split_binary/2,
     timestamp/0,
     universaltime/0,
     localtime/0,
@@ -1223,6 +1224,18 @@ binary_to_term(_Binary) ->
 term_to_binary(_Term) ->
     erlang:nif_error(undefined).
 
+%%-----------------------------------------------------------------------------
+%% @returns A tuple with two subbinaries
+%% @param   Bin    binary to split
+%% @param   Pos    position to split the binary, from 0 to `byte_size(Bin)'
+%% @doc Split a binary into two sub-binaries. This operation is not destructive
+%% and will create two new binaries.
+%% @end
+%%-----------------------------------------------------------------------------
+-spec split_binary(Bin :: binary(), Pos :: non_neg_integer()) -> {binary(), binary()}.
+split_binary(_Bin, _Pos) ->
+    erlang:nif_error(undefined).
+
 %%-----------------------------------------------------------------------------
 %% @returns A tuple representing the current timestamp.
 %% @see monotonic_time/1

src/libAtomVM/nifs.c

@@ -151,6 +151,7 @@ static term nif_erlang_system_info(Context *ctx, int argc, term argv[]);
 static term nif_erlang_system_flag(Context *ctx, int argc, term argv[]);
 static term nif_erlang_binary_to_term(Context *ctx, int argc, term argv[]);
 static term nif_erlang_term_to_binary(Context *ctx, int argc, term argv[]);
+static term nif_erlang_split_binary(Context *ctx, int argc, term argv[]);
 static term nif_erlang_throw(Context *ctx, int argc, term argv[]);
 static term nif_erlang_raise(Context *ctx, int argc, term argv[]);
 static term nif_ets_new(Context *ctx, int argc, term argv[]);
@@ -571,6 +572,12 @@ static const struct Nif term_to_binary_nif =
     .nif_ptr = nif_erlang_term_to_binary
 };
 
+static const struct Nif split_binary_nif =
+{
+    .base.type = NIFFunctionType,
+    .nif_ptr = nif_erlang_split_binary
+};
+
 static const struct Nif throw_nif =
 {
     .base.type = NIFFunctionType,
@@ -3022,6 +3029,35 @@ static term nif_erlang_term_to_binary(Context *ctx, int argc, term argv[])
     return ret;
 }
 
+static term nif_erlang_split_binary(Context *ctx, int argc, term argv[])
+{
+    UNUSED(argc);
+
+    term bin_term = argv[0];
+    term pos_term = argv[1];
+
+    VALIDATE_VALUE(bin_term, term_is_binary);
+    VALIDATE_VALUE(pos_term, term_is_integer);
+
+    int32_t size = term_binary_size(bin_term);
+    avm_int_t pos = term_to_int(pos_term);
+
+    if (UNLIKELY((pos < 0) || (pos > size))) {
+        RAISE_ERROR(BADARG_ATOM);
+    }
+
+    size_t alloc_heap_size = term_sub_binary_heap_size(bin_term, pos) + term_sub_binary_heap_size(bin_term, size - pos) + TUPLE_SIZE(2);
+    if (UNLIKELY(memory_ensure_free_with_roots(ctx, alloc_heap_size, 1, &bin_term, MEMORY_CAN_SHRINK) != MEMORY_GC_OK)) {
+        RAISE_ERROR(OUT_OF_MEMORY_ATOM);
+    }
+    term sub_binary_a = term_maybe_create_sub_binary(bin_term, 0, pos, &ctx->heap, ctx->global);
+    term sub_binary_b = term_maybe_create_sub_binary(bin_term, pos, size - pos, &ctx->heap, ctx->global);
+    term tuple = term_alloc_tuple(2, &ctx->heap);
+    term_put_tuple_element(tuple, 0, sub_binary_a);
+    term_put_tuple_element(tuple, 1, sub_binary_b);
+    return tuple;
+}
+
 static term nif_binary_at_2(Context *ctx, int argc, term argv[])
 {
     UNUSED(argc);

src/libAtomVM/nifs.gperf

@@ -112,6 +112,7 @@ erlang:put/2, &put_nif
 erlang:binary_to_term/1, &binary_to_term_nif
 erlang:binary_to_term/2, &binary_to_term_nif
 erlang:term_to_binary/1, &term_to_binary_nif
+erlang:split_binary/2, &split_binary_nif
 erlang:throw/1, &throw_nif
 erlang:raise/3, &raise_nif
 erlang:unlink/1, &unlink_nif

tests/erlang_tests/CMakeLists.txt

@@ -277,6 +277,7 @@ compile_erlang(test_unicode)
 
 compile_erlang(test_binary_part)
 compile_erlang(test_binary_split)
+compile_erlang(test_split_binary)
 
 compile_erlang(plusone)
 compile_erlang(plusone2)
@@ -753,6 +754,7 @@ add_custom_target(erlang_test_modules DEPENDS
 
     test_binary_part.beam
     test_binary_split.beam
+    test_split_binary.beam
 
     plusone.beam
     plusone2.beam

tests/erlang_tests/test_split_binary.erl

@@ -0,0 +1,60 @@
+%
+% This file is part of AtomVM.
+%
+% Copyright 2024 Paul Guyot <[email protected]>
+%
+% 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.
+%
+% SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
+%
+
+-module(test_split_binary).
+
+-export([
+    start/0,
+    id/1
+]).
+
+start() ->
+    ok = test_split_binary(),
+    0.
+
+test_split_binary() ->
+    {<<"a">>, <<"bcde">>} = split_binary(?MODULE:id(<<"abcde">>), 1),
+    {<<>>, <<"abcde">>} = split_binary(?MODULE:id(<<"abcde">>), 0),
+    {<<>>, <<>>} = split_binary(?MODULE:id(<<>>), 0),
+    {<<"abcde">>, <<>>} = split_binary(?MODULE:id(<<"abcde">>), 5),
+    ok =
+        try
+            _ = split_binary(?MODULE:id(<<"abcde">>), 6),
+            unexpected
+        catch
+            error:badarg -> ok
+        end,
+    ok =
+        try
+            _ = split_binary(?MODULE:id(<<"abcde">>), -1),
+            unexpected
+        catch
+            error:badarg -> ok
+        end,
+    ok =
+        try
+            _ = split_binary(?MODULE:id(<<>>), 1),
+            unexpected
+        catch
+            error:badarg -> ok
+        end,
+    ok.
+
+id(X) -> X.

tests/test.c

@@ -319,6 +319,7 @@ struct Test tests[] = {
 
     TEST_CASE_EXPECTED(test_binary_part, 12),
     TEST_CASE_EXPECTED(test_binary_split, 16),
+    TEST_CASE(test_split_binary),
 
     TEST_CASE_COND(plusone, 134217728, LONG_MAX != 9223372036854775807),