Merge pull request #1279 from petermm/system.ex

System.ex monotonic_time/1 system_time/1

Carbon copy from elixir with :native time unit removed, as it's not supported
by current erlang implementation.

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

Author: bettio

libs/exavmlib/lib/CMakeLists.txt

@@ -49,6 +49,7 @@ set(ELIXIR_MODULES
     Process
     Protocol.UndefinedError
     Range
+    System
     Tuple
 
     ArithmeticError

libs/exavmlib/lib/System.ex

@@ -0,0 +1,51 @@
+#
+# This file is part of elixir-lang.
+#
+# Copyright 2012-2024 Elixir Contributors
+# https://github.com/elixir-lang/elixir/blob/v1.17/lib/elixir/lib/system.ex
+#
+# 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
+#
+
+defmodule System do
+  @compile {:autoload, false}
+  @type time_unit ::
+          :second
+          | :millisecond
+          | :microsecond
+
+  @doc """
+  Returns the current monotonic time in the given time unit.
+
+  This time is monotonically increasing and starts in an unspecified
+  point in time.
+  """
+  @spec monotonic_time(time_unit) :: integer
+  def monotonic_time(unit) do
+    :erlang.monotonic_time(unit)
+  end
+
+  @doc """
+  Returns the current system time in the given time unit.
+
+  It is the VM view of the `os_time/0`. They may not match in
+  case of time warps although the VM works towards aligning
+  them. This time is not monotonic.
+  """
+  @spec system_time(time_unit) :: integer
+  def system_time(unit) do
+    :erlang.system_time(unit)
+  end
+end