1 files changed, 41 insertions, 0 deletions
diff --git a/pw_sync_stl/public/pw_sync_stl/binary_semaphore_inline.h b/pw_sync_stl/public/pw_sync_stl/binary_semaphore_inline.h
new file mode 100644
index 000000000..ca5a1e3e2
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+++ b/pw_sync_stl/public/pw_sync_stl/binary_semaphore_inline.h
@@ -0,0 +1,41 @@
+// Copyright 2020 The Pigweed Authors
+//
+// 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
+//
+//     https://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.
+#pragma once
+
+#include "pw_chrono/system_clock.h"
+#include "pw_sync/binary_semaphore.h"
+
+namespace pw::sync {
+
+inline BinarySemaphore::BinarySemaphore()
+    : native_type_{.mutex = {}, .condition = {}, .count = 0} {}
+
+inline BinarySemaphore::~BinarySemaphore() {}
+
+inline bool BinarySemaphore::try_acquire_for(
+    chrono::SystemClock::duration for_at_least) {
+  // Due to spurious condition variable wakeups we prefer not to use wait_for()
+  // as we may grossly extend the effective deadline after a spruious wakeup.
+  // Ergo we instead use the derived deadline which can be re-used many times
+  // without shifting the effective deadline. For more details on spurious
+  // wakeups and CVs on Windows and POSIX see:
+  //   https://en.wikipedia.org/wiki/Spurious_wakeup
+  return try_acquire_until(chrono::SystemClock::now() + for_at_least);
+}
+
+inline BinarySemaphore::native_handle_type BinarySemaphore::native_handle() {
+  return native_type_;
+}
+
+}  // namespace pw::sync