From 1cd874911db0d4c0463264edd0d46067d072eccb Mon Sep 17 00:00:00 2001
From: Ciro Nishiguchi <ciro.nishiguchi@ni.com>
Date: Wed, 23 Oct 2019 09:36:27 -0500
Subject: rfnoc: Split up offload I/O service into multiple files

---
 host/lib/include/uhdlib/utils/semaphore.hpp | 71 +++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 host/lib/include/uhdlib/utils/semaphore.hpp

(limited to 'host/lib/include/uhdlib/utils')

diff --git a/host/lib/include/uhdlib/utils/semaphore.hpp b/host/lib/include/uhdlib/utils/semaphore.hpp
new file mode 100644
index 000000000..ae77ed102
--- /dev/null
+++ b/host/lib/include/uhdlib/utils/semaphore.hpp
@@ -0,0 +1,71 @@
+//
+// Copyright 2019 Ettus Research, a National Instruments brand
+//
+// SPDX-License-Identifier: GPL-3.0-or-later
+//
+
+#include <condition_variable>
+#include <chrono>
+#include <mutex>
+
+#ifndef INCLUDED_UHDLIB_UTILS_SEMAPHORE_HPP
+#define INCLUDED_UHDLIB_UTILS_SEMAPHORE_HPP
+
+namespace uhd {
+
+/*!
+ * A sempahore built using std::condition_variable
+ */
+class semaphore
+{
+public:
+    void notify()
+    {
+        std::unique_lock<std::mutex> lock(_cv_mutex);
+        _count++;
+        _cv.notify_one();
+    }
+
+    void wait()
+    {
+        std::unique_lock<std::mutex> lock(_cv_mutex);
+        _cv.wait(lock, [this]() { return this->_count != 0; });
+        _count--;
+    }
+
+    bool try_wait()
+    {
+        std::unique_lock<std::mutex> lock(_cv_mutex);
+        if (_count != 0) {
+            _count--;
+            return true;
+        }
+        return false;
+    }
+
+    bool wait_for(size_t timeout_ms)
+    {
+        std::chrono::milliseconds timeout(timeout_ms);
+        std::unique_lock<std::mutex> lock(_cv_mutex);
+        if (_cv.wait_for(lock, timeout, [this]() { return this->_count != 0; })) {
+            _count--;
+            return true;
+        }
+        return false;
+    }
+
+    size_t count()
+    {
+        std::unique_lock<std::mutex> lock(_cv_mutex);
+        return _count;
+    }
+
+private:
+    std::condition_variable _cv;
+    std::mutex _cv_mutex;
+    size_t _count = 0;
+};
+
+} // namespace uhd
+
+#endif /* INCLUDED_UHDLIB_UTILS_SEMAPHORE_HPP */
-- 
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