1 files changed, 39 insertions, 0 deletions
diff --git a/lib/utils/semaphore.cpp b/lib/utils/semaphore.cpp
new file mode 100644
index 000000000..f4f5b2b53
--- /dev/null
+++ b/lib/utils/semaphore.cpp
@@ -0,0 +1,39 @@
+/*
+* Semaphore
+* by Pierre Gaston (http://p9as.blogspot.com/2012/06/c11-semaphores.html)
+* modified by Joel Low for Botan
+*
+*/
+
+#include <botan/internal/semaphore.h>
+
+namespace Botan {
+
+void Semaphore::release(size_t n)
+   {
+   for(size_t i = 0; i != n; ++i)
+      {
+      std::lock_guard<std::mutex> lock(m_mutex);
+
+      ++m_value;
+
+      if(m_value <= 0)
+         {
+         ++m_wakeups;
+         m_cond.notify_one();
+         }
+      }
+   }
+
+void Semaphore::acquire()
+   {
+   std::unique_lock<std::mutex> lock(m_mutex);
+   --m_value;
+   if(m_value < 0)
+      {
+      m_cond.wait(lock, [this] { return m_wakeups > 0; });
+      --m_wakeups;
+      }
+   }
+
+}