/*
* Semaphore
* (C) 2013 Joel Low
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/internal/semaphore.h>

#if defined(BOTAN_TARGET_OS_HAS_THREADS)

// Based on code by Pierre Gaston (http://p9as.blogspot.com/2012/06/c11-semaphores.html)

namespace Botan {

void Semaphore::release(size_t n)
   {
   for(size_t i = 0; i != n; ++i)
      {
      lock_guard_type<mutex_type> lock(m_mutex);

      ++m_value;

      if(m_value <= 0)
         {
         ++m_wakeups;
         m_cond.notify_one();
         }
      }
   }

void Semaphore::acquire()
   {
   std::unique_lock<mutex_type> lock(m_mutex);
   --m_value;
   if(m_value < 0)
      {
      m_cond.wait(lock, [this] { return m_wakeups > 0; });
      --m_wakeups;
      }
   }

}

#endif
