mutex_gcc_sync.h

/******************************************************************************
The MIT License(MIT)
 
Embedded Template Library.
https://github.com/ETLCPP/etl
https://www.etlcpp.com
 
Copyright(c) 2017 John Wellbelove
 
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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******************************************************************************/
 
#ifndef ETL_MUTEX_GCC_SYNC_INCLUDED
#define ETL_MUTEX_GCC_SYNC_INCLUDED
 
#include "../platform.h"
 
#include <stdint.h>
 
namespace etl
{
  //***************************************************************************
  //***************************************************************************
  class mutex
  {
  public:
 
    mutex()
      : flag(0)
    {
      __sync_lock_release(&flag);
    }
 
    void lock()
    {
      while (__sync_lock_test_and_set(&flag, 1U))
      {
      }
    }
 
    bool try_lock()
    {
      return (__sync_lock_test_and_set(&flag, 1U) == 0U);
    }
 
    void unlock()
    {
      __sync_lock_release(&flag);
    }
 
  private:
 
    mutex(const mutex&) ETL_DELETE;
    mutex& operator=(const mutex&) ETL_DELETE;
 
    char flag;
  };
}
 
#endif