win32 读写锁

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#define _RW_LOCK_h_

#include "stdint.h"
#include <wtypes.h>
#include <winbase.h>

#define RWLOCK_FREE 0
#define RWLOCK_LOCKED 1

class CRWLock
{
public:
inline CRWLock(void):m_ulRLock(0),m_ulWLock(0),m_ulPreLock(0){};
void WLock(void);
void RLock(void);

inline void WUnLock(void)
{
  InterlockedExchange((LPLONG)&m_ulWLock, RWLOCK_FREE);
}

inline void RUnLock(void)
{
  if (m_ulRLock>0)
  {
   InterlockedDecrement((LPLONG)&m_ulRLock);
  }
}

inline void Lock(void){WLock();}
inline void UnLock(void){WUnLock();}
private:
uint32_t volatile m_ulWLock;
uint32_t volatile m_ulRLock;
uint32_t volatile m_ulPreLock;

};

#endif

#include "CRWLock.h"

void CRWLock::WLock(void)
{

while (InterlockedCompareExchange((PVOID*)&m_ulPreLock, (PVOID)RWLOCK_LOCKED, (PVOID)RWLOCK_FREE) != 0)
{
  Sleep(0);
}

while (InterlockedCompareExchange((PVOID*)&m_ulRLock, (PVOID)RWLOCK_FREE, (PVOID)RWLOCK_FREE) != 0)
{
  Sleep(0);
}

while (InterlockedCompareExchange((PVOID*)&m_ulWLock, (PVOID)RWLOCK_LOCKED, (PVOID)RWLOCK_FREE) != 0)
{
  Sleep(0);
}

InterlockedExchange((LPLONG)&m_ulPreLock, RWLOCK_FREE);
}

void CRWLock::RLock(void)
{
while (InterlockedCompareExchange((PVOID*)&m_ulPreLock, (PVOID)RWLOCK_LOCKED, (PVOID)RWLOCK_FREE) != 0)
{
Sleep(0);
}

while (InterlockedCompareExchange((PVOID*)&m_ulWLock, (PVOID)RWLOCK_FREE, (PVOID)RWLOCK_FREE) != 0)
{
Sleep(0);
}

InterlockedIncrement((LPLONG)&m_ulRLock);

InterlockedExchange((LPLONG)&m_ulPreLock, RWLOCK_FREE);
}