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File Name: mfx_critical_section.cpp

\* ****************************************************************************** */

#include "mfx_critical_section.h"

#if defined(_WIN32) || defined(_WIN64)

#include <windows.h>
// SDK re-declares the following functions with different call declarator.
// We don't need them. Just redefine them to nothing.
#define _interlockedbittestandset fake_set
#define _interlockedbittestandreset fake_reset
#define _interlockedbittestandset64 fake_set64
#define _interlockedbittestandreset64 fake_reset64
#include <intrin.h>

#define MFX_WAIT() SwitchToThread()

// static section of the file
namespace
{

enum
{
    MFX_SC_IS_FREE = 0,
    MFX_SC_IS_TAKEN = 1
};

} // namespace

namespace MFX
{

mfxU32 mfxInterlockedCas32(mfxCriticalSection *pCSection, mfxU32 value_to_exchange, mfxU32 value_to_compare)
{
    return _InterlockedCompareExchange(pCSection, value_to_exchange, value_to_compare);
}

mfxU32 mfxInterlockedXchg32(mfxCriticalSection *pCSection, mfxU32 value)  
{ 
    return _InterlockedExchange(pCSection, value);
}

void mfxEnterCriticalSection(mfxCriticalSection *pCSection)
{
    while (MFX_SC_IS_TAKEN == mfxInterlockedCas32(pCSection,
                                                  MFX_SC_IS_TAKEN,
                                                  MFX_SC_IS_FREE))
    {
        MFX_WAIT();
    }
} // void mfxEnterCriticalSection(mfxCriticalSection *pCSection)

void mfxLeaveCriticalSection(mfxCriticalSection *pCSection)
{
    mfxInterlockedXchg32(pCSection, MFX_SC_IS_FREE);
} // void mfxLeaveCriticalSection(mfxCriticalSection *pCSection)

} // namespace MFX

#endif // #if defined(_WIN32) || defined(_WIN64)