/*
 * Copyright (C) 2013 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions are
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 *
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 * in the documentation and/or other materials provided with the
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 * this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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#ifndef SKY_ENGINE_WTF_SPINLOCK_H_
#define SKY_ENGINE_WTF_SPINLOCK_H_

// DESCRIPTION
// spinLockLock() and spinLockUnlock() are simple spinlock primitives based on
// the standard CPU primitive of atomic increment and decrement of an int at
// a given memory address.

#include "sky/engine/wtf/Atomics.h"

namespace WTF {

ALWAYS_INLINE void spinLockLock(int volatile* lock)
{
    while (UNLIKELY(atomicTestAndSetToOne(lock))) {
        while (*lock) { } // Spin without spamming locked instructions.
    }
}

ALWAYS_INLINE void spinLockUnlock(int volatile* lock)
{
    atomicSetOneToZero(lock);
}

} // namespace WTF

using WTF::spinLockLock;
using WTF::spinLockUnlock;

#endif  // SKY_ENGINE_WTF_SPINLOCK_H_