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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// Copyright (c) 2008-2021 NVIDIA Corporation. All rights reserved.
// Copyright (c) 2004-2008 AGEIA Technologies, Inc. All rights reserved.
// Copyright (c) 2001-2004 NovodeX AG. All rights reserved.

#include "PsAllocator.h"
#include "PsAtomic.h"
#include "PsSList.h"
#include "PsThread.h"
#include <pthread.h>

#if PX_IOS || PX_EMSCRIPTEN
#define USE_MUTEX
#endif

namespace physx {
namespace shdfnd {
namespace {
#if defined(USE_MUTEX)
class ScopedMutexLock {
  pthread_mutex_t &mMutex;

public:
  PX_INLINE ScopedMutexLock(pthread_mutex_t &mutex) : mMutex(mutex) { pthread_mutex_lock(&mMutex); }

  PX_INLINE ~ScopedMutexLock() { pthread_mutex_unlock(&mMutex); }
};

typedef ScopedMutexLock ScopedLock;
#else
struct ScopedSpinLock {
  PX_FORCE_INLINE ScopedSpinLock(volatile int32_t &lock) : mLock(lock) {
    while (__sync_lock_test_and_set(&mLock, 1)) {
      // spinning without atomics is usually
      // causing less bus traffic. -> only one
      // CPU is modifying the cache line.
      while (lock)
        PxSpinLockPause();
    }
  }

  PX_FORCE_INLINE ~ScopedSpinLock() { __sync_lock_release(&mLock); }

private:
  volatile int32_t &mLock;
};

typedef ScopedSpinLock ScopedLock;
#endif

struct SListDetail {
  SListEntry *head;
#if defined(USE_MUTEX)
  pthread_mutex_t lock;
#else
  volatile int32_t lock;
#endif
};

template <typename T> SListDetail *getDetail(T *impl) { return reinterpret_cast<SListDetail *>(impl); }
} // namespace

SListImpl::SListImpl() {
  getDetail(this)->head = NULL;

#if defined(USE_MUTEX)
  pthread_mutex_init(&getDetail(this)->lock, NULL);
#else
  getDetail(this)->lock = 0; // 0 == unlocked
#endif
}

SListImpl::~SListImpl() {
#if defined(USE_MUTEX)
  pthread_mutex_destroy(&getDetail(this)->lock);
#endif
}

void SListImpl::push(SListEntry *entry) {
  ScopedLock lock(getDetail(this)->lock);
  entry->mNext = getDetail(this)->head;
  getDetail(this)->head = entry;
}

SListEntry *SListImpl::pop() {
  ScopedLock lock(getDetail(this)->lock);
  SListEntry *result = getDetail(this)->head;
  if (result != NULL)
    getDetail(this)->head = result->mNext;
  return result;
}

SListEntry *SListImpl::flush() {
  ScopedLock lock(getDetail(this)->lock);
  SListEntry *result = getDetail(this)->head;
  getDetail(this)->head = NULL;
  return result;
}

uint32_t SListImpl::getSize() { return sizeof(SListDetail); }

} // namespace shdfnd
} // namespace physx
