NativeXorshift64CASFree.cs

using Unity.Burst;
using Unity.Collections;
using Unity.Collections.LowLevel.Unsafe;
using Unity.Jobs.LowLevel.Unsafe;
using System.Threading;

[NativeContainer]
[NativeContainerIsAtomicWriteOnly]
public unsafe struct NativeXorshift64CASFree {
	private const int LongsPerCacheLine = JobsUtility.CacheLineSize / sizeof(long);

	[NativeDisableUnsafePtrRestriction]
	ulong *m_Buffer;

	Allocator m_AllocatorLabel;

#if ENABLE_UNITY_COLLECTIONS_CHECKS
	AtomicSafetyHandle m_Safety;
	[NativeSetClassTypeToNullOnSchedule] DisposeSentinel m_DisposeSentinel;
#endif

	[NativeSetThreadIndex] int m_ThreadIndex;

	public NativeXorshift64(ulong seed, Allocator label) {
		m_AllocatorLabel = label;

		m_Buffer = (ulong *)UnsafeUtility.Malloc(JobsUtility.MaxJobThreadCount * sizeof(long) * LongsPerCacheLine, JobsUtility.CacheLineSize, m_AllocatorLabel);

#if ENABLE_UNITY_COLLECTIONS_CHECKS
#if UNITY_2018_3_OR_NEWER
		DisposeSentinel.Create(out m_Safety, out m_DisposeSentinel, 0, label);
#else
		DisposeSentinel.Create(out m_Safety, out m_DisposeSentinel, 0);
#endif
#endif

		m_ThreadIndex = 0;

		for (int i = 0; i < JobsUtility.MaxJobThreadCount; i++) {
			m_Buffer[i * LongsPerCacheLine] = seed + (ulong)i;
		}
	}

	public void Dispose() {
#if ENABLE_UNITY_COLLECTIONS_CHECKS
#if UNITY_2018_3_OR_NEWER
            DisposeSentinel.Dispose(ref m_Safety, ref m_DisposeSentinel);
#else
            DisposeSentinel.Dispose(m_Safety, ref m_DisposeSentinel);
#endif
#endif

		UnsafeUtility.Free(m_Buffer, m_AllocatorLabel);
	}

	public ulong Next() {
#if ENABLE_UNITY_COLLECTIONS_CHECKS
		AtomicSafetyHandle.CheckWriteAndThrow(m_Safety);
#endif

		ulong c = m_Buffer[LongsPerCacheLine * m_ThreadIndex];

		c = c ^ (c << 13);
		c = c ^ (c >> 17);
		c = c ^ (c << 15);

		m_Buffer[LongsPerCacheLine * m_ThreadIndex] = c;

		return c;
	}
}