com.unity.demoteam.digital-human/Runtime/MeshTools/UnsafeArrayULong.cs

using System;
using Unity.Collections;
using Unity.Collections.LowLevel.Unsafe;

public unsafe struct UnsafeArrayULong : IDisposable
{
    public ulong* val;
    private long valSize;

    private Allocator allocator;

    public UnsafeArrayULong(int capacity, Allocator allocator = Allocator.Temp)
    {
        this.val = (ulong*)UnsafeUtility.Malloc(sizeof(ulong) * capacity, 1, allocator);
        this.valSize = sizeof(ulong) * capacity;

        this.allocator = allocator;
    }

    public void Clear(ulong value)
    {
        if (value == 0uL)
            UnsafeUtility.MemClear(val, valSize);
        else
            UnsafeUtility.MemCpyReplicate(val, &value, sizeof(ulong), (int)valSize / sizeof(ulong));
    }

    public void Dispose()
    {
        if (val != null)
            UnsafeUtility.Free(val, allocator);
    }
}