1 files changed, 288 insertions, 0 deletions
diff --git a/Other/AstarPathfindingDemo/Packages/com.arongranberg.astar/Core/Collections/HierarchicalBitset.cs b/Other/AstarPathfindingDemo/Packages/com.arongranberg.astar/Core/Collections/HierarchicalBitset.cs
new file mode 100644
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+++ b/Other/AstarPathfindingDemo/Packages/com.arongranberg.astar/Core/Collections/HierarchicalBitset.cs
@@ -0,0 +1,288 @@
+using System.Collections;
+using System.Collections.Generic;
+using System.Diagnostics;
+using Unity.Burst;
+using Unity.Collections;
+using Unity.Collections.LowLevel.Unsafe;
+using Unity.Mathematics;
+using UnityEngine.Assertions;
+
+namespace Pathfinding.Util {
+	/// <summary>
+	/// Thread-safe hierarchical bitset.
+	///
+	/// Stores an array of bits. Each bit can be set or cleared individually from any thread.
+	///
+	/// Note: Setting the capacity is not thread-safe, nor is iterating over the bitset while it is being modified.
+	/// </summary>
+	[BurstCompile]
+	public struct HierarchicalBitset {
+		UnsafeSpan<ulong> l1;
+		UnsafeSpan<ulong> l2;
+		UnsafeSpan<ulong> l3;
+		Allocator allocator;
+
+		const int Log64 = 6;
+
+		public HierarchicalBitset (int size, Allocator allocator) {
+			this.allocator = allocator;
+			l1 = new UnsafeSpan<ulong>(allocator, (size + 64 - 1) >> Log64);
+			l2 = new UnsafeSpan<ulong>(allocator, (size + (64*64 - 1)) >> Log64 >> Log64);
+			l3 = new UnsafeSpan<ulong>(allocator, (size + (64*64*64 - 1)) >> Log64 >> Log64 >> Log64);
+			l1.FillZeros();
+			l2.FillZeros();
+			l3.FillZeros();
+		}
+
+		public bool IsCreated => Capacity > 0;
+
+		public void Dispose () {
+			l1.Free(allocator);
+			l2.Free(allocator);
+			l3.Free(allocator);
+			this = default;
+		}
+
+		public int Capacity {
+			get {
+				return l1.Length << Log64;
+			}
+			set {
+				if (value < Capacity) throw new System.ArgumentException("Shrinking the bitset is not supported");
+				if (value == Capacity) return;
+				var b = new HierarchicalBitset(value, allocator);
+
+				// Copy the old data
+				l1.CopyTo(b.l1);
+				l2.CopyTo(b.l2);
+				l3.CopyTo(b.l3);
+
+				Dispose();
+				this = b;
+			}
+		}
+
+		/// <summary>Number of set bits in the bitset</summary>
+		public int Count () {
+			int count = 0;
+			for (int i = 0; i < l1.Length; i++) {
+				count += math.countbits(l1[i]);
+			}
+			return count;
+		}
+
+		/// <summary>True if the bitset is empty</summary>
+		public bool IsEmpty {
+			get {
+				for (int i = 0; i < l3.Length; i++) {
+					if (l3[i] != 0) return false;
+				}
+				return true;
+			}
+		}
+
+		/// <summary>Clear all bits</summary>
+		public void Clear () {
+			// TODO: Optimize?
+			l1.FillZeros();
+			l2.FillZeros();
+			l3.FillZeros();
+		}
+
+		public void GetIndices (NativeList<int> result) {
+			var buffer = new NativeArray<int>(256, Allocator.Temp);
+			var iter = GetIterator(buffer.AsUnsafeSpan());
+			while (iter.MoveNext()) {
+				var span = iter.Current;
+				for (int i = 0; i < span.Length; i++) {
+					result.Add(span[i]);
+				}
+			}
+		}
+
+
+		[System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
+		static bool SetAtomic (ref UnsafeSpan<ulong> span, int index) {
+			var cellIndex = index >> Log64;
+			var currentValue = span[cellIndex];
+			// Note: 1 << index will only use the lower 6 bits of index
+			if ((currentValue & (1UL << index)) != 0) {
+				// Bit already set
+				return true;
+			}
+
+			// TODO: Use Interlocked.Or in newer .net versions
+			while (true) {
+				var actualValue = (ulong)System.Threading.Interlocked.CompareExchange(ref UnsafeUtility.As<ulong, long>(ref span[cellIndex]), (long)(currentValue | (1UL << index)), (long)currentValue);
+				if (actualValue != currentValue) currentValue = actualValue;
+				else break;
+			}
+			return false;
+		}
+
+		[System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
+		static bool ResetAtomic (ref UnsafeSpan<ulong> span, int index) {
+			var cellIndex = index >> Log64;
+			var currentValue = span[cellIndex];
+			// Note: 1 << index will only use the lower 6 bits of index
+			if ((currentValue & (1UL << index)) == 0) {
+				// Bit already cleared
+				return true;
+			}
+
+			// TODO: Use Interlocked.Or in newer .net versions
+			while (true) {
+				var actualValue = (ulong)System.Threading.Interlocked.CompareExchange(ref UnsafeUtility.As<ulong, long>(ref span[cellIndex]), (long)(currentValue & ~(1UL << index)), (long)currentValue);
+				if (actualValue != currentValue) currentValue = actualValue;
+				else break;
+			}
+			return false;
+		}
+
+		/// <summary>Get the value of a bit</summary>
+		[System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
+		public bool Get (int index) {
+			// Note: 1 << index will only use the lower 6 bits of index
+			return (l1[index >> Log64] & (1UL << index)) != 0;
+		}
+
+		/// <summary>Set a given bit to 1</summary>
+		[System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
+		public void Set (int index) {
+			if (SetAtomic(ref l1, index)) return;
+			SetAtomic(ref l2, index >> Log64);
+			SetAtomic(ref l3, index >> (2*Log64));
+		}
+
+		/// <summary>Set a given bit to 0</summary>
+		[System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
+		public void Reset (int index) {
+			if (ResetAtomic(ref l1, index)) return;
+			if (l1[index >> Log64] == 0) ResetAtomic(ref l2, index >> Log64);
+			if (l2[index >> (2*Log64)] == 0) ResetAtomic(ref l3, index >> (2*Log64));
+		}
+
+		/// <summary>Get an iterator over all set bits.</summary>
+		/// <param name="scratchBuffer">A buffer to use for temporary storage. A slice of this buffer will be returned on each iteration, filled with the indices of the set bits.</param>
+		public Iterator GetIterator (UnsafeSpan<int> scratchBuffer) {
+			return new Iterator(this, scratchBuffer);
+		}
+
+		[BurstCompile]
+		public struct Iterator : IEnumerator<UnsafeSpan<int> >, IEnumerable<UnsafeSpan<int> > {
+			HierarchicalBitset bitSet;
+			UnsafeSpan<int> result;
+			int resultCount;
+			int l3index;
+			int l3bitIndex;
+			int l2bitIndex;
+
+			public UnsafeSpan<int> Current => result.Slice(0, resultCount);
+
+			object IEnumerator.Current => throw new System.NotImplementedException();
+
+			public void Reset() => throw new System.NotImplementedException();
+
+			public void Dispose () {}
+
+			public IEnumerator<UnsafeSpan<int> > GetEnumerator() => this;
+
+			IEnumerator IEnumerable.GetEnumerator() => throw new System.NotImplementedException();
+
+			static int l2index(int l3index, int l3bitIndex) => (l3index << Log64) + l3bitIndex;
+			static int l1index(int l2index, int l2bitIndex) => (l2index << Log64) + l2bitIndex;
+
+			public Iterator (HierarchicalBitset bitSet, UnsafeSpan<int> result) {
+				this.bitSet = bitSet;
+				this.result = result;
+				resultCount = 0;
+				l3index = 0;
+				l3bitIndex = 0;
+				l2bitIndex = 0;
+				if (result.Length < 128) {
+					// Minimum is actually 64, but that can be very inefficient
+					throw new System.ArgumentException("Result array must be at least 128 elements long");
+				}
+			}
+
+			public bool MoveNext () {
+				return MoveNextBurst(ref this);
+			}
+
+			[BurstCompile]
+			public static bool MoveNextBurst (ref Iterator iter) {
+				return iter.MoveNextInternal();
+			}
+
+			// Inline
+			[System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
+			bool MoveNextInternal () {
+				// Store various data in local variables to avoid writing them to memory every time they are updated
+				uint resultCount = 0;
+				int l3index = this.l3index;
+				int l3bitIndex = this.l3bitIndex;
+				int l2bitIndex = this.l2bitIndex;
+				Assert.IsTrue(l2bitIndex < 64 && l3bitIndex < 64);
+
+				for (; l3index < bitSet.l3.length; l3index++) {
+					// Get the L3 cell, and mask out all bits we have already visited
+					var l3cell = bitSet.l3[l3index] & (~0UL << l3bitIndex);
+					if (l3cell == 0) continue;
+
+					while (l3cell != 0) {
+						// Find the next set bit in the L3 cell
+						l3bitIndex = math.tzcnt(l3cell);
+
+						// Nest check for level 2
+						int l2index = Iterator.l2index(l3index, l3bitIndex);
+						// The l2 cell is guaranteed to be non-zero, even after masking out the bits we have already visited
+						var l2cell = bitSet.l2[l2index] & (~0UL << l2bitIndex);
+						Assert.AreNotEqual(0, l2cell);
+
+						while (l2cell != 0) {
+							l2bitIndex = math.tzcnt(l2cell);
+							// Stop the loop if we have almost filled the result array
+							// Each L1 cell may contain up to 64 set bits
+							if (resultCount + 64 > result.Length) {
+								this.resultCount = (int)resultCount;
+								this.l3index = l3index;
+								this.l3bitIndex = l3bitIndex;
+								this.l2bitIndex = l2bitIndex;
+								return true;
+							}
+
+							int l1index = Iterator.l1index(l2index, l2bitIndex);
+							var l1cell = bitSet.l1[l1index];
+							int l1indexStart = l1index << Log64;
+							Assert.AreNotEqual(0, l1cell);
+
+							while (l1cell != 0) {
+								var l1bitIndex = math.tzcnt(l1cell);
+								l1cell &= l1cell - 1UL; // clear lowest bit
+								int index = l1indexStart + l1bitIndex;
+								Unity.Burst.CompilerServices.Hint.Assume(resultCount < (uint)result.Length);
+								result[resultCount++] = index;
+							}
+
+							l2cell &= l2cell - 1UL;
+						}
+
+						// Skip a bit at the L3 level
+						l3cell &= l3cell - 1UL; // clear lowest bit
+						// Enter new L2 level
+						l2bitIndex = 0;
+					}
+
+					l2bitIndex = 0;
+					l3bitIndex = 0;
+				}
+
+				this.resultCount = (int)resultCount;
+				this.l3index = l3index;
+				this.l3bitIndex = l3bitIndex;
+				this.l2bitIndex = l2bitIndex;
+				return resultCount > 0;
+			}
+		}
+	}
+}