1 files changed, 67 insertions, 20 deletions

diff --git a/ARMeilleure/Common/BitMap.cs b/ARMeilleure/Common/BitMap.cs
index 9dff271b..35100536 100644
--- a/ARMeilleure/Common/BitMap.cs
+++ b/ARMeilleure/Common/BitMap.cs
@@ -1,20 +1,50 @@
 using System.Collections;
 using System.Collections.Generic;
+using System.Numerics;
 
 namespace ARMeilleure.Common
 {
-    class BitMap : IEnumerable<int>
+    class BitMap : IEnumerator<int>
     {
-        private const int IntSize = 32;
+        private const int IntSize = 64;
         private const int IntMask = IntSize - 1;
 
-        private List<int> _masks;
+        private List<long> _masks;
+
+        private int _enumIndex;
+        private long _enumMask;
+        private int _enumBit;
+
+        public int Current => _enumIndex * IntSize + _enumBit;
+        object IEnumerator.Current => Current;
+
+        public BitMap()
+        {
+            _masks = new List<long>(0);
+        }
 
         public BitMap(int initialCapacity)
         {
             int count = (initialCapacity + IntMask) / IntSize;
 
-            _masks = new List<int>(count);
+            _masks = new List<long>(count);
+
+            while (count-- > 0)
+            {
+                _masks.Add(0);
+            }
+        }
+
+        public void Reset(int initialCapacity)
+        {
+            int count = (initialCapacity + IntMask) / IntSize;
+
+            if (count > _masks.Capacity)
+            {
+                _masks.Capacity = count;
+            }
+
+            _masks.Clear();
 
             while (count-- > 0)
             {
@@ -29,7 +59,7 @@ namespace ARMeilleure.Common
             int wordIndex = bit / IntSize;
             int wordBit   = bit & IntMask;
 
-            int wordMask = 1 << wordBit;
+            long wordMask = 1L << wordBit;
 
             if ((_masks[wordIndex] & wordMask) != 0)
             {
@@ -48,7 +78,7 @@ namespace ARMeilleure.Common
             int wordIndex = bit / IntSize;
             int wordBit   = bit & IntMask;
 
-            int wordMask = 1 << wordBit;
+            long wordMask = 1L << wordBit;
 
             _masks[wordIndex] &= ~wordMask;
         }
@@ -60,7 +90,7 @@ namespace ARMeilleure.Common
             int wordIndex = bit / IntSize;
             int wordBit   = bit & IntMask;
 
-            return (_masks[wordIndex] & (1 << wordBit)) != 0;
+            return (_masks[wordIndex] & (1L << wordBit)) != 0;
         }
 
         public bool Set(BitMap map)
@@ -71,7 +101,7 @@ namespace ARMeilleure.Common
 
             for (int index = 0; index < _masks.Count; index++)
             {
-                int newValue = _masks[index] | map._masks[index];
+                long newValue = _masks[index] | map._masks[index];
 
                 if (_masks[index] != newValue)
                 {
@@ -92,7 +122,7 @@ namespace ARMeilleure.Common
 
             for (int index = 0; index < _masks.Count; index++)
             {
-                int newValue = _masks[index] & ~map._masks[index];
+                long newValue = _masks[index] & ~map._masks[index];
 
                 if (_masks[index] != newValue)
                 {
@@ -105,6 +135,10 @@ namespace ARMeilleure.Common
             return modified;
         }
 
+ #region IEnumerable<long> Methods
+
+        // Note: The bit enumerator is embedded in this class to avoid creating garbage when enumerating.
+
         private void EnsureCapacity(int size)
         {
             while (_masks.Count * IntSize < size)
@@ -115,24 +149,37 @@ namespace ARMeilleure.Common
 
         public IEnumerator<int> GetEnumerator()
         {
-            for (int index = 0; index < _masks.Count; index++)
-            {
-                int mask = _masks[index];
+            Reset();
+            return this;
+        }
 
-                while (mask != 0)
+        public bool MoveNext()
+        {
+            if (_enumMask != 0)
+            {
+                _enumMask &= ~(1L << _enumBit);
+            }
+            while (_enumMask == 0)
+            {
+                if (++_enumIndex >= _masks.Count)
                 {
-                    int bit = BitUtils.LowestBitSet(mask);
-
-                    mask &= ~(1 << bit);
-
-                    yield return index * IntSize + bit;
+                    return false;
                 }
+                _enumMask = _masks[_enumIndex];
             }
+            _enumBit = BitOperations.TrailingZeroCount(_enumMask);
+            return true;
         }
 
-        IEnumerator IEnumerable.GetEnumerator()
+        public void Reset()
         {
-            return GetEnumerator();
+            _enumIndex = -1;
+            _enumMask = 0;
+            _enumBit = 0;
         }
+
+        public void Dispose() { }
+
+#endregion
     }
 }
\ No newline at end of file