1 files changed, 499 insertions, 0 deletions
diff --git a/src/Ryujinx.Common/Collections/IntervalTree.cs b/src/Ryujinx.Common/Collections/IntervalTree.cs
new file mode 100644
index 00000000..b5188cc7
--- /dev/null
+++ b/src/Ryujinx.Common/Collections/IntervalTree.cs
@@ -0,0 +1,499 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace Ryujinx.Common.Collections
+{
+    /// <summary>
+    /// An Augmented Interval Tree based off of the "TreeDictionary"'s Red-Black Tree. Allows fast overlap checking of ranges.
+    /// </summary>
+    /// <typeparam name="K">Key</typeparam>
+    /// <typeparam name="V">Value</typeparam>
+    public class IntervalTree<K, V> : IntrusiveRedBlackTreeImpl<IntervalTreeNode<K, V>> where K : IComparable<K>
+    {
+        private const int ArrayGrowthSize = 32;
+
+        #region Public Methods
+
+        /// <summary>
+        /// Gets the values of the interval whose key is <paramref name="key"/>.
+        /// </summary>
+        /// <param name="key">Key of the node value to get</param>
+        /// <param name="overlaps">Overlaps array to place results in</param>
+        /// <returns>Number of values found</returns>
+        /// <exception cref="ArgumentNullException"><paramref name="key"/> is null</exception>
+        public int Get(K key, ref V[] overlaps)
+        {
+            ArgumentNullException.ThrowIfNull(key);
+
+            IntervalTreeNode<K, V> node = GetNode(key);
+
+            if (node == null)
+            {
+                return 0;
+            }
+
+            if (node.Values.Count > overlaps.Length)
+            {
+                Array.Resize(ref overlaps, node.Values.Count);
+            }
+
+            int overlapsCount = 0;
+            foreach (RangeNode<K, V> value in node.Values)
+            {
+                overlaps[overlapsCount++] = value.Value;
+            }
+
+            return overlapsCount;
+        }
+
+        /// <summary>
+        /// Returns the values of the intervals whose start and end keys overlap the given range.
+        /// </summary>
+        /// <param name="start">Start of the range</param>
+        /// <param name="end">End of the range</param>
+        /// <param name="overlaps">Overlaps array to place results in</param>
+        /// <param name="overlapCount">Index to start writing results into the array. Defaults to 0</param>
+        /// <returns>Number of values found</returns>
+        /// <exception cref="ArgumentNullException"><paramref name="start"/> or <paramref name="end"/> is null</exception>
+        public int Get(K start, K end, ref V[] overlaps, int overlapCount = 0)
+        {
+            ArgumentNullException.ThrowIfNull(start);
+            ArgumentNullException.ThrowIfNull(end);
+
+            GetValues(Root, start, end, ref overlaps, ref overlapCount);
+
+            return overlapCount;
+        }
+
+        /// <summary>
+        /// Adds a new interval into the tree whose start is <paramref name="start"/>, end is <paramref name="end"/> and value is <paramref name="value"/>.
+        /// </summary>
+        /// <param name="start">Start of the range to add</param>
+        /// <param name="end">End of the range to insert</param>
+        /// <param name="value">Value to add</param>
+        /// <exception cref="ArgumentNullException"><paramref name="start"/>, <paramref name="end"/> or <paramref name="value"/> are null</exception>
+        public void Add(K start, K end, V value)
+        {
+            ArgumentNullException.ThrowIfNull(start);
+            ArgumentNullException.ThrowIfNull(end);
+            ArgumentNullException.ThrowIfNull(value);
+
+            Insert(start, end, value);
+        }
+
+        /// <summary>
+        /// Removes the given <paramref name="value"/> from the tree, searching for it with <paramref name="key"/>.
+        /// </summary>
+        /// <param name="key">Key of the node to remove</param>
+        /// <param name="value">Value to remove</param>
+        /// <exception cref="ArgumentNullException"><paramref name="key"/> is null</exception>
+        /// <returns>Number of deleted values</returns>
+        public int Remove(K key, V value)
+        {
+            ArgumentNullException.ThrowIfNull(key);
+
+            int removed = Delete(key, value);
+
+            Count -= removed;
+
+            return removed;
+        }
+
+        /// <summary>
+        /// Adds all the nodes in the dictionary into <paramref name="list"/>.
+        /// </summary>
+        /// <returns>A list of all RangeNodes sorted by Key Order</returns>
+        public List<RangeNode<K, V>> AsList()
+        {
+            List<RangeNode<K, V>> list = new List<RangeNode<K, V>>();
+
+            AddToList(Root, list);
+
+            return list;
+        }
+
+        #endregion
+
+        #region Private Methods (BST)
+
+        /// <summary>
+        /// Adds all RangeNodes that are children of or contained within <paramref name="node"/> into <paramref name="list"/>, in Key Order.
+        /// </summary>
+        /// <param name="node">The node to search for RangeNodes within</param>
+        /// <param name="list">The list to add RangeNodes to</param>
+        private void AddToList(IntervalTreeNode<K, V> node, List<RangeNode<K, V>> list)
+        {
+            if (node == null)
+            {
+                return;
+            }
+
+            AddToList(node.Left, list);
+
+            list.AddRange(node.Values);
+
+            AddToList(node.Right, list);
+        }
+
+        /// <summary>
+        /// Retrieve the node reference whose key is <paramref name="key"/>, or null if no such node exists.
+        /// </summary>
+        /// <param name="key">Key of the node to get</param>
+        /// <returns>Node reference in the tree</returns>
+        /// <exception cref="ArgumentNullException"><paramref name="key"/> is null</exception>
+        private IntervalTreeNode<K, V> GetNode(K key)
+        {
+            ArgumentNullException.ThrowIfNull(key);
+
+            IntervalTreeNode<K, V> node = Root;
+            while (node != null)
+            {
+                int cmp = key.CompareTo(node.Start);
+                if (cmp < 0)
+                {
+                    node = node.Left;
+                }
+                else if (cmp > 0)
+                {
+                    node = node.Right;
+                }
+                else
+                {
+                    return node;
+                }
+            }
+            return null;
+        }
+
+        /// <summary>
+        /// Retrieve all values that overlap the given start and end keys.
+        /// </summary>
+        /// <param name="start">Start of the range</param>
+        /// <param name="end">End of the range</param>
+        /// <param name="overlaps">Overlaps array to place results in</param>
+        /// <param name="overlapCount">Overlaps count to update</param>
+        private void GetValues(IntervalTreeNode<K, V> node, K start, K end, ref V[] overlaps, ref int overlapCount)
+        {
+            if (node == null || start.CompareTo(node.Max) >= 0)
+            {
+                return;
+            }
+
+            GetValues(node.Left, start, end, ref overlaps, ref overlapCount);
+
+            bool endsOnRight = end.CompareTo(node.Start) > 0;
+            if (endsOnRight)
+            {
+                if (start.CompareTo(node.End) < 0)
+                {
+                    // Contains this node. Add overlaps to list.
+                    foreach (RangeNode<K,V> overlap in node.Values)
+                    {
+                        if (start.CompareTo(overlap.End) < 0)
+                        {
+                            if (overlaps.Length >= overlapCount)
+                            {
+                                Array.Resize(ref overlaps, overlapCount + ArrayGrowthSize);
+                            }
+
+                            overlaps[overlapCount++] = overlap.Value;
+                        }
+                    }
+                }
+
+                GetValues(node.Right, start, end, ref overlaps, ref overlapCount);
+            }
+        }
+
+        /// <summary>
+        /// Inserts a new node into the tree with a given <paramref name="start"/>, <paramref name="end"/> and <paramref name="value"/>.
+        /// </summary>
+        /// <param name="start">Start of the range to insert</param>
+        /// <param name="end">End of the range to insert</param>
+        /// <param name="value">Value to insert</param>
+        private void Insert(K start, K end, V value)
+        {
+            IntervalTreeNode<K, V> newNode = BSTInsert(start, end, value);
+            RestoreBalanceAfterInsertion(newNode);
+        }
+
+        /// <summary>
+        /// Propagate an increase in max value starting at the given node, heading up the tree.
+        /// This should only be called if the max increases - not for rebalancing or removals.
+        /// </summary>
+        /// <param name="node">The node to start propagating from</param>
+        private void PropagateIncrease(IntervalTreeNode<K, V> node)
+        {
+            K max = node.Max;
+            IntervalTreeNode<K, V> ptr = node;
+
+            while ((ptr = ptr.Parent) != null)
+            {
+                if (max.CompareTo(ptr.Max) > 0)
+                {
+                    ptr.Max = max;
+                }
+                else
+                {
+                    break;
+                }
+            }
+        }
+
+        /// <summary>
+        /// Propagate recalculating max value starting at the given node, heading up the tree.
+        /// This fully recalculates the max value from all children when there is potential for it to decrease.
+        /// </summary>
+        /// <param name="node">The node to start propagating from</param>
+        private void PropagateFull(IntervalTreeNode<K, V> node)
+        {
+            IntervalTreeNode<K, V> ptr = node;
+
+            do
+            {
+                K max = ptr.End;
+
+                if (ptr.Left != null && ptr.Left.Max.CompareTo(max) > 0)
+                {
+                    max = ptr.Left.Max;
+                }
+
+                if (ptr.Right != null && ptr.Right.Max.CompareTo(max) > 0)
+                {
+                    max = ptr.Right.Max;
+                }
+
+                ptr.Max = max;
+            } while ((ptr = ptr.Parent) != null);
+        }
+
+        /// <summary>
+        /// Insertion Mechanism for the interval tree. Similar to a BST insert, with the start of the range as the key.
+        /// Iterates the tree starting from the root and inserts a new node where all children in the left subtree are less than <paramref name="start"/>, and all children in the right subtree are greater than <paramref name="start"/>.
+        /// Each node can contain multiple values, and has an end address which is the maximum of all those values.
+        /// Post insertion, the "max" value of the node and all parents are updated.
+        /// </summary>
+        /// <param name="start">Start of the range to insert</param>
+        /// <param name="end">End of the range to insert</param>
+        /// <param name="value">Value to insert</param>
+        /// <returns>The inserted Node</returns>
+        private IntervalTreeNode<K, V> BSTInsert(K start, K end, V value)
+        {
+            IntervalTreeNode<K, V> parent = null;
+            IntervalTreeNode<K, V> node = Root;
+
+            while (node != null)
+            {
+                parent = node;
+                int cmp = start.CompareTo(node.Start);
+                if (cmp < 0)
+                {
+                    node = node.Left;
+                }
+                else if (cmp > 0)
+                {
+                    node = node.Right;
+                }
+                else
+                {
+                    node.Values.Add(new RangeNode<K, V>(start, end, value));
+
+                    if (end.CompareTo(node.End) > 0)
+                    {
+                        node.End = end;
+                        if (end.CompareTo(node.Max) > 0)
+                        {
+                            node.Max = end;
+                            PropagateIncrease(node);
+                        }
+                    }
+
+                    Count++;
+                    return node;
+                }
+            }
+            IntervalTreeNode<K, V> newNode = new IntervalTreeNode<K, V>(start, end, value, parent);
+            if (newNode.Parent == null)
+            {
+                Root = newNode;
+            }
+            else if (start.CompareTo(parent.Start) < 0)
+            {
+                parent.Left = newNode;
+            }
+            else
+            {
+                parent.Right = newNode;
+            }
+
+            PropagateIncrease(newNode);
+            Count++;
+            return newNode;
+        }
+
+        /// <summary>
+        /// Removes instances of <paramref name="value"> from the dictionary after searching for it with <paramref name="key">.
+        /// </summary>
+        /// <param name="key">Key to search for</param>
+        /// <param name="value">Value to delete</param>
+        /// <returns>Number of deleted values</returns>
+        private int Delete(K key, V value)
+        {
+            IntervalTreeNode<K, V> nodeToDelete = GetNode(key);
+
+            if (nodeToDelete == null)
+            {
+                return 0;
+            }
+
+            int removed = nodeToDelete.Values.RemoveAll(node => node.Value.Equals(value));
+
+            if (nodeToDelete.Values.Count > 0)
+            {
+                if (removed > 0)
+                {
+                    nodeToDelete.End = nodeToDelete.Values.Max(node => node.End);
+
+                    // Recalculate max from children and new end.
+                    PropagateFull(nodeToDelete);
+                }
+
+                return removed;
+            }
+
+            IntervalTreeNode<K, V> replacementNode;
+
+            if (LeftOf(nodeToDelete) == null || RightOf(nodeToDelete) == null)
+            {
+                replacementNode = nodeToDelete;
+            }
+            else
+            {
+                replacementNode = PredecessorOf(nodeToDelete);
+            }
+
+            IntervalTreeNode<K, V> tmp = LeftOf(replacementNode) ?? RightOf(replacementNode);
+
+            if (tmp != null)
+            {
+                tmp.Parent = ParentOf(replacementNode);
+            }
+
+            if (ParentOf(replacementNode) == null)
+            {
+                Root = tmp;
+            }
+            else if (replacementNode == LeftOf(ParentOf(replacementNode)))
+            {
+                ParentOf(replacementNode).Left = tmp;
+            }
+            else
+            {
+                ParentOf(replacementNode).Right = tmp;
+            }
+
+            if (replacementNode != nodeToDelete)
+            {
+                nodeToDelete.Start = replacementNode.Start;
+                nodeToDelete.Values = replacementNode.Values;
+                nodeToDelete.End = replacementNode.End;
+                nodeToDelete.Max = replacementNode.Max;
+            }
+
+            PropagateFull(replacementNode);
+
+            if (tmp != null && ColorOf(replacementNode) == Black)
+            {
+                RestoreBalanceAfterRemoval(tmp);
+            }
+
+            return removed;
+        }
+
+        #endregion
+
+        protected override void RotateLeft(IntervalTreeNode<K, V> node)
+        {
+            if (node != null)
+            {
+                base.RotateLeft(node);
+
+                PropagateFull(node);
+            }
+        }
+
+        protected override void RotateRight(IntervalTreeNode<K, V> node)
+        {
+            if (node != null)
+            {
+                base.RotateRight(node);
+
+                PropagateFull(node);
+            }
+        }
+
+        public bool ContainsKey(K key)
+        {
+            ArgumentNullException.ThrowIfNull(key);
+
+            return GetNode(key) != null;
+        }
+    }
+
+    /// <summary>
+    /// Represents a value and its start and end keys.
+    /// </summary>
+    /// <typeparam name="K"></typeparam>
+    /// <typeparam name="V"></typeparam>
+    public readonly struct RangeNode<K, V>
+    {
+        public readonly K Start;
+        public readonly K End;
+        public readonly V Value;
+
+        public RangeNode(K start, K end, V value)
+        {
+            Start = start;
+            End = end;
+            Value = value;
+        }
+    }
+
+    /// <summary>
+    /// Represents a node in the IntervalTree which contains start and end keys of type K, and a value of generic type V.
+    /// </summary>
+    /// <typeparam name="K">Key type of the node</typeparam>
+    /// <typeparam name="V">Value type of the node</typeparam>
+    public class IntervalTreeNode<K, V> : IntrusiveRedBlackTreeNode<IntervalTreeNode<K, V>>
+    {
+        /// <summary>
+        /// The start of the range.
+        /// </summary>
+        internal K Start;
+
+        /// <summary>
+        /// The end of the range - maximum of all in the Values list.
+        /// </summary>
+        internal K End;
+
+        /// <summary>
+        /// The maximum end value of this node and all its children.
+        /// </summary>
+        internal K Max;
+
+        /// <summary>
+        /// Values contained on the node that shares a common Start value.
+        /// </summary>
+        internal List<RangeNode<K, V>> Values;
+
+        internal IntervalTreeNode(K start, K end, V value, IntervalTreeNode<K, V> parent)
+        {
+            Start = start;
+            End = end;
+            Max = end;
+            Values = new List<RangeNode<K, V>> { new RangeNode<K, V>(start, end, value) };
+            Parent = parent;
+        }
+    }
+}