mirror of
https://github.com/GreemDev/Ryujinx.git
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197 lines
6.8 KiB
C#
197 lines
6.8 KiB
C#
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using System;
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using System.Collections.Generic;
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using System.Numerics;
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using System.Runtime.InteropServices;
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namespace ARMeilleure.Common
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{
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/// <summary>
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/// Represents an expandable table of the type <typeparamref name="TEntry"/>, whose entries will remain at the same
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/// address through out the table's lifetime.
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/// </summary>
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/// <typeparam name="TEntry">Type of the entry in the table</typeparam>
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class EntryTable<TEntry> : IDisposable where TEntry : unmanaged
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{
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private bool _disposed;
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private int _freeHint;
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private readonly int _pageCapacity; // Number of entries per page.
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private readonly int _pageLogCapacity;
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private readonly Dictionary<int, IntPtr> _pages;
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private readonly BitMap _allocated;
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/// <summary>
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/// Initializes a new instance of the <see cref="EntryTable{TEntry}"/> class with the desired page size in
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/// bytes.
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/// </summary>
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/// <param name="pageSize">Desired page size in bytes</param>
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/// <exception cref="ArgumentOutOfRangeException"><paramref name="pageSize"/> is less than 0</exception>
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/// <exception cref="ArgumentException"><typeparamref name="TEntry"/>'s size is zero</exception>
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/// <remarks>
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/// The actual page size may be smaller or larger depending on the size of <typeparamref name="TEntry"/>.
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/// </remarks>
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public unsafe EntryTable(int pageSize = 4096)
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{
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if (pageSize < 0)
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{
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throw new ArgumentOutOfRangeException(nameof(pageSize), "Page size cannot be negative.");
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}
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if (sizeof(TEntry) == 0)
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{
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throw new ArgumentException("Size of TEntry cannot be zero.");
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}
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_allocated = new BitMap();
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_pages = new Dictionary<int, IntPtr>();
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_pageLogCapacity = BitOperations.Log2((uint)(pageSize / sizeof(TEntry)));
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_pageCapacity = 1 << _pageLogCapacity;
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}
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/// <summary>
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/// Allocates an entry in the <see cref="EntryTable{TEntry}"/>.
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/// </summary>
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/// <returns>Index of entry allocated in the table</returns>
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/// <exception cref="ObjectDisposedException"><see cref="EntryTable{TEntry}"/> instance was disposed</exception>
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public int Allocate()
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{
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if (_disposed)
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{
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throw new ObjectDisposedException(null);
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}
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lock (_allocated)
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{
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if (_allocated.IsSet(_freeHint))
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{
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_freeHint = _allocated.FindFirstUnset();
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}
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int index = _freeHint++;
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var page = GetPage(index);
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_allocated.Set(index);
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GetValue(page, index) = default;
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return index;
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}
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}
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/// <summary>
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/// Frees the entry at the specified <paramref name="index"/>.
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/// </summary>
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/// <param name="index">Index of entry to free</param>
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/// <exception cref="ObjectDisposedException"><see cref="EntryTable{TEntry}"/> instance was disposed</exception>
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public void Free(int index)
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{
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if (_disposed)
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{
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throw new ObjectDisposedException(null);
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}
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lock (_allocated)
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{
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if (_allocated.IsSet(index))
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{
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_allocated.Clear(index);
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_freeHint = index;
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}
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}
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}
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/// <summary>
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/// Gets a reference to the entry at the specified allocated <paramref name="index"/>.
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/// </summary>
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/// <param name="index">Index of the entry</param>
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/// <returns>Reference to the entry at the specified <paramref name="index"/></returns>
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/// <exception cref="ObjectDisposedException"><see cref="EntryTable{TEntry}"/> instance was disposed</exception>
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/// <exception cref="ArgumentException">Entry at <paramref name="index"/> is not allocated</exception>
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public ref TEntry GetValue(int index)
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{
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if (_disposed)
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{
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throw new ObjectDisposedException(null);
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}
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lock (_allocated)
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{
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if (!_allocated.IsSet(index))
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{
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throw new ArgumentException("Entry at the specified index was not allocated", nameof(index));
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}
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var page = GetPage(index);
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return ref GetValue(page, index);
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}
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}
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/// <summary>
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/// Gets a reference to the entry at using the specified <paramref name="index"/> from the specified
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/// <paramref name="page"/>.
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/// </summary>
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/// <param name="page">Page to use</param>
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/// <param name="index">Index to use</param>
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/// <returns>Reference to the entry</returns>
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private ref TEntry GetValue(Span<TEntry> page, int index)
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{
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return ref page[index & (_pageCapacity - 1)];
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}
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/// <summary>
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/// Gets the page for the specified <see cref="index"/>.
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/// </summary>
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/// <param name="index">Index to use</param>
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/// <returns>Page for the specified <see cref="index"/></returns>
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private unsafe Span<TEntry> GetPage(int index)
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{
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var pageIndex = (int)((uint)(index & ~(_pageCapacity - 1)) >> _pageLogCapacity);
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if (!_pages.TryGetValue(pageIndex, out IntPtr page))
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{
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page = Marshal.AllocHGlobal(sizeof(TEntry) * _pageCapacity);
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_pages.Add(pageIndex, page);
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}
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return new Span<TEntry>((void*)page, _pageCapacity);
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}
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/// <summary>
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/// Releases all resources used by the <see cref="EntryTable{TEntry}"/> instance.
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/// </summary>
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public void Dispose()
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{
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Dispose(true);
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GC.SuppressFinalize(this);
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}
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/// <summary>
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/// Releases all unmanaged and optionally managed resources used by the <see cref="EntryTable{TEntry}{T}"/>
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/// instance.
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/// </summary>
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/// <param name="disposing"><see langword="true"/> to dispose managed resources also; otherwise just unmanaged resouces</param>
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protected virtual void Dispose(bool disposing)
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{
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if (!_disposed)
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{
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foreach (var page in _pages.Values)
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{
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Marshal.FreeHGlobal(page);
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}
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_disposed = true;
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}
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}
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/// <summary>
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/// Frees resources used by the <see cref="EntryTable{TEntry}"/> instance.
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/// </summary>
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~EntryTable()
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{
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Dispose(false);
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}
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}
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}
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