Refactor memory managers to a common base class, consolidate Read() method logic (#6360)

* - add new abstract class `VirtualMemoryManagerBase`
- rename `MemoryManagerBase` to `VirtualMemoryManagerRefCountedBase` and derive from `VirtualMemoryManagerBase`
- change `AddressSpaceManager`, `HvMemoryManager`, `MemoryManager`, and `MemoryManagerHostMapped` to implement abstract members and use the inherited `void VirtualMemoryManagerBase.Read(TVirtual va, Span<byte> data)` implementation.

* move property `AddressSpaceSize` up by the other properties

2 files changed, 102 insertions, 74 deletions

diff --git a/src/Ryujinx.Memory/AddressSpaceManager.cs b/src/Ryujinx.Memory/AddressSpaceManager.cs
index 021d3366..b953eb30 100644
--- a/src/Ryujinx.Memory/AddressSpaceManager.cs
+++ b/src/Ryujinx.Memory/AddressSpaceManager.cs
@@ -11,12 +11,8 @@ namespace Ryujinx.Memory
     /// Represents a address space manager.
     /// Supports virtual memory region mapping, address translation and read/write access to mapped regions.
     /// </summary>
-    public sealed class AddressSpaceManager : IVirtualMemoryManager, IWritableBlock
+    public sealed class AddressSpaceManager : VirtualMemoryManagerBase<ulong, nuint>, IVirtualMemoryManager, IWritableBlock
     {
-        public const int PageBits = PageTable<nuint>.PageBits;
-        public const int PageSize = PageTable<nuint>.PageSize;
-        public const int PageMask = PageTable<nuint>.PageMask;
-
         /// <inheritdoc/>
         public bool Supports4KBPages => true;
 
@@ -25,11 +21,11 @@ namespace Ryujinx.Memory
         /// </summary>
         public int AddressSpaceBits { get; }
 
-        private readonly ulong _addressSpaceSize;
-
         private readonly MemoryBlock _backingMemory;
         private readonly PageTable<nuint> _pageTable;
 
+        protected override ulong AddressSpaceSize { get; }
+
         /// <summary>
         /// Creates a new instance of the memory manager.
         /// </summary>
@@ -47,7 +43,7 @@ namespace Ryujinx.Memory
             }
 
             AddressSpaceBits = asBits;
-            _addressSpaceSize = asSize;
+            AddressSpaceSize = asSize;
             _backingMemory = backingMemory;
             _pageTable = new PageTable<nuint>();
         }
@@ -103,12 +99,6 @@ namespace Ryujinx.Memory
         }
 
         /// <inheritdoc/>
-        public void Read(ulong va, Span<byte> data)
-        {
-            ReadImpl(va, data);
-        }
-
-        /// <inheritdoc/>
         public void Write<T>(ulong va, T value) where T : unmanaged
         {
             Write(va, MemoryMarshal.Cast<T, byte>(MemoryMarshal.CreateSpan(ref value, 1)));
@@ -174,7 +164,7 @@ namespace Ryujinx.Memory
             {
                 Span<byte> data = new byte[size];
 
-                ReadImpl(va, data);
+                Read(va, data);
 
                 return data;
             }
@@ -346,34 +336,6 @@ namespace Ryujinx.Memory
             return regions;
         }
 
-        private void ReadImpl(ulong va, Span<byte> data)
-        {
-            if (data.Length == 0)
-            {
-                return;
-            }
-
-            AssertValidAddressAndSize(va, (ulong)data.Length);
-
-            int offset = 0, size;
-
-            if ((va & PageMask) != 0)
-            {
-                size = Math.Min(data.Length, PageSize - (int)(va & PageMask));
-
-                GetHostSpanContiguous(va, size).CopyTo(data[..size]);
-
-                offset += size;
-            }
-
-            for (; offset < data.Length; offset += size)
-            {
-                size = Math.Min(data.Length - offset, PageSize);
-
-                GetHostSpanContiguous(va + (ulong)offset, size).CopyTo(data.Slice(offset, size));
-            }
-        }
-
         /// <inheritdoc/>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public bool IsMapped(ulong va)
@@ -414,37 +376,6 @@ namespace Ryujinx.Memory
             return true;
         }
 
-        private bool ValidateAddress(ulong va)
-        {
-            return va < _addressSpaceSize;
-        }
-
-        /// <summary>
-        /// Checks if the combination of virtual address and size is part of the addressable space.
-        /// </summary>
-        /// <param name="va">Virtual address of the range</param>
-        /// <param name="size">Size of the range in bytes</param>
-        /// <returns>True if the combination of virtual address and size is part of the addressable space</returns>
-        private bool ValidateAddressAndSize(ulong va, ulong size)
-        {
-            ulong endVa = va + size;
-            return endVa >= va && endVa >= size && endVa <= _addressSpaceSize;
-        }
-
-        /// <summary>
-        /// Ensures the combination of virtual address and size is part of the addressable space.
-        /// </summary>
-        /// <param name="va">Virtual address of the range</param>
-        /// <param name="size">Size of the range in bytes</param>
-        /// <exception cref="InvalidMemoryRegionException">Throw when the memory region specified outside the addressable space</exception>
-        private void AssertValidAddressAndSize(ulong va, ulong size)
-        {
-            if (!ValidateAddressAndSize(va, size))
-            {
-                throw new InvalidMemoryRegionException($"va=0x{va:X16}, size=0x{size:X16}");
-            }
-        }
-
         private unsafe Span<byte> GetHostSpanContiguous(ulong va, int size)
         {
             return new Span<byte>((void*)GetHostAddress(va), size);
@@ -471,5 +402,11 @@ namespace Ryujinx.Memory
         {
             // Only the ARM Memory Manager has tracking for now.
         }
+
+        protected override unsafe Span<byte> GetPhysicalAddressSpan(nuint pa, int size)
+            => new((void*)pa, size);
+
+        protected override nuint TranslateVirtualAddressForRead(ulong va)
+            => GetHostAddress(va);
     }
 }
diff --git a/src/Ryujinx.Memory/VirtualMemoryManagerBase.cs b/src/Ryujinx.Memory/VirtualMemoryManagerBase.cs
new file mode 100644
index 00000000..cbec88cc
--- /dev/null
+++ b/src/Ryujinx.Memory/VirtualMemoryManagerBase.cs
@@ -0,0 +1,91 @@
+using System;
+using System.Numerics;
+
+namespace Ryujinx.Memory
+{
+    public abstract class VirtualMemoryManagerBase<TVirtual, TPhysical>
+        where TVirtual : IBinaryInteger<TVirtual>
+        where TPhysical : IBinaryInteger<TPhysical>
+    {
+        public const int PageBits = 12;
+        public const int PageSize = 1 << PageBits;
+        public const int PageMask = PageSize - 1;
+
+        protected abstract TVirtual AddressSpaceSize { get; }
+
+        public virtual void Read(TVirtual va, Span<byte> data)
+        {
+            if (data.Length == 0)
+            {
+                return;
+            }
+
+            AssertValidAddressAndSize(va, TVirtual.CreateChecked(data.Length));
+
+            int offset = 0, size;
+
+            if ((int.CreateTruncating(va) & PageMask) != 0)
+            {
+                TPhysical pa = TranslateVirtualAddressForRead(va);
+
+                size = Math.Min(data.Length, PageSize - ((int.CreateTruncating(va) & PageMask)));
+
+                GetPhysicalAddressSpan(pa, size).CopyTo(data[..size]);
+
+                offset += size;
+            }
+
+            for (; offset < data.Length; offset += size)
+            {
+                TPhysical pa = TranslateVirtualAddressForRead(va + TVirtual.CreateChecked(offset));
+
+                size = Math.Min(data.Length - offset, PageSize);
+
+                GetPhysicalAddressSpan(pa, size).CopyTo(data.Slice(offset, size));
+            }
+        }
+
+        /// <summary>
+        /// Ensures the combination of virtual address and size is part of the addressable space.
+        /// </summary>
+        /// <param name="va">Virtual address of the range</param>
+        /// <param name="size">Size of the range in bytes</param>
+        /// <exception cref="InvalidMemoryRegionException">Throw when the memory region specified outside the addressable space</exception>
+        protected void AssertValidAddressAndSize(TVirtual va, TVirtual size)
+        {
+            if (!ValidateAddressAndSize(va, size))
+            {
+                throw new InvalidMemoryRegionException($"va=0x{va:X16}, size=0x{size:X16}");
+            }
+        }
+
+        protected abstract Span<byte> GetPhysicalAddressSpan(TPhysical pa, int size);
+
+        protected abstract TPhysical TranslateVirtualAddressForRead(TVirtual va);
+
+        /// <summary>
+        /// Checks if the virtual address is part of the addressable space.
+        /// </summary>
+        /// <param name="va">Virtual address</param>
+        /// <returns>True if the virtual address is part of the addressable space</returns>
+        protected bool ValidateAddress(TVirtual va)
+        {
+            return va < AddressSpaceSize;
+        }
+
+        /// <summary>
+        /// Checks if the combination of virtual address and size is part of the addressable space.
+        /// </summary>
+        /// <param name="va">Virtual address of the range</param>
+        /// <param name="size">Size of the range in bytes</param>
+        /// <returns>True if the combination of virtual address and size is part of the addressable space</returns>
+        protected bool ValidateAddressAndSize(TVirtual va, TVirtual size)
+        {
+            TVirtual endVa = va + size;
+            return endVa >= va && endVa >= size && endVa <= AddressSpaceSize;
+        }
+
+        protected static void ThrowInvalidMemoryRegionException(string message)
+            => throw new InvalidMemoryRegionException(message);
+    }
+}