1 files changed, 96 insertions, 0 deletions
diff --git a/src/Ryujinx.Graphics.Gpu/Engine/DeviceStateWithShadow.cs b/src/Ryujinx.Graphics.Gpu/Engine/DeviceStateWithShadow.cs
new file mode 100644
index 00000000..74a9aa04
--- /dev/null
+++ b/src/Ryujinx.Graphics.Gpu/Engine/DeviceStateWithShadow.cs
@@ -0,0 +1,96 @@
+using Ryujinx.Graphics.Device;
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
+using System.Runtime.CompilerServices;
+
+namespace Ryujinx.Graphics.Gpu.Engine
+{
+    /// <summary>
+    /// State interface with a shadow memory control register.
+    /// </summary>
+    interface IShadowState
+    {
+        /// <summary>
+        /// MME shadow ram control mode.
+        /// </summary>
+        SetMmeShadowRamControlMode SetMmeShadowRamControlMode { get; }
+    }
+
+    /// <summary>
+    /// Represents a device's state, with a additional shadow state.
+    /// </summary>
+    /// <typeparam name="TState">Type of the state</typeparam>
+    class DeviceStateWithShadow<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicFields)] TState> : IDeviceState where TState : unmanaged, IShadowState
+    {
+        private readonly DeviceState<TState> _state;
+        private readonly DeviceState<TState> _shadowState;
+
+        /// <summary>
+        /// Current device state.
+        /// </summary>
+        public ref TState State => ref _state.State;
+
+        /// <summary>
+        /// Creates a new instance of the device state, with shadow state.
+        /// </summary>
+        /// <param name="callbacks">Optional that will be called if a register specified by name is read or written</param>
+        /// <param name="debugLogCallback">Optional callback to be used for debug log messages</param>
+        public DeviceStateWithShadow(IReadOnlyDictionary<string, RwCallback> callbacks = null, Action<string> debugLogCallback = null)
+        {
+            _state = new DeviceState<TState>(callbacks, debugLogCallback);
+            _shadowState = new DeviceState<TState>();
+        }
+
+        /// <summary>
+        /// Reads a value from a register.
+        /// </summary>
+        /// <param name="offset">Register offset in bytes</param>
+        /// <returns>Value stored on the register</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public int Read(int offset)
+        {
+            return _state.Read(offset);
+        }
+
+        /// <summary>
+        /// Writes a value to a register.
+        /// </summary>
+        /// <param name="offset">Register offset in bytes</param>
+        /// <param name="value">Value to be written</param>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public void Write(int offset, int value)
+        {
+            WriteWithRedundancyCheck(offset, value, out _);
+        }
+
+        /// <summary>
+        /// Writes a value to a register, returning a value indicating if <paramref name="value"/>
+        /// is different from the current value on the register.
+        /// </summary>
+        /// <param name="offset">Register offset in bytes</param>
+        /// <param name="value">Value to be written</param>
+        /// <param name="changed">True if the value was changed, false otherwise</param>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public void WriteWithRedundancyCheck(int offset, int value, out bool changed)
+        {
+            var shadowRamControl = _state.State.SetMmeShadowRamControlMode;
+            if (shadowRamControl == SetMmeShadowRamControlMode.MethodPassthrough || offset < 0x200)
+            {
+                _state.WriteWithRedundancyCheck(offset, value, out changed);
+            }
+            else if (shadowRamControl == SetMmeShadowRamControlMode.MethodTrack ||
+                     shadowRamControl == SetMmeShadowRamControlMode.MethodTrackWithFilter)
+            {
+                _shadowState.Write(offset, value);
+                _state.WriteWithRedundancyCheck(offset, value, out changed);
+            }
+            else /* if (shadowRamControl == SetMmeShadowRamControlMode.MethodReplay) */
+            {
+                Debug.Assert(shadowRamControl == SetMmeShadowRamControlMode.MethodReplay);
+                _state.WriteWithRedundancyCheck(offset, _shadowState.Read(offset), out changed);
+            }
+        }
+    }
+}