1 files changed, 57 insertions, 0 deletions
diff --git a/src/Ryujinx.HLE/HOS/Tamper/CodeEmitters/LegacyArithmetic.cs b/src/Ryujinx.HLE/HOS/Tamper/CodeEmitters/LegacyArithmetic.cs
new file mode 100644
index 00000000..479c80ec
--- /dev/null
+++ b/src/Ryujinx.HLE/HOS/Tamper/CodeEmitters/LegacyArithmetic.cs
@@ -0,0 +1,57 @@
+using Ryujinx.HLE.Exceptions;
+using Ryujinx.HLE.HOS.Tamper.Operations;
+using System;
+
+namespace Ryujinx.HLE.HOS.Tamper.CodeEmitters
+{
+    /// <summary>
+    /// Code type 7 allows performing arithmetic on registers. However, it has been deprecated by Code
+    /// type 9, and is only kept for backwards compatibility.
+    /// </summary>
+    class LegacyArithmetic
+    {
+        const int OperationWidthIndex  = 1;
+        const int DestinationRegisterIndex = 3;
+        const int OperationTypeIndex = 4;
+        const int ValueImmediateIndex = 8;
+
+        const int ValueImmediateSize = 8;
+
+        private const byte Add = 0; // reg += rhs
+        private const byte Sub = 1; // reg -= rhs
+        private const byte Mul = 2; // reg *= rhs
+        private const byte Lsh = 3; // reg <<= rhs
+        private const byte Rsh = 4; // reg >>= rhs
+
+        public static void Emit(byte[] instruction, CompilationContext context)
+        {
+            // 7T0RC000 VVVVVVVV
+            // T: Width of arithmetic operation(1, 2, 4, or 8 bytes).
+            // R: Register to apply arithmetic to.
+            // C: Arithmetic operation to apply, see below.
+            // V: Value to use for arithmetic operation.
+
+            byte operationWidth = instruction[OperationWidthIndex];
+            Register register = context.GetRegister(instruction[DestinationRegisterIndex]);
+            byte operation = instruction[OperationTypeIndex];
+            ulong immediate = InstructionHelper.GetImmediate(instruction, ValueImmediateIndex, ValueImmediateSize);
+            Value<ulong> rightHandSideValue = new Value<ulong>(immediate);
+
+            void Emit(Type operationType)
+            {
+                InstructionHelper.Emit(operationType, operationWidth, context, register, register, rightHandSideValue);
+            }
+
+            switch (operation)
+            {
+                case Add: Emit(typeof(OpAdd<>)); break;
+                case Sub: Emit(typeof(OpSub<>)); break;
+                case Mul: Emit(typeof(OpMul<>)); break;
+                case Lsh: Emit(typeof(OpLsh<>)); break;
+                case Rsh: Emit(typeof(OpRsh<>)); break;
+                default:
+                    throw new TamperCompilationException($"Invalid arithmetic operation {operation} in Atmosphere cheat");
+            }
+        }
+    }
+}