1 files changed, 51 insertions, 0 deletions
diff --git a/ARMeilleure/Decoders/OpCodeMemImm.cs b/ARMeilleure/Decoders/OpCodeMemImm.cs
new file mode 100644
index 00000000..517434f2
--- /dev/null
+++ b/ARMeilleure/Decoders/OpCodeMemImm.cs
@@ -0,0 +1,51 @@
+namespace ARMeilleure.Decoders
+{
+    class OpCodeMemImm : OpCodeMem
+    {
+        public    long Immediate { get; protected set; }
+        public    bool WBack     { get; protected set; }
+        public    bool PostIdx   { get; protected set; }
+        protected bool Unscaled  { get; private   set; }
+
+        private enum MemOp
+        {
+            Unscaled     = 0,
+            PostIndexed  = 1,
+            Unprivileged = 2,
+            PreIndexed   = 3,
+            Unsigned
+        }
+
+        public OpCodeMemImm(InstDescriptor inst, ulong address, int opCode) : base(inst, address, opCode)
+        {
+            Extend64 = ((opCode >> 22) & 3) == 2;
+            WBack    = ((opCode >> 24) & 1) == 0;
+
+            // The type is not valid for the Unsigned Immediate 12-bits encoding,
+            // because the bits 11:10 are used for the larger Immediate offset.
+            MemOp type = WBack ? (MemOp)((opCode >> 10) & 3) : MemOp.Unsigned;
+
+            PostIdx  = type == MemOp.PostIndexed;
+            Unscaled = type == MemOp.Unscaled ||
+                       type == MemOp.Unprivileged;
+
+            // Unscaled and Unprivileged doesn't write back,
+            // but they do use the 9-bits Signed Immediate.
+            if (Unscaled)
+            {
+                WBack = false;
+            }
+
+            if (WBack || Unscaled)
+            {
+                // 9-bits Signed Immediate.
+                Immediate = (opCode << 11) >> 23;
+            }
+            else
+            {
+                // 12-bits Unsigned Immediate.
+                Immediate = ((opCode >> 10) & 0xfff) << Size;
+            }
+        }
+    }
+}
+\ No newline at end of file