A64: Implement SIMD instructions XTN, XTN2

src/frontend/A64/translate/impl/simd_two_register_misc.cpp

@@ -0,0 +1,26 @@
+/* This file is part of the dynarmic project.
+ * Copyright (c) 2018 MerryMage
+ * This software may be used and distributed according to the terms of the GNU
+ * General Public License version 2 or any later version.
+ */
+
+#include "frontend/A64/translate/impl/impl.h"
+
+namespace Dynarmic::A64 {
+
+bool TranslatorVisitor::XTN(bool Q, Imm<2> size, Vec Vn, Vec Vd) {
+    if (size == 0b11) {
+        return ReservedValue();
+    }
+    const size_t esize = 8 << size.ZeroExtend<size_t>();
+    const size_t datasize = 64;
+    const size_t part = Q ? 1 : 0;
+
+    const IR::U128 operand = V(2 * datasize, Vn);
+    const IR::U128 result = ir.VectorNarrow(2 * esize, operand);
+
+    Vpart(datasize, Vd, part, result);
+    return true;
+}
+
+} // namespace Dynarmic::A64