Implemented the PKHTB and PKHBT instructions with tests. (#40)

src/CMakeLists.txt

@@ -24,6 +24,7 @@ set(SRCS
     frontend/translate/translate_arm/extension.cpp
     frontend/translate/translate_arm/load_store.cpp
     frontend/translate/translate_arm/multiply.cpp
+    frontend/translate/translate_arm/packing.cpp
     frontend/translate/translate_arm/parallel.cpp
     frontend/translate/translate_arm/reversal.cpp
     frontend/translate/translate_arm/status_register_access.cpp

src/frontend/translate/translate_arm/packing.cpp

@@ -0,0 +1,41 @@
+/* This file is part of the dynarmic project.
+ * Copyright (c) 2016 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 "translate_arm.h"
+
+namespace Dynarmic {
+namespace Arm {
+
+bool ArmTranslatorVisitor::arm_PKHBT(Cond cond, Reg n, Reg d, Imm5 imm5, Reg m) {
+    if (n == Reg::PC || d == Reg::PC || m == Reg::PC)
+        return UnpredictableInstruction();
+
+    if (ConditionPassed(cond)) {
+        auto shifted = EmitImmShift(ir.GetRegister(m), ShiftType::LSL, imm5, ir.Imm1(false)).result;
+        auto lower_half = ir.And(ir.GetRegister(n), ir.Imm32(0x0000FFFF));
+        auto upper_half = ir.And(shifted, ir.Imm32(0xFFFF0000));
+        ir.SetRegister(d, ir.Or(lower_half, upper_half));
+    }
+
+    return true;
+}
+
+bool ArmTranslatorVisitor::arm_PKHTB(Cond cond, Reg n, Reg d, Imm5 imm5, Reg m) {
+    if (n == Reg::PC || d == Reg::PC || m == Reg::PC)
+        return UnpredictableInstruction();
+
+    if (ConditionPassed(cond)) {
+        auto shifted = EmitImmShift(ir.GetRegister(m), ShiftType::ASR, imm5, ir.Imm1(false)).result;
+        auto lower_half = ir.And(shifted, ir.Imm32(0x0000FFFF));
+        auto upper_half = ir.And(ir.GetRegister(n), ir.Imm32(0xFFFF0000));
+        ir.SetRegister(d, ir.Or(lower_half, upper_half));
+    }
+
+    return true;
+}
+
+} // namespace Arm
+} // namespace Dynarmic

src/frontend/translate/translate_arm/translate_arm.h

@@ -218,8 +218,8 @@ struct ArmTranslatorVisitor final {
     bool arm_USADA8(Cond cond, Reg d, Reg a, Reg m, Reg n) { return InterpretThisInstruction(); }
 
     // Packing instructions
-    bool arm_PKHBT(Cond cond, Reg n, Reg d, Imm5 imm5, Reg m) { return InterpretThisInstruction(); }
-    bool arm_PKHTB(Cond cond, Reg n, Reg d, Imm5 imm5, Reg m) { return InterpretThisInstruction(); }
+    bool arm_PKHBT(Cond cond, Reg n, Reg d, Imm5 imm5, Reg m);
+    bool arm_PKHTB(Cond cond, Reg n, Reg d, Imm5 imm5, Reg m);
 
     // Reversal instructions
     bool arm_REV(Cond cond, Reg d, Reg m);

tests/arm/fuzz_arm.cpp

@@ -929,4 +929,24 @@ TEST_CASE("Test ARM SEL instruction", "[JitX64]") {
             return sel_instr.Generate(false);
         });
     }
-}
+}
+
+TEST_CASE("Fuzz ARM packing instructions", "[JitX64]") {
+    auto is_pkh_valid = [](u32 inst) -> bool {
+        // R15 as Rd, Rn, or Rm is UNPREDICTABLE
+        return Bits<16, 19>(inst) != 0b1111 &&
+               Bits<12, 15>(inst) != 0b1111 &&
+               Bits<0, 3>(inst) != 0b1111;
+    };
+
+    const std::array<InstructionGenerator, 2> instructions = {{
+        InstructionGenerator("cccc01101000nnnnddddvvvvv001mmmm", is_pkh_valid), // PKHBT
+        InstructionGenerator("cccc01101000nnnnddddvvvvv101mmmm", is_pkh_valid), // PKHTB
+    }};
+
+    SECTION("Packing") {
+        FuzzJitArm(1, 1, 10000, [&instructions]() -> u32 {
+            return instructions[RandInt<size_t>(0, instructions.size() - 1)].Generate();
+        });
+    }
+}