From 258ca93c5383b17f9dffadefb5a5355b1d16ffe6 Mon Sep 17 00:00:00 2001
From: Lioncash <mathew1800@gmail.com>
Date: Sat, 13 Mar 2021 14:08:05 -0500
Subject: [PATCH] thumb32: Implement TBB/TBH

---
 src/CMakeLists.txt                            |  1 +
 src/frontend/A32/decoder/thumb32.inc          |  4 +-
 .../impl/thumb32_load_store_dual.cpp          | 50 +++++++++++++++++++
 .../A32/translate/impl/translate_thumb.h      |  4 ++
 4 files changed, 57 insertions(+), 2 deletions(-)
 create mode 100644 src/frontend/A32/translate/impl/thumb32_load_store_dual.cpp

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 949e50ac..6f478101 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -163,6 +163,7 @@ if ("A32" IN_LIST DYNARMIC_FRONTENDS)
         frontend/A32/translate/impl/thumb32_data_processing_shifted_register.cpp
         frontend/A32/translate/impl/thumb32_load_byte.cpp
         frontend/A32/translate/impl/thumb32_load_halfword.cpp
+        frontend/A32/translate/impl/thumb32_load_store_dual.cpp
         frontend/A32/translate/impl/thumb32_load_store_multiple.cpp
         frontend/A32/translate/impl/thumb32_load_word.cpp
         frontend/A32/translate/impl/thumb32_long_multiply.cpp
diff --git a/src/frontend/A32/decoder/thumb32.inc b/src/frontend/A32/decoder/thumb32.inc
index e5def4ca..b29b691f 100644
--- a/src/frontend/A32/decoder/thumb32.inc
+++ b/src/frontend/A32/decoder/thumb32.inc
@@ -22,8 +22,8 @@ INST(thumb32_LDMDB,          "LDMDB/LDMEA",              "1110100100W1nnnniiiiii
 //INST(thumb32_STREXB,         "STREXB",                   "111010001100------------0100----")
 //INST(thumb32_STREXH,         "STREXH",                   "111010001100------------0101----")
 //INST(thumb32_STREXD,         "STREXD",                   "111010001100------------0111----")
-//INST(thumb32_TBB,            "TBB",                      "111010001101------------0000----")
-//INST(thumb32_TBH,            "TBH",                      "111010001101------------0001----")
+INST(thumb32_TBB,            "TBB",                      "111010001101nnnn111100000000mmmm")
+INST(thumb32_TBH,            "TBH",                      "111010001101nnnn111100000001mmmm")
 //INST(thumb32_LDREXB,         "LDREXB",                   "111010001101------------0100----")
 //INST(thumb32_LDREXH,         "LDREXH",                   "111010001101------------0101----")
 //INST(thumb32_LDREXD,         "LDREXD",                   "111010001101------------0111----")
diff --git a/src/frontend/A32/translate/impl/thumb32_load_store_dual.cpp b/src/frontend/A32/translate/impl/thumb32_load_store_dual.cpp
new file mode 100644
index 00000000..408def8a
--- /dev/null
+++ b/src/frontend/A32/translate/impl/thumb32_load_store_dual.cpp
@@ -0,0 +1,50 @@
+/* This file is part of the dynarmic project.
+ * Copyright (c) 2021 MerryMage
+ * SPDX-License-Identifier: 0BSD
+ */
+
+#include "common/bit_util.h"
+#include "frontend/A32/translate/impl/translate_thumb.h"
+
+namespace Dynarmic::A32 {
+static bool ITBlockCheck(const A32::IREmitter& ir) {
+    return ir.current_location.IT().IsInITBlock() && !ir.current_location.IT().IsLastInITBlock();
+}
+
+static bool TableBranch(ThumbTranslatorVisitor& v, Reg n, Reg m, bool half) {
+    if (m == Reg::PC) {
+        return v.UnpredictableInstruction();
+    }
+    if (ITBlockCheck(v.ir)) {
+        return v.UnpredictableInstruction();
+    }
+
+    const auto reg_m = v.ir.GetRegister(m);
+    const auto reg_n = v.ir.GetRegister(n);
+
+    IR::U32 halfwords;
+    if (half) {
+        const auto data = v.ir.ReadMemory16(v.ir.Add(reg_n, v.ir.LogicalShiftLeft(reg_m, v.ir.Imm8(1))));
+        halfwords = v.ir.ZeroExtendToWord(data);
+    } else {
+        halfwords = v.ir.ZeroExtendToWord(v.ir.ReadMemory8(v.ir.Add(reg_n, reg_m)));
+    }
+
+    const auto current_pc = v.ir.Imm32(v.ir.PC());
+    const auto branch_value = v.ir.Add(current_pc, v.ir.Add(halfwords, halfwords));
+
+    v.ir.UpdateUpperLocationDescriptor();
+    v.ir.BranchWritePC(branch_value);
+    v.ir.SetTerm(IR::Term::FastDispatchHint{});
+    return false;
+}
+
+bool ThumbTranslatorVisitor::thumb32_TBB(Reg n, Reg m) {
+    return TableBranch(*this, n, m, false);
+}
+
+bool ThumbTranslatorVisitor::thumb32_TBH(Reg n, Reg m) {
+    return TableBranch(*this, n, m, true);
+}
+
+} // namespace Dynarmic::A32
diff --git a/src/frontend/A32/translate/impl/translate_thumb.h b/src/frontend/A32/translate/impl/translate_thumb.h
index 174f601c..0ddab7da 100644
--- a/src/frontend/A32/translate/impl/translate_thumb.h
+++ b/src/frontend/A32/translate/impl/translate_thumb.h
@@ -179,6 +179,10 @@ struct ThumbTranslatorVisitor final {
     bool thumb32_STMIA(bool W, Reg n, Imm<15> reg_list);
     bool thumb32_STMDB(bool W, Reg n, Imm<15> reg_list);
 
+    // thumb32 load/store dual, load/store exclusive, table branch instructions
+    bool thumb32_TBB(Reg n, Reg m);
+    bool thumb32_TBH(Reg n, Reg m);
+
     // thumb32 data processing (shifted register) instructions
     bool thumb32_TST_reg(Reg n, Imm<3> imm3, Imm<2> imm2, ShiftType type, Reg m);
     bool thumb32_AND_reg(bool S, Reg n, Imm<3> imm3, Reg d, Imm<2> imm2, ShiftType type, Reg m);