Qt: Add debugger UI

README.md

@@ -17,6 +17,7 @@ A "BIOS" ROM image is required to to start the emulator and to play games. You c
 
 ## Latest News
 
+- 2020/12/16: Integrated CPU debugger added in Qt frontend.
 - 2020/12/13: Button layout for the touchscreen controller in the Android version can now be customized.
 - 2020/12/10: Translation support added for Android version. Currently Brazillian Portuguese, Italian, and Dutch are available.
 - 2020/11/27: Cover support added for game list in Android version. Procedure is the same as the desktop version, except you should place cover images in `<storage>/duckstation/covers` (see [Adding Game Covers](https://github.com/stenzek/duckstation/wiki/Adding-Game-Covers)).

src/duckstation-qt/CMakeLists.txt

@@ -29,6 +29,11 @@ set(SRCS
   consolesettingswidget.ui
   controllersettingswidget.cpp
   controllersettingswidget.h
+  debuggermodels.cpp
+  debuggermodels.h
+  debuggerwindow.cpp
+  debuggerwindow.h
+  debuggerwindow.ui
   displaysettingswidget.cpp
   displaysettingswidget.h
   displaysettingswidget.ui
@@ -68,6 +73,8 @@ set(SRCS
   memorycardeditordialog.ui
   memorycardsettingswidget.cpp
   memorycardsettingswidget.h
+  memoryviewwidget.cpp
+  memoryviewwidget.h
   postprocessingchainconfigwidget.cpp
   postprocessingchainconfigwidget.h
   postprocessingchainconfigwidget.ui

src/duckstation-qt/debuggermodels.cpp

@@ -0,0 +1,417 @@
+#include "debuggermodels.h"
+#include "common/log.h"
+#include "core/cpu_core.h"
+#include "core/cpu_core_private.h"
+#include "core/cpu_disasm.h"
+#include <QtGui/QColor>
+#include <QtGui/QIcon>
+#include <QtGui/QPalette>
+#include <QtWidgets/QApplication>
+Log_SetChannel(DebuggerModels);
+
+static constexpr int NUM_COLUMNS = 5;
+static constexpr int STACK_RANGE = 128;
+static constexpr u32 STACK_VALUE_SIZE = sizeof(u32);
+
+DebuggerCodeModel::DebuggerCodeModel(QObject* parent /*= nullptr*/) : QAbstractTableModel(parent)
+{
+  resetCodeView(0);
+  m_pc_pixmap = QIcon(QStringLiteral(":/icons/debug-pc.png")).pixmap(QSize(12, 12));
+  m_breakpoint_pixmap = QIcon(QStringLiteral(":/icons/media-record.png")).pixmap(QSize(12, 12));
+}
+
+DebuggerCodeModel::~DebuggerCodeModel() {}
+
+int DebuggerCodeModel::rowCount(const QModelIndex& parent /*= QModelIndex()*/) const
+{
+  return static_cast<int>((m_code_region_end - m_code_region_start) / CPU::INSTRUCTION_SIZE);
+}
+
+int DebuggerCodeModel::columnCount(const QModelIndex& parent /*= QModelIndex()*/) const
+{
+  return NUM_COLUMNS;
+}
+
+int DebuggerCodeModel::getRowForAddress(VirtualMemoryAddress address) const
+{
+  return static_cast<int>((address - m_code_region_start) / CPU::INSTRUCTION_SIZE);
+}
+
+VirtualMemoryAddress DebuggerCodeModel::getAddressForRow(int row) const
+{
+  return m_code_region_start + (static_cast<u32>(row) * CPU::INSTRUCTION_SIZE);
+}
+
+VirtualMemoryAddress DebuggerCodeModel::getAddressForIndex(QModelIndex index) const
+{
+  return getAddressForRow(index.row());
+}
+
+int DebuggerCodeModel::getRowForPC() const
+{
+  return getRowForAddress(m_last_pc);
+}
+
+QVariant DebuggerCodeModel::data(const QModelIndex& index, int role /*= Qt::DisplayRole*/) const
+{
+  if (index.column() < 0 || index.column() >= NUM_COLUMNS)
+    return QVariant();
+
+  if (role == Qt::DisplayRole)
+  {
+    const VirtualMemoryAddress address = getAddressForRow(index.row());
+    switch (index.column())
+    {
+      case 0:
+        // breakpoint
+        return QVariant();
+
+      case 1:
+      {
+        // Address
+        return QVariant(QString::asprintf("0x%08X", address));
+      }
+
+      case 2:
+      {
+        // Bytes
+        u32 instruction_bits;
+        if (!CPU::SafeReadInstruction(address, &instruction_bits))
+          return QStringLiteral("<invalid>");
+
+        return QString::asprintf("%08X", instruction_bits);
+      }
+
+      case 3:
+      {
+        // Instruction
+        u32 instruction_bits;
+        if (!CPU::SafeReadInstruction(address, &instruction_bits))
+          return QStringLiteral("<invalid>");
+
+        Log_DevPrintf("Disassemble %08X", address);
+        SmallString str;
+        CPU::DisassembleInstruction(&str, address, instruction_bits);
+        return QString::fromUtf8(str.GetCharArray(), static_cast<int>(str.GetLength()));
+      }
+
+      case 4:
+      {
+        // Comment
+        if (address != m_last_pc)
+          return QVariant();
+
+        u32 instruction_bits;
+        if (!CPU::SafeReadInstruction(address, &instruction_bits))
+          return QStringLiteral("<invalid>");
+
+        TinyString str;
+        CPU::DisassembleInstructionComment(&str, address, instruction_bits, &CPU::g_state.regs);
+        return QString::fromUtf8(str.GetCharArray(), static_cast<int>(str.GetLength()));
+      }
+
+      default:
+        return QVariant();
+    }
+  }
+  else if (role == Qt::DecorationRole)
+  {
+    if (index.column() == 0)
+    {
+      // breakpoint
+      const VirtualMemoryAddress address = getAddressForRow(index.row());
+      if (m_last_pc == address)
+        return m_pc_pixmap;
+      else if (hasBreakpointAtAddress(address))
+        return m_breakpoint_pixmap;
+    }
+
+    return QVariant();
+  }
+  else if (role == Qt::BackgroundRole)
+  {
+    const VirtualMemoryAddress address = getAddressForRow(index.row());
+
+    // breakpoint
+    if (hasBreakpointAtAddress(address))
+      return QVariant(QColor(171, 97, 107));
+
+    //     if (address == m_last_pc)
+    //       return QApplication::palette().toolTipBase();
+    if (address == m_last_pc)
+      return QColor(100, 100, 0);
+    else
+      return QVariant();
+  }
+  else if (role == Qt::ForegroundRole)
+  {
+    const VirtualMemoryAddress address = getAddressForRow(index.row());
+
+    //     if (address == m_last_pc)
+    //       return QApplication::palette().toolTipText();
+    if (address == m_last_pc || hasBreakpointAtAddress(address))
+      return QColor(Qt::white);
+    else
+      return QVariant();
+  }
+  else
+  {
+    return QVariant();
+  }
+}
+
+QVariant DebuggerCodeModel::headerData(int section, Qt::Orientation orientation, int role /*= Qt::DisplayRole*/) const
+{
+  if (orientation != Qt::Horizontal)
+    return QVariant();
+
+  if (role != Qt::DisplayRole)
+    return QVariant();
+
+  static const char* header_names[] = {"", "Address", "Bytes", "Instruction", "Comment"};
+  if (section < 0 || section >= countof(header_names))
+    return QVariant();
+
+  return header_names[section];
+}
+
+bool DebuggerCodeModel::updateRegion(VirtualMemoryAddress address)
+{
+  CPU::Segment segment = CPU::GetSegmentForAddress(address);
+  std::optional<Bus::MemoryRegion> region = Bus::GetMemoryRegionForAddress(CPU::VirtualAddressToPhysical(address));
+  if (!region.has_value() || (address >= m_code_region_start && address < m_code_region_end))
+    return false;
+
+  static constexpr unsigned NUM_INSTRUCTIONS_BEFORE = 4096;
+  static constexpr unsigned NUM_INSTRUCTIONS_AFTER = 4096;
+  static constexpr unsigned NUM_BYTES_BEFORE = NUM_INSTRUCTIONS_BEFORE * sizeof(CPU::Instruction);
+  static constexpr unsigned NUM_BYTES_AFTER = NUM_INSTRUCTIONS_AFTER * sizeof(CPU::Instruction);
+
+  const VirtualMemoryAddress start_address =
+    CPU::PhysicalAddressToVirtual(Bus::GetMemoryRegionStart(region.value()), segment);
+  const VirtualMemoryAddress end_address =
+    CPU::PhysicalAddressToVirtual(Bus::GetMemoryRegionEnd(region.value()), segment);
+
+  beginResetModel();
+  m_code_region_start = ((address - start_address) < NUM_BYTES_BEFORE) ? start_address : (address - NUM_BYTES_BEFORE);
+  m_code_region_end = ((end_address - address) < NUM_BYTES_AFTER) ? end_address : (address + NUM_BYTES_AFTER);
+  m_current_segment = segment;
+  m_current_code_region = region.value();
+  endResetModel();
+  return true;
+}
+
+bool DebuggerCodeModel::emitDataChangedForAddress(VirtualMemoryAddress address)
+{
+  CPU::Segment segment = CPU::GetSegmentForAddress(address);
+  std::optional<Bus::MemoryRegion> region = Bus::GetMemoryRegionForAddress(CPU::VirtualAddressToPhysical(address));
+  if (!region.has_value() || segment != m_current_segment || region != m_current_code_region)
+    return false;
+
+  const int row = getRowForAddress(address);
+  emit dataChanged(index(row, 0), index(row, NUM_COLUMNS - 1));
+  return true;
+}
+
+bool DebuggerCodeModel::hasBreakpointAtAddress(VirtualMemoryAddress address) const
+{
+  return std::find(m_breakpoints.begin(), m_breakpoints.end(), address) != m_breakpoints.end();
+}
+
+void DebuggerCodeModel::resetCodeView(VirtualMemoryAddress start_address)
+{
+  updateRegion(start_address);
+}
+
+void DebuggerCodeModel::setPC(VirtualMemoryAddress pc)
+{
+  const VirtualMemoryAddress prev_pc = m_last_pc;
+
+  m_last_pc = pc;
+  if (!updateRegion(pc))
+  {
+    emitDataChangedForAddress(prev_pc);
+    emitDataChangedForAddress(pc);
+  }
+}
+
+void DebuggerCodeModel::ensureAddressVisible(VirtualMemoryAddress address)
+{
+  updateRegion(address);
+}
+
+void DebuggerCodeModel::setBreakpointList(std::vector<VirtualMemoryAddress> bps)
+{
+  clearBreakpoints();
+
+  m_breakpoints = std::move(bps);
+  for (VirtualMemoryAddress bp : m_breakpoints)
+    emitDataChangedForAddress(bp);
+}
+
+void DebuggerCodeModel::clearBreakpoints()
+{
+  std::vector<VirtualMemoryAddress> old_bps(std::move(m_breakpoints));
+
+  for (VirtualMemoryAddress old_bp : old_bps)
+    emitDataChangedForAddress(old_bp);
+}
+
+void DebuggerCodeModel::setBreakpointState(VirtualMemoryAddress address, bool enabled)
+{
+  if (enabled)
+  {
+    if (std::find(m_breakpoints.begin(), m_breakpoints.end(), address) != m_breakpoints.end())
+      return;
+
+    m_breakpoints.push_back(address);
+    emitDataChangedForAddress(address);
+  }
+  else
+  {
+    auto it = std::find(m_breakpoints.begin(), m_breakpoints.end(), address);
+    if (it == m_breakpoints.end())
+      return;
+
+    m_breakpoints.erase(it);
+    emitDataChangedForAddress(address);
+  }
+}
+
+DebuggerRegistersModel::DebuggerRegistersModel(QObject* parent /*= nullptr*/) : QAbstractListModel(parent) {}
+
+DebuggerRegistersModel::~DebuggerRegistersModel() {}
+
+int DebuggerRegistersModel::rowCount(const QModelIndex& parent /*= QModelIndex()*/) const
+{
+  return static_cast<int>(CPU::Reg::count);
+}
+
+int DebuggerRegistersModel::columnCount(const QModelIndex& parent /*= QModelIndex()*/) const
+{
+  return 2;
+}
+
+QVariant DebuggerRegistersModel::data(const QModelIndex& index, int role /*= Qt::DisplayRole*/) const
+{
+  u32 reg_index = static_cast<u32>(index.row());
+  if (reg_index >= static_cast<u32>(CPU::Reg::count))
+    return QVariant();
+
+  if (index.column() < 0 || index.column() > 1)
+    return QVariant();
+
+  switch (index.column())
+  {
+    case 0: // address
+    {
+      if (role == Qt::DisplayRole)
+        return QString::fromUtf8(CPU::GetRegName(static_cast<CPU::Reg>(reg_index)));
+    }
+    break;
+
+    case 1: // data
+    {
+      if (role == Qt::DisplayRole)
+      {
+        return QString::asprintf("0x%08X", CPU::g_state.regs.r[reg_index]);
+      }
+      else if (role == Qt::ForegroundRole)
+      {
+        if (CPU::g_state.regs.r[reg_index] != m_old_reg_values[reg_index])
+          return QColor(255, 50, 50);
+      }
+    }
+    break;
+
+    default:
+      break;
+  }
+
+  return QVariant();
+}
+
+QVariant DebuggerRegistersModel::headerData(int section, Qt::Orientation orientation,
+                                            int role /*= Qt::DisplayRole*/) const
+{
+  if (orientation != Qt::Horizontal)
+    return QVariant();
+
+  if (role != Qt::DisplayRole)
+    return QVariant();
+
+  static const char* header_names[] = {"Register", "Value"};
+  if (section < 0 || section >= countof(header_names))
+    return QVariant();
+
+  return header_names[section];
+}
+
+void DebuggerRegistersModel::invalidateView()
+{
+  beginResetModel();
+  endResetModel();
+}
+
+void DebuggerRegistersModel::saveCurrentValues()
+{
+  for (u32 i = 0; i < static_cast<u32>(CPU::Reg::count); i++)
+    m_old_reg_values[i] = CPU::g_state.regs.r[i];
+}
+
+DebuggerStackModel::DebuggerStackModel(QObject* parent /*= nullptr*/) : QAbstractListModel(parent) {}
+
+DebuggerStackModel::~DebuggerStackModel() {}
+
+int DebuggerStackModel::rowCount(const QModelIndex& parent /*= QModelIndex()*/) const
+{
+  return STACK_RANGE * 2;
+}
+
+int DebuggerStackModel::columnCount(const QModelIndex& parent /*= QModelIndex()*/) const
+{
+  return 2;
+}
+
+QVariant DebuggerStackModel::data(const QModelIndex& index, int role /*= Qt::DisplayRole*/) const
+{
+  if (index.column() < 0 || index.column() > 1)
+    return QVariant();
+
+  if (role != Qt::DisplayRole)
+    return QVariant();
+
+  const u32 sp = CPU::g_state.regs.sp;
+  const VirtualMemoryAddress address =
+    (sp - static_cast<u32>(STACK_RANGE * STACK_VALUE_SIZE)) + static_cast<u32>(index.row()) * STACK_VALUE_SIZE;
+
+  if (index.column() == 0)
+    return QString::asprintf("0x%08X", address);
+
+  u32 value;
+  if (!CPU::SafeReadMemoryWord(address, &value))
+    return QStringLiteral("<invalid>");
+
+  return QString::asprintf("0x%08X", ZeroExtend32(value));
+}
+
+QVariant DebuggerStackModel::headerData(int section, Qt::Orientation orientation, int role /*= Qt::DisplayRole*/) const
+{
+  if (orientation != Qt::Horizontal)
+    return QVariant();
+
+  if (role != Qt::DisplayRole)
+    return QVariant();
+
+  static const char* header_names[] = {"Address", "Value"};
+  if (section < 0 || section >= countof(header_names))
+    return QVariant();
+
+  return header_names[section];
+}
+
+void DebuggerStackModel::invalidateView()
+{
+  beginResetModel();
+  endResetModel();
+}

src/duckstation-qt/debuggermodels.h

@@ -0,0 +1,84 @@
+#pragma once
+#include "core/bus.h"
+#include "core/cpu_types.h"
+#include <QtCore/QAbstractListModel>
+#include <QtCore/QAbstractTableModel>
+#include <QtGui/QPixmap>
+#include <map>
+
+class DebuggerCodeModel : public QAbstractTableModel
+{
+  Q_OBJECT
+
+public:
+  DebuggerCodeModel(QObject* parent = nullptr);
+  virtual ~DebuggerCodeModel();
+
+  virtual int rowCount(const QModelIndex& parent = QModelIndex()) const override;
+  virtual int columnCount(const QModelIndex& parent = QModelIndex()) const override;
+  virtual QVariant data(const QModelIndex& index, int role = Qt::DisplayRole) const override;
+  virtual QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const override;
+
+  // Returns the row for this instruction pointer
+  void resetCodeView(VirtualMemoryAddress start_address);
+  int getRowForAddress(VirtualMemoryAddress address) const;
+  int getRowForPC() const;
+  VirtualMemoryAddress getAddressForRow(int row) const;
+  VirtualMemoryAddress getAddressForIndex(QModelIndex index) const;
+  void setPC(VirtualMemoryAddress pc);
+  void ensureAddressVisible(VirtualMemoryAddress address);
+  void setBreakpointList(std::vector<VirtualMemoryAddress> bps);
+  void setBreakpointState(VirtualMemoryAddress address, bool enabled);
+  void clearBreakpoints();
+
+private:
+  bool updateRegion(VirtualMemoryAddress address);
+  bool emitDataChangedForAddress(VirtualMemoryAddress address);
+  bool hasBreakpointAtAddress(VirtualMemoryAddress address) const;
+
+  Bus::MemoryRegion m_current_code_region = Bus::MemoryRegion::Count;
+  CPU::Segment m_current_segment = CPU::Segment::KUSEG;
+  VirtualMemoryAddress m_code_region_start = 0;
+  VirtualMemoryAddress m_code_region_end = 0;
+  VirtualMemoryAddress m_last_pc = 0;
+  std::vector<VirtualMemoryAddress> m_breakpoints;
+
+  QPixmap m_pc_pixmap;
+  QPixmap m_breakpoint_pixmap;
+};
+
+class DebuggerRegistersModel : public QAbstractListModel
+{
+  Q_OBJECT
+
+public:
+  DebuggerRegistersModel(QObject* parent = nullptr);
+  virtual ~DebuggerRegistersModel();
+
+  virtual int rowCount(const QModelIndex& parent = QModelIndex()) const override;
+  virtual int columnCount(const QModelIndex& parent = QModelIndex()) const override;
+  virtual QVariant data(const QModelIndex& index, int role = Qt::DisplayRole) const override;
+  virtual QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const override;
+
+  void invalidateView();
+  void saveCurrentValues();
+
+private:
+  u32 m_old_reg_values[static_cast<u32>(CPU::Reg::count)] = {};
+};
+
+class DebuggerStackModel : public QAbstractListModel
+{
+  Q_OBJECT
+
+public:
+  DebuggerStackModel(QObject* parent = nullptr);
+  virtual ~DebuggerStackModel();
+
+  virtual int rowCount(const QModelIndex& parent = QModelIndex()) const override;
+  virtual int columnCount(const QModelIndex& parent = QModelIndex()) const override;
+  virtual QVariant data(const QModelIndex& index, int role = Qt::DisplayRole) const override;
+  virtual QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const override;
+
+  void invalidateView();
+};

src/duckstation-qt/debuggerwindow.cpp

@@ -0,0 +1,597 @@
+#include "debuggerwindow.h"
+#include "core/cpu_core_private.h"
+#include "debuggermodels.h"
+#include "qthostinterface.h"
+#include <QtCore/QSignalBlocker>
+#include <QtGui/QFontDatabase>
+#include <QtWidgets/QFileDialog>
+#include <QtWidgets/QInputDialog>
+#include <QtWidgets/QMessageBox>
+
+DebuggerWindow::DebuggerWindow(QWidget* parent /* = nullptr */)
+  : QMainWindow(parent), m_active_memory_region(Bus::MemoryRegion::Count)
+{
+  m_ui.setupUi(this);
+  setupAdditionalUi();
+  connectSignals();
+  createModels();
+  setMemoryViewRegion(Bus::MemoryRegion::RAM);
+  setUIEnabled(false);
+}
+
+DebuggerWindow::~DebuggerWindow() {}
+
+void DebuggerWindow::onEmulationPaused(bool paused)
+{
+  if (paused)
+  {
+    setUIEnabled(true);
+    refreshAll();
+    refreshBreakpointList();
+  }
+  else
+  {
+    setUIEnabled(false);
+  }
+
+  {
+    QSignalBlocker sb(m_ui.actionPause);
+    m_ui.actionPause->setChecked(paused);
+  }
+}
+
+void DebuggerWindow::onDebuggerMessageReported(const QString& message)
+{
+  m_ui.statusbar->showMessage(message, 0);
+}
+
+void DebuggerWindow::refreshAll()
+{
+  m_registers_model->invalidateView();
+  m_stack_model->invalidateView();
+  m_ui.memoryView->repaint();
+
+  m_code_model->setPC(CPU::g_state.regs.pc);
+  scrollToPC();
+}
+
+void DebuggerWindow::scrollToPC()
+{
+  return scrollToCodeAddress(CPU::g_state.regs.pc);
+}
+
+void DebuggerWindow::scrollToCodeAddress(VirtualMemoryAddress address)
+{
+  m_code_model->ensureAddressVisible(address);
+
+  int row = m_code_model->getRowForAddress(address);
+  if (row >= 0)
+  {
+    qApp->processEvents(QEventLoop::ExcludeUserInputEvents);
+    m_ui.codeView->scrollTo(m_code_model->index(row, 0));
+  }
+}
+
+void DebuggerWindow::onPauseActionToggled(bool paused)
+{
+  if (!paused)
+  {
+    m_registers_model->saveCurrentValues();
+    setUIEnabled(false);
+  }
+
+  QtHostInterface::GetInstance()->pauseSystem(paused);
+}
+
+void DebuggerWindow::onRunToCursorTriggered()
+{
+  std::optional<VirtualMemoryAddress> addr = getSelectedCodeAddress();
+  if (!addr.has_value())
+  {
+    QMessageBox::critical(this, windowTitle(), tr("No address selected."));
+    return;
+  }
+
+  CPU::AddBreakpoint(addr.value(), true, true);
+  QtHostInterface::GetInstance()->pauseSystem(false);
+}
+
+void DebuggerWindow::onGoToPCTriggered()
+{
+  scrollToPC();
+}
+
+void DebuggerWindow::onGoToAddressTriggered()
+{
+  std::optional<VirtualMemoryAddress> address = promptForAddress(tr("Enter code address:"));
+  if (!address.has_value())
+    return;
+
+  scrollToCodeAddress(address.value());
+}
+
+void DebuggerWindow::onDumpAddressTriggered()
+{
+  std::optional<VirtualMemoryAddress> address = promptForAddress(tr("Enter memory address:"));
+  if (!address.has_value())
+    return;
+
+  scrollToMemoryAddress(address.value());
+}
+
+void DebuggerWindow::onFollowAddressTriggered()
+{
+  //
+}
+
+void DebuggerWindow::onAddBreakpointTriggered()
+{
+  std::optional<VirtualMemoryAddress> address = promptForAddress(tr("Enter code address:"));
+  if (!address.has_value())
+    return;
+
+  if (CPU::HasBreakpointAtAddress(address.value()))
+  {
+    QMessageBox::critical(this, windowTitle(), tr("A breakpoint already exists at this address."));
+    return;
+  }
+
+  toggleBreakpoint(address.value());
+}
+
+void DebuggerWindow::onToggleBreakpointTriggered()
+{
+  std::optional<VirtualMemoryAddress> address = getSelectedCodeAddress();
+  if (!address.has_value())
+    return;
+
+  toggleBreakpoint(address.value());
+}
+
+void DebuggerWindow::onClearBreakpointsTriggered()
+{
+  clearBreakpoints();
+}
+
+void DebuggerWindow::onStepIntoActionTriggered()
+{
+  Assert(System::IsPaused());
+  m_registers_model->saveCurrentValues();
+  QtHostInterface::GetInstance()->singleStepCPU();
+  refreshAll();
+}
+
+void DebuggerWindow::onStepOverActionTriggered()
+{
+  Assert(System::IsPaused());
+  if (!CPU::AddStepOverBreakpoint())
+  {
+    onStepIntoActionTriggered();
+    return;
+  }
+
+  // unpause to let it run to the breakpoint
+  m_registers_model->saveCurrentValues();
+  QtHostInterface::GetInstance()->pauseSystem(false);
+}
+
+void DebuggerWindow::onStepOutActionTriggered()
+{
+  Assert(System::IsPaused());
+  if (!CPU::AddStepOutBreakpoint())
+  {
+    QMessageBox::critical(this, tr("Debugger"), tr("Failed to add step-out breakpoint, are you in a valid function?"));
+    return;
+  }
+
+  // unpause to let it run to the breakpoint
+  m_registers_model->saveCurrentValues();
+  QtHostInterface::GetInstance()->pauseSystem(false);
+}
+
+void DebuggerWindow::onCodeViewItemActivated(QModelIndex index)
+{
+  if (!index.isValid())
+    return;
+
+  const VirtualMemoryAddress address = m_code_model->getAddressForIndex(index);
+  switch (index.column())
+  {
+    case 0: // breakpoint
+    case 3: // disassembly
+      toggleBreakpoint(address);
+      break;
+
+    case 1: // address
+    case 2: // bytes
+      scrollToMemoryAddress(address);
+      break;
+
+    case 4: // comment
+      tryFollowLoadStore(address);
+      break;
+  }
+}
+
+void DebuggerWindow::onMemorySearchTriggered()
+{
+  m_ui.memoryView->clearHighlightRange();
+
+  const QString pattern_str = m_ui.memorySearchString->text();
+  if (pattern_str.isEmpty())
+    return;
+
+  std::vector<u8> pattern;
+  std::vector<u8> mask;
+  u8 spattern = 0;
+  u8 smask = 0;
+  bool msb = false;
+
+  pattern.reserve(static_cast<size_t>(pattern_str.length()) / 2);
+  mask.reserve(static_cast<size_t>(pattern_str.length()) / 2);
+
+  for (int i = 0; i < pattern_str.length(); i++)
+  {
+    const QChar ch = pattern_str[i];
+    if (ch == ' ')
+      continue;
+
+    if (ch == '?')
+    {
+      spattern = (spattern << 4);
+      smask = (smask << 4);
+    }
+    else if (ch.isDigit())
+    {
+      spattern = (spattern << 4) | static_cast<u8>(ch.digitValue());
+      smask = (smask << 4) | 0xF;
+    }
+    else if (ch.unicode() >= 'a' && ch.unicode() <= 'f')
+    {
+      spattern = (spattern << 4) | (0xA + static_cast<u8>(ch.unicode() - 'a'));
+      smask = (smask << 4) | 0xF;
+    }
+    else if (ch.unicode() >= 'A' && ch.unicode() <= 'F')
+    {
+      spattern = (spattern << 4) | (0xA + static_cast<u8>(ch.unicode() - 'A'));
+      smask = (smask << 4) | 0xF;
+    }
+    else
+    {
+      QMessageBox::critical(this, windowTitle(),
+                            tr("Invalid search pattern. It should contain hex digits or question marks."));
+      return;
+    }
+
+    if (msb)
+    {
+      pattern.push_back(spattern);
+      mask.push_back(smask);
+      spattern = 0;
+      smask = 0;
+    }
+
+    msb = !msb;
+  }
+
+  if (msb)
+  {
+    // partial byte on the end
+    spattern = (spattern << 4);
+    smask = (smask << 4);
+    pattern.push_back(spattern);
+    mask.push_back(smask);
+  }
+
+  if (pattern.empty())
+  {
+    QMessageBox::critical(this, windowTitle(),
+                          tr("Invalid search pattern. It should contain hex digits or question marks."));
+    return;
+  }
+
+  std::optional<PhysicalMemoryAddress> found_address =
+    Bus::SearchMemory(m_next_memory_search_address, pattern.data(), mask.data(), static_cast<u32>(pattern.size()));
+  bool wrapped_around = false;
+  if (!found_address.has_value())
+  {
+    found_address = Bus::SearchMemory(0, pattern.data(), mask.data(), static_cast<u32>(pattern.size()));
+    if (!found_address.has_value())
+    {
+      m_ui.statusbar->showMessage(tr("Pattern not found."));
+      return;
+    }
+
+    wrapped_around = true;
+  }
+
+  m_next_memory_search_address = found_address.value() + 1;
+  if (scrollToMemoryAddress(found_address.value()))
+  {
+    const size_t highlight_offset = found_address.value() - m_ui.memoryView->addressOffset();
+    m_ui.memoryView->setHighlightRange(highlight_offset, highlight_offset + pattern.size());
+  }
+
+  if (wrapped_around)
+  {
+    m_ui.statusbar->showMessage(tr("Pattern found at 0x%1 (passed the end of memory).")
+                                  .arg(static_cast<uint>(found_address.value()), 8, 10, static_cast<QChar>('0')));
+  }
+  else
+  {
+    m_ui.statusbar->showMessage(
+      tr("Pattern found at 0x%1.").arg(static_cast<uint>(found_address.value()), 8, 10, static_cast<QChar>('0')));
+  }
+}
+
+void DebuggerWindow::onMemorySearchStringChanged(const QString&)
+{
+  m_next_memory_search_address = 0;
+}
+
+void DebuggerWindow::closeEvent(QCloseEvent* event)
+{
+  QMainWindow::closeEvent(event);
+  QtHostInterface::GetInstance()->pauseSystem(true, true);
+  CPU::ClearBreakpoints();
+  QtHostInterface::GetInstance()->pauseSystem(false);
+  emit closed();
+}
+
+void DebuggerWindow::setupAdditionalUi()
+{
+#ifdef WIN32
+  QFont fixedFont;
+  fixedFont.setFamily(QStringLiteral("Consolas"));
+  fixedFont.setFixedPitch(true);
+  fixedFont.setStyleHint(QFont::TypeWriter);
+  fixedFont.setPointSize(10);
+#else
+  const QFont fixedFont = QFontDatabase::systemFont(QFontDatabase::FixedFont);
+#endif
+  m_ui.codeView->setFont(fixedFont);
+  m_ui.registerView->setFont(fixedFont);
+  m_ui.memoryView->setFont(fixedFont);
+  m_ui.stackView->setFont(fixedFont);
+
+  setCentralWidget(nullptr);
+  delete m_ui.centralwidget;
+}
+
+void DebuggerWindow::connectSignals()
+{
+  QtHostInterface* hi = QtHostInterface::GetInstance();
+  connect(hi, &QtHostInterface::emulationPaused, this, &DebuggerWindow::onEmulationPaused);
+  connect(hi, &QtHostInterface::debuggerMessageReported, this, &DebuggerWindow::onDebuggerMessageReported);
+
+  connect(m_ui.actionPause, &QAction::toggled, this, &DebuggerWindow::onPauseActionToggled);
+  connect(m_ui.actionRunToCursor, &QAction::triggered, this, &DebuggerWindow::onRunToCursorTriggered);
+  connect(m_ui.actionGoToPC, &QAction::triggered, this, &DebuggerWindow::onGoToPCTriggered);
+  connect(m_ui.actionGoToAddress, &QAction::triggered, this, &DebuggerWindow::onGoToAddressTriggered);
+  connect(m_ui.actionDumpAddress, &QAction::triggered, this, &DebuggerWindow::onDumpAddressTriggered);
+  connect(m_ui.actionStepInto, &QAction::triggered, this, &DebuggerWindow::onStepIntoActionTriggered);
+  connect(m_ui.actionStepOver, &QAction::triggered, this, &DebuggerWindow::onStepOverActionTriggered);
+  connect(m_ui.actionStepOut, &QAction::triggered, this, &DebuggerWindow::onStepOutActionTriggered);
+  connect(m_ui.actionAddBreakpoint, &QAction::triggered, this, &DebuggerWindow::onAddBreakpointTriggered);
+  connect(m_ui.actionToggleBreakpoint, &QAction::triggered, this, &DebuggerWindow::onToggleBreakpointTriggered);
+  connect(m_ui.actionClearBreakpoints, &QAction::triggered, this, &DebuggerWindow::onClearBreakpointsTriggered);
+  connect(m_ui.actionClose, &QAction::triggered, this, &DebuggerWindow::close);
+
+  connect(m_ui.codeView, &QTreeView::activated, this, &DebuggerWindow::onCodeViewItemActivated);
+
+  connect(m_ui.memoryRegionRAM, &QRadioButton::clicked, [this]() { setMemoryViewRegion(Bus::MemoryRegion::RAM); });
+  connect(m_ui.memoryRegionEXP1, &QRadioButton::clicked, [this]() { setMemoryViewRegion(Bus::MemoryRegion::EXP1); });
+  connect(m_ui.memoryRegionScratchpad, &QRadioButton::clicked,
+          [this]() { setMemoryViewRegion(Bus::MemoryRegion::Scratchpad); });
+  connect(m_ui.memoryRegionBIOS, &QRadioButton::clicked, [this]() { setMemoryViewRegion(Bus::MemoryRegion::BIOS); });
+
+  connect(m_ui.memorySearch, &QPushButton::clicked, this, &DebuggerWindow::onMemorySearchTriggered);
+  connect(m_ui.memorySearchString, &QLineEdit::textChanged, this, &DebuggerWindow::onMemorySearchStringChanged);
+}
+
+void DebuggerWindow::disconnectSignals()
+{
+  QtHostInterface* hi = QtHostInterface::GetInstance();
+  hi->disconnect(this);
+}
+
+void DebuggerWindow::createModels()
+{
+  m_code_model = std::make_unique<DebuggerCodeModel>();
+  m_ui.codeView->setModel(m_code_model.get());
+
+  // set default column width in code view
+  m_ui.codeView->setColumnWidth(0, 40);
+  m_ui.codeView->setColumnWidth(1, 80);
+  m_ui.codeView->setColumnWidth(2, 80);
+  m_ui.codeView->setColumnWidth(3, 250);
+  m_ui.codeView->setColumnWidth(4, m_ui.codeView->width() - (40 + 80 + 80 + 250));
+
+  m_registers_model = std::make_unique<DebuggerRegistersModel>();
+  m_ui.registerView->setModel(m_registers_model.get());
+  // m_ui->registerView->resizeRowsToContents();
+
+  m_stack_model = std::make_unique<DebuggerStackModel>();
+  m_ui.stackView->setModel(m_stack_model.get());
+
+  m_ui.breakpointsWidget->setColumnWidth(0, 50);
+  m_ui.breakpointsWidget->setColumnWidth(1, 80);
+  m_ui.breakpointsWidget->setColumnWidth(2, 40);
+  m_ui.breakpointsWidget->setRootIsDecorated(false);
+}
+
+void DebuggerWindow::setUIEnabled(bool enabled)
+{
+  // Disable all UI elements that depend on execution state
+  m_ui.codeView->setEnabled(enabled);
+  m_ui.registerView->setEnabled(enabled);
+  m_ui.stackView->setEnabled(enabled);
+  m_ui.memoryView->setEnabled(enabled);
+  m_ui.actionRunToCursor->setEnabled(enabled);
+  m_ui.actionAddBreakpoint->setEnabled(enabled);
+  m_ui.actionToggleBreakpoint->setEnabled(enabled);
+  m_ui.actionClearBreakpoints->setEnabled(enabled);
+  m_ui.actionDumpAddress->setEnabled(enabled);
+  m_ui.actionStepInto->setEnabled(enabled);
+  m_ui.actionStepOver->setEnabled(enabled);
+  m_ui.actionStepOut->setEnabled(enabled);
+  m_ui.actionGoToAddress->setEnabled(enabled);
+  m_ui.actionGoToPC->setEnabled(enabled);
+  m_ui.memoryRegionRAM->setEnabled(enabled);
+  m_ui.memoryRegionEXP1->setEnabled(enabled);
+  m_ui.memoryRegionScratchpad->setEnabled(enabled);
+  m_ui.memoryRegionBIOS->setEnabled(enabled);
+}
+
+void DebuggerWindow::setMemoryViewRegion(Bus::MemoryRegion region)
+{
+  if (m_active_memory_region == region)
+    return;
+
+  m_active_memory_region = region;
+
+  switch (region)
+  {
+    case Bus::MemoryRegion::RAM:
+    case Bus::MemoryRegion::RAMMirror1:
+    case Bus::MemoryRegion::RAMMirror2:
+    case Bus::MemoryRegion::RAMMirror3:
+      m_ui.memoryView->setData(Bus::GetMemoryRegionStart(region), Bus::g_ram, Bus::RAM_SIZE);
+      break;
+
+    case Bus::MemoryRegion::Scratchpad:
+      m_ui.memoryView->setData(CPU::DCACHE_LOCATION, CPU::g_state.dcache.data(), CPU::DCACHE_SIZE);
+      break;
+
+    case Bus::MemoryRegion::BIOS:
+      m_ui.memoryView->setData(Bus::BIOS_BASE, Bus::g_bios, Bus::BIOS_SIZE);
+      break;
+
+    case Bus::MemoryRegion::EXP1:
+    default:
+      // TODO
+      m_ui.memoryView->setData(Bus::EXP1_BASE, nullptr, 0);
+      break;
+  }
+
+#define SET_REGION_RADIO_BUTTON(name, rb_region)                                                                       \
+  do                                                                                                                   \
+  {                                                                                                                    \
+    QSignalBlocker sb(name);                                                                                           \
+    name->setChecked(region == rb_region);                                                                             \
+  } while (0)
+
+  SET_REGION_RADIO_BUTTON(m_ui.memoryRegionRAM, Bus::MemoryRegion::RAM);
+  SET_REGION_RADIO_BUTTON(m_ui.memoryRegionEXP1, Bus::MemoryRegion::EXP1);
+  SET_REGION_RADIO_BUTTON(m_ui.memoryRegionScratchpad, Bus::MemoryRegion::Scratchpad);
+  SET_REGION_RADIO_BUTTON(m_ui.memoryRegionBIOS, Bus::MemoryRegion::BIOS);
+
+#undef SET_REGION_REGION_BUTTON
+
+  m_ui.memoryView->repaint();
+}
+
+void DebuggerWindow::toggleBreakpoint(VirtualMemoryAddress address)
+{
+  const bool new_bp_state = !CPU::HasBreakpointAtAddress(address);
+  if (new_bp_state)
+  {
+    if (!CPU::AddBreakpoint(address, false))
+      return;
+  }
+  else
+  {
+    if (!CPU::RemoveBreakpoint(address))
+      return;
+  }
+
+  m_code_model->setBreakpointState(address, new_bp_state);
+  refreshBreakpointList();
+}
+
+void DebuggerWindow::clearBreakpoints()
+{
+  m_code_model->clearBreakpoints();
+  CPU::ClearBreakpoints();
+}
+
+std::optional<VirtualMemoryAddress> DebuggerWindow::promptForAddress(const QString& label)
+{
+  const QString address_str(QInputDialog::getText(this, windowTitle(), tr("Enter memory address:")));
+  if (address_str.isEmpty())
+    return std::nullopt;
+
+  bool ok;
+  uint address;
+  if (address_str.startsWith("0x"))
+    address = address_str.midRef(2).toUInt(&ok, 16);
+  else if (address_str[0] == '0')
+    address = address_str.midRef(2).toUInt(&ok, 8);
+  else
+    address = address_str.midRef(2).toUInt(&ok, 8);
+
+  if (!ok)
+  {
+    QMessageBox::critical(this, windowTitle(),
+                          tr("Invalid address. It should be in hex (0x12345678) or decimal (12345678)"));
+    return std::nullopt;
+  }
+
+  return address;
+}
+
+std::optional<VirtualMemoryAddress> DebuggerWindow::getSelectedCodeAddress()
+{
+  QItemSelectionModel* sel_model = m_ui.codeView->selectionModel();
+  const QModelIndexList indices(sel_model->selectedIndexes());
+  if (indices.empty())
+    return std::nullopt;
+
+  return m_code_model->getAddressForIndex(indices[0]);
+}
+
+bool DebuggerWindow::tryFollowLoadStore(VirtualMemoryAddress address)
+{
+  CPU::Instruction inst;
+  if (!CPU::SafeReadInstruction(address, &inst.bits))
+    return false;
+
+  const std::optional<VirtualMemoryAddress> ea = GetLoadStoreEffectiveAddress(inst, &CPU::g_state.regs);
+  if (!ea.has_value())
+    return false;
+
+  scrollToMemoryAddress(ea.value());
+  return true;
+}
+
+bool DebuggerWindow::scrollToMemoryAddress(VirtualMemoryAddress address)
+{
+  const PhysicalMemoryAddress phys_address = CPU::VirtualAddressToPhysical(address);
+  std::optional<Bus::MemoryRegion> region = Bus::GetMemoryRegionForAddress(phys_address);
+  if (!region.has_value())
+    return false;
+
+  setMemoryViewRegion(region.value());
+
+  const PhysicalMemoryAddress offset = phys_address - Bus::GetMemoryRegionStart(region.value());
+  m_ui.memoryView->scrolltoOffset(offset);
+  return true;
+}
+
+void DebuggerWindow::refreshBreakpointList()
+{
+  while (m_ui.breakpointsWidget->topLevelItemCount() > 0)
+    delete m_ui.breakpointsWidget->takeTopLevelItem(0);
+
+  const CPU::BreakpointList bps(CPU::GetBreakpointList());
+  for (const CPU::Breakpoint& bp : bps)
+  {
+    QTreeWidgetItem* item = new QTreeWidgetItem();
+    item->setFlags(item->flags() | Qt::ItemIsUserCheckable);
+    item->setCheckState(0, bp.enabled ? Qt::Checked : Qt::Unchecked);
+    item->setText(0, QString::asprintf("%u", bp.number));
+    item->setText(1, QString::asprintf("0x%08X", bp.address));
+    item->setText(2, QString::asprintf("%u", bp.hit_count));
+    m_ui.breakpointsWidget->addTopLevelItem(item);
+  }
+}

src/duckstation-qt/debuggerwindow.h

@@ -0,0 +1,79 @@
+#pragma once
+#include "core/types.h"
+#include "ui_debuggerwindow.h"
+#include <QtWidgets/QMainWindow>
+#include <memory>
+#include <optional>
+
+namespace Bus {
+enum class MemoryRegion;
+}
+
+class DebuggerCodeModel;
+class DebuggerRegistersModel;
+class DebuggerStackModel;
+
+class DebuggerWindow : public QMainWindow
+{
+  Q_OBJECT
+
+public:
+  explicit DebuggerWindow(QWidget* parent = nullptr);
+  ~DebuggerWindow();
+
+Q_SIGNALS:
+  void closed();
+
+protected:
+  void closeEvent(QCloseEvent* event);
+
+private Q_SLOTS:
+  void onEmulationPaused(bool paused);
+  void onDebuggerMessageReported(const QString& message);
+
+  void refreshAll();
+
+  void scrollToPC();
+
+  void onPauseActionToggled(bool paused);
+  void onRunToCursorTriggered();
+  void onGoToPCTriggered();
+  void onGoToAddressTriggered();
+  void onDumpAddressTriggered();
+  void onFollowAddressTriggered();
+  void onAddBreakpointTriggered();
+  void onToggleBreakpointTriggered();
+  void onClearBreakpointsTriggered();
+  void onStepIntoActionTriggered();
+  void onStepOverActionTriggered();
+  void onStepOutActionTriggered();
+  void onCodeViewItemActivated(QModelIndex index);
+  void onMemorySearchTriggered();
+  void onMemorySearchStringChanged(const QString&);
+
+private:
+  void setupAdditionalUi();
+  void connectSignals();
+  void disconnectSignals();
+  void createModels();
+  void setUIEnabled(bool enabled);
+  void setMemoryViewRegion(Bus::MemoryRegion region);
+  void toggleBreakpoint(VirtualMemoryAddress address);
+  void clearBreakpoints();
+  std::optional<VirtualMemoryAddress> promptForAddress(const QString& label);
+  std::optional<VirtualMemoryAddress> getSelectedCodeAddress();
+  bool tryFollowLoadStore(VirtualMemoryAddress address);
+  void scrollToCodeAddress(VirtualMemoryAddress address);
+  bool scrollToMemoryAddress(VirtualMemoryAddress address);
+  void refreshBreakpointList();
+
+  Ui::DebuggerWindow m_ui;
+
+  std::unique_ptr<DebuggerCodeModel> m_code_model;
+  std::unique_ptr<DebuggerRegistersModel> m_registers_model;
+  std::unique_ptr<DebuggerStackModel> m_stack_model;
+
+  Bus::MemoryRegion m_active_memory_region;
+
+  PhysicalMemoryAddress m_next_memory_search_address = 0;
+};

src/duckstation-qt/debuggerwindow.ui

@@ -0,0 +1,477 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>DebuggerWindow</class>
+ <widget class="QMainWindow" name="DebuggerWindow">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>1210</width>
+    <height>800</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>CPU Debugger</string>
+  </property>
+  <property name="dockNestingEnabled">
+   <bool>true</bool>
+  </property>
+  <widget class="QWidget" name="centralwidget"/>
+  <widget class="QMenuBar" name="menubar">
+   <property name="geometry">
+    <rect>
+     <x>0</x>
+     <y>0</y>
+     <width>1210</width>
+     <height>21</height>
+    </rect>
+   </property>
+   <widget class="QMenu" name="menu_Debugger">
+    <property name="title">
+     <string>&amp;Debug</string>
+    </property>
+    <addaction name="actionPause"/>
+    <addaction name="actionRunToCursor"/>
+    <addaction name="separator"/>
+    <addaction name="actionGoToPC"/>
+    <addaction name="actionGoToAddress"/>
+    <addaction name="actionDumpAddress"/>
+    <addaction name="separator"/>
+    <addaction name="actionStepInto"/>
+    <addaction name="actionStepOver"/>
+    <addaction name="actionStepOut"/>
+    <addaction name="separator"/>
+    <addaction name="actionClose"/>
+   </widget>
+   <widget class="QMenu" name="menuBreakpoints">
+    <property name="title">
+     <string>Breakpoints</string>
+    </property>
+    <addaction name="actionAddBreakpoint"/>
+    <addaction name="actionToggleBreakpoint"/>
+    <addaction name="actionClearBreakpoints"/>
+   </widget>
+   <addaction name="menu_Debugger"/>
+   <addaction name="menuBreakpoints"/>
+  </widget>
+  <widget class="QStatusBar" name="statusbar"/>
+  <widget class="QToolBar" name="toolBar">
+   <property name="windowTitle">
+    <string>toolBar</string>
+   </property>
+   <attribute name="toolBarArea">
+    <enum>TopToolBarArea</enum>
+   </attribute>
+   <attribute name="toolBarBreak">
+    <bool>false</bool>
+   </attribute>
+   <addaction name="actionPause"/>
+   <addaction name="actionRunToCursor"/>
+   <addaction name="separator"/>
+   <addaction name="actionGoToPC"/>
+   <addaction name="actionGoToAddress"/>
+   <addaction name="actionDumpAddress"/>
+   <addaction name="separator"/>
+   <addaction name="actionAddBreakpoint"/>
+   <addaction name="actionToggleBreakpoint"/>
+   <addaction name="actionClearBreakpoints"/>
+   <addaction name="separator"/>
+   <addaction name="actionStepInto"/>
+   <addaction name="actionStepOver"/>
+   <addaction name="actionStepOut"/>
+  </widget>
+  <widget class="QDockWidget" name="dockWidget_2">
+   <property name="features">
+    <set>QDockWidget::DockWidgetFloatable|QDockWidget::DockWidgetMovable</set>
+   </property>
+   <property name="windowTitle">
+    <string>Disassembly</string>
+   </property>
+   <attribute name="dockWidgetArea">
+    <number>4</number>
+   </attribute>
+   <widget class="QTreeView" name="codeView">
+    <property name="sizePolicy">
+     <sizepolicy hsizetype="Expanding" vsizetype="Expanding">
+      <horstretch>0</horstretch>
+      <verstretch>0</verstretch>
+     </sizepolicy>
+    </property>
+    <attribute name="headerVisible">
+     <bool>false</bool>
+    </attribute>
+   </widget>
+  </widget>
+  <widget class="QDockWidget" name="dockWidget_3">
+   <property name="features">
+    <set>QDockWidget::DockWidgetFloatable|QDockWidget::DockWidgetMovable</set>
+   </property>
+   <property name="windowTitle">
+    <string>Registers</string>
+   </property>
+   <attribute name="dockWidgetArea">
+    <number>4</number>
+   </attribute>
+   <widget class="QTreeView" name="registerView">
+    <property name="sizePolicy">
+     <sizepolicy hsizetype="Expanding" vsizetype="Expanding">
+      <horstretch>0</horstretch>
+      <verstretch>0</verstretch>
+     </sizepolicy>
+    </property>
+    <property name="maximumSize">
+     <size>
+      <width>220</width>
+      <height>16777215</height>
+     </size>
+    </property>
+   </widget>
+  </widget>
+  <widget class="QDockWidget" name="dockWidget">
+   <property name="sizePolicy">
+    <sizepolicy hsizetype="Preferred" vsizetype="Preferred">
+     <horstretch>1</horstretch>
+     <verstretch>0</verstretch>
+    </sizepolicy>
+   </property>
+   <property name="features">
+    <set>QDockWidget::DockWidgetFloatable|QDockWidget::DockWidgetMovable</set>
+   </property>
+   <property name="windowTitle">
+    <string>Memory</string>
+   </property>
+   <attribute name="dockWidgetArea">
+    <number>8</number>
+   </attribute>
+   <widget class="QWidget" name="dockWidgetContents_3">
+    <layout class="QVBoxLayout" name="verticalLayout">
+     <item>
+      <widget class="MemoryViewWidget" name="memoryView" native="true">
+       <property name="sizePolicy">
+        <sizepolicy hsizetype="Preferred" vsizetype="Expanding">
+         <horstretch>0</horstretch>
+         <verstretch>0</verstretch>
+        </sizepolicy>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <layout class="QHBoxLayout" name="horizontalLayout">
+       <item>
+        <widget class="QRadioButton" name="memoryRegionRAM">
+         <property name="text">
+          <string>RAM</string>
+         </property>
+         <property name="checked">
+          <bool>true</bool>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <widget class="QRadioButton" name="memoryRegionScratchpad">
+         <property name="text">
+          <string>Scratchpad</string>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <widget class="QRadioButton" name="memoryRegionEXP1">
+         <property name="text">
+          <string>EXP1</string>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <widget class="QRadioButton" name="memoryRegionBIOS">
+         <property name="text">
+          <string>BIOS</string>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <spacer name="horizontalSpacer">
+         <property name="orientation">
+          <enum>Qt::Horizontal</enum>
+         </property>
+         <property name="sizeHint" stdset="0">
+          <size>
+           <width>40</width>
+           <height>20</height>
+          </size>
+         </property>
+        </spacer>
+       </item>
+       <item>
+        <layout class="QHBoxLayout" name="horizontalLayout_2">
+         <item>
+          <widget class="QLineEdit" name="memorySearchString"/>
+         </item>
+         <item>
+          <widget class="QPushButton" name="memorySearch">
+           <property name="text">
+            <string>Search</string>
+           </property>
+          </widget>
+         </item>
+        </layout>
+       </item>
+      </layout>
+     </item>
+    </layout>
+   </widget>
+  </widget>
+  <widget class="QDockWidget" name="dockWidget_5">
+   <property name="sizePolicy">
+    <sizepolicy hsizetype="Maximum" vsizetype="Preferred">
+     <horstretch>0</horstretch>
+     <verstretch>0</verstretch>
+    </sizepolicy>
+   </property>
+   <property name="maximumSize">
+    <size>
+     <width>200</width>
+     <height>524287</height>
+    </size>
+   </property>
+   <property name="features">
+    <set>QDockWidget::DockWidgetFloatable|QDockWidget::DockWidgetMovable</set>
+   </property>
+   <property name="windowTitle">
+    <string>Breakpoints</string>
+   </property>
+   <attribute name="dockWidgetArea">
+    <number>8</number>
+   </attribute>
+   <widget class="QTreeWidget" name="breakpointsWidget">
+    <property name="selectionMode">
+     <enum>QAbstractItemView::SingleSelection</enum>
+    </property>
+    <property name="selectionBehavior">
+     <enum>QAbstractItemView::SelectRows</enum>
+    </property>
+    <property name="sortingEnabled">
+     <bool>true</bool>
+    </property>
+    <attribute name="headerMinimumSectionSize">
+     <number>20</number>
+    </attribute>
+    <column>
+     <property name="text">
+      <string>#</string>
+     </property>
+    </column>
+    <column>
+     <property name="text">
+      <string>Address</string>
+     </property>
+    </column>
+    <column>
+     <property name="text">
+      <string>Hit Count</string>
+     </property>
+    </column>
+   </widget>
+  </widget>
+  <widget class="QDockWidget" name="dockWidget_4">
+   <property name="features">
+    <set>QDockWidget::DockWidgetFloatable|QDockWidget::DockWidgetMovable</set>
+   </property>
+   <property name="windowTitle">
+    <string>Stack</string>
+   </property>
+   <attribute name="dockWidgetArea">
+    <number>8</number>
+   </attribute>
+   <widget class="QTreeView" name="stackView">
+    <property name="maximumSize">
+     <size>
+      <width>220</width>
+      <height>16777215</height>
+     </size>
+    </property>
+   </widget>
+  </widget>
+  <action name="actionPause">
+   <property name="checkable">
+    <bool>true</bool>
+   </property>
+   <property name="icon">
+    <iconset resource="resources/resources.qrc">
+     <normaloff>:/icons/media-playback-pause.png</normaloff>:/icons/media-playback-pause.png</iconset>
+   </property>
+   <property name="text">
+    <string>Pause/Continue</string>
+   </property>
+   <property name="toolTip">
+    <string>&amp;Pause/Continue</string>
+   </property>
+   <property name="shortcut">
+    <string>F5</string>
+   </property>
+  </action>
+  <action name="actionStepInto">
+   <property name="icon">
+    <iconset resource="resources/resources.qrc">
+     <normaloff>:/icons/debug-step-into-instruction.png</normaloff>:/icons/debug-step-into-instruction.png</iconset>
+   </property>
+   <property name="text">
+    <string>Step Into</string>
+   </property>
+   <property name="toolTip">
+    <string>&amp;Step Into</string>
+   </property>
+   <property name="shortcut">
+    <string>F11</string>
+   </property>
+  </action>
+  <action name="actionStepOver">
+   <property name="icon">
+    <iconset resource="resources/resources.qrc">
+     <normaloff>:/icons/debug-step-over.png</normaloff>:/icons/debug-step-over.png</iconset>
+   </property>
+   <property name="text">
+    <string>Step Over</string>
+   </property>
+   <property name="toolTip">
+    <string>Step &amp;Over</string>
+   </property>
+   <property name="shortcut">
+    <string>F10</string>
+   </property>
+  </action>
+  <action name="actionToggleBreakpoint">
+   <property name="icon">
+    <iconset resource="resources/resources.qrc">
+     <normaloff>:/icons/media-record@2x.png</normaloff>:/icons/media-record@2x.png</iconset>
+   </property>
+   <property name="text">
+    <string>Toggle Breakpoint</string>
+   </property>
+   <property name="toolTip">
+    <string>Toggle &amp;Breakpoint</string>
+   </property>
+   <property name="shortcut">
+    <string>F9</string>
+   </property>
+  </action>
+  <action name="actionClose">
+   <property name="text">
+    <string>&amp;Close</string>
+   </property>
+  </action>
+  <action name="actionStepOut">
+   <property name="icon">
+    <iconset resource="resources/resources.qrc">
+     <normaloff>:/icons/debug-step-out.png</normaloff>:/icons/debug-step-out.png</iconset>
+   </property>
+   <property name="text">
+    <string>Step Out</string>
+   </property>
+   <property name="toolTip">
+    <string>Step O&amp;ut</string>
+   </property>
+   <property name="shortcut">
+    <string>Ctrl+F11</string>
+   </property>
+  </action>
+  <action name="actionRunToCursor">
+   <property name="icon">
+    <iconset resource="resources/resources.qrc">
+     <normaloff>:/icons/debug-run-cursor.png</normaloff>:/icons/debug-run-cursor.png</iconset>
+   </property>
+   <property name="text">
+    <string>Run To Cursor</string>
+   </property>
+   <property name="toolTip">
+    <string>&amp;Run To Cursor</string>
+   </property>
+   <property name="shortcut">
+    <string>Ctrl+F10</string>
+   </property>
+  </action>
+  <action name="actionClearBreakpoints">
+   <property name="icon">
+    <iconset resource="resources/resources.qrc">
+     <normaloff>:/icons/edit-clear-16.png</normaloff>:/icons/edit-clear-16.png</iconset>
+   </property>
+   <property name="text">
+    <string>Clear Breakpoints</string>
+   </property>
+   <property name="toolTip">
+    <string>&amp;Clear Breakpoints</string>
+   </property>
+   <property name="shortcut">
+    <string>Ctrl+Del</string>
+   </property>
+  </action>
+  <action name="actionAddBreakpoint">
+   <property name="icon">
+    <iconset resource="resources/resources.qrc">
+     <normaloff>:/icons/list-add.png</normaloff>:/icons/list-add.png</iconset>
+   </property>
+   <property name="text">
+    <string>Add Breakpoint</string>
+   </property>
+   <property name="toolTip">
+    <string>Add &amp;Breakpoint</string>
+   </property>
+   <property name="shortcut">
+    <string>Ctrl+F9</string>
+   </property>
+  </action>
+  <action name="actionGoToPC">
+   <property name="icon">
+    <iconset resource="resources/resources.qrc">
+     <normaloff>:/icons/document-open.png</normaloff>:/icons/document-open.png</iconset>
+   </property>
+   <property name="text">
+    <string>Go To PC</string>
+   </property>
+   <property name="toolTip">
+    <string>&amp;Go To PC</string>
+   </property>
+   <property name="shortcut">
+    <string>Ctrl+P</string>
+   </property>
+  </action>
+  <action name="actionGoToAddress">
+   <property name="icon">
+    <iconset resource="resources/resources.qrc">
+     <normaloff>:/icons/applications-system.png</normaloff>:/icons/applications-system.png</iconset>
+   </property>
+   <property name="text">
+    <string>Go To Address</string>
+   </property>
+   <property name="toolTip">
+    <string>Go To &amp;Address</string>
+   </property>
+   <property name="shortcut">
+    <string>Ctrl+G</string>
+   </property>
+  </action>
+  <action name="actionDumpAddress">
+   <property name="icon">
+    <iconset resource="resources/resources.qrc">
+     <normaloff>:/icons/antialias-icon.png</normaloff>:/icons/antialias-icon.png</iconset>
+   </property>
+   <property name="text">
+    <string>&amp;Dump Address</string>
+   </property>
+   <property name="shortcut">
+    <string>Ctrl+D</string>
+   </property>
+  </action>
+ </widget>
+ <customwidgets>
+  <customwidget>
+   <class>MemoryViewWidget</class>
+   <extends>QWidget</extends>
+   <header>memoryviewwidget.h</header>
+   <container>1</container>
+  </customwidget>
+ </customwidgets>
+ <resources>
+  <include location="resources/resources.qrc"/>
+ </resources>
+ <connections/>
+</ui>

src/duckstation-qt/duckstation-qt.vcxproj

@@ -59,6 +59,8 @@
     <ClCompile Include="cheatmanagerdialog.cpp" />
     <ClCompile Include="cheatcodeeditordialog.cpp" />
     <ClCompile Include="consolesettingswidget.cpp" />
+    <ClCompile Include="debuggermodels.cpp" />
+    <ClCompile Include="debuggerwindow.cpp" />
     <ClCompile Include="enhancementsettingswidget.cpp" />
     <ClCompile Include="gamelistmodel.cpp" />
     <ClCompile Include="gamelistsearchdirectoriesmodel.cpp" />
@@ -68,6 +70,7 @@
     <ClCompile Include="inputbindingdialog.cpp" />
     <ClCompile Include="inputbindingmonitor.cpp" />
     <ClCompile Include="inputbindingwidgets.cpp" />
+    <ClCompile Include="memoryviewwidget.cpp" />
     <ClCompile Include="qtdisplaywidget.cpp" />
     <ClCompile Include="gamelistsettingswidget.cpp" />
     <ClCompile Include="gamelistwidget.cpp" />
@@ -106,7 +109,10 @@
     <QtMoc Include="gamelistmodel.h" />
     <QtMoc Include="gamelistsearchdirectoriesmodel.h" />
     <QtMoc Include="autoupdaterdialog.h" />
+    <QtMoc Include="debuggermodels.h" />
+    <QtMoc Include="debuggerwindow.h" />
     <ClInclude Include="inputbindingmonitor.h" />
+    <QtMoc Include="memoryviewwidget.h" />
     <ClInclude Include="resource.h" />
     <ClInclude Include="settingwidgetbinder.h" />
     <QtMoc Include="consolesettingswidget.h" />
@@ -216,6 +222,8 @@
     <ClCompile Include="$(IntDir)moc_gamelistwidget.cpp" />
     <ClCompile Include="$(IntDir)moc_gamepropertiesdialog.cpp" />
     <ClCompile Include="$(IntDir)moc_generalsettingswidget.cpp" />
+    <ClCompile Include="$(IntDir)moc_debuggermodels.cpp" />
+    <ClCompile Include="$(IntDir)moc_debuggerwindow.cpp" />
     <ClCompile Include="$(IntDir)moc_displaysettingswidget.cpp" />
     <ClCompile Include="$(IntDir)moc_hotkeysettingswidget.cpp" />
     <ClCompile Include="$(IntDir)moc_inputbindingdialog.cpp" />
@@ -223,6 +231,7 @@
     <ClCompile Include="$(IntDir)moc_mainwindow.cpp" />
     <ClCompile Include="$(IntDir)moc_memorycardsettingswidget.cpp" />
     <ClCompile Include="$(IntDir)moc_memorycardeditordialog.cpp" />
+    <ClCompile Include="$(IntDir)moc_memoryviewwidget.cpp" />
     <ClCompile Include="$(IntDir)moc_postprocessingchainconfigwidget.cpp" />
     <ClCompile Include="$(IntDir)moc_postprocessingshaderconfigwidget.cpp" />
     <ClCompile Include="$(IntDir)moc_postprocessingsettingswidget.cpp" />
@@ -251,35 +260,48 @@
       <FileType>Document</FileType>
     </QtUi>
   </ItemGroup>
+  <ItemGroup>
+    <QtUi Include="autoupdaterdialog.ui">
+      <FileType>Document</FileType>
+    </QtUi>
+  </ItemGroup>
   <ItemGroup>
     <QtTs Include="translations\duckstation-qt_de.ts">
       <FileType>Document</FileType>
     </QtTs>
+    <QtTs Include="translations\duckstation-qt_es.ts">
+      <FileType>Document</FileType>
+    </QtTs>
+    <QtTs Include="translations\duckstation-qt_fr.ts">
+      <FileType>Document</FileType>
+    </QtTs>
     <QtTs Include="translations\duckstation-qt_he.ts">
       <FileType>Document</FileType>
     </QtTs>
+    <QtTs Include="translations\duckstation-qt_it.ts">
+      <FileType>Document</FileType>
+    </QtTs>
+    <QtTs Include="translations\duckstation-qt_ja.ts">
+      <FileType>Document</FileType>
+    </QtTs>
+    <QtTs Include="translations\duckstation-qt_nl.ts">
+      <FileType>Document</FileType>
+    </QtTs>
     <QtTs Include="translations\duckstation-qt_pt-br.ts">
       <FileType>Document</FileType>
     </QtTs>
     <QtTs Include="translations\duckstation-qt_pt-pt.ts">
       <FileType>Document</FileType>
     </QtTs>
+    <QtTs Include="translations\duckstation-qt_ru.ts">
+      <FileType>Document</FileType>
+    </QtTs>
     <QtTs Include="translations\duckstation-qt_zh-cn.ts">
       <FileType>Document</FileType>
     </QtTs>
   </ItemGroup>
   <ItemGroup>
-    <QtUi Include="autoupdaterdialog.ui">
-      <FileType>Document</FileType>
-    </QtUi>
-  </ItemGroup>
-  <ItemGroup>
-    <None Include="translations\duckstation-qt_es.ts" />
-    <None Include="translations\duckstation-qt_fr.ts" />
-    <None Include="translations\duckstation-qt_it.ts" />
-    <None Include="translations\duckstation-qt_nl.ts" />
-    <None Include="translations\duckstation-qt_ru.ts" />
-    <None Include="translations\duckstation-qt_ja.ts" />
+    <None Include="debuggerwindow.ui" />
   </ItemGroup>
   <Target Name="CopyCommonDataFiles" AfterTargets="Build" Inputs="@(CommonDataFiles)" Outputs="@(CommonDataFiles -> '$(BinaryOutputDir)%(RecursiveDir)%(Filename)%(Extension)')">
     <Message Text="Copying common data files" Importance="High" />
@@ -778,4 +800,4 @@
   <ImportGroup Label="ExtensionTargets">
     <Import Project="..\..\dep\msvc\vsprops\QtCompile.targets" />
   </ImportGroup>
-</Project>
+</Project>

src/duckstation-qt/duckstation-qt.vcxproj.filters

@@ -65,6 +65,12 @@
     <ClCompile Include="cheatcodeeditordialog.cpp" />
     <ClCompile Include="$(IntDir)moc_cheatmanagerdialog.cpp" />
     <ClCompile Include="$(IntDir)moc_cheatcodeeditordialog.cpp" />
+    <ClCompile Include="debuggerwindow.cpp" />
+    <ClCompile Include="debuggermodels.cpp" />
+    <ClCompile Include="memoryviewwidget.cpp" />
+    <ClCompile Include="$(IntDir)moc_debuggerdialog.cpp" />
+    <ClCompile Include="$(IntDir)moc_debuggermodels.cpp" />
+    <ClCompile Include="$(IntDir)moc_memoryviewwidget.cpp" />
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="qtutils.h" />
@@ -111,6 +117,9 @@
     <QtMoc Include="postprocessingsettingswidget.h" />
     <QtMoc Include="cheatmanagerdialog.h" />
     <QtMoc Include="cheatcodeeditordialog.h" />
+    <QtMoc Include="debuggermodels.h" />
+    <QtMoc Include="debuggerwindow.h" />
+    <QtMoc Include="memoryviewwidget.h" />
   </ItemGroup>
   <ItemGroup>
     <QtUi Include="consolesettingswidget.ui" />
@@ -142,46 +151,47 @@
   <ItemGroup>
     <Image Include="duckstation-qt.ico" />
   </ItemGroup>
+  <ItemGroup>
+    <QtResource Include="resources\resources.qrc">
+      <Filter>resources</Filter>
+    </QtResource>
+  </ItemGroup>
+  <ItemGroup>
+    <None Include="debuggerwindow.ui" />
+  </ItemGroup>
   <ItemGroup>
     <QtTs Include="translations\duckstation-qt_de.ts">
       <Filter>translations</Filter>
     </QtTs>
+    <QtTs Include="translations\duckstation-qt_es.ts">
+      <Filter>translations</Filter>
+    </QtTs>
+    <QtTs Include="translations\duckstation-qt_fr.ts">
+      <Filter>translations</Filter>
+    </QtTs>
     <QtTs Include="translations\duckstation-qt_he.ts">
       <Filter>translations</Filter>
     </QtTs>
+    <QtTs Include="translations\duckstation-qt_it.ts">
+      <Filter>translations</Filter>
+    </QtTs>
+    <QtTs Include="translations\duckstation-qt_ja.ts">
+      <Filter>translations</Filter>
+    </QtTs>
+    <QtTs Include="translations\duckstation-qt_nl.ts">
+      <Filter>translations</Filter>
+    </QtTs>
     <QtTs Include="translations\duckstation-qt_pt-br.ts">
       <Filter>translations</Filter>
     </QtTs>
     <QtTs Include="translations\duckstation-qt_pt-pt.ts">
       <Filter>translations</Filter>
     </QtTs>
+    <QtTs Include="translations\duckstation-qt_ru.ts">
+      <Filter>translations</Filter>
+    </QtTs>
     <QtTs Include="translations\duckstation-qt_zh-cn.ts">
       <Filter>translations</Filter>
     </QtTs>
   </ItemGroup>
-  <ItemGroup>
-    <None Include="translations\duckstation-qt_es.ts">
-      <Filter>translations</Filter>
-    </None>
-    <None Include="translations\duckstation-qt_it.ts">
-      <Filter>translations</Filter>
-    </None>
-    <None Include="translations\duckstation-qt_ru.ts">
-      <Filter>translations</Filter>
-    </None>
-    <None Include="translations\duckstation-qt_nl.ts">
-      <Filter>translations</Filter>
-    </None>
-    <None Include="translations\duckstation-qt_fr.ts">
-      <Filter>translations</Filter>
-    </None>
-    <None Include="translations\duckstation-qt_ja.ts">
-      <Filter>translations</Filter>
-    </None>
-  </ItemGroup>
-  <ItemGroup>
-    <QtResource Include="resources\resources.qrc">
-      <Filter>resources</Filter>
-    </QtResource>
-  </ItemGroup>
 </Project>

src/duckstation-qt/mainwindow.cpp

@@ -6,6 +6,7 @@
 #include "core/host_display.h"
 #include "core/settings.h"
 #include "core/system.h"
+#include "debuggerwindow.h"
 #include "frontend-common/game_list.h"
 #include "gamelistsettingswidget.h"
 #include "gamelistwidget.h"
@@ -60,6 +61,8 @@ MainWindow::~MainWindow()
 {
   Assert(!m_display_widget);
   m_host_interface->setMainWindow(nullptr);
+
+  Assert(!m_debugger_window);
 }
 
 void MainWindow::reportError(const QString& message)
@@ -311,6 +314,12 @@ void MainWindow::onEmulationStopped()
     delete m_cheat_manager_dialog;
     m_cheat_manager_dialog = nullptr;
   }
+
+  if (m_debugger_window)
+  {
+    delete m_debugger_window;
+    m_debugger_window = nullptr;
+  }
 }
 
 void MainWindow::onEmulationPaused(bool paused)
@@ -761,6 +770,7 @@ void MainWindow::updateEmulationActions(bool starting, bool running)
   m_ui.menuChangeDisc->setDisabled(starting || !running);
   m_ui.menuCheats->setDisabled(starting || !running);
   m_ui.actionCheatManager->setDisabled(starting || !running);
+  m_ui.actionCPUDebugger->setDisabled(starting || !running);
 
   m_ui.actionSaveState->setDisabled(starting || !running);
   m_ui.menuSaveState->setDisabled(starting || !running);
@@ -850,7 +860,7 @@ void MainWindow::connectSignals()
           [this]() { getSettingsDialog()->getGameListSettingsWidget()->addSearchDirectory(this); });
   connect(m_ui.actionPowerOff, &QAction::triggered, m_host_interface, &QtHostInterface::powerOffSystem);
   connect(m_ui.actionReset, &QAction::triggered, m_host_interface, &QtHostInterface::resetSystem);
-  connect(m_ui.actionPause, &QAction::toggled, m_host_interface, &QtHostInterface::pauseSystem);
+  connect(m_ui.actionPause, &QAction::toggled, [this](bool active) { m_host_interface->pauseSystem(active); });
   connect(m_ui.actionScreenshot, &QAction::triggered, m_host_interface, &QtHostInterface::saveScreenshot);
   connect(m_ui.actionScanForNewGames, &QAction::triggered, this,
           [this]() { m_host_interface->refreshGameList(false, false); });
@@ -899,6 +909,7 @@ void MainWindow::connectSignals()
   connect(m_ui.actionCheckForUpdates, &QAction::triggered, this, &MainWindow::onCheckForUpdatesActionTriggered);
   connect(m_ui.actionMemory_Card_Editor, &QAction::triggered, this, &MainWindow::onToolsMemoryCardEditorTriggered);
   connect(m_ui.actionCheatManager, &QAction::triggered, this, &MainWindow::onToolsCheatManagerTriggered);
+  connect(m_ui.actionCPUDebugger, &QAction::triggered, this, &MainWindow::onToolsCPUDebuggerTriggered);
   connect(m_ui.actionOpenDataDirectory, &QAction::triggered, this, &MainWindow::onToolsOpenDataDirectoryTriggered);
   connect(m_ui.actionGridViewShowTitles, &QAction::triggered, m_game_list_widget, &GameListWidget::setShowCoverTitles);
   connect(m_ui.actionGridViewZoomIn, &QAction::triggered, m_game_list_widget, [this]() {
@@ -1325,6 +1336,26 @@ void MainWindow::onToolsCheatManagerTriggered()
   m_cheat_manager_dialog->show();
 }
 
+void MainWindow::onToolsCPUDebuggerTriggered()
+{
+  if (!m_debugger_window)
+  {
+    m_debugger_window = new DebuggerWindow();
+    m_debugger_window->setWindowIcon(windowIcon());
+    connect(m_debugger_window, &DebuggerWindow::closed, this, &MainWindow::onCPUDebuggerClosed);
+  }
+
+  m_debugger_window->show();
+  m_host_interface->pauseSystem(true);
+}
+
+void MainWindow::onCPUDebuggerClosed()
+{
+  Assert(m_debugger_window);
+  m_debugger_window->deleteLater();
+  m_debugger_window = nullptr;
+}
+
 void MainWindow::onToolsOpenDataDirectoryTriggered()
 {
   QtUtils::OpenURL(this, QUrl::fromLocalFile(m_host_interface->getUserDirectoryRelativePath(QString())));

src/duckstation-qt/mainwindow.h

@@ -16,6 +16,7 @@ class QtDisplayWidget;
 class AutoUpdaterDialog;
 class MemoryCardEditorDialog;
 class CheatManagerDialog;
+class DebuggerWindow;
 
 class HostDisplay;
 struct GameListEntry;
@@ -83,12 +84,14 @@ private Q_SLOTS:
   void onCheckForUpdatesActionTriggered();
   void onToolsMemoryCardEditorTriggered();
   void onToolsCheatManagerTriggered();
+  void onToolsCPUDebuggerTriggered();
   void onToolsOpenDataDirectoryTriggered();
 
   void onGameListEntrySelected(const GameListEntry* entry);
   void onGameListEntryDoubleClicked(const GameListEntry* entry);
   void onGameListContextMenuRequested(const QPoint& point, const GameListEntry* entry);
   void onGameListSetCoverImageRequested(const GameListEntry* entry);
+  void onCPUDebuggerClosed();
 
   void checkForUpdates(bool display_message);
   void onUpdateCheckComplete();
@@ -137,6 +140,7 @@ private:
   AutoUpdaterDialog* m_auto_updater_dialog = nullptr;
   MemoryCardEditorDialog* m_memory_card_editor_dialog = nullptr;
   CheatManagerDialog* m_cheat_manager_dialog = nullptr;
+  DebuggerWindow* m_debugger_window = nullptr;
 
   bool m_emulation_running = false;
   bool m_was_paused_by_focus_loss = false;

src/duckstation-qt/mainwindow.ui

@@ -176,6 +176,8 @@
     <addaction name="actionDebugDumpCPUtoVRAMCopies"/>
     <addaction name="actionDebugDumpVRAMtoCPUCopies"/>
     <addaction name="actionDumpAudio"/>
+    <addaction name="separator"/>
+    <addaction name="actionCPUDebugger" />
     <addaction name="actionDumpRAM"/>
     <addaction name="separator"/>
     <addaction name="actionDebugShowVRAM"/>
@@ -736,6 +738,11 @@
     <string>C&amp;heat Manager</string>
    </property>
   </action>
+  <action name="actionCPUDebugger">
+   <property name="text">
+    <string>CPU D&amp;ebugger</string>
+   </property>
+  </action>
   <action name="actionViewGameGrid">
    <property name="text">
     <string>Game &amp;Grid</string>

src/duckstation-qt/memoryviewwidget.cpp

@@ -0,0 +1,234 @@
+#include "memoryviewwidget.h"
+#include <QtGui/QPainter>
+#include <QtWidgets/QScrollBar>
+
+MemoryViewWidget::MemoryViewWidget(QWidget* parent /* = nullptr */, size_t address_offset /* = 0 */,
+                                   const void* data_ptr /* = nullptr */, size_t data_size /* = 0 */)
+  : QAbstractScrollArea(parent)
+{
+  m_bytes_per_line = 16;
+
+  updateMetrics();
+
+  connect(verticalScrollBar(), &QScrollBar::valueChanged, this, &MemoryViewWidget::adjustContent);
+  connect(horizontalScrollBar(), &QScrollBar::valueChanged, this, &MemoryViewWidget::adjustContent);
+
+  if (data_ptr)
+    setData(address_offset, data_ptr, data_size);
+}
+
+MemoryViewWidget::~MemoryViewWidget() = default;
+
+int MemoryViewWidget::addressWidth() const
+{
+  return (8 * m_char_width) + m_char_width;
+}
+
+int MemoryViewWidget::hexWidth() const
+{
+  return (m_bytes_per_line * 4) * m_char_width;
+}
+
+int MemoryViewWidget::asciiWidth() const
+{
+  return (m_bytes_per_line * 2 + 1) * m_char_width;
+}
+
+void MemoryViewWidget::updateMetrics()
+{
+  m_char_width = fontMetrics().horizontalAdvance(QChar('0'));
+  m_char_height = fontMetrics().height();
+}
+
+void MemoryViewWidget::setData(size_t address_offset, const void* data_ptr, size_t data_size)
+{
+  m_data = data_ptr;
+  m_data_size = data_size;
+  m_address_offset = address_offset;
+  adjustContent();
+}
+
+void MemoryViewWidget::setHighlightRange(size_t start, size_t end)
+{
+  m_highlight_start = start;
+  m_highlight_end = end;
+  viewport()->update();
+}
+
+void MemoryViewWidget::clearHighlightRange()
+{
+  m_highlight_start = 0;
+  m_highlight_end = 0;
+  viewport()->update();
+}
+
+void MemoryViewWidget::scrolltoOffset(size_t offset)
+{
+  const unsigned row = static_cast<unsigned>(offset / m_bytes_per_line);
+  verticalScrollBar()->setSliderPosition(static_cast<int>(row));
+  horizontalScrollBar()->setSliderPosition(0);
+}
+
+void MemoryViewWidget::scrollToAddress(size_t address)
+{
+  const unsigned row = static_cast<unsigned>((address - m_start_offset) / m_bytes_per_line);
+  verticalScrollBar()->setSliderPosition(static_cast<int>(row));
+  horizontalScrollBar()->setSliderPosition(0);
+}
+
+void MemoryViewWidget::setFont(const QFont& font)
+{
+  QAbstractScrollArea::setFont(font);
+  updateMetrics();
+}
+
+void MemoryViewWidget::resizeEvent(QResizeEvent*)
+{
+  adjustContent();
+}
+
+template<typename T>
+static bool RangesOverlap(T x1, T x2, T y1, T y2)
+{
+  return (x2 >= y1 && x1 < y2);
+}
+
+void MemoryViewWidget::paintEvent(QPaintEvent*)
+{
+  QPainter painter(viewport());
+  painter.setFont(font());
+  if (!m_data)
+    return;
+
+  const QColor highlight_color(100, 100, 0);
+  const int offsetX = horizontalScrollBar()->value();
+
+  int y = m_char_height;
+  QString address;
+
+  painter.setPen(viewport()->palette().color(QPalette::WindowText));
+
+  y += m_char_height;
+
+  const unsigned num_rows = static_cast<unsigned>(m_end_offset - m_start_offset) / m_bytes_per_line;
+  for (unsigned row = 0; row <= num_rows; row++)
+  {
+    const size_t data_offset = m_start_offset + (row * m_bytes_per_line);
+    const unsigned row_address = static_cast<unsigned>(m_address_offset + data_offset);
+    const int draw_x = m_char_width / 2 - offsetX;
+    if (RangesOverlap(data_offset, data_offset + m_bytes_per_line, m_highlight_start, m_highlight_end))
+      painter.fillRect(0, y - m_char_height + 3, addressWidth(), m_char_height, highlight_color);
+
+    const QString address_text(QString::asprintf("%08X", row_address));
+    painter.drawText(draw_x, y, address_text);
+    y += m_char_height;
+  }
+
+  int x;
+  int lx = addressWidth();
+  painter.drawLine(lx - offsetX, 0, lx - offsetX, height());
+  y = m_char_height;
+
+  // hex data
+  const int HEX_CHAR_WIDTH = 4 * m_char_width;
+
+  x = lx - offsetX;
+  for (unsigned col = 0; col < m_bytes_per_line; col++)
+  {
+    if ((col % 2) != 0)
+      painter.fillRect(x, 0, HEX_CHAR_WIDTH, height(), viewport()->palette().color(QPalette::AlternateBase));
+
+    x += HEX_CHAR_WIDTH;
+  }
+
+  y = m_char_height;
+  x = lx - offsetX + m_char_width;
+  for (unsigned col = 0; col < m_bytes_per_line; col++)
+  {
+    painter.drawText(x, y, QString::asprintf("%02X", col));
+    x += HEX_CHAR_WIDTH;
+  }
+
+  painter.drawLine(0, y + 3, width(), y + 3);
+  y += m_char_height;
+
+  size_t offset = m_start_offset;
+  for (unsigned row = 0; row <= num_rows; row++)
+  {
+    x = lx - offsetX + m_char_width;
+    for (unsigned col = 0; col < m_bytes_per_line && offset < m_data_size; col++, offset++)
+    {
+      unsigned char value;
+      std::memcpy(&value, static_cast<const unsigned char*>(m_data) + offset, sizeof(value));
+      if (offset >= m_highlight_start && offset < m_highlight_end)
+        painter.fillRect(x - m_char_width, y - m_char_height + 3, HEX_CHAR_WIDTH, m_char_height, highlight_color);
+
+      painter.drawText(x, y, QString::asprintf("%02X", value));
+      x += HEX_CHAR_WIDTH;
+    }
+    y += m_char_height;
+  }
+
+  lx = addressWidth() + hexWidth();
+  painter.drawLine(lx - offsetX, 0, lx - offsetX, height());
+
+  lx += m_char_width;
+
+  y = m_char_height;
+  x = (lx - offsetX);
+  for (unsigned col = 0; col < m_bytes_per_line; col++)
+  {
+    const QChar ch = (col < 0xA) ? (static_cast<QChar>('0' + col)) : (static_cast<QChar>('A' + (col - 0xA)));
+    painter.drawText(x, y, ch);
+    x += 2 * m_char_width;
+  }
+
+  y += m_char_height;
+
+  offset = m_start_offset;
+  for (unsigned row = 0; row <= num_rows; row++)
+  {
+    x = lx - offsetX;
+    for (unsigned col = 0; col < m_bytes_per_line && offset < m_data_size; col++, offset++)
+    {
+      unsigned char value;
+      std::memcpy(&value, static_cast<const unsigned char*>(m_data) + offset, sizeof(value));
+      if (offset >= m_highlight_start && offset < m_highlight_end)
+        painter.fillRect(x, y - m_char_height + 3, 2 * m_char_width, m_char_height, highlight_color);
+
+      if (!std::isprint(value))
+        value = '.';
+      painter.drawText(x, y, static_cast<QChar>(value));
+      x += 2 * m_char_width;
+    }
+    y += m_char_height;
+  }
+}
+
+void MemoryViewWidget::adjustContent()
+{
+  if (!m_data)
+  {
+    setEnabled(false);
+    return;
+  }
+
+  setEnabled(true);
+
+  int w = addressWidth() + hexWidth() + asciiWidth();
+  horizontalScrollBar()->setRange(0, w - viewport()->width());
+  horizontalScrollBar()->setPageStep(viewport()->width());
+
+  m_rows_visible = viewport()->height() / m_char_height;
+  int val = verticalScrollBar()->value();
+  m_start_offset = (size_t)val * m_bytes_per_line;
+  m_end_offset = m_start_offset + m_rows_visible * m_bytes_per_line - 1;
+  if (m_end_offset >= m_data_size)
+    m_end_offset = m_data_size - 1;
+
+  const int lineCount = static_cast<int>(m_data_size / m_bytes_per_line);
+  verticalScrollBar()->setRange(0, lineCount - m_rows_visible);
+  verticalScrollBar()->setPageStep(m_rows_visible);
+
+  viewport()->update();
+}

src/duckstation-qt/memoryviewwidget.h

@@ -0,0 +1,53 @@
+#pragma once
+#include <QtWidgets/QAbstractScrollArea>
+
+// Based on https://stackoverflow.com/questions/46375673/how-can-realize-my-own-memory-viewer-by-qt
+
+class MemoryViewWidget : public QAbstractScrollArea
+{
+public:
+  Q_OBJECT
+public:
+  MemoryViewWidget(QWidget* parent = nullptr, size_t address_offset = 0, const void* data_ptr = nullptr,
+                   size_t data_size = 0);
+  ~MemoryViewWidget();
+
+  size_t addressOffset() const { return m_address_offset; }
+
+  void setData(size_t address_offset, const void* data_ptr, size_t data_size);
+  void setHighlightRange(size_t start, size_t end);
+  void clearHighlightRange();
+  void scrolltoOffset(size_t offset);
+  void scrollToAddress(size_t address);
+  void setFont(const QFont& font);
+
+protected:
+  void paintEvent(QPaintEvent*);
+  void resizeEvent(QResizeEvent*);
+
+private Q_SLOTS:
+  void adjustContent();
+
+private:
+  int addressWidth() const;
+  int hexWidth() const;
+  int asciiWidth() const;
+  void updateMetrics();
+
+  const void* m_data;
+  size_t m_data_size;
+  size_t m_address_offset;
+
+  size_t m_start_offset;
+  size_t m_end_offset;
+
+  size_t m_highlight_start = 0;
+  size_t m_highlight_end = 0;
+
+  unsigned m_bytes_per_line;
+
+  int m_char_width;
+  int m_char_height;
+
+  int m_rows_visible;
+};

src/duckstation-qt/qthostinterface.cpp

@@ -821,11 +821,13 @@ void QtHostInterface::resetSystem()
   HostInterface::ResetSystem();
 }
 
-void QtHostInterface::pauseSystem(bool paused)
+void QtHostInterface::pauseSystem(bool paused, bool wait_until_paused /* = false */)
 {
   if (!isOnWorkerThread())
   {
-    QMetaObject::invokeMethod(this, "pauseSystem", Qt::QueuedConnection, Q_ARG(bool, paused));
+    QMetaObject::invokeMethod(this, "pauseSystem",
+                              wait_until_paused ? Qt::BlockingQueuedConnection : Qt::QueuedConnection,
+                              Q_ARG(bool, paused), Q_ARG(bool, wait_until_paused));
     return;
   }
 
@@ -1222,6 +1224,21 @@ void QtHostInterface::stopDumpingAudio()
   StopDumpingAudio();
 }
 
+void QtHostInterface::singleStepCPU()
+{
+  if (!isOnWorkerThread())
+  {
+    QMetaObject::invokeMethod(this, "singleStepCPU", Qt::BlockingQueuedConnection);
+    return;
+  }
+
+  if (!System::IsValid())
+    return;
+
+  System::SingleStepCPU();
+  renderDisplay();
+}
+
 void QtHostInterface::dumpRAM(const QString& filename)
 {
   if (!isOnWorkerThread())

src/duckstation-qt/qthostinterface.h

@@ -155,7 +155,7 @@ public Q_SLOTS:
   void powerOffSystem();
   void synchronousPowerOffSystem();
   void resetSystem();
-  void pauseSystem(bool paused);
+  void pauseSystem(bool paused, bool wait_until_paused = false);
   void changeDisc(const QString& new_disc_filename);
   void changeDiscFromPlaylist(quint32 index);
   void loadState(const QString& filename);
@@ -165,6 +165,7 @@ public Q_SLOTS:
   void setAudioOutputMuted(bool muted);
   void startDumpingAudio();
   void stopDumpingAudio();
+  void singleStepCPU();
   void dumpRAM(const QString& filename);
   void saveScreenshot();
   void redrawDisplayWindow();

src/duckstation-qt/resources/resources.qrc

@@ -24,6 +24,17 @@
     <file>icons/conical-flask-red.png</file>
     <file>icons/conical-flask-red@2x.png</file>
     <file>icons/cover-placeholder.png</file>
+    <file>icons/debug-execute-from-cursor.png</file>
+    <file>icons/debug-execute-to-cursor.png</file>
+    <file>icons/debug-run-cursor.png</file>
+    <file>icons/debug-run.png</file>
+    <file>icons/debug-pc.png</file>
+    <file>icons/debug-pc@2x.png</file>
+    <file>icons/debug-step-instruction.png</file>
+    <file>icons/debug-step-into-instruction.png</file>
+    <file>icons/debug-step-into.png</file>
+    <file>icons/debug-step-out.png</file>
+    <file>icons/debug-step-over.png</file>
     <file>icons/document-open.png</file>
     <file>icons/document-open@2x.png</file>
     <file>icons/document-save.png</file>