Forward and back navigation in disasm view (#529)

implements browser style back/forward navigation in the disassembly view, accessible via Alt+Left/Alt+Right and mouse back/forward buttons.

Author: Sightem

gui/qt/debugger.cpp

@@ -110,6 +110,9 @@ void MainWindow::debugStep(int mode) {
     } else {
         disasm.base = static_cast<int32_t>(cpu.registers.PC);
         disasmGet(true);
+
+        m_stepCtx.active = true;
+        m_stepCtx.seqNext = static_cast<uint32_t>(disasm.next);
         debug_step(mode, static_cast<uint32_t>(disasm.next));
     }
     emu.resume();
@@ -392,6 +395,7 @@ void MainWindow::debugCommand(int reason, uint32_t data) {
 
     if (reason == DBG_READY) {
         guiReset = false;
+        navDisasmClear();
         emu.resume();
         return;
     }
@@ -850,6 +854,17 @@ void MainWindow::debugPopulate() {
     osUpdate();
     stackUpdate();
     disasmUpdateAddr(m_prevDisasmAddr = cpu.registers.PC, true);
+    // Track step navigation: append on control-flow (branch taken),
+    // replace on linear advance. Non-step stops do not modify history
+    if (m_stepCtx.active) {
+        bool tookBranch = (static_cast<uint32_t>(cpu.registers.PC) != m_stepCtx.seqNext);
+        if (tookBranch) {
+            navDisasmPush(m_prevDisasmAddr, true);
+        } else {
+            navDisasmReplace(m_prevDisasmAddr, true);
+        }
+        m_stepCtx.active = false;
+    }
 
     memUpdate();
 
@@ -1964,6 +1979,98 @@ void MainWindow::disasmUpdateAddr(int base, bool pane) {
     connect(m_disasm->verticalScrollBar(), &QScrollBar::valueChanged, this, &MainWindow::disasmScroll);
 }
 
+// ------------------------------------------------
+// Disassembly navigation history helpers
+// ------------------------------------------------
+
+uint32_t MainWindow::currentDisasmAddress() const {
+    if (m_prevDisasmAddr) {
+        return m_prevDisasmAddr;
+    }
+    QString sel = m_disasm ? m_disasm->getSelectedAddr() : QString();
+    if (!sel.isEmpty()) {
+        return static_cast<uint32_t>(hex2int(sel));
+    }
+    return cpu.registers.PC;
+}
+
+void MainWindow::navDisasmEnsureSeeded() {
+    if (m_disasmNavIndex == -1) {
+        m_disasmNav.reserve(kMaxDisasmHistory);
+        // seed with the last PC location and current pane mode so that fully backing out returns to the same stop context
+        m_disasmNav.push_back({ currentDisasmAddress(), m_disasmPane });
+        m_disasmNavIndex = 0;
+    }
+}
+
+void MainWindow::navDisasmPush(uint32_t addr, bool pane) {
+    if (m_isApplyingDisasmNav) {
+        disasmUpdateAddr(static_cast<int>(addr), pane);
+        return;
+    }
+    if (m_disasmNavIndex >= 0 && m_disasmNavIndex < m_disasmNav.size()) {
+        const DisasmNavEntry &cur = m_disasmNav[m_disasmNavIndex];
+        if (cur.addr == addr && cur.pane == pane) {
+            disasmUpdateAddr(static_cast<int>(addr), pane);
+            return;
+        }
+    }
+    if (m_disasmNavIndex + 1 < m_disasmNav.size()) {
+        m_disasmNav.resize(m_disasmNavIndex + 1);
+    }
+    if (m_disasmNav.size() >= kMaxDisasmHistory) {
+        m_disasmNav.remove(0);
+        if (m_disasmNavIndex > 0) { --m_disasmNavIndex; }
+    }
+    m_disasmNav.push_back({addr, pane});
+    m_disasmNavIndex = m_disasmNav.size() - 1;
+    m_isApplyingDisasmNav = true;
+    disasmUpdateAddr(static_cast<int>(addr), pane);
+    m_isApplyingDisasmNav = false;
+}
+
+void MainWindow::navDisasmReplace(uint32_t addr, bool pane) {
+    if (m_isApplyingDisasmNav) {
+        return;
+    }
+    navDisasmEnsureSeeded();
+    if (m_disasmNavIndex < 0) {
+        m_disasmNav.push_back({addr, pane});
+        m_disasmNavIndex = m_disasmNav.size() - 1;
+    } else {
+        m_disasmNav[m_disasmNavIndex] = {addr, pane};
+    }
+}
+
+bool MainWindow::navDisasmBack() {
+    if (m_disasmNavIndex > 0) {
+        --m_disasmNavIndex;
+        const auto &e = m_disasmNav[m_disasmNavIndex];
+        m_isApplyingDisasmNav = true;
+        disasmUpdateAddr(static_cast<int>(e.addr), e.pane);
+        m_isApplyingDisasmNav = false;
+        return true;
+    }
+    return false;
+}
+
+bool MainWindow::navDisasmForward() {
+    if (m_disasmNavIndex >= 0 && m_disasmNavIndex + 1 < m_disasmNav.size()) {
+        ++m_disasmNavIndex;
+        const auto &e = m_disasmNav[m_disasmNavIndex];
+        m_isApplyingDisasmNav = true;
+        disasmUpdateAddr(static_cast<int>(e.addr), e.pane);
+        m_isApplyingDisasmNav = false;
+        return true;
+    }
+    return false;
+}
+
+void MainWindow::navDisasmClear() {
+    m_disasmNav.clear();
+    m_disasmNavIndex = -1;
+}
+
 // ------------------------------------------------
 // Misc
 // ------------------------------------------------
@@ -1993,7 +2100,8 @@ void MainWindow::gotoPressed() {
 }
 
 void MainWindow::gotoDisasmAddr(uint32_t address) {
-    disasmUpdateAddr(address, false);
+    navDisasmEnsureSeeded();
+    navDisasmPush(address, false);
     raiseContainingDock(ui->disasm);
     ui->disasm->setFocus();
 }
@@ -2111,6 +2219,16 @@ bool MainWindow::eventFilter(QObject *obj, QEvent *e) {
         return QMainWindow::eventFilter(obj, e);
     }
 
+    // Mouse back/forward in Disassembly view
+    if (obj == m_disasm && e->type() == QEvent::MouseButtonPress) {
+        auto *me = static_cast<QMouseEvent*>(e);
+        if (me->button() == Qt::BackButton) {
+            if (navDisasmBack()) { e->accept(); return true; }
+        } else if (me->button() == Qt::ForwardButton) {
+            if (navDisasmForward()) { e->accept(); return true; }
+        }
+    }
+
     if (e->type() == QEvent::MouseButtonPress) {
         QString name = obj->objectName();
 

gui/qt/mainwindow.cpp

@@ -97,6 +97,7 @@ MainWindow::MainWindow(CEmuOpts &cliOpts, QWidget *p) : QMainWindow(p), ui(new U
     m_breakpoints = ui->breakpoints;
     m_ports = ui->ports;
     m_disasm = ui->disasm;
+    m_disasm->installEventFilter(this);
 
     ui->console->setMaximumBlockCount(1000);
 
@@ -518,6 +519,11 @@ MainWindow::MainWindow(CEmuOpts &cliOpts, QWidget *p) : QMainWindow(p), ui(new U
     m_shortcutStepOver = new QShortcut(QKeySequence(Qt::Key_F7), this);
     m_shortcutStepNext = new QShortcut(QKeySequence(Qt::Key_F8), this);
     m_shortcutStepOut = new QShortcut(QKeySequence(Qt::Key_F9), this);
+    m_shortcutNavBack = new QShortcut(QKeySequence(Qt::ALT | Qt::Key_Left), this);
+    m_shortcutNavForward = new QShortcut(QKeySequence(Qt::ALT | Qt::Key_Right), this);
+
+    connect(m_shortcutNavBack, &QShortcut::activated, this, [this]{ navDisasmBack(); });
+    connect(m_shortcutNavForward, &QShortcut::activated, this, [this]{ navDisasmForward(); });
     m_shortcutDebug = new QShortcut(QKeySequence(Qt::Key_F10), this);
     m_shortcutFullscreen = new QShortcut(QKeySequence(Qt::Key_F11), this);
     m_shortcutAsm = new QShortcut(QKeySequence(Qt::Key_Pause), this);
@@ -2695,6 +2701,11 @@ void MainWindow::contextDisasm(const QPoint &posa) {
     uint32_t addr = static_cast<uint32_t>(hex2int(addrStr));
 
     QMenu menu;
+    QAction *backAct = menu.addAction(tr("Back"));
+    QAction *fwdAct = menu.addAction(tr("Forward"));
+    backAct->setEnabled(m_disasmNavIndex > 0);
+    fwdAct->setEnabled(m_disasmNavIndex >= 0 && m_disasmNavIndex + 1 < m_disasmNav.size());
+    menu.addSeparator();
     QAction *runUntil = menu.addAction(ACTION_RUN_UNTIL);
     menu.addSeparator();
     QAction *toggleBreak = menu.addAction(ACTION_TOGGLE_BREAK);
@@ -2706,7 +2717,11 @@ void MainWindow::contextDisasm(const QPoint &posa) {
     QAction *setPc = menu.addAction(tr("Set PC"));
 
     QAction *item = menu.exec(globalPos);
-    if (item == setPc) {
+    if (item == backAct) {
+        navDisasmBack();
+    } else if (item == fwdAct) {
+        navDisasmForward();
+    } else if (item == setPc) {
         ui->pcregView->setText(addrStr);
         debug_set_pc(addr);
         disasmUpdateAddr(static_cast<int>(cpu.registers.PC), true);

gui/qt/mainwindow.h

@@ -706,6 +706,8 @@ private slots:
     QShortcut *m_shortcutStepOver;
     QShortcut *m_shortcutStepNext;
     QShortcut *m_shortcutStepOut;
+    QShortcut *m_shortcutNavBack;
+    QShortcut *m_shortcutNavForward;
     QShortcut *m_shortcutDebug;
     QShortcut *m_shortcutFullscreen;
     QShortcut *m_shortcutAsm;
@@ -937,6 +939,29 @@ private slots:
     QTableWidget *m_ports = nullptr;
     DataWidget *m_disasm = nullptr;
 
+    struct DisasmNavEntry {
+        uint32_t addr;
+        bool pane;
+    };
+
+    QVector<DisasmNavEntry> m_disasmNav;
+    int m_disasmNavIndex = -1;
+    bool m_isApplyingDisasmNav = false;
+    static constexpr int kMaxDisasmHistory = 200;
+
+    [[nodiscard]] uint32_t currentDisasmAddress() const;
+    void navDisasmEnsureSeeded();
+    void navDisasmPush(uint32_t addr, bool pane);
+    void navDisasmReplace(uint32_t addr, bool pane);
+    bool navDisasmBack();
+    bool navDisasmForward();
+    void navDisasmClear();
+
+    struct StepNavCtx {
+        bool active = false;
+        uint32_t seqNext = 0; // sequential next PC at step start
+    } m_stepCtx;
+
 #ifdef LIBUSB_SUPPORT
     libusb_context *m_usbContext = nullptr;
     libusb_hotplug_callback_handle m_usbHotplugCallbackHandle{};