SIO: Add debugging option to redirect to TTY

Until I bother to finish my sio branch...

src/core/bus.cpp

@@ -953,7 +953,7 @@ void Bus::AddTTYCharacter(char ch)
     }
     s_tty_line_buffer.clear();
   }
-  else
+  else if (ch != '\0')
   {
     s_tty_line_buffer += ch;
   }

src/core/settings.cpp

@@ -510,6 +510,7 @@ void Settings::Load(const SettingsInterface& si, const SettingsInterface& contro
   pio_flash_image_path = si.GetStringValue("PIO", "FlashImagePath");
   pio_flash_write_enable = si.GetBoolValue("PIO", "FlashImageWriteEnable", false);
   pio_switch_active = si.GetBoolValue("PIO", "SwitchActive", true);
+  sio_redirect_to_tty = si.GetBoolValue("SIO", "RedirectToTTY", false);
 
   pcdrv_enable = si.GetBoolValue("PCDrv", "Enabled", false);
   pcdrv_enable_writes = si.GetBoolValue("PCDrv", "EnableWrites", false);
@@ -797,6 +798,7 @@ void Settings::Save(SettingsInterface& si, bool ignore_base) const
   si.SetStringValue("PIO", "FlashImagePath", pio_flash_image_path.c_str());
   si.SetBoolValue("PIO", "FlashImageWriteEnable", pio_flash_write_enable);
   si.SetBoolValue("PIO", "SwitchActive", pio_switch_active);
+  si.SetBoolValue("SIO", "RedirectToTTY", sio_redirect_to_tty);
 
   si.SetBoolValue("PCDrv", "Enabled", pcdrv_enable);
   si.SetBoolValue("PCDrv", "EnableWrites", pcdrv_enable_writes);

src/core/settings.h

@@ -340,6 +340,7 @@ struct Settings : public GPUSettings
   bool memory_card_fast_forward_access : 1 = false;
   bool pio_switch_active : 1 = true;
   bool pio_flash_write_enable : 1 = false;
+  bool sio_redirect_to_tty : 1 = false;
   bool pcdrv_enable_writes : 1 = false;
 
   // achievements

src/core/sio.cpp

@@ -1,7 +1,8 @@
-// SPDX-FileCopyrightText: 2019-2024 Connor McLaughlin <stenzek@gmail.com>
+// SPDX-FileCopyrightText: 2019-2025 Connor McLaughlin <stenzek@gmail.com>
 // SPDX-License-Identifier: CC-BY-NC-ND-4.0
 
 #include "sio.h"
+#include "bus.h"
 #include "controller.h"
 
 #include "util/state_wrapper.h"
@@ -137,7 +138,11 @@ void SIO::WriteRegister(u32 offset, u32 value)
   {
     case 0x00: // SIO_DATA
     {
-      WARNING_LOG("SIO_DATA (W) <- 0x{:02X}", value);
+      if (g_settings.sio_redirect_to_tty)
+        Bus::AddTTYCharacter(static_cast<char>(value));
+      else
+        WARNING_LOG("SIO_DATA (W) <- 0x{:02X}", value);
+
       return;
     }
 

src/duckstation-qt/advancedsettingswidget.cpp

@@ -317,6 +317,7 @@ void AdvancedSettingsWidget::addTweakOptions()
 
   addBooleanTweakOption(m_dialog, m_ui.tweakOptionTable, tr("Export Shared Memory"), "Hacks", "ExportSharedMemory",
                         false);
+  addBooleanTweakOption(m_dialog, m_ui.tweakOptionTable, tr("Redirect SIO to TTY"), "SIO", "RedirectToTTY", false);
   addBooleanTweakOption(m_dialog, m_ui.tweakOptionTable, tr("Enable PCDrv"), "PCDrv", "Enabled", false);
   addBooleanTweakOption(m_dialog, m_ui.tweakOptionTable, tr("Enable PCDrv Writes"), "PCDrv", "EnableWrites", false);
   addDirectoryOption(m_dialog, m_ui.tweakOptionTable, tr("PCDrv Root Directory"), "PCDrv", "Root");
@@ -360,6 +361,7 @@ void AdvancedSettingsWidget::onResetToDefaultClicked()
     setBooleanTweakOption(m_ui.tweakOptionTable, i++, false);                // Enable GDB Server
     setIntRangeTweakOption(m_ui.tweakOptionTable, i++, Settings::DEFAULT_GDB_SERVER_PORT); // GDB Server Port
     setBooleanTweakOption(m_ui.tweakOptionTable, i++, false);                              // Export Shared Memory
+    setBooleanTweakOption(m_ui.tweakOptionTable, i++, false);                              // Redirect SIO to TTY
     setBooleanTweakOption(m_ui.tweakOptionTable, i++, false);                              // Enable PCDRV
     setBooleanTweakOption(m_ui.tweakOptionTable, i++, false);                              // Enable PCDRV Writes
     setDirectoryOption(m_ui.tweakOptionTable, i++, "");                                    // PCDrv Root Directory