Improve handling of dangling RAM using status heartbeat

Author: aglab2

Hacktice/Canary.cs

@@ -17,5 +17,6 @@ internal class Canary
         public const uint HackticeStatusActive = 0x41435456; // ACTV
         public const uint HackticeStatusDisabled = 0x4453424c; // DSBL
         public const uint HackticeStatusUpgrading = 0x55504752; // UPGR
+        public const uint HackticeStatusHeartbeat = 0x48524254; // HRBT
     }
 }

Hacktice/Emulator.cs

@@ -28,6 +28,7 @@ Hacktice header has 20 bytes in size and consists of
          */
         const int HackticeHeaderSize = 20;
         private IntPtr? _ptrHackticeHeader;
+        private IntPtr? _ptrHackticeStatus;
         private byte[] _hackticeHeader = new byte[HackticeHeaderSize];
         private byte[] _ram; // just a cache
 
@@ -297,6 +298,7 @@ public bool RefreshHacktice()
                     return true;
 
                 _ptrHackticeHeader = null;
+                _ptrHackticeStatus = null;
             }
 
             if (!(_ram is object))
@@ -309,6 +311,7 @@ public bool RefreshHacktice()
             {
                 // attempt all locations and find if any is reasonable
                 _ptrHackticeHeader = new IntPtr((long)(_ramPtrBase + (ulong)location));
+                _ptrHackticeStatus = new IntPtr((long)(_ramPtrBase + (ulong)location + 8));
                 if (RefreshHackticeHeaderAndCheckIfValid())
                     return true;
             }
@@ -438,5 +441,10 @@ public void FixSapphireTimer()
             _process.WriteBytes(new IntPtr((long)(_ramPtrBase + 0x2E3A4C)), new byte[] { 0xf9, 0x00 });
             _process.WriteBytes(new IntPtr((long)(_ramPtrBase + 0x2E3A34)), new byte[] { 0xe5, 0x00 });
         }
+
+        public void WriteStatus(uint status)
+        {
+            _process.WriteBytes(_ptrHackticeStatus.Value, BitConverter.GetBytes(status));
+        }
     }
 }

Hacktice/Tool.cs

@@ -26,6 +26,8 @@ enum State
         };
 
         const string SapphireEEPROMName = "SM64 Sapphire";
+        const int MaxBeatsToCheck = 200;
+        const int HeartbeatLeaveaway = 10;
 
         readonly System.Threading.Timer _timer;
 
@@ -34,10 +36,11 @@ enum State
         readonly Emulator _emulator = new Emulator();
         readonly Version _payloadVersion;
         Config _lastSeenEmulatorConfig = new Config();
+        int _heartbeatActive = 0;
         private State EmulatorState
         {
             get { return _stateValue; }
-            set { var oldValue = _stateValue; _stateValue = value; if (oldValue != _stateValue) { UpdateEmulatorState(); } }
+            set { var oldValue = _stateValue; _stateValue = value; if (oldValue != _stateValue) { _heartbeatActive = 0; UpdateEmulatorState(); } }
         }
 
         // Used from UI thread to avoid event loops
@@ -318,30 +321,44 @@ private void PrepareHacktice()
                 if (!_emulator.RefreshHacktice())
                     return;
 
-                newState = State.HACKTICE_CORRUPTED;
+                if (_heartbeatActive >= 0)
                 {
-                    int status = _emulator.HackticeStatus;
-                    if (status == Canary.HackticeStatusInit)
+                    newState = State.HACKTICE_CORRUPTED;
                     {
-                        newState = State.HACKTICE_INJECTED;
-                        return;
-                    }
-                    if (status == Canary.HackticeStatusActive)
-                    {
-                        newState = _emulator.HackticeVersion == _payloadVersion ? State.HACKTICE_RUNNING : State.HACKTICE_RUNNING_CAN_UPGRADE;
-                        return;
-                    }
-                    if (status == Canary.HackticeStatusDisabled)
-                    {
-                        newState = State.HACKTICE_UPGRADE_DISABLED;
-                        return;
-                    }
-                    if (status == Canary.HackticeStatusUpgrading)
-                    {
-                        newState = State.HACKTICE_UPGRADE_DATA_WRITTEN;
-                        return;
+                        int status = _emulator.HackticeStatus;
+                        if (status == Canary.HackticeStatusInit)
+                        {
+                            newState = State.HACKTICE_INJECTED;
+                            return;
+                        }
+                        if (status == Canary.HackticeStatusHeartbeat)
+                        {
+                            newState = State.ROM;
+                            return;
+                        }
+                        if (status == Canary.HackticeStatusActive)
+                        {
+                            newState = _emulator.HackticeVersion == _payloadVersion ? State.HACKTICE_RUNNING : State.HACKTICE_RUNNING_CAN_UPGRADE;
+                            return;
+                        }
+                        if (status == Canary.HackticeStatusDisabled)
+                        {
+                            newState = State.HACKTICE_UPGRADE_DISABLED;
+                            return;
+                        }
+                        if (status == Canary.HackticeStatusUpgrading)
+                        {
+                            newState = State.HACKTICE_UPGRADE_DATA_WRITTEN;
+                            return;
+                        }
                     }
                 }
+                else
+                {
+                    // there is a bit of leaveaway before we start complaining that hacktice does not run
+                    newState = State.HACKTICE_RUNNING;
+                    return;
+                }
             }
             finally
             {
@@ -407,6 +424,13 @@ private void EmulatorStateUpdate(object state)
 
                 if (EmulatorState >= State.HACKTICE_RUNNING)
                 {
+                    _heartbeatActive++;
+                    if (_heartbeatActive >= MaxBeatsToCheck) 
+                    {
+                        _emulator.WriteStatus(Canary.HackticeStatusHeartbeat);
+                        _heartbeatActive = -HeartbeatLeaveaway;
+                    }
+
                     var userUpdatedConfig = NeedToUpdateConfig;
 
                     // TODO: This logic gets complicated, separate this away