Added SRAM save game functionality

Core/Memory/SmsMemoryBus.cs

@@ -23,6 +23,7 @@ namespace Core.Memory
 
         // A flag to handle cartridges that don't use paging (like early 32KB games)
         private bool _isCartridgeLoaded = false;
+        public bool SramUsed { get; private set; } = false;
 
         public void LoadCartridge(byte[] romData)
         {
@@ -57,7 +58,7 @@ namespace Core.Memory
                 if ((_mapperControl & 0x08) != 0)
                 {
                     int ramBank = (_mapperControl & 0x04) != 0 ? 1 : 0;
-                    int ramOffset = (ramBank * 0x4000) + (address & 0x3FFF);
+                    int ramOffset = (ramBank * 0x4000) + (address & 0x1FFF);
                     return _cartridgeRam[ramOffset];
                 }
 
@@ -139,8 +140,9 @@ namespace Core.Memory
                 // Bypass the lock if they are trying to save their game!
                 if (address >= 0x8000 && (_mapperControl & 0x08) != 0)
                 {
+                    SramUsed = true;
                     int ramBank = (_mapperControl & 0x04) != 0 ? 1 : 0;
-                    int ramOffset = (ramBank * 0x4000) + (address & 0x3FFF);
+                    int ramOffset = (ramBank * 0x4000) + (address & 0x1FFF);
                     _cartridgeRam[ramOffset] = value;
                     return;
                 }
@@ -196,11 +198,37 @@ namespace Core.Memory
 
             return _cartridgeRom[absoluteAddress];
         }
+        public void LoadSaveData(string filePath)
+        {
+            if (System.IO.File.Exists(filePath))
+            {
+                byte[] saveData = System.IO.File.ReadAllBytes(filePath);
+                Array.Copy(saveData, _cartridgeRam, Math.Min(saveData.Length, _cartridgeRam.Length));
+                SramUsed = true; // We loaded a save, so it's active!
+            }
+            else
+            {
+                for (int i = 0; i < _cartridgeRam.Length; i++)
+                {
+                    _cartridgeRam[i] = 0xFF;
+                }
+                SramUsed = false;
+            }
+        }
+
+        public void SaveSaveData(string filePath)
+        {
+            // Only write a file to the hard drive if the game actually used the Save RAM!
+            if (SramUsed)
+            {
+                System.IO.File.WriteAllBytes(filePath, _cartridgeRam);
+            }
+        }
 
         public void CleanRAMData()
         {
             Array.Clear(_workRam, 0, _workRam.Length);
-            Array.Clear(_cartridgeRam, 0, _cartridgeRam.Length);
+            _mapperControl = 0;
         }
     }
 }

Desktop/Form1.cs

@@ -22,6 +22,7 @@ namespace Desktop
         public double FrameTime { get; private set; } = 0;
         public double FramesPerSecond { get; private set; } = 0;
         private string _currentRomName = "No ROM";
+        private string _currentRomPath = "";
         private Stopwatch _stopwatch = new System.Diagnostics.Stopwatch();
         public bool IsRunning { get; private set; } = false;
 
@@ -181,7 +182,6 @@ namespace Desktop
         {
             IsRunning = false;
         }
-
         private async void LoadRomAndStart(string filePath)
         {
             StopEmulator();
@@ -190,20 +190,59 @@ namespace Desktop
                 await _emulatorTask;
             }
 
+            // 1. SAVE THE PREVIOUS GAME!
+            SaveCurrentSram();
+
             // 2. Load the file
             byte[] rom = File.ReadAllBytes(filePath);
 
             // 3. Jam it into the Sega Mapper
             _machine.LoadCartridge(rom);
 
+            // 4. Update the path tracking
+            _currentRomPath = filePath;
             _currentRomName = Path.GetFileNameWithoutExtension(filePath);
             this.Text = $"Parsons Master System - {_currentRomName}";
 
-            // 5. Turn the power on!
+            // 5. LOAD THE NEW SAVE DATA!
+            string savPath = Path.ChangeExtension(_currentRomPath, ".sav");
+            _machine.MemoryBus.LoadSaveData(savPath);
 
+            // 6. Turn the power on!
             StartEmulator();
         }
 
+        //private async void LoadRomAndStart(string filePath)
+        //{
+        //    StopEmulator();
+        //    if (_emulatorTask != null)
+        //    {
+        //        await _emulatorTask;
+        //    }
+
+        //    // 2. Load the file
+        //    byte[] rom = File.ReadAllBytes(filePath);
+
+        //    // 3. Jam it into the Sega Mapper
+        //    _machine.LoadCartridge(rom);
+
+        //    _currentRomName = Path.GetFileNameWithoutExtension(filePath);
+        //    this.Text = $"Parsons Master System - {_currentRomName}";
+
+        //    // 5. Turn the power on!
+
+        //    StartEmulator();
+        //}
+        private void SaveCurrentSram()
+        {
+            if (!string.IsNullOrEmpty(_currentRomPath) && _machine != null)
+            {
+                // Swaps ".sms" for ".sav"
+                string savPath = Path.ChangeExtension(_currentRomPath, ".sav");
+                _machine.MemoryBus.SaveSaveData(savPath);
+            }
+        }
+
         private void PopulateIncludedRomsMenu()
         {
             // The folder you used for Golden Axe Warrior
@@ -264,7 +303,7 @@ namespace Desktop
 
         private void exitToolStripMenuItem_Click(object sender, EventArgs e)
         {
-            Environment.Exit(0);
+           this.Close();
         }
 
         private void Form1_KeyDown(object sender, KeyEventArgs e)
@@ -308,6 +347,7 @@ namespace Desktop
         private void ParsonsForm1_FormClosing(object sender, FormClosingEventArgs e)
         {
             IsRunning = false;
+            SaveCurrentSram();
             _audioPlayer?.Stop();
         }
     }