added backup of cartridge do be used with reload

src/views/game_view.cpp

@@ -81,9 +81,10 @@ void GameView::render()
     retro8::io::Loader loader;
 
     if (_path.empty())
-      _path = "cartridges/lands-of-yocta.png";
+      _path = "cartridges/pico-racer.png";
 
     loader.load(_path, machine);
+    machine.memory().backupCartridge();
 
     int32_t fps = machine.code().require60fps() ? 60 : 30;
     manager->setFrameRate(fps);

src/vm/lua_bridge.cpp

@@ -784,6 +784,18 @@ namespace platform
     return 0;
   }
 
+  int reload(lua_State* L)
+  {
+    assert(lua_gettop(L) <= 3);
+    
+    address_t dest = lua_to_or_default(L, number, 1, 0);
+    address_t src = lua_to_or_default(L, number, 1, 0);
+    int32_t length = lua_to_or_default(L, number, 1, address::CART_DATA_LENGTH);
+    
+    std::memcpy(machine.memory().base() + dest, machine.memory().backup() + src, length);
+
+    return 0;
+  }
 
   int btn(lua_State* L)
   {
@@ -971,6 +983,7 @@ void lua::registerFunctions(lua_State* L)
   lua_register(L, "peek", platform::peek);
   lua_register(L, "memset", platform::memset);
   lua_register(L, "memcpy", platform::memcpy);
+  lua_register(L, "reload", platform::reload);
 
   lua_register(L, "flip", platform::flip);
 }

src/vm/memory.h

@@ -31,11 +31,14 @@ namespace retro8
 
     static constexpr address_t TILE_MAP_LOW = 0x1000;
     static constexpr address_t TILE_MAP_HIGH = 0x2000;
+    
+    static constexpr int32_t CART_DATA_LENGTH = 0x4300;
   };
 
   class Memory
   {
   private:
+    uint8_t _backup[address::CART_DATA_LENGTH];
     uint8_t memory[1024 * 32];
 
     static constexpr size_t BYTES_PER_PALETTE = sizeof(retro8::gfx::palette_t);
@@ -54,6 +57,12 @@ namespace retro8
       cursor()->reset();
     }
 
+    void backupCartridge()
+    {
+      std::memcpy(_backup, memory, address::CART_DATA_LENGTH);
+    }
+
+    const uint8_t* backup() const { return _backup; }
     uint8_t* base() { return memory; }
 
     gfx::color_byte_t* penColor() { return as<gfx::color_byte_t>(address::PEN_COLOR); }