Move detection of MVC file out of FSNode class. There are several reasons for this:

- It more properly belongs in the class actually opening the ROM, since FSNode can represent more than just ROM files.
 - Some ports don't have proper FSNode support, so MVC would break there.
 - In general, it makes FSNode::read more general, able to read partial files.

src/common/FSNodeZIP.cxx

@@ -180,7 +180,7 @@ bool FilesystemNodeZIP::getChildren(AbstractFSList& myList, ListMode mode) const
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-size_t FilesystemNodeZIP::read(ByteBuffer& image) const
+size_t FilesystemNodeZIP::read(ByteBuffer& image, size_t) const
 {
   switch(_error)
   {
@@ -205,7 +205,7 @@ size_t FilesystemNodeZIP::read(stringstream& image) const
   // For now, we just read into a buffer and store in the stream
   // TODO: maybe there's a more efficient way to do this?
   ByteBuffer buffer;
-  size_t size = read(buffer);
+  size_t size = read(buffer, 0);
   if(size > 0)
     image.write(reinterpret_cast<char*>(buffer.get()), size);
 

src/common/FSNodeZIP.hxx

@@ -62,8 +62,8 @@ class FilesystemNodeZIP : public AbstractFSNode
     bool getChildren(AbstractFSList& list, ListMode mode) const override;
     AbstractFSNodePtr getParent() const override;
 
-    size_t read(ByteBuffer& image) const override;
-    size_t read(stringstream& image) const override;
+    size_t read(ByteBuffer& buffer, size_t size) const override;
+    size_t read(stringstream& buffer) const override;
     size_t write(const ByteBuffer& buffer, size_t size) const override;
     size_t write(const stringstream& buffer) const override;
 

src/emucore/Bankswitch.hxx

@@ -45,7 +45,7 @@ class Bankswitch
       _DPCP,  _E0,     _E7,    _E78K,  _EF,    _EFSC,  _F0,
       _F4,    _F4SC,   _F6,    _F6SC,  _F8,    _F8SC,  _FA,
       _FA2,   _FC,     _FE,    _MDM,   _MVC,   _SB,    _TVBOY,
-	  _UA,    _UASW,  _WD,     _WDSW,  _X07,
+      _UA,    _UASW,   _WD,    _WDSW,  _X07,
     #ifdef CUSTOM_ARM
       _CUSTOM,
     #endif

src/emucore/CartDetector.cxx

@@ -697,31 +697,31 @@ bool CartDetector::isProbablyMVC(const ByteBuffer& image, size_t size)
 {
   // MVC version 0
   uInt8 sig[] = { 'M', 'V', 'C', 0 };
-  int	sigSize = sizeof(sig);
+  int sigSize = sizeof(sig);
   return searchForBytes(image, std::min<size_t>(size, sigSize+1), sig, sigSize);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-size_t CartDetector::isProbablyMVC(std::istream &in, size_t maxSize)
+size_t CartDetector::isProbablyMVC(const FilesystemNode& rom)
 {
-  const size_t	frameSize = 2 * CartridgeMVC::MVC_FIELD_PAD_SIZE;
-  bool			found = false;
+  constexpr size_t frameSize = 2 * CartridgeMVC::MVC_FIELD_PAD_SIZE;
 
-  // Returns size of field if stream is probably an MVC movie cartridge
+  if(Bankswitch::typeFromExtension(rom) == Bankswitch::Type::_MVC)
+    return frameSize;
 
-  if (maxSize >= frameSize)
+  Serializer s(rom.getPath(), Serializer::Mode::ReadOnly);
+  if(s)
   {
-	auto	pos = in.tellg();
+    if(s.size() < frameSize)
+      return 0;
 
-	ByteBuffer	image = make_unique<uInt8[]>(frameSize);
-	in.read(reinterpret_cast<char*>(image.get()), frameSize);
+    uInt8 image[frameSize];
+    s.getByteArray(image, frameSize);
 
-	in.seekg(pos);
-
-	found = isProbablyMVC(image, frameSize);
+    uInt8 sig[] = { 'M', 'V', 'C', 0 };  // MVC version 0
+    return searchForBytes(image, frameSize, sig, 4) ? frameSize : 0;
   }
-
-  return found ? frameSize : 0;
+  return 0;
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

src/emucore/CartDetector.hxx

@@ -19,6 +19,7 @@
 #define CARTRIDGE_DETECTOR_HXX
 
 #include "Bankswitch.hxx"
+#include "FSNode.hxx"
 #include "bspf.hxx"
 
 /**
@@ -40,12 +41,11 @@ class CartDetector
     */
     static Bankswitch::Type autodetectType(const ByteBuffer& image, size_t size);
 
-
     /**
-	  MVC cartridges are of arbitary large length
+      MVC cartridges are of arbitary large length
       Returns size of frame if stream is probably an MVC movie cartridge
     */
-    static size_t isProbablyMVC(std::istream &in, size_t size);
+    static size_t isProbablyMVC(const FilesystemNode& rom);
 
   private:
     /**

src/emucore/CartMVC.cxx

@@ -1340,3 +1340,15 @@ bool CartridgeMVC::poke(uInt16 address, uInt8 value)
 {
   return myMovie->process(address);
 }
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+bool CartridgeMVC::save(Serializer& out) const
+{
+  return false;  // TODO: implement this
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+bool CartridgeMVC::load(Serializer& in)
+{
+  return false;  // TODO: implement this
+}

src/emucore/CartMVC.hxx

@@ -51,7 +51,7 @@ class CartridgeMVC : public Cartridge
       @param bsSize    The size specified by the bankswitching scheme
     */
     CartridgeMVC(const string& path, size_t size, const string& md5,
-                 const Settings& settings, size_t bsSize = 1_KB);
+                 const Settings& settings, size_t bsSize = 8_KB);
     ~CartridgeMVC() override;
 
     /**
@@ -113,7 +113,7 @@ class CartridgeMVC : public Cartridge
       @param out  The Serializer object to use
       @return  False on any errors, else true
     */
-    bool save(Serializer& out) const override { return false; }
+    bool save(Serializer& out) const override;
 
     /**
       Load the current state of this cart from the given Serializer.
@@ -121,7 +121,7 @@ class CartridgeMVC : public Cartridge
       @param in  The Serializer object to use
       @return  False on any errors, else true
     */
-    bool load(Serializer& in) override { return false; }
+    bool load(Serializer& in) override;
 
   private:
     // Currently not used:

src/emucore/FSNode.cxx

@@ -333,7 +333,7 @@ bool FilesystemNode::rename(const string& newfile)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-size_t FilesystemNode::read(ByteBuffer& buffer) const
+size_t FilesystemNode::read(ByteBuffer& buffer, size_t size) const
 {
   size_t sizeRead = 0;
 
@@ -342,7 +342,7 @@ size_t FilesystemNode::read(ByteBuffer& buffer) const
     throw runtime_error("File not found/readable");
 
   // First let the private subclass attempt to open the file
-  if (_realNode && (sizeRead = _realNode->read(buffer)) > 0)
+  if (_realNode && (sizeRead = _realNode->read(buffer, size)) > 0)
     return sizeRead;
 
   // Otherwise, the default behaviour is to read from a normal C++ ifstream
@@ -355,12 +355,8 @@ size_t FilesystemNode::read(ByteBuffer& buffer) const
 
     if (sizeRead == 0)
       throw runtime_error("Zero-byte file");
-
-	// In the case of MVC (MovieCart) files, contents are streaming data
-	// of arbitrary length, so just read first frame.
-	size_t subSize = CartDetector::isProbablyMVC(in, sizeRead);
-	if (subSize > 0)
-		sizeRead = subSize;
+    else if (size != 0)
+      sizeRead = size;
 
     buffer = make_unique<uInt8[]>(sizeRead);
     in.read(reinterpret_cast<char*>(buffer.get()), sizeRead);

src/emucore/FSNode.hxx

@@ -244,12 +244,13 @@ class FilesystemNode
      * Read data (binary format) into the given buffer.
      *
      * @param buffer  The buffer to contain the data (allocated in this method).
+     * @param size    The amount of data to read (0 means read all data).
      *
      * @return  The number of bytes read (0 in the case of failure)
      *          This method can throw exceptions, and should be used inside
      *          a try-catch block.
      */
-    size_t read(ByteBuffer& buffer) const;
+    size_t read(ByteBuffer& buffer, size_t size = 0) const;
 
     /**
      * Read data (text format) into the given stream.
@@ -438,12 +439,13 @@ class AbstractFSNode
      * Read data (binary format) into the given buffer.
      *
      * @param buffer  The buffer to contain the data (allocated in this method).
+     * @param size    The amount of data to read (0 means read all data).
      *
      * @return  The number of bytes read (0 in the case of failure)
      *          This method can throw exceptions, and should be used inside
      *          a try-catch block.
      */
-    virtual size_t read(ByteBuffer& buffer) const { return 0; }
+    virtual size_t read(ByteBuffer& buffer, size_t size) const { return 0; }
 
     /**
      * Read data (text format) into the given stream.

src/emucore/OSystem.cxx

@@ -44,6 +44,7 @@
 #include "MD5.hxx"
 #include "Cart.hxx"
 #include "CartCreator.hxx"
+#include "CartDetector.hxx"
 #include "FrameBuffer.hxx"
 #include "TIASurface.hxx"
 #include "TIAConstants.hxx"
@@ -688,8 +689,16 @@ ByteBuffer OSystem::openROM(const FilesystemNode& rom, string& md5, size_t& size
   // but also adds a properties entry if the one for the ROM doesn't
   // contain a valid name
 
+  // First check if this is a 'streaming' ROM (one where we only read
+  // a portion of the file)
+  size_t sizeToRead = CartDetector::isProbablyMVC(rom);
+
+  // Next check if rom is a valid size
+  // TODO: We should check if ROM is < Cart::maxSize(), but only
+  //       if it's not a ZIP file (that size should be higher; still TBD)
+
   ByteBuffer image;
-  if((size = rom.read(image)) == 0)
+  if((size = rom.read(image, sizeToRead)) == 0)
     return nullptr;
 
   // If we get to this point, we know we have a valid file to open

src/emucore/Serializer.cxx

@@ -94,11 +94,15 @@ void Serializer::rewind()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-size_t Serializer::size() const
+size_t Serializer::size()
 {
-  myStream->seekp(0, std::ios::end);
+  std::streampos oldPos = myStream->tellp();
 
-  return myStream->tellp();
+  myStream->seekp(0, std::ios::end);
+  size_t s = myStream->tellp();
+  setPosition(oldPos);
+
+  return s;
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

src/emucore/Serializer.hxx

@@ -70,9 +70,9 @@ class Serializer
     void rewind();
 
     /**
-      Returns the current write pointer location.
+      Returns the current total size of the stream.
     */
-    size_t size() const;
+    size_t size();
 
     /**
       Reads a byte value (unsigned 8-bit) from the current input stream.