Add support for 2600-daptor II when flashed as an AVox-USB converter.

Basically, for this device we use software flow control rather than hardware CTS signal.

Changes.txt

@@ -34,8 +34,8 @@
     one ZIP file, and distribute just that file.
 
   * Extended AtariVox support to handle flow control, so that long phrases
-    are no longer corrupted/cut off.  Note that some USB-serial adaptors
-    don't support this mode, so there may still be issues with those.
+    are no longer corrupted/cut off.  This includes properly supporting the
+    2600-daptor II, which is flashable to an AVox-USB converter.
 
   * Added option to select the audio device.
 

src/emucore/AtariVox.cxx

@@ -56,10 +56,27 @@ bool AtariVox::read(DigitalPin pin)
   switch(pin)
   {
     // Pin 2: SpeakJet READY
-    //        CTS (Clear To Send) is sent directly to pin 2
-    //        We also deal with the case where devices send CTS inverted
+    //        READY signal is sent directly to pin 2
     case DigitalPin::Two:
-      return setPin(pin, mySerialPort->isCTS() ^ myCTSFlip);
+    {
+      // Some USB-serial adaptors support only CTS, others support only
+      // software flow control
+      // So we check the state of both then AND the results, on the
+      // assumption that if a mode isn't supported, then it reads as TRUE
+      // and doesn't change the boolean result
+      // Thus the logic is:
+      //   READY_SIGNAL = READY_STATE_CTS && READY_STATE_FLOW
+      // Note that we also have to take inverted CTS into account
+
+      // When using software flow control, only update on a state change
+      uInt8 flowCtrl = 0;
+      if(mySerialPort->readByte(flowCtrl))
+        myReadyStateSoftFlow = flowCtrl == 0x11;  // XON
+
+      // Now combine the results of CTS and'ed with flow control
+      return setPin(pin,
+          (mySerialPort->isCTS() ^ myCTSFlip) && myReadyStateSoftFlow);
+    }
 
     default:
       return SaveKey::read(pin);

src/emucore/AtariVox.hxx

@@ -32,7 +32,7 @@ class FilesystemNode;
   This code owes a great debt to Alex Herbert's AtariVox documentation and
   driver code.
 
-  @author  B. Watson
+  @author  B. Watson, Stephen Anthony
 */
 class AtariVox : public SaveKey
 {
@@ -91,7 +91,9 @@ class AtariVox : public SaveKey
     */
     void reset() override;
 
-    string about(bool swappedPorts) const override { return Controller::about(swappedPorts) + myAboutString; }
+    string about(bool swappedPorts) const override {
+      return Controller::about(swappedPorts) + myAboutString;
+    }
 
   private:
    void clockDataIn(bool value);
@@ -117,9 +119,11 @@ class AtariVox : public SaveKey
     // "close enough".
     uInt64 myLastDataWriteCycle{0};
 
-    // Some USB-Serial adaptors either don't support CTS, or send the signal
-    // as inverted; we detect that when opening the port, and flip the signal
-    // when necessary
+    // When using software flow control, assume the device starts in READY mode
+    bool myReadyStateSoftFlow{true};
+
+    // Some USB-Serial adaptors send the CTS signal inverted; we detect
+    // that when opening the port, and flip the signal when necessary
     bool myCTSFlip{false};
 
     // Holds information concerning serial port usage

src/emucore/SerialPort.hxx

@@ -43,7 +43,6 @@ class SerialPort
 
     /**
       Read a byte from the serial port.
-      NOTE: This is for potential future use; no class currently uses this.
 
       @param data  Destination for the byte read from the port
       @return  True if a byte was read, else false

src/macos/SerialPortMACOS.cxx

@@ -63,14 +63,21 @@ bool SerialPortMACOS::openPort(const string& device)
   return true;
 }
 
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+bool SerialPortMACOS::readByte(uInt8& data)
+{
+  if(myHandle)
+    return read(myHandle, &data, 1) == 1;
+
+  return false;
+}
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool SerialPortMACOS::writeByte(uInt8 data)
 {
   if(myHandle)
-  {
-//    cerr << "SerialPortMACOS::writeByte " << int(data) << endl;
     return write(myHandle, &data, 1) == 1;
-  }
+
   return false;
 }
 

src/macos/SerialPortMACOS.hxx

@@ -40,6 +40,14 @@ class SerialPortMACOS : public SerialPort
     */
     bool openPort(const string& device) override;
 
+    /**
+      Read a byte from the serial port.
+
+      @param data  Destination for the byte read from the port
+      @return  True if a byte was read, else false
+    */
+    bool readByte(uInt8& data) override;
+
     /**
       Write a byte to the serial port.
 

src/unix/SerialPortUNIX.cxx

@@ -49,7 +49,9 @@ bool SerialPortUNIX::openPort(const string& device)
   if(myHandle <= 0)
     return false;
 
-  // Open the device in nonblocking mode
+  // Clear buffers, then open the device in nonblocking mode
+  tcflush(myHandle, TCOFLUSH);
+  tcflush(myHandle, TCIFLUSH);
   fcntl(myHandle, F_SETFL, FNDELAY);
 
   struct termios termios;
@@ -64,14 +66,21 @@ bool SerialPortUNIX::openPort(const string& device)
   return true;
 }
 
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+bool SerialPortUNIX::readByte(uInt8& data)
+{
+  if(myHandle)
+    return read(myHandle, &data, 1) == 1;
+
+  return false;
+}
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool SerialPortUNIX::writeByte(uInt8 data)
 {
   if(myHandle)
-  {
-//    cerr << "SerialPortUNIX::writeByte " << int(data) << endl;
     return write(myHandle, &data, 1) == 1;
-  }
+
   return false;
 }
 

src/unix/SerialPortUNIX.hxx

@@ -40,6 +40,14 @@ class SerialPortUNIX : public SerialPort
     */
     bool openPort(const string& device) override;
 
+    /**
+      Read a byte from the serial port.
+
+      @param data  Destination for the byte read from the port
+      @return  True if a byte was read, else false
+    */
+    bool readByte(uInt8& data) override;
+
     /**
       Write a byte to the serial port.
 

src/windows/SerialPortWINDOWS.cxx

@@ -62,6 +62,14 @@ bool SerialPortWINDOWS::openPort(const string& device)
       dcb.Parity = NOPARITY;
       dcb.StopBits = ONESTOPBIT;
       SetCommState(myHandle, &dcb);
+
+      COMMTIMEOUTS commtimeouts;
+      commtimeouts.ReadIntervalTimeout = MAXDWORD;
+      commtimeouts.ReadTotalTimeoutMultiplier = 0;
+      commtimeouts.ReadTotalTimeoutConstant = 1;
+      commtimeouts.WriteTotalTimeoutMultiplier = 0;
+      commtimeouts.WriteTotalTimeoutConstant = 0;
+      SetCommTimeouts(myHandle, &commtimeouts);
     }
     else
       return false;
@@ -69,13 +77,26 @@ bool SerialPortWINDOWS::openPort(const string& device)
   return true;
 }
 
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+bool SerialPortWINDOWS::readByte(uInt8& data)
+{
+  if(myHandle)
+  {
+    DWORD read;
+    ReadFile(myHandle, &data, 1, &read, NULL);
+    return read == 1;
+  }
+  return false;
+}
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool SerialPortWINDOWS::writeByte(uInt8 data)
 {
   if(myHandle)
   {
     DWORD written;
-    return WriteFile(myHandle, &data, 1, &written, 0) == TRUE;
+    WriteFile(myHandle, &data, 1, &written, NULL);
+    return written == 1;
   }
   return false;
 }

src/windows/SerialPortWINDOWS.hxx

@@ -39,6 +39,14 @@ class SerialPortWINDOWS : public SerialPort
     */
     bool openPort(const string& device) override;
 
+    /**
+      Read a byte from the serial port.
+
+      @param data  Destination for the byte read from the port
+      @return  True if a byte was read, else false
+    */
+    bool readByte(uInt8& data) override;
+
     /**
       Write a byte to the serial port.