Add SerialPort::isCTS() to all ports, and connect it to AtariVox.

src/emucore/AtariVox.cxx

@@ -50,10 +50,11 @@ bool AtariVox::read(DigitalPin pin)
   switch(pin)
   {
     // Pin 2: SpeakJet READY
-    //        CTS enabled means the SpeakJet can accept more data
+    //        CTS (Clear To Send) is connected inverted
+    //        So CTS = 0 means the buffer is full, which pulls pin 2 high
     case DigitalPin::Two:
     {
-      return setPin(pin, mySerialPort->isCTS());
+      return setPin(pin, !mySerialPort->isCTS());
     }
 
     default:

src/macos/SerialPortMACOS.cxx

@@ -73,3 +73,15 @@ bool SerialPortMACOS::writeByte(uInt8 data)
   }
   return false;
 }
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+bool SerialPortMACOS::isCTS()
+{
+  if(myHandle)
+  {
+    int status = 0;
+    ioctl(myHandle, TIOCMGET, &status);
+    return status & TIOCM_CTS;
+  }
+  return false;
+}

src/macos/SerialPortMACOS.hxx

@@ -48,6 +48,13 @@ class SerialPortMACOS : public SerialPort
     */
     bool writeByte(uInt8 data) override;
 
+  /**
+    Test for 'Clear To Send' enabled.
+
+    @return  True if CTS signal enabled, else false
+  */
+  bool isCTS() override;
+
   private:
     // File descriptor for serial connection
     int myHandle{0};

src/unix/SerialPortUNIX.cxx

@@ -49,6 +49,9 @@ bool SerialPortUNIX::openPort(const string& device)
   if(myHandle <= 0)
     return false;
 
+  // Open the device in nonblocking mode
+  fcntl(myHandle, F_SETFL, FNDELAY);
+
   struct termios termios;
   memset(&termios, 0, sizeof(struct termios));
 
@@ -71,3 +74,15 @@ bool SerialPortUNIX::writeByte(uInt8 data)
   }
   return false;
 }
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+bool SerialPortUNIX::isCTS()
+{
+  if(myHandle)
+  {
+    int status = 0;
+    ioctl(myHandle, TIOCMGET, &status);
+    return status & TIOCM_CTS;
+  }
+  return false;
+}

src/unix/SerialPortUNIX.hxx

@@ -48,6 +48,13 @@ class SerialPortUNIX : public SerialPort
     */
     bool writeByte(uInt8 data) override;
 
+    /**
+      Test for 'Clear To Send' enabled.
+
+      @return  True if CTS signal enabled, else false
+    */
+    bool isCTS() override;
+
   private:
     // File descriptor for serial connection
     int myHandle{0};

src/windows/SerialPortWINDOWS.cxx

@@ -79,3 +79,15 @@ bool SerialPortWINDOWS::writeByte(uInt8 data)
   }
   return false;
 }
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+bool SerialPortWINDOWS::isCTS()
+{
+  if(myHandle)
+  {
+    DWORD modemStat;
+    GetCommModemStatus(myHandle, &modemStat);
+    return modemStat & MS_CTS_ON;
+  }
+  return false;
+}

src/windows/SerialPortWINDOWS.hxx

@@ -47,6 +47,14 @@ class SerialPortWINDOWS : public SerialPort
     */
     bool writeByte(uInt8 data) override;
 
+    /**
+      Test for 'Clear To Send' enabled.  By default, assume it's always
+      OK to send more data.
+
+      @return  True if CTS signal enabled, else false
+    */
+    bool isCTS() override;
+
   private:
     // Handle to serial port
     HANDLE myHandle{0};

src/windows/Stella.vcxproj

@@ -1774,6 +1774,7 @@
     <ClInclude Include="..\emucore\MindLink.hxx" />
     <ClInclude Include="..\emucore\PointingDevice.hxx" />
     <ClInclude Include="..\emucore\ProfilingRunner.hxx" />
+    <ClInclude Include="..\emucore\SerialPort.hxx" />
     <ClInclude Include="..\emucore\TIASurface.hxx" />
     <ClInclude Include="..\emucore\tia\Audio.hxx" />
     <ClInclude Include="..\emucore\tia\AudioChannel.hxx" />

src/windows/Stella.vcxproj.filters

@@ -2087,6 +2087,9 @@
     <ClInclude Include="..\gui\WhatsNewDialog.hxx">
       <Filter>Header Files\gui</Filter>
     </ClInclude>
+    <ClInclude Include="..\emucore\SerialPort.hxx">
+      <Filter>Header Files\emucore</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <None Include="stella.ico">