From 3fa7dadcbaa42eb3005b3657b600119613f1b851 Mon Sep 17 00:00:00 2001
From: Stephen Anthony <sa666666@gmail.com>
Date: Sun, 2 Aug 2020 10:59:41 -0230
Subject: [PATCH] Finalize AVox CTS support.  Now more testing is needed ...

---
 Changes.txt              |  4 ++++
 src/emucore/AtariVox.cxx | 16 ++++++++++------
 src/emucore/AtariVox.hxx |  5 +++++
 3 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/Changes.txt b/Changes.txt
index 9db31b627..61b036ebc 100644
--- a/Changes.txt
+++ b/Changes.txt
@@ -33,6 +33,10 @@
     Basically, you are now able to put many files that Stella uses inside
     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.
+
   * Added option to select the audio device.
 
   * Added option to display detected settings info when a ROM is loaded.
diff --git a/src/emucore/AtariVox.cxx b/src/emucore/AtariVox.cxx
index fd75024e4..731232456 100644
--- a/src/emucore/AtariVox.cxx
+++ b/src/emucore/AtariVox.cxx
@@ -28,7 +28,13 @@ AtariVox::AtariVox(Jack jack, const Event& event, const System& system,
 {
   mySerialPort = MediaFactory::createSerialPort();
   if(mySerialPort->openPort(portname))
-    myAboutString = " (using serial port \'" + portname + "\')";
+  {
+    myCTSFlip = !mySerialPort->isCTS();
+    if(myCTSFlip)
+      myAboutString = " (serial port \'" + portname + "\', inverted CTS)";
+    else
+      myAboutString = " (serial port \'" + portname + "\')";
+  }
   else
     myAboutString = " (invalid serial port \'" + portname + "\')";
 
@@ -50,12 +56,10 @@ bool AtariVox::read(DigitalPin pin)
   switch(pin)
   {
     // Pin 2: SpeakJet READY
-    //        CTS (Clear To Send) is connected inverted
-    //        So CTS = 0 means the buffer is full, which pulls pin 2 high
+    //        CTS (Clear To Send) is sent directly to pin 2
+    //        We also deal with the case where devices send CTS inverted
     case DigitalPin::Two:
-    {
-      return setPin(pin, !mySerialPort->isCTS());
-    }
+      return setPin(pin, mySerialPort->isCTS() ^ myCTSFlip);
 
     default:
       return SaveKey::read(pin);
diff --git a/src/emucore/AtariVox.hxx b/src/emucore/AtariVox.hxx
index 3251234ed..132b2c377 100644
--- a/src/emucore/AtariVox.hxx
+++ b/src/emucore/AtariVox.hxx
@@ -117,6 +117,11 @@ 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
+    bool myCTSFlip{false};
+
     // Holds information concerning serial port usage
     string myAboutString;