From 9e23fa3c7279c4b85e77c7ac9a9b81bf99de935c Mon Sep 17 00:00:00 2001
From: estolberg <estolberg@8b62c5a3-ac7e-4cc8-8f21-d9a121418aba>
Date: Mon, 3 Mar 2008 16:27:16 +0000
Subject: [PATCH] Fixed a bug that was preventing driving controllers on the
 Stelladaptor to coexist peacefully with other PC inputs. Also corrected the
 driving controller movement drection for the Stelladaptor.

git-svn-id: svn://svn.code.sf.net/p/stella/code/trunk@1416 8b62c5a3-ac7e-4cc8-8f21-d9a121418aba
---
 stella/src/emucore/Driving.cxx | 37 +++++++++++++++++++++-------------
 stella/src/emucore/Driving.hxx | 11 ++++++++--
 2 files changed, 32 insertions(+), 16 deletions(-)

diff --git a/stella/src/emucore/Driving.cxx b/stella/src/emucore/Driving.cxx
index 84ca8b227..28e82421a 100644
--- a/stella/src/emucore/Driving.cxx
+++ b/stella/src/emucore/Driving.cxx
@@ -13,7 +13,7 @@
 // See the file "license" for information on usage and redistribution of
 // this file, and for a DISCLAIMER OF ALL WARRANTIES.
 //
-// $Id: Driving.cxx,v 1.15 2008-03-02 19:20:50 stephena Exp $
+// $Id: Driving.cxx,v 1.16 2008-03-03 16:27:16 estolberg Exp $
 //============================================================================
 
 #include "Event.hxx"
@@ -58,8 +58,10 @@ Driving::~Driving()
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 void Driving::update()
 {
-  int grayIndex = 0;
-
+  // Make sure direct gray codes from Stelladaptor stay in sync with
+  // simulated gray codes generated by PC keyboard or PC joystick
+  myCounter = (myGrayIndex << 2) | (myCounter & 3);
+  
   // Digital events (from keyboard or joystick hats & buttons)
   myDigitalPinState[Six] = (myEvent.get(myFireEvent) == 0);
 
@@ -69,24 +71,31 @@ void Driving::update()
 
   // Only consider the lower-most bits (corresponding to pins 1 & 2)
   myCounter &= 0x0f;
-  grayIndex = myCounter >> 2;
+  myGrayIndex = myCounter >> 2;
  
   // Stelladaptor is the only controller that should set this
   int yaxis = myEvent.get(myYAxisValue);
-  if(yaxis <= -16384-4096)
-    grayIndex = 2;
-  else if(yaxis > 16384+4096)
-    grayIndex = 1;
-  else if(yaxis >= 16384-4096)
-    grayIndex = 0;
-  else if(yaxis < -16384+4096)
-    grayIndex = 3;
-  
+
+  // Only overwrite gray code when Stelladaptor input has changed
+  // (that means real changes, not just analog signal jitter)
+  if((yaxis < (myLastYaxis - 1024)) || (yaxis > (myLastYaxis + 1024)))
+  {
+    myLastYaxis = yaxis;
+    if(yaxis <= -16384-4096)
+      myGrayIndex = 3; // up
+    else if(yaxis > 16384+4096)
+      myGrayIndex = 1; // down
+    else if(yaxis >= 16384-4096)
+      myGrayIndex = 2; // up + down
+    else if(yaxis < 16384-4096)
+      myGrayIndex = 0; // no movement
+  }
+
   // Gray codes for rotation
   static const uInt8 graytable[] = { 0x03, 0x01, 0x00, 0x02 };
 
   // Determine which bits are set
-  uInt8 gray = graytable[grayIndex];
+  uInt8 gray = graytable[myGrayIndex];
   myDigitalPinState[One] = (gray & 0x1) != 0;
   myDigitalPinState[Two] = (gray & 0x2) != 0;
 }
diff --git a/stella/src/emucore/Driving.hxx b/stella/src/emucore/Driving.hxx
index 3d89d0e13..990308613 100644
--- a/stella/src/emucore/Driving.hxx
+++ b/stella/src/emucore/Driving.hxx
@@ -13,7 +13,7 @@
 // See the file "license" for information on usage and redistribution of
 // this file, and for a DISCLAIMER OF ALL WARRANTIES.
 //
-// $Id: Driving.hxx,v 1.9 2008-03-02 19:20:50 stephena Exp $
+// $Id: Driving.hxx,v 1.10 2008-03-03 16:27:16 estolberg Exp $
 //============================================================================
 
 #ifndef DRIVING_HXX
@@ -27,7 +27,7 @@
   The standard Atari 2600 Indy 500 driving controller.
 
   @author  Bradford W. Mott
-  @version $Id: Driving.hxx,v 1.9 2008-03-02 19:20:50 stephena Exp $
+  @version $Id: Driving.hxx,v 1.10 2008-03-03 16:27:16 estolberg Exp $
 */
 class Driving : public Controller
 {
@@ -57,6 +57,13 @@ class Driving : public Controller
     // Counter to iterate through the gray codes
     uInt32 myCounter;
 
+    // Index into the gray code table
+    uInt32 myGrayIndex;
+
+    // Y axis value from last yaxis event that was used to generate a new
+    // gray code
+    int myLastYaxis;
+
     // Pre-compute the events we care about based on given port
     // This will eliminate test for left or right port in update()
     Event::Type myCWEvent, myCCWEvent, myFireEvent, myXAxisValue, myYAxisValue;