From b3bfc86ccc522dbce4ada9c038c7ad5bfdee6f39 Mon Sep 17 00:00:00 2001
From: Christian Speckner <christian.speckner@mayflower.de>
Date: Wed, 29 Mar 2017 18:18:35 +0200
Subject: [PATCH] Introduce shadow registers, start refactoring TIADebug to use
 them.

---
 src/debugger/TIADebug.cxx  | 4 ++--
 src/emucore/tia/Player.hxx | 1 -
 src/emucore/tia/TIA.cxx    | 9 +++++++++
 src/emucore/tia/TIA.hxx    | 5 +++++
 4 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/src/debugger/TIADebug.cxx b/src/debugger/TIADebug.cxx
index 4bb8022e3..5bb5f6afd 100644
--- a/src/debugger/TIADebug.cxx
+++ b/src/debugger/TIADebug.cxx
@@ -185,7 +185,7 @@ bool TIADebug::vdelP0(int newVal)
   if(newVal > -1)
     mySystem.poke(VDELP0, bool(newVal));
 
-  return myTIA.myPlayer0.vdelp();
+  return (myTIA.valueLastWrittenToRegister(VDELP0) & 0x01) > 0;
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -194,7 +194,7 @@ bool TIADebug::vdelP1(int newVal)
   if(newVal > -1)
     mySystem.poke(VDELP1, bool(newVal));
 
-  return myTIA.myPlayer1.vdelp();
+  return (myTIA.valueLastWrittenToRegister(VDELP1) & 0x01) > 0;
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
diff --git a/src/emucore/tia/Player.hxx b/src/emucore/tia/Player.hxx
index 1279dcfc1..07227478e 100644
--- a/src/emucore/tia/Player.hxx
+++ b/src/emucore/tia/Player.hxx
@@ -44,7 +44,6 @@ class Player : public Serializable
     bool refp() const { return myIsReflected; }
 
     void vdelp(uInt8 value);
-    bool vdelp() const { return myIsDelaying; }
 
     void toggleEnabled(bool enabled);
 
diff --git a/src/emucore/tia/TIA.cxx b/src/emucore/tia/TIA.cxx
index 68e7cbc57..b5fc7bbe1 100644
--- a/src/emucore/tia/TIA.cxx
+++ b/src/emucore/tia/TIA.cxx
@@ -118,6 +118,8 @@ void TIA::reset()
   mySubClock = 0;
   myXDelta = 0;
 
+  memset(myShadowRegisters, 0, 64);
+
   myBackground.reset();
   myPlayfield.reset();
   myMissile0.reset();
@@ -432,6 +434,7 @@ bool TIA::poke(uInt16 address, uInt8 value)
   updateEmulation();
 
   address &= 0x3F;
+  myShadowRegisters[address] = value;
 
   switch (address)
   {
@@ -923,6 +926,12 @@ void TIA::updateScanlineByTrace(int target)
     updateScanlineByStep();
 }
 
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+uInt8 TIA::valueLastWrittenToRegister(uInt8 reg) const
+{
+  return reg < 64 ? myShadowRegisters[reg] : 0;
+}
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 void TIA::updateEmulation()
 {
diff --git a/src/emucore/tia/TIA.hxx b/src/emucore/tia/TIA.hxx
index ee766a005..4a3ea8363 100644
--- a/src/emucore/tia/TIA.hxx
+++ b/src/emucore/tia/TIA.hxx
@@ -308,6 +308,9 @@ class TIA : public Device
     */
     void updateScanlineByTrace(int target);
 
+    // Retrieve the last value written to a certain register
+    uInt8 valueLastWrittenToRegister(uInt8 reg) const;
+
     /**
       Save the current state of this device to the given Serializer.
 
@@ -459,6 +462,8 @@ class TIA : public Device
 
     double myTimestamp;
 
+    uInt8 myShadowRegisters[64];
+
     // Automatic framerate correction based on number of scanlines
     bool myAutoFrameEnabled;