Reverted INTIM handling to version 3.7.2, which fixes hangs in Mr. Roboto.

git-svn-id: svn://svn.code.sf.net/p/stella/code/trunk@2584 8b62c5a3-ac7e-4cc8-8f21-d9a121418aba

Changes.txt

@@ -29,6 +29,9 @@
   * Tweaked bankswitch autodetection for the 0840, F8 and FE schemes;
     several homebrews that didn't run before now work correctly.
 
+  * Fixed regression in M6532 INTIM reads; at least one known ROM
+    (Mr. Roboto Berzerk hack) wasn't working properly.
+
 -Have fun!
 
 

src/emucore/M6532.cxx

@@ -180,7 +180,12 @@ uInt8 M6532::peek(uInt16 addr)
 
       // Get number of clocks since timer was set
       Int32 timer = timerClocks();  
-      if(timer >= 0)
+
+      // Note that this constant comes from z26, and corresponds to
+      // 256 intervals of T1024T (ie, the maximum that the timer should hold)
+      // I'm not sure why this is required, but quite a few ROMs fail
+      // if we just check >= 0.
+      if(!(timer & 0x40000))
       {
         // Return at 'divide by TIMxT' interval rate
         return (timer >> myIntervalShift) & 0xff;