Optimized Distella in the case of 2K ROMs. Now only half the

address space is shown (either $F000 - $F7FF or $F800 - $FFFF).
This eliminates a lot of .byte directives that are invalid in
2K mode anyway, and speeds up the disassembly a little.


git-svn-id: svn://svn.code.sf.net/p/stella/code/trunk@2113 8b62c5a3-ac7e-4cc8-8f21-d9a121418aba

src/debugger/CartDebug.cxx

@@ -261,7 +261,9 @@ bool CartDebug::fillDisassemblyList(AddressList& addresses,
 
   myDisassembly.list.clear();
   myDisassembly.fieldwidth = 10 + myLabelLength;
-  DiStella distella(*this, myDisassembly.list, addresses, resolvedata);
+  uInt16 banksize =
+    !BSPF_equalsIgnoreCase(myConsole.cartridge().name(), "Cartridge2K") ? 4 : 2;
+  DiStella distella(*this, myDisassembly.list, addresses, banksize, resolvedata);
 
   // Parts of the disassembly will be accessed later in different ways
   // We place those parts in separate maps, to speed up access
@@ -297,7 +299,9 @@ string CartDebug::disassemble(uInt16 start, uInt16 lines) const
   Disassembly disasm;
   AddressList addresses;
   addresses.push_back(start);
-  DiStella distella(*this, disasm.list, addresses, false);
+  uInt16 banksize =
+    !BSPF_equalsIgnoreCase(myConsole.cartridge().name(), "Cartridge2K") ? 4 : 2;
+  DiStella distella(*this, disasm.list, addresses, banksize, false);
 
   // Fill the string with disassembled data
   start &= 0xFFF;

src/debugger/DiStella.cxx

@@ -23,7 +23,7 @@
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 DiStella::DiStella(const CartDebug& dbg, CartDebug::DisassemblyList& list,
-                   AddressList& addresses, bool resolvedata)
+                   AddressList& addresses, uInt16 banksize, bool resolvedata)
   : myDbg(dbg),
     myList(list)
 {
@@ -33,42 +33,53 @@ DiStella::DiStella(const CartDebug& dbg, CartDebug::DisassemblyList& list,
   while(!myAddressQueue.empty())
     myAddressQueue.pop();
 
+  AddressList::iterator it = addresses.begin();
+  uInt16 start = *it++;
+
+  if(start & 0x1000)
+  {
+    if(banksize == 4)  // 4K ROM space
+    {
       /*============================================
         The offset is the address where the code segment
-    starts.  For a 4K game, it is usually 0xf000,
+        starts.  For a 4K game, it is usually 0xf000.
-    which would then have the code data end at 0xffff,
-    but that is not necessarily the case.  Because the
-    Atari 2600 only has 13 address lines, it's possible
-    that the "code" can be considered to start in a lot
-    of different places.  So, we use the start
-    address as a reference to determine where the
-    offset is, logically-anded to produce an offset
-    that is a multiple of 4K.
 
         Example:
           Start address = $D973, so therefore
           Offset to code = $D000
           Code range = $D000-$DFFF
       =============================================*/
-
-  AddressList::iterator it = addresses.begin();
-  uInt16 start = *it++;
-
-  if(start & 0x1000)  // ROM space
-  {
       myAppData.start  = 0x0000;
       myAppData.end    = 0x0FFF;
       myAppData.length = 4096;
+
+      myOffset = (start - (start % 0x1000));
+    }
+    else  // 2K ROM space
+    {
+      /*============================================
+        The offset is the address where the code segment
+        starts.  For a 2K game, it is usually 0xf800,
+        but can also be 0xf000.
+      =============================================*/
+      myAppData.start  = 0x0000;
+      myAppData.end    = 0x07FF;
+      myAppData.length = 2048;
+
+      myOffset = (start & 0xF800);
+    }
   }
   else  // ZP RAM
   {
+    // For now, we assume all accesses below $1000 are zero-page 
     myAppData.start  = 0x0080;
     myAppData.end    = 0x00FF;
     myAppData.length = 128;
-  }
-  memset(labels, 0, 0x1000);
 
-  myOffset = (start - (start % 0x1000));
+    myOffset = 0;
+  }
+
+  memset(labels, 0, 0x1000);
   myAddressQueue.push(start);
 
   if(resolvedata)

src/debugger/DiStella.hxx

@@ -49,10 +49,11 @@ class DiStella
       @param dbg         The CartDebug instance containing all label information
       @param list        The results of the disassembly are placed here
       @param addresses   The address(es) at which to start disassembly
+      @param banksize    Size of the bank in KB (possible values are 4 or 2)
       @param resolvedata If enabled, try to determine code vs. data sections
     */
     DiStella(const CartDebug& dbg, CartDebug::DisassemblyList& list,
-             AddressList& addresses, bool resolvedata = true);
+             AddressList& addresses, uInt16 banksize = 4, bool resolvedata = true);
 
     ~DiStella();