Updated FA2 autodetection for Harmony ROMs (29/32K). Basically these

are detected and the ARM code discarded.


git-svn-id: svn://svn.code.sf.net/p/stella/code/trunk@2616 8b62c5a3-ac7e-4cc8-8f21-d9a121418aba

Changes.txt

@@ -44,6 +44,9 @@
         support, as well as 'virtual' formats (such as showing the list
         of files for 2in1/4in1/8in1/etc within the UI).
 
+  * Improved bankswitch autodetection for FA2 ROMs; 29K and 32K versions
+    (meant for Harmony cart) are now recognized.
+
   * Improved bankswitch autodetection for X07 ROMs (although there's only
     two known ROMs in existence, so the detection probably isn't robust).
 

src/emucore/Cart.cxx

@@ -430,7 +430,12 @@ string Cartridge::autodetectType(const uInt8* image, uInt32 size)
   }
   else if(size == 29*1024)  // 29K
   {
+    if(isProbablyDPCplus(image, size))
       type = "DPC+";
+    else if(isProbablyARM(image, size))
+      type = "FA2";
+    else
+      type = "4K";  // probably a bad ROM
   }
   else if(size == 32*1024)  // 32K
   {
@@ -444,6 +449,8 @@ string Cartridge::autodetectType(const uInt8* image, uInt32 size)
       type = "DPC+";
     else if(isProbablyCTY(image, size))
       type = "CTY";
+    else if(isProbablyFA2(image, size))
+      type = "FA2";
     else
       type = "F4";
   }
@@ -544,6 +551,21 @@ bool Cartridge::isProbablySC(const uInt8* image, uInt32 size)
   return true;
 }
 
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+bool Cartridge::isProbablyARM(const uInt8* image, uInt32 size)
+{
+  // ARM code contains the following 'loader' patterns in the first 1K
+  // Thanks to Thomas Jentzsch of AtariAge for this advice
+  uInt8 signature[2][4] = {
+    { 0xA0, 0xC1, 0x1F, 0xE0 },
+    { 0x00, 0x80, 0x02, 0xE0 }
+  };
+  if(searchForBytes(image, 1024, signature[0], 4, 1))
+    return true;
+  else
+    return searchForBytes(image, 1024, signature[1], 4, 1);
+}
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool Cartridge::isProbably0840(const uInt8* image, uInt32 size)
 {
@@ -707,6 +729,21 @@ bool Cartridge::isProbablyEF(const uInt8* image, uInt32 size)
   return false;
 }
 
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+bool Cartridge::isProbablyFA2(const uInt8* image, uInt32 size)
+{
+  // This currently tests only the 32K version of FA2; the 24 and 28K
+  // versions are easy, in that they're the only possibility with those
+  // file sizes
+
+  // 32K version has all zeros in 29K-32K area
+  for(uInt32 i = 29*1024; i < 32*1024; ++i)
+    if(image[i] != 0)
+      return false;
+
+  return true;
+}
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool Cartridge::isProbablyFE(const uInt8* image, uInt32 size)
 {

src/emucore/Cart.hxx

@@ -271,6 +271,11 @@ class Cartridge : public Device
     */
     static bool isProbablySC(const uInt8* image, uInt32 size);
 
+    /**
+      Returns true if the image probably contains ARM code in the first 1K
+    */
+    static bool isProbablyARM(const uInt8* image, uInt32 size);
+
     /**
       Returns true if the image is probably a 0840 bankswitching cartridge
     */
@@ -326,6 +331,11 @@ class Cartridge : public Device
     */
     static bool isProbablyF6(const uInt8* image, uInt32 size);
 
+    /**
+      Returns true if the image is probably an FA2 bankswitching cartridge
+    */
+    static bool isProbablyFA2(const uInt8* image, uInt32 size);
+
     /**
       Returns true if the image is probably an FE bankswitching cartridge
     */

src/emucore/CartFA2.cxx

@@ -32,6 +32,13 @@ CartridgeFA2::CartridgeFA2(const uInt8* image, uInt32 size, const OSystem& osyst
     myRamAccessTimeout(0),
     mySize(size)
 {
+  // 29/32K version of FA2 has valid data @ 1K - 29K
+  if(size >= 29 * 1024)
+  {
+    image += 1024;
+    mySize = 28 * 1024; 
+  }
+
   // Allocate array for the ROM image
   myImage = new uInt8[mySize];