Supporting ADFs with less than 80 cylinders (#791)

Emulator/Media/DiskFiles/ADFFile.cpp

@@ -31,18 +31,15 @@ bool
 ADFFile::isCompatible(std::istream &stream)
 {
     isize length = util::streamLength(stream);
-    
+
     // Some ADFs contain an additional byte at the end. Ignore it.
     length &= ~1;
-
-    // There are no magic bytes. Hence, we only check the file size.
-    return
-    length == ADFSIZE_35_DD ||
-    length == ADFSIZE_35_DD_81 ||
-    length == ADFSIZE_35_DD_82 ||
-    length == ADFSIZE_35_DD_83 ||
-    length == ADFSIZE_35_DD_84 ||
-    length == ADFSIZE_35_HD;
+
+    // The size must be a multiple of the cylinder size
+    if (length % 11264) return false;
+
+    // Check some more limits
+    return length <= ADFSIZE_35_DD_84 || length == ADFSIZE_35_HD;
 }
 
 isize
@@ -138,6 +135,13 @@ ADFFile::init(MutableFileSystem &volume)
     volume.exportVolume(data.ptr, data.size);
 }
 
+void
+ADFFile::finalizeRead()
+{
+    // Add some empty cylinders if the file contains less than 80
+    if (data.size < ADFSIZE_35_DD) data.resize(ADFSIZE_35_DD, 0);
+}
+
 isize
 ADFFile::numCyls() const
 {

Emulator/Media/DiskFiles/ADFFile.h

@@ -79,7 +79,7 @@ class ADFFile : public FloppyFile {
     bool isCompatiblePath(const string &path) const override { return isCompatible(path); }
     bool isCompatibleStream(std::istream &stream) const override { return isCompatible(stream); }
     FileType type() const override { return FILETYPE_ADF; }
-
+    void finalizeRead() override;
 
     //
     // Methods from DiskFile