* Replaced too simple prefix with a more general concept of a makernote header.

* Added "FOVEON" and "*" to registry.
* Code and documentation cleanup.

src/sigmamn.cpp

@@ -20,7 +20,7 @@
  */
 /*
   File:      sigmamn.cpp
-  Version:   $Name:  $ $Revision: 1.4 $
+  Version:   $Name:  $ $Revision: 1.5 $
   Author(s): Andreas Huggel (ahu) <ahuggel@gmx.net>
   History:   02-Apr-04, ahu: created
   Credits:   Sigma and Foveon MakerNote implemented according to the specification
@@ -29,7 +29,7 @@
  */
 // *****************************************************************************
 #include "rcsid.hpp"
-EXIV2_RCSID("@(#) $Name:  $ $Revision: 1.4 $ $RCSfile: sigmamn.cpp,v $")
+EXIV2_RCSID("@(#) $Name:  $ $Revision: 1.5 $ $RCSfile: sigmamn.cpp,v $")
 
 // *****************************************************************************
 // included header files
@@ -42,6 +42,7 @@ EXIV2_RCSID("@(#) $Name:  $ $Revision: 1.4 $ $RCSfile: sigmamn.cpp,v $")
 #include <string>
 #include <sstream>
 #include <iomanip>
+#include <cassert>
 
 // Define DEBUG_MAKERNOTE to output debug information to std::cerr
 #undef DEBUG_MAKERNOTE
@@ -84,15 +85,42 @@ namespace Exiv2 {
     SigmaMakerNote::SigmaMakerNote(bool alloc)
         : IfdMakerNote(sigmaMnTagInfo, alloc), sectionName_("Sigma")
     {
-        // My one and only Sigma sample has two undocumented extra bytes 
-        // (0x01, 0x00) between the ID string and the start of the
-        // Makernote IFD. Adding them to the ID string is a hack...
-        prefix_ = std::string("SIGMA\0\0\0\x1\0", 10);
     }
 
-    MakerNote* SigmaMakerNote::clone(bool alloc) const 
+    int SigmaMakerNote::readHeader(const char* buf,
+                                   long len, 
+                                   ByteOrder byteOrder)
     {
-        return createSigmaMakerNote(alloc); 
+        if (len < 10) return 1;
+
+        // Copy the header. My one and only Sigma sample has two undocumented
+        // extra bytes (0x01, 0x00) between the ID string and the start of the
+        // Makernote IFD. So we copy 10 bytes into the header.
+        header_.alloc(10);
+        memcpy(header_.pData_, buf, header_.size_);
+        // Adjust the offset of the IFD for the prefix
+        adjOffset_ = 10;
+        return 0;
+    }
+
+    int SigmaMakerNote::checkHeader() const
+    {
+        int rc = 0;
+        // Check the SIGMA or FOVEON prefix
+        if (   header_.size_ < 10
+            || std::string(header_.pData_, 8) != std::string("SIGMA\0\0\0", 8)
+            && std::string(header_.pData_, 8) != std::string("FOVEON\0\0", 8)) {
+            rc = 2;
+        }
+        return rc;
+    }
+
+    SigmaMakerNote* SigmaMakerNote::clone(bool alloc) const 
+    {
+        SigmaMakerNote* pMakerNote = new SigmaMakerNote(alloc);
+        assert(pMakerNote);
+        pMakerNote->readHeader(header_.pData_, header_.size_, byteOrder_);
+        return pMakerNote;
     }
 
     std::ostream& SigmaMakerNote::printTag(std::ostream& os, 

src/sigmamn.hpp

@@ -21,9 +21,9 @@
 /*!
   @file    sigmamn.hpp
   @brief   Sigma and Foveon MakerNote implemented according to the specification
-           in "SIGMA and FOVEON EXIF MakerNote Documentation" by Foveon.
+           <a href="http://www.x3f.info/technotes/FileDocs/MakerNoteDoc.html">
-           <http://www.x3f.info/technotes/FileDocs/MakerNoteDoc.html>
+           SIGMA and FOVEON EXIF MakerNote Documentation</a> by Foveon.           
-  @version $Name:  $ $Revision: 1.3 $
+  @version $Name:  $ $Revision: 1.4 $
   @author  Andreas Huggel (ahu)
            <a href="mailto:ahuggel@gmx.net">ahuggel@gmx.net</a>
   @date    02-Apr-04, ahu: created
@@ -81,9 +81,17 @@ namespace Exiv2 {
         virtual ~SigmaMakerNote() {}
         //@}
 
+        //! @name Manipulators
+        //@{        
+        int readHeader(const char* buf, 
+                       long len,
+                       ByteOrder byteOrder);
+        //@}
+
         //! @name Accessors
         //@{
-        MakerNote* clone(bool alloc =true) const;
+        int checkHeader() const;
+        SigmaMakerNote* clone(bool alloc =true) const;
         //! Return the name of the makernote section ("Sigma")
         std::string sectionName(uint16 tag) const { return sectionName_; }
         std::ostream& printTag(std::ostream& os,
@@ -109,8 +117,10 @@ namespace Exiv2 {
             {
                 MakerNoteFactory& mnf = MakerNoteFactory::instance();
                 mnf.registerMakerNote("SIGMA", "*", createSigmaMakerNote); 
+                mnf.registerMakerNote("FOVEON", "*", createSigmaMakerNote); 
             }
         };
+        // DATA
         /*!
           The static member variable is initialized before main (see note) and
           will in the process register the MakerNote class. (Remember the