http://code.google.com/p/rpcs3/source/detail?r=44

wxWidgets/include/wx/private/fileback.h

@@ -0,0 +1,83 @@
+/////////////////////////////////////////////////////////////////////////////
+// Name:        include/wx/private/fileback.h
+// Purpose:     Back an input stream with memory or a file
+// Author:      Mike Wetherell
+// RCS-ID:      $Id: fileback.h 61872 2009-09-09 22:37:05Z VZ $
+// Copyright:   (c) 2006 Mike Wetherell
+// Licence:     wxWindows licence
+/////////////////////////////////////////////////////////////////////////////
+
+#ifndef _WX_FILEBACK_H__
+#define _WX_FILEBACK_H__
+
+#include "wx/defs.h"
+
+#if wxUSE_FILESYSTEM
+
+#include "wx/stream.h"
+
+// ----------------------------------------------------------------------------
+// Backs an input stream with memory or a file to make it seekable.
+//
+// One or more wxBackedInputStreams can be used to read it's data. The data is
+// reference counted, so stays alive until the last wxBackingFile or
+// wxBackedInputStream using it is destroyed.
+// ----------------------------------------------------------------------------
+
+class WXDLLIMPEXP_BASE wxBackingFile
+{
+public:
+    enum { DefaultBufSize = 16384 };
+
+    // Takes ownership of stream. If the stream is smaller than bufsize, the
+    // backing file is never created and the backing is done with memory.
+    wxBackingFile(wxInputStream *stream,
+                  size_t bufsize = DefaultBufSize,
+                  const wxString& prefix = wxT("wxbf"));
+
+    wxBackingFile() : m_impl(NULL) { }
+    ~wxBackingFile();
+
+    wxBackingFile(const wxBackingFile& backer);
+    wxBackingFile& operator=(const wxBackingFile& backer);
+
+    operator bool() const { return m_impl != NULL; }
+
+private:
+    class wxBackingFileImpl *m_impl;
+    friend class wxBackedInputStream;
+};
+
+// ----------------------------------------------------------------------------
+// An input stream to read from a wxBackingFile.
+// ----------------------------------------------------------------------------
+
+class WXDLLIMPEXP_BASE wxBackedInputStream : public wxInputStream
+{
+public:
+    wxBackedInputStream(const wxBackingFile& backer);
+
+    // If the length of the backer's parent stream is unknown then GetLength()
+    // returns wxInvalidOffset until the parent has been read to the end.
+    wxFileOffset GetLength() const;
+
+    // Returns the length, reading the parent stream to the end if necessary.
+    wxFileOffset FindLength() const;
+
+    bool IsSeekable() const { return true; }
+
+protected:
+    size_t OnSysRead(void *buffer, size_t size);
+    wxFileOffset OnSysSeek(wxFileOffset pos, wxSeekMode mode);
+    wxFileOffset OnSysTell() const;
+
+private:
+    wxBackingFile m_backer;
+    wxFileOffset m_pos;
+
+    DECLARE_NO_COPY_CLASS(wxBackedInputStream)
+};
+
+#endif // wxUSE_FILESYSTEM
+
+#endif // _WX_FILEBACK_H__