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diff --git a/src/stlplus/persistence/persistent_bitset.tpp b/src/stlplus/persistence/persistent_bitset.tpp
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index 0000000..e6b4d54
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+++ b/src/stlplus/persistence/persistent_bitset.tpp
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+////////////////////////////////////////////////////////////////////////////////
+
+//   Author:    Andy Rushton
+//   Copyright: (c) Southampton University 1999-2004
+//              (c) Andy Rushton           2004-2009
+//   License:   BSD License, see ../docs/license.html
+
+////////////////////////////////////////////////////////////////////////////////
+#include "persistent_int.hpp"
+
+namespace stlplus
+{
+
+  ////////////////////////////////////////////////////////////////////////////////
+  // format: data msB first, packed into bytes with lowest index at the byte's lsb
+
+  // Note: the interface does not provide access to the internal storage and yet
+  // to be efficient the std::bitset must be packed as bytes. Thus I have to do it the
+  // hard way.
+
+  template<size_t N>
+  void dump_bitset(dump_context& context, const std::bitset<N>& data)
+    throw(persistent_dump_failed)
+  {
+    size_t bits = data.size();
+    size_t bytes = (bits+7)/8;
+    for (size_t B = bytes; B--; )
+    {
+      unsigned char ch = 0;
+      for (size_t b = 0; b < 8; b++)
+      {
+        size_t bit = B*8+b;
+        if (bit < bits && data.test(bit))
+          ch |= (0x01 << b);
+      }
+      dump_unsigned_char(context,ch);
+    }
+  }
+
+  template<size_t N>
+  void restore_bitset(restore_context& context, std::bitset<N>& data)
+    throw(persistent_restore_failed)
+  {
+    size_t bits = data.size();
+    size_t bytes = (bits+7)/8;
+    for (size_t B = bytes; B--; )
+    {
+      unsigned char ch = 0;
+      restore_unsigned_char(context,ch);
+      for (size_t b = 0; b < 8; b++)
+      {
+        size_t bit = B*8+b;
+        if (bit >= bits) break;
+        data.set(bit, ch & (0x01 << b) ? true : false);
+      }
+    }
+  }
+
+  ////////////////////////////////////////////////////////////////////////////////
+
+} // end namespace stlplus