Re: bit field serialization

"Greg G" <GregG@discussions.microsoft.com> ha scritto nel messaggio
news:C3C9643C-4F1E-4F33-927E-2DB90BADAD25@microsoft.com...


I don't understand what is the internal reresentation that you use for
bitfields.
Do you store bit fields into an unsigned int, which is a DWORD on 32-bits
architectures?
If so, I imagine you have a DWORD data member of your class, e.g. DWORD
m_dwBits;
so you just have to write/read this field in the serialization process, i.e.
something like this:

void CMyBitField::Serialize( CArchive& archive)
{
  if( archive.IsStroring() )
  {
    archive << m_dwBits;
  }
  else
  {
    archive >> m_dwBits;
  }
}

Of course, in this way you are limited to 32 bit fields.

You might also consider using the std::valarray<bool> specialization of
valarray template:

http://msdn2.microsoft.com/en-us/library/sch31sbx(VS.80).aspx

So, you might have a std::valarray<bool> instance into your CMyBitField
class, and for serialization you might write first the size of the valarray
(the element count, the number of bits), then the elements themself, e.g.
using code like so (not tested):

// std::valarray<bool> m_bits; // data member storing the bit fields
void CMyBitField::Serialize( CArchive& archive)
{
  if( archive.IsStroring() )
  {
    // Write number of bits
    archive << (DWORD)m_bits.size();

   // Write the bit values
    for ( size_t i = 0; i < m_bits.size(); i++ )
      archive << m_bits[i];
  }
  else
  {
    // Read number of bits
    DWORD bitCount;
    archive >> bitCount;
    ASSERT( bitCount != 0 );

    // Read bit values
    m_bits.resize( bitCount )
       for ( size_t i = 0; i < numberOfBits; i++ )
        archive >> m_bits[i];
    }
  }
}

However, you might consider using XML for serialization, too.

G