diff --git a/src/util/hei_bit_string.cpp b/src/util/hei_bit_string.cpp
new file mode 100755
index 0000000..bdc8694
--- /dev/null
+++ b/src/util/hei_bit_string.cpp
@@ -0,0 +1,446 @@
+
+#include <prdfBitString.H>
+
+#include <prdfAssert.h>
+
+#include <algorithm>
+
+namespace libhei
+{
+
+//##############################################################################
+//                             BitString class
+//##############################################################################
+
+const uint32_t BitString::CPU_WORD_BIT_LEN = sizeof(CPU_WORD) * 8;
+
+const CPU_WORD BitString::CPU_WORD_MASK = static_cast<CPU_WORD>(-1);
+
+//------------------------------------------------------------------------------
+
+CPU_WORD BitString::getField( uint32_t i_pos, uint32_t i_len ) const
+{
+    PRDF_ASSERT( nullptr != getBufAddr() );      // must to have a valid address
+    PRDF_ASSERT( 0 < i_len );                    // must have at least one bit
+    PRDF_ASSERT( i_len <= CPU_WORD_BIT_LEN );    // i_len length must be valid
+    PRDF_ASSERT( i_pos + i_len <= getBitLen() ); // field must be within range
+
+    // The returned value.
+    CPU_WORD o_val = 0;
+
+    // Get the relative address and position of the field.
+    uint32_t relPos = 0;
+    CPU_WORD * relAddr = getRelativePosition( relPos, i_pos );
+
+    // The return value may cross two CPU_WORD addresses. Get length of each
+    // chunk, mask to clear the right-handed bits, and the shift value to make
+    // each chunk left-justified.
+    uint32_t len0 = i_len, len1 = 0;
+    if ( CPU_WORD_BIT_LEN < relPos + i_len )
+    {
+        len0 = CPU_WORD_BIT_LEN - relPos;
+        len1 = i_len - len0;
+    }
+
+    CPU_WORD mask0 = CPU_WORD_MASK << (CPU_WORD_BIT_LEN - len0);
+    CPU_WORD mask1 = CPU_WORD_MASK << (CPU_WORD_BIT_LEN - len1);
+
+    uint32_t shift0 = relPos;
+    uint32_t shift1 = CPU_WORD_BIT_LEN - relPos;
+
+    // Get first half of the value.
+    o_val = (*relAddr << shift0) & mask0;
+
+    // Get the second half of the value, if needed
+    if ( CPU_WORD_BIT_LEN < relPos + i_len )
+    {
+        ++relAddr;
+        o_val |= (*relAddr & mask1) >> shift1;
+    }
+
+    return o_val;
+}
+
+//------------------------------------------------------------------------------
+
+void BitString::setField( uint32_t i_pos, uint32_t i_len, CPU_WORD i_val )
+{
+    PRDF_ASSERT( nullptr != getBufAddr() );      // must to have a valid address
+    PRDF_ASSERT( 0 < i_len );                    // must have at least one bit
+    PRDF_ASSERT( i_len <= CPU_WORD_BIT_LEN );    // i_len length must be valid
+    PRDF_ASSERT( i_pos + i_len <= getBitLen() ); // field must be within range
+
+    // Get the relative address and position of the field.
+    uint32_t relPos = 0;
+    CPU_WORD * relAddr = getRelativePosition( relPos, i_pos );
+
+    // The value is left-justified. Ignore all other bits.
+    CPU_WORD mask = CPU_WORD_MASK << (CPU_WORD_BIT_LEN - i_len);
+    CPU_WORD val  = i_val & mask;
+
+    // Set first half of the value.
+    *relAddr &= ~(mask >> relPos); // Clear field
+    *relAddr |=  (val  >> relPos); // Set field
+
+    // Get the second half of the value, if needed
+    if ( CPU_WORD_BIT_LEN < relPos + i_len )
+    {
+        relAddr++;
+        *relAddr &= ~(mask << (CPU_WORD_BIT_LEN - relPos)); // Clear field
+        *relAddr |=  (val  << (CPU_WORD_BIT_LEN - relPos)); // Set field
+    }
+}
+
+//------------------------------------------------------------------------------
+
+void BitString::setPattern( uint32_t i_sPos, uint32_t i_sLen,
+                            CPU_WORD i_pattern, uint32_t i_pLen )
+{
+    PRDF_ASSERT(nullptr != getBufAddr());        // must to have a valid address
+    PRDF_ASSERT(0 < i_sLen);                     // must have at least one bit
+    PRDF_ASSERT(i_sPos + i_sLen <= getBitLen()); // field must be within range
+    PRDF_ASSERT(0 < i_pLen);                     // must have at least one bit
+    PRDF_ASSERT(i_pLen <= CPU_WORD_BIT_LEN);     // i_pLen length must be valid
+
+    // Get a bit string for the pattern subset (right justified).
+    BitString bso ( i_pLen, &i_pattern, CPU_WORD_BIT_LEN - i_pLen );
+
+    // Iterate the range in chunks the size of i_pLen.
+    uint32_t endPos = i_sPos + i_sLen;
+    for ( uint32_t pos = i_sPos; pos < endPos; pos += i_pLen )
+    {
+        // The true chunk size is either i_pLen or the leftovers at the end.
+        uint32_t len = std::min( i_pLen, endPos - pos );
+
+        // Get this chunk's pattern value, truncate (left justified) if needed.
+        CPU_WORD pattern = bso.getField( 0, len );
+
+        // Set the pattern in this string.
+        setField( pos, len, pattern );
+    }
+}
+
+//------------------------------------------------------------------------------
+
+void BitString::setString( const BitString & i_sStr, uint32_t i_sPos,
+                           uint32_t i_sLen, uint32_t i_dPos )
+{
+    // Ensure the source parameters are valid.
+    PRDF_ASSERT( nullptr != i_sStr.getBufAddr() );
+    PRDF_ASSERT( 0 < i_sLen ); // at least one bit to copy
+    PRDF_ASSERT( i_sPos + i_sLen <= i_sStr.getBitLen() );
+
+    // Ensure the destination has at least one bit available to copy.
+    PRDF_ASSERT( nullptr != getBufAddr() );
+    PRDF_ASSERT( i_dPos < getBitLen() );
+
+    // If the source length is greater than the destination length than the
+    // extra source bits are ignored.
+    uint32_t actLen = std::min( i_sLen, getBitLen() - i_dPos );
+
+    // The bit strings may be in overlapping memory spaces. So we need to copy
+    // the data in the correct direction to prevent overlapping.
+    uint32_t sRelOffset = 0, dRelOffset = 0;
+    CPU_WORD * sRelAddr = i_sStr.getRelativePosition( sRelOffset, i_sPos );
+    CPU_WORD * dRelAddr =        getRelativePosition( dRelOffset, i_dPos );
+
+    // Copy the data.
+    if ( (dRelAddr == sRelAddr) && (dRelOffset == sRelOffset) )
+    {
+        // Do nothing. The source and destination are the same.
+    }
+    else if ( (dRelAddr < sRelAddr) ||
+              ((dRelAddr == sRelAddr) && (dRelOffset < sRelOffset)) )
+    {
+        // Copy the data forward.
+        for ( uint32_t pos = 0; pos < actLen; pos += CPU_WORD_BIT_LEN )
+        {
+            uint32_t len = std::min( actLen - pos, CPU_WORD_BIT_LEN );
+
+            CPU_WORD value = i_sStr.getField( i_sPos + pos, len );
+            setField( i_dPos + pos, len, value );
+        }
+    }
+    else // Copy the data backwards.
+    {
+        // Get the first position of the last chunk (CPU_WORD aligned).
+        uint32_t lastPos = ((actLen-1) / CPU_WORD_BIT_LEN) * CPU_WORD_BIT_LEN;
+
+        // Start with the last chunk and work backwards.
+        for ( int32_t pos = lastPos; 0 <= pos; pos -= CPU_WORD_BIT_LEN )
+        {
+            uint32_t len = std::min( actLen - pos, CPU_WORD_BIT_LEN );
+
+            CPU_WORD value = i_sStr.getField( i_sPos + pos, len );
+            setField( i_dPos + pos, len, value );
+        }
+    }
+}
+
+//------------------------------------------------------------------------------
+
+void BitString::maskString( const BitString & i_mask )
+{
+    // Get the length of the smallest string.
+    uint32_t actLen = std::min( getBitLen(), i_mask.getBitLen() );
+
+    for ( uint32_t pos = 0; pos < actLen; pos += CPU_WORD_BIT_LEN )
+    {
+        uint32_t len = std::min( actLen - pos, CPU_WORD_BIT_LEN );
+
+        CPU_WORD dVal =        getField( pos, len );
+        CPU_WORD sVal = i_mask.getField( pos, len );
+
+        setField( pos, len, dVal & ~sVal );
+    }
+}
+
+//------------------------------------------------------------------------------
+
+bool BitString::isEqual( const BitString & i_str ) const
+{
+    if ( getBitLen() != i_str.getBitLen() )
+        return false; // size not equal
+
+    for ( uint32_t pos = 0; pos < getBitLen(); pos += CPU_WORD_BIT_LEN )
+    {
+        uint32_t len = std::min( getBitLen() - pos, CPU_WORD_BIT_LEN );
+
+        if ( getField(pos, len) != i_str.getField(pos, len) )
+            return false; // bit strings do not match
+    }
+
+    return true; // bit strings match
+}
+
+//------------------------------------------------------------------------------
+
+bool BitString::isZero() const
+{
+    for ( uint32_t pos = 0; pos < getBitLen(); pos += CPU_WORD_BIT_LEN )
+    {
+        uint32_t len = std::min( getBitLen() - pos, CPU_WORD_BIT_LEN );
+
+        if ( 0 != getField(pos, len) )
+            return false; // something is non-zero
+    }
+
+    return true; // everything was zero
+}
+
+//------------------------------------------------------------------------------
+
+uint32_t BitString::getSetCount( uint32_t i_pos, uint32_t i_len ) const
+{
+    uint32_t endPos = i_pos + i_len;
+
+    PRDF_ASSERT( endPos <= getBitLen() );
+
+    uint32_t count = 0;
+
+    for ( uint32_t i = i_pos; i < endPos; i++ )
+    {
+        if ( isBitSet(i) ) count++;
+    }
+
+    return count;
+}
+
+//------------------------------------------------------------------------------
+
+BitStringBuffer BitString::operator~() const
+{
+    BitStringBuffer bsb( getBitLen() );
+
+    for ( uint32_t pos = 0; pos < getBitLen(); pos += CPU_WORD_BIT_LEN )
+    {
+        uint32_t len = std::min( getBitLen() - pos, CPU_WORD_BIT_LEN );
+
+        CPU_WORD dVal = getField( pos, len );
+
+        bsb.setField( pos, len, ~dVal );
+    }
+
+    return bsb;
+}
+
+//------------------------------------------------------------------------------
+
+BitStringBuffer BitString::operator&( const BitString & i_bs ) const
+{
+    // Get the length of the smallest string.
+    uint32_t actLen = std::min( getBitLen(), i_bs.getBitLen() );
+
+    BitStringBuffer bsb( actLen );
+
+    for ( uint32_t pos = 0; pos < actLen; pos += CPU_WORD_BIT_LEN )
+    {
+        uint32_t len = std::min( actLen - pos, CPU_WORD_BIT_LEN );
+
+        CPU_WORD dVal =      getField( pos, len );
+        CPU_WORD sVal = i_bs.getField( pos, len );
+
+        bsb.setField( pos, len, dVal & sVal );
+    }
+
+    return bsb;
+}
+
+//------------------------------------------------------------------------------
+
+BitStringBuffer BitString::operator|( const BitString & i_bs ) const
+{
+    // Get the length of the smallest string.
+    uint32_t actLen = std::min( getBitLen(), i_bs.getBitLen() );
+
+    BitStringBuffer bsb( actLen );
+
+    for ( uint32_t pos = 0; pos < actLen; pos += CPU_WORD_BIT_LEN )
+    {
+        uint32_t len = std::min( actLen - pos, CPU_WORD_BIT_LEN );
+
+        CPU_WORD dVal =      getField( pos, len );
+        CPU_WORD sVal = i_bs.getField( pos, len );
+
+        bsb.setField( pos, len, dVal | sVal );
+    }
+
+    return bsb;
+}
+
+//------------------------------------------------------------------------------
+
+BitStringBuffer BitString::operator>>( uint32_t i_shift ) const
+{
+    BitStringBuffer bsb( getBitLen() ); // default all zeros
+
+    if ( i_shift < getBitLen() )
+    {
+        // bso overlays bsb, containing the shifted offset.
+        BitString bso ( bsb.getBitLen() - i_shift, bsb.getBufAddr(), i_shift );
+
+        // Copy this into bso.
+        bso.setString( *this );
+    }
+
+    return bsb;
+}
+
+//------------------------------------------------------------------------------
+
+BitStringBuffer BitString::operator<<( uint32_t i_shift ) const
+{
+    BitStringBuffer bsb( getBitLen() ); // default all zeros
+
+    if ( i_shift < getBitLen() )
+    {
+        // bso overlays *this, containing the shifted offset.
+        BitString bso ( this->getBitLen() - i_shift, this->getBufAddr(),
+                        i_shift );
+
+        // Copy bso into bsb.
+        bsb.setString( bso );
+    }
+
+    return bsb;
+}
+
+//------------------------------------------------------------------------------
+
+CPU_WORD * BitString::getRelativePosition( uint32_t & o_relPos,
+                                           uint32_t   i_absPos ) const
+{
+    PRDF_ASSERT( nullptr != getBufAddr() ); // must to have a valid address
+    PRDF_ASSERT( i_absPos < getBitLen() );  // must be a valid position
+
+    o_relPos = (i_absPos + iv_offset) % CPU_WORD_BIT_LEN;
+
+    return iv_bufAddr + ((i_absPos + iv_offset) / CPU_WORD_BIT_LEN);
+}
+
+//##############################################################################
+//                          BitStringBuffer class
+//##############################################################################
+
+BitStringBuffer::BitStringBuffer( uint32_t i_bitLen ) :
+    BitString( i_bitLen, nullptr )
+{
+    initBuffer();
+}
+
+//------------------------------------------------------------------------------
+
+BitStringBuffer::~BitStringBuffer()
+{
+    delete [] getBufAddr();
+}
+
+//------------------------------------------------------------------------------
+
+BitStringBuffer::BitStringBuffer( const BitString & i_bs ) :
+    BitString( i_bs.getBitLen(), nullptr )
+{
+    initBuffer();
+    if ( !i_bs.isZero() ) setString( i_bs );
+}
+
+//------------------------------------------------------------------------------
+
+BitStringBuffer::BitStringBuffer( const BitStringBuffer & i_bsb ) :
+    BitString( i_bsb.getBitLen(), nullptr )
+{
+    initBuffer();
+    if ( !i_bsb.isZero() ) setString( i_bsb );
+}
+
+//------------------------------------------------------------------------------
+
+BitStringBuffer & BitStringBuffer::operator=( const BitString & i_bs )
+{
+    // The initBuffer() function will deallocate the buffer as well, however we
+    // also need to deallocate the buffer here before we set the length.
+    delete [] getBufAddr();
+    setBufAddr( nullptr );
+
+    setBitLen( i_bs.getBitLen() );
+    initBuffer();
+    if ( !i_bs.isZero() ) setString( i_bs );
+
+    return *this;
+}
+
+//------------------------------------------------------------------------------
+
+BitStringBuffer & BitStringBuffer::operator=( const BitStringBuffer & i_bsb )
+{
+    if ( this != &i_bsb ) // Check for assignment to self
+    {
+        // The initBuffer() function will deallocate the buffer as well, however
+        // we also need to deallocate the buffer here before we set the length.
+        delete [] getBufAddr();
+        setBufAddr( nullptr );
+
+        setBitLen( i_bsb.getBitLen() );
+        initBuffer();
+        if ( !i_bsb.isZero() ) setString( i_bsb );
+    }
+
+    return *this;
+}
+
+//------------------------------------------------------------------------------
+
+void BitStringBuffer::initBuffer()
+{
+    // Deallocate the current buffer.
+    delete [] getBufAddr();
+
+    // Allocate the new buffer.
+    setBufAddr( new CPU_WORD[ getNumCpuWords(getBitLen()) ] );
+
+    // Clear the new buffer.
+    if ( !isZero() ) clearAll();
+}
+
+} // end namespace libhei
+