LWPoolAreaBookKeeper.icc

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/*
  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
*/
 
#undef LW_FIELDS
#define LW_FIELDS (reinterpret_cast<BitField*>(reinterpret_cast<char*>(this)+sizeof(LWPoolAreaBookKeeper)))
 
inline bool LWPoolAreaBookKeeper::isCompletelyFull() const
{
  return m_nUnusedEntries==m_nEntries;
}
 
inline bool LWPoolAreaBookKeeper::isCompletelyEmpty() const
{
  return m_nUnusedEntries==0;
}
 
inline unsigned LWPoolAreaBookKeeper::numberOfAvailableEntries() const
{
  return m_nUnusedEntries;
}
 
inline unsigned LWPoolAreaBookKeeper::numberOfEntriesHandedOut() const
{
  return m_nEntries-m_nUnusedEntries;
}
 
//____________________________________________________________________
inline void LWPoolAreaBookKeeper::returnEntry(unsigned iEntry)
{
  assert(!isCompletelyFull());
  const unsigned iField(iEntry/LW_ENTRIESPERGROUP);
  const unsigned iBit(iEntry%LW_ENTRIESPERGROUP);
  BitField & b = LW_FIELDS[iField];
  //Toggle the bit to set it:
  assert( ! (b & 1 << iBit) );
  b ^= 1 << iBit;
  assert(b & 1 << iBit);
  assert(b);
  m_nonEmptyField = iField;
  ++m_nUnusedEntries;
}
 
//____________________________________________________________________
inline unsigned LWPoolAreaBookKeeper::acquireEntry()
{
  assert((m_nonEmptyField==UINT_MAX)==(!m_nUnusedEntries));
  if (!m_nUnusedEntries)
    return UINT_MAX;
  assert(!isCompletelyEmpty());
  BitField & b = LW_FIELDS[m_nonEmptyField];
  assert(b);
  const unsigned firstSetBit = ffs(b)-1;//ffs(..) starts at 1 if rightmost bit is set,
                        //etc., up to 32 if only the leftmost
                        //bit is set.
  assert(firstSetBit<LW_ENTRIESPERGROUP);
 
 
  //Remember:
  //Set bit x in number: number |= 1 << x;
  //Clear bit x in number: number &= ~(1 << x);
  //Toggle bit x in number: number ^= 1 << x;
 
  //Toggle the bit to clear it:
  assert(b & 1 << firstSetBit);
  b ^= 1 << firstSetBit;
  assert( ! (b & 1 << firstSetBit) );
 
  const unsigned iEntry(LW_ENTRIESPERGROUP*m_nonEmptyField+firstSetBit);
  if (!b)
    findNewNonEmptyField();
  --m_nUnusedEntries;
  assert((m_nonEmptyField==UINT_MAX)==(!m_nUnusedEntries));
  return iEntry;
}
#undef LW_FIELDS