cds/details/bit_reverse_counter.h

   1 //$$CDS-header$$
   2
   3 #ifndef __CDS_DETAILS_BIT_REVERSE_COUNTER_H
   4 #define __CDS_DETAILS_BIT_REVERSE_COUNTER_H
   5
   6 #include <cds/algo/bitop.h>
   7
   8 //@cond
   9 namespace cds { namespace bitop {
  10
  11     template <typename Counter = size_t>
  12     class bit_reverse_counter
  13     {
  14     public:
  15         typedef Counter     counter_type;
  16
  17     private:
  18         counter_type        m_nCounter;
  19         counter_type        m_nReversed;
  20         int                 m_nHighBit;
  21
  22     public:
  23         bit_reverse_counter()
  24             : m_nCounter(0)
  25             , m_nReversed(0)
  26             , m_nHighBit(-1)
  27         {}
  28
  29         counter_type inc()
  30         {
  31             ++m_nCounter;
  32             int nBit;
  33             for ( nBit = m_nHighBit - 1; nBit >= 0; --nBit ) {
  34                 if ( !cds::bitop::complement( m_nReversed, nBit ))
  35                     break;
  36             }
  37             if ( nBit < 0 ) {
  38                 m_nReversed = m_nCounter;
  39                 ++m_nHighBit;
  40             }
  41             return m_nReversed;
  42         }
  43
  44         counter_type dec()
  45         {
  46             --m_nCounter;
  47             int nBit;
  48             for ( nBit = m_nHighBit - 1; nBit >= 0; --nBit ) {
  49                 if ( cds::bitop::complement( m_nReversed, nBit ) )
  50                     break;
  51             }
  52             if ( nBit < 0 ) {
  53                 m_nReversed = m_nCounter;
  54                 --m_nHighBit;
  55             }
  56             return m_nReversed;
  57         }
  58
  59         counter_type    value() const
  60         {
  61             return m_nCounter;
  62         }
  63
  64         counter_type    reversed_value() const
  65         {
  66             return m_nReversed;
  67         }
  68     };
  69
  70 }}   // namespace cds::bitop
  71 //@endcond
  72
  73 #endif // #ifndef __CDS_DETAILS_BIT_REVERSE_COUNTER_H