ut0bitset.h

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/** @file include/ut0bitset.h
 Utilities for bitset operations
 
 Created 11/05/2018 Bin Su
 ***********************************************************************/
 
#ifndef ut0bitset_h
#define ut0bitset_h
 
/** A simple bitset wrapper class, whose size can be specified
after the object has been defined */
class Bitset {
 public:
  /** Constructor */
  Bitset() : m_bitset(nullptr), m_size(0) {}
 
  /** Destructor */
  ~Bitset() = default;
 
  /** Initialize the bitset with a byte array and size
  @param[in]    bitset  byte array for this bitset
  @param[in]    size   size of the byte array */
  void init(byte *bitset, size_t size) {
    m_bitset = bitset;
    m_size = size;
    m_capacity = size;
  }
 
  /** Copy a byte array and size to current bitmap
  @param[in]    bitset  byte array for this bitset
  @param[in]    size   size of the byte array */
  void copy(const byte *bitset, size_t size) {
    ut_ad(m_capacity >= size);
    memcpy(m_bitset, bitset, size);
    m_size = size;
  }
 
  /** Set the specified bit to the value 'bit'
  @param[in]    pos     specified bit
  @param[in]    v       true or false */
  void set(size_t pos, bool v = true) {
    ut_ad(pos / 8 < m_size);
    m_bitset[pos / 8] &= ~(0x1 << (pos & 0x7));
    m_bitset[pos / 8] |= (static_cast<uint>(v) << (pos & 0x7));
  }
 
  /** Set all bits to true */
  void set() { memset(m_bitset, 0xFF, m_size); }
 
  /** Set all bits to false */
  void reset() { memset(m_bitset, 0, m_size); }
 
  /** Test if the specified bit is set or not
  @param[in]    pos     the specified bit
  @return True if this bit is set, otherwise false */
  bool test(size_t pos) const {
    ut_ad(pos / 8 < m_size);
    return ((m_bitset[pos / 8] >> (pos & 0x7)) & 0x1);
  }
 
  /** Get the size of current bitset
  @return the size of the bitset */
  size_t size() const { return (m_size); }
 
  /** Get the capacity of current bitset
  @return the capacity of the bitset */
  size_t capacity() const { return (m_capacity); }
 
  /** Get the bitset, don't allow to modify it!
  @return current bitset */
  const byte *bitset() const { return (m_bitset); }
 
  /** Set current bitset with specified one. Current bitset should have
  called init() to allocate its own bitmap memory which should be big
  enough for the assignment.
  @param[in]    from    set the bitset from this one
  @return current bitset object */
  Bitset &operator=(const Bitset &from) {
    ut_ad(m_capacity >= from.m_size);
    memcpy(m_bitset, from.m_bitset, from.m_size);
    m_size = from.m_size;
 
    return (*this);
  }
 
 private:
  /** Bitset bytes */
  byte *m_bitset;
 
  /** Bitset size in bytes */
  size_t m_size;
 
  /** Bitset capacity, could be bigger than m_size if one smaller bitmap
  has been assigned to it, after a copy() called */
  size_t m_capacity;
};
 
#endif