bitmask.cpp

"More for C++" is a class library that provides some features that are usually common for object ori

//
//  This file is part of the "More for C++" library
//
//  Copyright (c) 1999-2003 by Thorsten Goertz ([e-mail])
//
//  The "More for C++" library is free software; you can redistribute it and/or
//  modify it under the terms of the license that comes with this package.
//
//  Read "license.txt" for more details.
//
//  THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
//  WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES
//  OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.

////////////////////////////////////////////////////////////////////////////////

#include <cstring>
#include "bitmask.hpp"

using namespace more::core;

////////////////////////////////////////////////////////////////////////////////

size_t BitMask::calcSize
(
  size_t nNoOfBits
)
{
  return ( nNoOfBits + 7 ) >> 3;
}

////////////////////////////////////////////////////////////////////////////////

BitMask::BitMask
(
  byte*   pBytesForBits,
  size_t  nNoOfBytes,
  size_t  nNoOfBits
)
{
  initialize( pBytesForBits, nNoOfBytes, nNoOfBits );
}

////////////////////////////////////////////////////////////////////////////////

void BitMask::initialize
(
  byte*   pBytesForBits,
  size_t  nNoOfBytes,
  size_t  nNoOfBits
)
{
  m_pBytesForBits = pBytesForBits;
  m_nNoOfBytes = nNoOfBytes;
  m_nNoOfBits = nNoOfBits;
}

////////////////////////////////////////////////////////////////////////////////

size_t BitMask::getNoOfBits( ) const
{
  return m_nNoOfBits;
}

////////////////////////////////////////////////////////////////////////////////

void BitMask::clear( )
{
  if( m_pBytesForBits != 0 )
  {
    memset( m_pBytesForBits, 0, m_nNoOfBytes );
  }
}

////////////////////////////////////////////////////////////////////////////////

void BitMask::setBit
(
  size_t  nIndex,
  bool    bValue
)
{
  size_t  nIndexOfByte = nIndex / 8;
  byte    nMask = byte( 0x80 >> nIndex % 8 );
  byte&   rnByte = m_pBytesForBits[nIndexOfByte];

  if( rnByte == 0 )
  {
    rnByte = nMask;
  }
  else
  {
    if( bValue == true )
    {
      rnByte |= nMask;
    }
    else
    {
      rnByte &= 0xFF ^ nMask;
    }
  }
}

////////////////////////////////////////////////////////////////////////////////

bool BitMask::getBit
(
  size_t nIndex

) const
{
  size_t  nIndexOfByte = nIndex / 8;
  byte    nByte = m_pBytesForBits[nIndexOfByte];

  if( nByte != 0 )
  {
    nByte &= byte( 0x80 >> nIndex % 8 );
  }

  return nByte != 0;
}

////////////////////////////////////////////////////////////////////////////////