//
// Copyright (C) 2000, 2001, 2002 Andrey Slepuhin <pooh@msu.ru>
//
// libp++ is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// libp++ is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with libp++; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
// $Source$
// $Revision$
// $Date$
// Author: Andrey Slepuhin <pooh@msu.ru>

#include "pxx_common.hh"

#ifndef __pxx_common_ih__
#define __pxx_common_ih__

namespace pxx
{

//
// This function returns a ceiling of a binary logarythm of its argument.
// Here are two implementations of this function. Choose the one that you like.
inline size_t get_order (size_t _size)
{
  if (_size > 0) _size--;
#if 1
  size_t b;
  int n = -8;
  do {
    b = _size & size_t(0xFF);
    _size >>= 8;
    n += 8;
  } while (_size != 0);
  return orders[b] + n + 1;
#else
  size_t n = 0;
  if (_size & 0xFFFF0000) { _size &= 0xFFFF0000; n += 16; }
  if (_size & 0xFF00FF00) { _size &= 0xFF00FF00; n += 8; }
  if (_size & 0xF0F0F0F0) { _size &= 0xF0F0F0F0; n += 4; }
  if (_size & 0xCCCCCCCC) { _size &= 0xCCCCCCCC; n += 2; }
  if (_size & 0xAAAAAAAA) n += 1;
  return n + 1;
#endif
}

//
// This functions checks whether a pointer is properly aligned. The second
// argument should be an exponent of 2.
inline bool ptr_is_aligned (void* _ptr, uintptr_t _align)
{
  return ((_align - 1) & uintptr_t(_ptr)) == 0;
}

//
// This function aligns a pointer, rounding it to a smaller value.
inline void* ptr_align (void* _ptr, uintptr_t _align)
{
  return (void*)(((uintptr_t)_ptr) & (~(_align - 1)));
}

//
// This function aligns an integer size, rounding it to a higher value.
inline size_t size_align (size_t _size, size_t _align)
{
  _align--;
  return (_size + _align) & (~(_align));
}

//
// These functions implement bit operations on pointer values.

inline void* ptr_and (void* _p1, void* _p2)
{
  return (void*)((uintptr_t)_p1 & (uintptr_t)_p2);
}

inline void* ptr_or (void* _p1, void* _p2)
{
  return (void*)((uintptr_t)_p1 | (uintptr_t)_p2);
}

inline void* ptr_xor (void* _p1, void* _p2)
{
  return (void*)((uintptr_t)_p1 ^ (uintptr_t)_p2);
}

//
// This function finds the least significant bit by which two pointers differ
// and returns an integer where this bit is set.
inline uintptr_t ptr_diff (void const* _p1, void const* _p2)
{
  uintptr_t diff = (uintptr_t)_p1 ^ (uintptr_t)_p2;
  return ((diff ^ (diff - 1)) >> 1) + 1;
}

template <typename type_t>
inline type_t* ptr_add (type_t* _ptr, size_t _value)
{
  return (type_t*)((char*)_ptr + _value);
}

//
// Pointer arithmetic.
template <typename type_t>
inline type_t* ptr_add_offset (type_t* _ptr, ssize_t _value)
{
  return (type_t*)((char*)_ptr + _value);
}

template <typename type_t>
inline type_t* ptr_sub_offset (type_t* _ptr, ssize_t _value)
{
  return (type_t*)((char*)_ptr - _value);
}

template <typename type1_t, typename type2_t>
inline ssize_t ptr_sub (type1_t* _ptr1, type2_t* _ptr2)
{
  return ((char*)_ptr1 - (char*)_ptr2);
}

}

#endif // __pxx_common_ih__