pagealloc.h

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// See the end of this file for license information.

#ifndef TORSION_PAGEALLOC_H
#define TORSION_PAGEALLOC_H

#include "list.h"
#include "arch.h"
#include "types.h"
#include "pagespan.h"


class Page_allocator {
protected:
  unsigned memory_begin;
  unsigned memory_end;
  Page* pages;        
  unsigned page_count;      
  unsigned free_list_count;   
  
  List<Page>* free_lists;
    
  Page*
  find_free_page(unsigned alignment, unsigned begin, unsigned end);

  Page*
  try_to_split_page(unsigned requested_alignment, unsigned begin, unsigned end);
  
  Page*
  split_page(Page* page, unsigned requested_alignment, unsigned begin,
             unsigned end);
    
  Page*
  try_to_coalesce_page(unsigned requested_alignment, unsigned begin,
                       unsigned end);

  Page*
  coalesce_page(Page* page, unsigned requested_alignment, unsigned begin,
                unsigned end);

public:
  void
  init(void* start, Size memory_size, unsigned max_alignment,
       void* metadata_end = NULL, bool managed_pages_are_physical = false);

  Page* alloc_page_within(unsigned alignment, void* owner, unsigned begin,
                          unsigned end);

  Page* alloc_page_above(unsigned alignment, void* owner, unsigned begin);

  Page* alloc_page_below(unsigned alignment, void* owner, unsigned end);

  Page* alloc_page(unsigned alignment, void* owner);

  void
  free_page(Page* page);
  
  Page*
  get_page_info(void* memory) const;

  inline void*
  get_metadata_start() {
    return (void*)pages;
  }

  void*
  get_max_metadata_start();

  inline bool
  manages(void* memory) {
    unsigned page_shifted = (unsigned)memory >> PAGE_ALIGNMENT;
    if (page_shifted >= memory_begin && page_shifted <= memory_end)
      return true;
    return false;
  }

  void
  print();
};

inline Page*
Page_allocator::alloc_page(unsigned alignment, void* owner) {
  return alloc_page_within(alignment, owner, memory_begin, memory_end - 1);
}

inline Page*
Page_allocator::alloc_page_above(unsigned alignment, void* owner,
                                 unsigned begin) {
  return alloc_page_within(alignment, owner, begin, memory_end - 1);
}

inline Page*
Page_allocator::alloc_page_below(unsigned alignment, void* owner,
                                 unsigned end) {
  return alloc_page_within(alignment, owner, memory_begin, end - 1);
}

inline Page*
Page_allocator::get_page_info(void* memory) const {
  return &pages[(unsigned(memory) >> PAGE_ALIGNMENT) - memory_begin];
}

#endif

/* Torsion Operating System, Copyright (C) 2000-2004 Dan Helfman
 *
 * This program 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.
 * 
 * This program 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 (in the COPYING file).
 * 
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

---

Torsion Operating System, Copyright (C) 2000-2004 Dan Helfman