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storage.h

Go to the documentation of this file.

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

#ifndef TORSION_STORAGE_H
#define TORSION_STORAGE_H

#include "blockdev.h"
#include "blockmap.h"
#include "segment.h"
#include "virtmem.h"
#include "addrmap.h"


class Superblock {
public:
  unsigned int signature;               
  unsigned int checkpoint_counter;      
  unsigned int block_directory;         
  unsigned int segment_directory;       
  unsigned int blocks_per_segment;      
  unsigned int curr_empty_segment;      
  static const unsigned int CORRECT_SIGNATURE = 0xbb66;

  static Superblock*
  create(unsigned int block_size) {
    return (Superblock*)virtual_mem.alloc(block_size);
  }
};


class Storage_system {
protected:
  Block_device* disk;                   
  Segment curr_segment;                 

  unsigned int first_block;             
  unsigned int blocks_per_segment;      
  unsigned int blocks_per_page;         
  unsigned int checkpoint_counter;      
  unsigned int curr_superblock;         
  Block_map block_map;                  
  Segment_map segment_map;              
  bool enabled;                         

public:
  void
  format(unsigned int first_block_to_use = 0, unsigned int segment_size = 0);

  // Determine whether a valid Torsion storage system begins on disk at
  // the given block number.
  bool
  is_formatted(unsigned int first_block_to_use = 0);

  void
  init(unsigned int first_block_to_use = 0);

  void
  write_superblock(unsigned int block_directory = 0,
                   unsigned int segment_directory = 0,
                   unsigned int curr_empty_segment = 0);

  void
  checkpoint();

  unsigned int
  log_page(void* page, bool update_block_map = true);

  unsigned int
  log_map(Address_map& map);

  unsigned int*
  load_table(Address_map& map, unsigned int dir_index);

  void
  load_page(void* virtual_page);

  void
  write_segment();

  void
  write_segment_if_full();

  inline void
  set_device(Block_device* device) {
    disk = device;
  }

  inline unsigned int
  block_to_segment_index(unsigned int segment_block) {
                                        // - 2 because of the two superblocks
    return (segment_block - first_block - 2) / blocks_per_segment;
  }

  inline unsigned int
  segment_index_to_block(unsigned int segment_index) {
                                        // + 2 because of the two superblocks
    return segment_index * blocks_per_segment + first_block + 2;
  }

  inline void
  enable() {
    enabled = true;
  }
  
  inline void
  disable() {
    enabled = false;
  }
};

#endif

/* Torsion Operating System, Copyright (C) 2000-2002 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) 2000-2002 Dan Helfman