freeldr/freeldr/cache/cm.h

   1 /*
   2  *  FreeLoader
   3  *  Copyright (C) 1998-2002  Brian Palmer  <brianp@sginet.com>
   4  *
   5  *  This program is free software; you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation; either version 2 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, write to the Free Software
  17  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18  */
  19
  20
  21 #include <freeldr.h>
  22 #include <rtl.h>
  23 #include <disk.h>
  24
  25 #ifndef __CM_H
  26 #define __CM_H
  27
  28 ///////////////////////////////////////////////////////////////////////////////////////
  29 //
  30 // This structure describes a cached block element. The disk is divided up into
  31 // cache blocks. For disks which LBA is not supported each block is the size of
  32 // one track. This will force the cache manager to make track sized reads, and
  33 // therefore maximizes throughput. For disks which support LBA the block size
  34 // is 64k because they have no cylinder, head, or sector boundaries.
  35 //
  36 ///////////////////////////////////////////////////////////////////////////////////////
  37 typedef struct
  38 {
  39         LIST_ITEM       ListEntry;                                      // Doubly linked list synchronization member
  40
  41         ULONG           BlockNumber;                            // Track index for CHS, 64k block index for LBA
  42         BOOL            LockedInCache;                          // Indicates that this block is locked in cache memory
  43         ULONG           AccessCount;                            // Access count for this block
  44
  45         PVOID           BlockData;                                      // Pointer to block data
  46
  47 } CACHE_BLOCK, *PCACHE_BLOCK;
  48
  49 ///////////////////////////////////////////////////////////////////////////////////////
  50 //
  51 // This structure describes a cached drive. It contains the BIOS drive number
  52 // and indicates whether or not LBA is supported. If LBA is not supported then
  53 // the drive's geometry is described here.
  54 //
  55 ///////////////////////////////////////////////////////////////////////////////////////
  56 typedef struct
  57 {
  58         ULONG                           DriveNumber;
  59         BOOL                            LbaSupported;
  60         GEOMETRY                        DriveGeometry;
  61
  62         ULONG                           BlockSize;                      // Block size (in sectors)
  63         PCACHE_BLOCK            CacheBlockHead;
  64
  65 } CACHE_DRIVE, *PCACHE_DRIVE;
  66
  67
  68 ///////////////////////////////////////////////////////////////////////////////////////
  69 //
  70 // Internal data
  71 //
  72 ///////////////////////////////////////////////////////////////////////////////////////
  73 extern  CACHE_DRIVE             CacheManagerDrive;
  74 extern  BOOL                    CacheManagerInitialized;
  75 extern  ULONG                   CacheBlockCount;
  76 extern  ULONG                   CacheSizeLimit;
  77 extern  ULONG                   CacheSizeCurrent;
  78
  79 ///////////////////////////////////////////////////////////////////////////////////////
  80 //
  81 // Internal functions
  82 //
  83 ///////////////////////////////////////////////////////////////////////////////////////
  84 PCACHE_BLOCK    CacheInternalGetBlockPointer(PCACHE_DRIVE CacheDrive, ULONG BlockNumber);                       // Returns a pointer to a CACHE_BLOCK structure given a block number
  85 PCACHE_BLOCK    CacheInternalFindBlock(PCACHE_DRIVE CacheDrive, ULONG BlockNumber);                                     // Searches the block list for a particular block
  86 PCACHE_BLOCK    CacheInternalAddBlockToCache(PCACHE_DRIVE CacheDrive, ULONG BlockNumber);                       // Adds a block to the cache's block list
  87 BOOL                    CacheInternalFreeBlock(PCACHE_DRIVE CacheDrive);                                                                        // Removes a block from the cache's block list & frees the memory
  88 VOID                    CacheInternalCheckCacheSizeLimits(PCACHE_DRIVE CacheDrive);                                                     // Checks the cache size limits to see if we can add a new block, if not calls CacheInternalFreeBlock()
  89 VOID                    CacheInternalDumpBlockList(PCACHE_DRIVE CacheDrive);                                                            // Dumps the list of cached blocks to the debug output port
  90 VOID                    CacheInternalOptimizeBlockList(PCACHE_DRIVE CacheDrive, PCACHE_BLOCK CacheBlock);       // Moves the specified block to the head of the list
  91
  92
  93 #endif // defined __CM_H