reactos/boot/freeldr/freeldr/include/cache.h

   1 /*
   2  *  FreeLoader
   3  *  Copyright (C) 1998-2003  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 #ifndef __CACHE_H
  22 #define __CACHE_H
  23
  24 ///////////////////////////////////////////////////////////////////////////////////////
  25 //
  26 // This structure describes a cached block element. The disk is divided up into
  27 // cache blocks. For disks which LBA is not supported each block is the size of
  28 // one track. This will force the cache manager to make track sized reads, and
  29 // therefore maximizes throughput. For disks which support LBA the block size
  30 // is 64k because they have no cylinder, head, or sector boundaries.
  31 //
  32 ///////////////////////////////////////////////////////////////////////////////////////
  33 typedef struct
  34 {
  35         LIST_ITEM       ListEntry;                                      // Doubly linked list synchronization member
  36
  37         ULONG                   BlockNumber;                            // Track index for CHS, 64k block index for LBA
  38         BOOL            LockedInCache;                          // Indicates that this block is locked in cache memory
  39         ULONG                   AccessCount;                            // Access count for this block
  40
  41         PVOID           BlockData;                                      // Pointer to block data
  42
  43 } CACHE_BLOCK, *PCACHE_BLOCK;
  44
  45 ///////////////////////////////////////////////////////////////////////////////////////
  46 //
  47 // This structure describes a cached drive. It contains the BIOS drive number
  48 // and indicates whether or not LBA is supported. If LBA is not supported then
  49 // the drive's geometry is described here.
  50 //
  51 ///////////////////////////////////////////////////////////////////////////////////////
  52 typedef struct
  53 {
  54         ULONG                   DriveNumber;
  55         ULONG                   BytesPerSector;
  56
  57         ULONG                   BlockSize;                      // Block size (in sectors)
  58         PCACHE_BLOCK            CacheBlockHead;
  59
  60 } CACHE_DRIVE, *PCACHE_DRIVE;
  61
  62
  63 ///////////////////////////////////////////////////////////////////////////////////////
  64 //
  65 // Internal data
  66 //
  67 ///////////////////////////////////////////////////////////////////////////////////////
  68 extern  CACHE_DRIVE             CacheManagerDrive;
  69 extern  BOOL                    CacheManagerInitialized;
  70 extern  ULONG                           CacheBlockCount;
  71 extern  ULONG                           CacheSizeLimit;
  72 extern  ULONG                           CacheSizeCurrent;
  73
  74 ///////////////////////////////////////////////////////////////////////////////////////
  75 //
  76 // Internal functions
  77 //
  78 ///////////////////////////////////////////////////////////////////////////////////////
  79 PCACHE_BLOCK    CacheInternalGetBlockPointer(PCACHE_DRIVE CacheDrive, ULONG BlockNumber);                               // Returns a pointer to a CACHE_BLOCK structure given a block number
  80 PCACHE_BLOCK    CacheInternalFindBlock(PCACHE_DRIVE CacheDrive, ULONG BlockNumber);                                     // Searches the block list for a particular block
  81 PCACHE_BLOCK    CacheInternalAddBlockToCache(PCACHE_DRIVE CacheDrive, ULONG BlockNumber);                               // Adds a block to the cache's block list
  82 BOOL                    CacheInternalFreeBlock(PCACHE_DRIVE CacheDrive);                                                                        // Removes a block from the cache's block list & frees the memory
  83 VOID                    CacheInternalCheckCacheSizeLimits(PCACHE_DRIVE CacheDrive);                                                     // Checks the cache size limits to see if we can add a new block, if not calls CacheInternalFreeBlock()
  84 VOID                    CacheInternalDumpBlockList(PCACHE_DRIVE CacheDrive);                                                            // Dumps the list of cached blocks to the debug output port
  85 VOID                    CacheInternalOptimizeBlockList(PCACHE_DRIVE CacheDrive, PCACHE_BLOCK CacheBlock);       // Moves the specified block to the head of the list
  86
  87
  88 BOOL    CacheInitializeDrive(ULONG DriveNumber);
  89 VOID    CacheInvalidateCacheData(VOID);
  90 BOOL    CacheReadDiskSectors(ULONG DiskNumber, ULONG StartSector, ULONG SectorCount, PVOID Buffer);
  91 BOOL    CacheForceDiskSectorsIntoCache(ULONG DiskNumber, ULONG StartSector, ULONG SectorCount);
  92 BOOL    CacheReleaseMemory(ULONG MinimumAmountToRelease);
  93
  94 #endif // defined __CACHE_H