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 along
  16  *  with this program; if not, write to the Free Software Foundation, Inc.,
  17  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  */
  19
  20
  21 #pragma once
  22
  23 #define TAG_CACHE_DATA 'DcaC'
  24 #define TAG_CACHE_BLOCK 'BcaC'
  25
  26 ///////////////////////////////////////////////////////////////////////////////////////
  27 //
  28 // This structure describes a cached block element. The disk is divided up into
  29 // cache blocks. For disks which LBA is not supported each block is the size of
  30 // one track. This will force the cache manager to make track sized reads, and
  31 // therefore maximizes throughput. For disks which support LBA the block size
  32 // is 64k because they have no cylinder, head, or sector boundaries.
  33 //
  34 ///////////////////////////////////////////////////////////////////////////////////////
  35 typedef struct
  36 {
  37     LIST_ENTRY    ListEntry;                    // Doubly linked list synchronization member
  38
  39     ULONG            BlockNumber;                // Track index for CHS, 64k block index for LBA
  40     BOOLEAN        LockedInCache;                // Indicates that this block is locked in cache memory
  41     ULONG            AccessCount;                // Access count for this block
  42
  43     PVOID        BlockData;                    // Pointer to block data
  44
  45 } CACHE_BLOCK, *PCACHE_BLOCK;
  46
  47 ///////////////////////////////////////////////////////////////////////////////////////
  48 //
  49 // This structure describes a cached drive. It contains the BIOS drive number
  50 // and indicates whether or not LBA is supported. If LBA is not supported then
  51 // the drive's geometry is described here.
  52 //
  53 ///////////////////////////////////////////////////////////////////////////////////////
  54 typedef struct
  55 {
  56     UCHAR            DriveNumber;
  57     ULONG            BytesPerSector;
  58
  59     ULONG            BlockSize;            // Block size (in sectors)
  60     LIST_ENTRY        CacheBlockHead;            // Contains CACHE_BLOCK structures
  61
  62 } CACHE_DRIVE, *PCACHE_DRIVE;
  63
  64
  65 ///////////////////////////////////////////////////////////////////////////////////////
  66 //
  67 // Internal data
  68 //
  69 ///////////////////////////////////////////////////////////////////////////////////////
  70 extern    CACHE_DRIVE        CacheManagerDrive;
  71 extern    BOOLEAN            CacheManagerInitialized;
  72 extern    ULONG                CacheBlockCount;
  73 extern    SIZE_T                CacheSizeLimit;
  74 extern    SIZE_T                CacheSizeCurrent;
  75
  76 ///////////////////////////////////////////////////////////////////////////////////////
  77 //
  78 // Internal functions
  79 //
  80 ///////////////////////////////////////////////////////////////////////////////////////
  81 PCACHE_BLOCK    CacheInternalGetBlockPointer(PCACHE_DRIVE CacheDrive, ULONG BlockNumber);                // Returns a pointer to a CACHE_BLOCK structure given a block number
  82 PCACHE_BLOCK    CacheInternalFindBlock(PCACHE_DRIVE CacheDrive, ULONG BlockNumber);                    // Searches the block list for a particular block
  83 PCACHE_BLOCK    CacheInternalAddBlockToCache(PCACHE_DRIVE CacheDrive, ULONG BlockNumber);                // Adds a block to the cache's block list
  84 BOOLEAN            CacheInternalFreeBlock(PCACHE_DRIVE CacheDrive);                                    // Removes a block from the cache's block list & frees the memory
  85 VOID            CacheInternalCheckCacheSizeLimits(PCACHE_DRIVE CacheDrive);                            // Checks the cache size limits to see if we can add a new block, if not calls CacheInternalFreeBlock()
  86 VOID            CacheInternalDumpBlockList(PCACHE_DRIVE CacheDrive);                                // Dumps the list of cached blocks to the debug output port
  87 VOID            CacheInternalOptimizeBlockList(PCACHE_DRIVE CacheDrive, PCACHE_BLOCK CacheBlock);    // Moves the specified block to the head of the list
  88
  89
  90 BOOLEAN    CacheInitializeDrive(UCHAR DriveNumber);
  91 VOID    CacheInvalidateCacheData(VOID);
  92 BOOLEAN    CacheReadDiskSectors(UCHAR DiskNumber, ULONGLONG StartSector, ULONG SectorCount, PVOID Buffer);
  93 BOOLEAN    CacheForceDiskSectorsIntoCache(UCHAR DiskNumber, ULONGLONG StartSector, ULONG SectorCount);
  94 BOOLEAN    CacheReleaseMemory(ULONG MinimumAmountToRelease);