rom/filesys/cdfs/bcache.h

   1 /*
   2  * Copyright (C) 2013, The AROS Development Team
   3  * All right reserved.
   4  * Author: Jason S. McMullan <jason.mcmullan@gmail.com>
   5  *
   6  * Licensed under the AROS PUBLIC LICENSE (APL) Version 1.1
   7  */
   8
   9 /* 'BCache' is a trivial write-through cache for block devices.
  10  */
  11
  12 #ifndef BCACHE_H
  13 #define BCACHE_H
  14
  15 #include <exec/io.h>
  16 #include <dos/filehandler.h>
  17
  18 /* DO NOT ALLOCATE NOR FREE THIS STRUCTURE MANUALLY!
  19  *
  20  * Feel free to add to other lists - bc_Node is for your use!
  21  */
  22 struct BCache {
  23     struct Node    bc_Node;
  24     /* The following are for quick reference only - DO NOT MODIFY! */
  25     ULONG          bc_BlockSize;    /* In bytes */
  26     ULONG          bc_Blocks;       /* # of blocks in the FSSM range */
  27     /* The rest is internally used by BCache */
  28 };
  29
  30 /* Create a buffer cache, based off of a FileSysStartupMsg.
  31  * Note that:
  32  *  bc_BlockSize will be fsm_Environ[DE_BLOCKSIZE]*4
  33  *            (default - 512)
  34  *  bc_Blocks is the number of blocks from DE_LOWCYL to DE_HIGHCYL
  35  *            (default - total # of blocks on the disk)
  36  */
  37 LONG BCache_Create(struct ExecBase *sysBase, struct FileSysStartupMsg *fssm, struct BCache **bcache);
  38
  39 /* Dispose of the cache, and close the underlying device
  40  *
  41  * NOTE: This does *not* call Remove() on bc_Node - do that
  42  *       before calling this routine!
  43  */
  44 VOID BCache_Delete(struct BCache *bcache);
  45
  46 /* Extend the cache by 'numbuffers' blocks
  47  */
  48 LONG BCache_Extend(struct BCache *bcache, LONG numbuffers);
  49
  50 /* Drop all cache
  51  * returns:
  52  *   RETURN_OK     - Cache flushed, disk present
  53  *   ERROR_NO_DISK - Cache flushed, no disk present
  54  */
  55 LONG BCache_Invalidate(struct BCache *bcache);
  56
  57 /* Determine state of underlying media
  58  *    RETURN_OK     - No change since last invalidate
  59  *    RETURN_WARN   - Disk has changed, but a disk is present
  60  *    ERROR_NO_DISK - No disk present
  61  */
  62 LONG BCache_Present(struct BCache *bcache);
  63
  64 /* Read block from disk, give pointer to the cached buffer
  65  * returns:
  66  *   RETURN_OK     - Disk present
  67  *                   Data read from disk
  68  *   RETURN_WARN   - Disk has changed since last BCache_Invalidate();
  69  *                   No data read from disk
  70  *   ERROR_NO_DISK - No disk present
  71  *                   No data read from disk
  72  *   any other     - Disk read error
  73  *                   Partial data read from disk
  74  */
  75 LONG BCache_Read(struct BCache *bcache, ULONG block, UBYTE **buffer);
  76
  77 /* Write buffer to blocks on the disk.
  78  * returns:
  79  *   RETURN_OK     - Disk present
  80  *                   Data written to disk
  81  *   RETURN_WARN   - Disk has changed since last BCache_Invalidate();
  82  *                   No data written to disk
  83  *   ERROR_NO_DISK - No disk present
  84  *                   No data written to disk
  85  *   any other     - Disk write error
  86  *                   Partial data written to disk
  87  */
  88 LONG BCache_Write(struct BCache *bcache, ULONG block, CONST UBYTE *buffer);
  89
  90 #endif /* BLOCKCACHE_H */