src/add-ons/kernel/file_systems/exfat/CachedBlock.h

   1 /*
   2  * Copyright 2001-2008, Axel Dörfler, axeld@pinc-software.de.
   3  * This file may be used under the terms of the MIT License.
   4  */
   5 #ifndef CACHED_BLOCK_H
   6 #define CACHED_BLOCK_H
   7
   8 //!     interface for the block cache
   9
  10 #include <fs_cache.h>
  11
  12 #include "Volume.h"
  13
  14
  15 class CachedBlock {
  16 public:
  17                                                         CachedBlock(Volume* volume);
  18                                                         CachedBlock(Volume* volume, off_t block);
  19                                                         ~CachedBlock();
  20
  21                         void                    Keep();
  22                         void                    Unset();
  23
  24                         const uint8*    SetTo(off_t block);
  25
  26                         const uint8*    Block() const { return fBlock; }
  27                         off_t                   BlockNumber() const { return fBlockNumber; }
  28
  29 private:
  30                                                         CachedBlock(const CachedBlock &);
  31                                                         CachedBlock &operator=(const CachedBlock &);
  32                                                                 // no implementation
  33
  34 protected:
  35                         Volume*                 fVolume;
  36                         off_t                   fBlockNumber;
  37                         uint8*                  fBlock;
  38 };
  39
  40
  41 // inlines
  42
  43
  44 inline
  45 CachedBlock::CachedBlock(Volume* volume)
  46         :
  47         fVolume(volume),
  48         fBlockNumber(0),
  49         fBlock(NULL)
  50 {
  51 }
  52
  53
  54 inline
  55 CachedBlock::CachedBlock(Volume* volume, off_t block)
  56         :
  57         fVolume(volume),
  58         fBlockNumber(0),
  59         fBlock(NULL)
  60 {
  61         SetTo(block);
  62 }
  63
  64
  65 inline
  66 CachedBlock::~CachedBlock()
  67 {
  68         Unset();
  69 }
  70
  71
  72 inline void
  73 CachedBlock::Keep()
  74 {
  75         fBlock = NULL;
  76 }
  77
  78
  79 inline void
  80 CachedBlock::Unset()
  81 {
  82         if (fBlock != NULL) {
  83                 block_cache_put(fVolume->BlockCache(), fBlockNumber);
  84                 fBlock = NULL;
  85         }
  86 }
  87
  88
  89 inline const uint8 *
  90 CachedBlock::SetTo(off_t block)
  91 {
  92         Unset();
  93         fBlockNumber = block;
  94         return fBlock = (uint8 *)block_cache_get(fVolume->BlockCache(), block);
  95 }
  96
  97 #endif  // CACHED_BLOCK_H