radio/src/disk_cache.h

   1 /*
   2  * Copyright (C) OpenTX
   3  *
   4  * Based on code named
   5  *   th9x - http://code.google.com/p/th9x
   6  *   er9x - http://code.google.com/p/er9x
   7  *   gruvin9x - http://code.google.com/p/gruvin9x
   8  *
   9  * License GPLv2: http://www.gnu.org/licenses/gpl-2.0.html
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License version 2 as
  13  * published by the Free Software Foundation.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  */
  20
  21 #ifndef _DISK_CACHE_H_
  22 #define _DISK_CACHE_H_
  23
  24 #include "diskio.h"
  25 #include "sdio_sd.h"
  26
  27 // tunable parameters
  28 #define DISK_CACHE_BLOCKS_NUM      32   // no cache blocks
  29 #define DISK_CACHE_BLOCK_SECTORS   16   // no sectors
  30
  31 #define DISK_CACHE_BLOCK_SIZE   (DISK_CACHE_BLOCK_SECTORS * BLOCK_SIZE)
  32
  33 class DiskCacheBlock
  34 {
  35 public:
  36   DiskCacheBlock();
  37   bool read(BYTE* buff, DWORD sector, UINT count);
  38   DRESULT fill(BYTE drv, BYTE* buff, DWORD sector, UINT count);
  39   void free(DWORD sector, UINT count);
  40   void free();
  41   bool empty() const;
  42
  43 private:
  44   uint8_t data[DISK_CACHE_BLOCK_SIZE];
  45   DWORD startSector;
  46   DWORD endSector;
  47 };
  48
  49 struct DiskCacheStats
  50 {
  51   uint32_t noHits;
  52   uint32_t noMisses;
  53   uint32_t noWrites;
  54 };
  55
  56 class DiskCache
  57 {
  58   public:
  59     DiskCache();
  60     DRESULT read(BYTE drv, BYTE* buff, DWORD sector, UINT count);
  61     DRESULT write(BYTE drv, const BYTE* buff, DWORD sector, UINT count);
  62     const DiskCacheStats & getStats() const;
  63     int getHitRate() const;
  64     void clear();
  65
  66   private:
  67     DiskCacheStats stats;
  68     uint32_t lastBlock;
  69     DiskCacheBlock * blocks;
  70 };
  71
  72 extern DiskCache diskCache;
  73
  74 #endif // _DISK_CACHE_H_