workbench/fs/fat/cache.h

   1 /*
   2  * Disk buffer cache
   3  *
   4  * Copyright © 2007 Robert Norris
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the same terms as AROS itself.
   8  *
   9  * $Id$
  10  */
  11
  12 #ifndef CACHE_H
  13 #define CACHE_H 1
  14
  15 #include <exec/types.h>
  16 #include <exec/devices.h>
  17
  18 struct cache_block {
  19     struct cache_block  *hash_next;     /* next block in this hash bucket */
  20     struct cache_block  *hash_prev;     /* previous block in this hash bucket */
  21
  22     struct cache_block  *free_next;     /* next block on free list */
  23     struct cache_block  *free_prev;     /* previous block on free list */
  24
  25     ULONG               use_count;      /* number of users of this block */
  26     BOOL                is_dirty;       /* does the block need to be written? */
  27
  28     struct Device       *device;        /* device this block was loaded from */
  29     struct Unit         *unit;          /* unit of aforementioned device */
  30
  31     ULONG               num;            /* block number */
  32
  33     UBYTE               *data;          /* actual block data */
  34 };
  35
  36 struct cache {
  37     ULONG               hash_size;      /* size of hash table */
  38     ULONG               hash_mask;      /* mask applied to block number to find correct hash bucket */
  39
  40     ULONG               block_size;     /* size of block */
  41
  42     ULONG               flags;          /* cache options */
  43
  44     struct cache_block  **blocks;       /* big list of all the blocks */
  45     ULONG               num_blocks;     /* number of blocks in the list */
  46     ULONG               num_in_use;     /* number of blocks currently in use (ie not on the free list) */
  47
  48     struct cache_block  **hash;         /* the hash table itself */
  49
  50     struct cache_block  *free_head;     /* first block in the free list */
  51     struct cache_block  *free_tail;     /* last block in the free list */
  52 };
  53
  54 struct cache *cache_new(ULONG hash_size, ULONG num_blocks, ULONG block_size, ULONG flags);
  55 void cache_free(struct cache *c);
  56
  57 ULONG cache_get_block(struct cache *c, struct Device *dev, struct Unit *unit, ULONG num, ULONG flags, struct cache_block **rb);
  58 ULONG cache_put_block(struct cache *c, struct cache_block *b, ULONG flags);
  59
  60 ULONG cache_get_blocks(struct cache *c, struct Device *dev, struct Unit *unit, ULONG num, ULONG nblocks, ULONG flags, struct cache_block **rb);
  61 ULONG cache_put_blocks(struct cache *c, struct cache_block **b, ULONG nblocks, ULONG flags);
  62
  63 ULONG cache_mark_block_dirty(struct cache *c, struct cache_block *b);
  64 ULONG cache_mark_blocks_dirty(struct cache *c, struct cache_block **b, ULONG nblocks);
  65
  66 #endif