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/io.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     struct cache_block  *dirty_next;    /* next block on dirty list */
  26
  27     ULONG               use_count;      /* number of users of this block */
  28     BOOL                is_dirty;       /* does the block need to be written? */
  29
  30     ULONG               num;            /* block number */
  31
  32     UBYTE               *data;          /* actual block data */
  33 };
  34
  35 struct cache {
  36     struct IOStdReq     *req;           /* io request for disk access. this hold the device and unit pointers */
  37
  38     ULONG               hash_size;      /* size of hash table */
  39     ULONG               hash_mask;      /* mask applied to block number to find correct hash bucket */
  40
  41     ULONG               num_blocks;     /* number of blocks allocated */
  42     ULONG               block_size;     /* size of block */
  43
  44     ULONG               flags;          /* cache options */
  45
  46     struct cache_block  **blocks;       /* big list of all the blocks */
  47     ULONG               num_in_use;     /* number of blocks currently in use (ie not on the free list) */
  48
  49     struct cache_block  **hash;         /* the hash table itself */
  50
  51     struct cache_block  *free_head;     /* first block in the free list */
  52     struct cache_block  *free_tail;     /* last block in the free list */
  53
  54     struct cache_block  *dirty;         /* list of dirty blocks */
  55
  56     ULONG               hits;           /* number of hits, for stats */
  57     ULONG               misses;         /* number of misses */
  58 };
  59
  60 /* flags for cache_new */
  61 #define CACHE_WRITETHROUGH  (1<<0)      /* write immediately */
  62 #define CACHE_WRITEBACK     (1<<1)      /* defer writes */
  63
  64 /* internal flags */
  65 #define CACHE_64_TD64       (1<<2)      /* have 64-bit via trackdisk64 requests */
  66 #define CACHE_64_NSD        (1<<3)      /* have 64-bit via new-style device requests */
  67 #define CACHE_64_SCSI       (1<<4)      /* have 64-bit via DirectSCSI requests */
  68 #define CACHE_64_MASK       (CACHE_64_NSD | CACHE_64_TD64 | CACHE_64_SCSI)
  69
  70 struct cache *cache_new(struct IOStdReq *req, ULONG hash_size, ULONG num_blocks, ULONG block_size, ULONG flags);
  71 void cache_free(struct cache *c);
  72
  73 ULONG cache_get_block(struct cache *c, ULONG num, ULONG flags, struct cache_block **rb);
  74 ULONG cache_put_block(struct cache *c, struct cache_block *b, ULONG flags);
  75
  76 ULONG cache_get_blocks(struct cache *c, ULONG num, ULONG nblocks, ULONG flags, struct cache_block **rb);
  77 ULONG cache_put_blocks(struct cache *c, struct cache_block **b, ULONG nblocks, ULONG flags);
  78
  79 ULONG cache_mark_block_dirty(struct cache *c, struct cache_block *b);
  80 ULONG cache_mark_blocks_dirty(struct cache *c, struct cache_block **b, ULONG nblocks);
  81
  82 ULONG cache_flush(struct cache *c);
  83
  84 void cache_stats(struct cache *c);
  85
  86 #endif