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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2014 by Michael Sevakis
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#ifndef DISK_CACHE_H
#define DISK_CACHE_H
/* This needs enough for all file handles to have a buffer in the worst case
* plus at least one reserved exclusively for the cache client and a couple
* for other file system code. The buffers are put to use by the cache if not
* taken for another purpose (meaning nothing is wasted sitting fallow).
*
* One map per volume is maintained in order to avoid collisions between
* volumes that would slow cache probing. DC_MAP_NUM_ENTRIES is the number
* for each map per volume. The buffers themselves are shared.
*/
#if MEMORYSIZE < 8
#define DC_NUM_ENTRIES 32
#define DC_MAP_NUM_ENTRIES 128
#elif MEMORYSIZE <= 32
#define DC_NUM_ENTRIES 48
#define DC_MAP_NUM_ENTRIES 128
#else /* MEMORYSIZE > 32 */
#define DC_NUM_ENTRIES 64
#define DC_MAP_NUM_ENTRIES 256
#endif /* MEMORYSIZE */
/* this _could_ be larger than a sector if that would ever be useful */
#define DC_CACHE_BUFSIZE SECTOR_SIZE
#include "mutex.h"
#include "mv.h"
static inline void dc_lock_cache(void)
{
extern struct mutex disk_cache_mutex;
mutex_lock(&disk_cache_mutex);
}
static inline void dc_unlock_cache(void)
{
extern struct mutex disk_cache_mutex;
mutex_unlock(&disk_cache_mutex);
}
void * dc_cache_probe(IF_MV(int volume,) unsigned long secnum,
unsigned int *flags);
void dc_dirty_buf(void *buf);
void dc_discard_buf(void *buf);
void dc_commit_all(IF_MV_NONVOID(int volume));
void dc_discard_all(IF_MV_NONVOID(int volume));
void dc_init(void) INIT_ATTR;
/* in addition to filling, writeback is implemented by the client */
extern void dc_writeback_callback(IF_MV(int volume, ) unsigned long sector,
void *buf);
/** These synchronize and can be called by anyone **/
/* expropriate a buffer from the cache of DC_CACHE_BUFSIZE bytes */
void * dc_get_buffer(void);
/* return buffer to the cache by buffer */
void dc_release_buffer(void *buf);
#endif /* DISK_CACHE_H */
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