1 files changed, 83 insertions, 0 deletions
diff --git a/firmware/include/disk_cache.h b/firmware/include/disk_cache.h
new file mode 100644
index 0000000..725b377
--- /dev/null
+++ b/firmware/include/disk_cache.h
@@ -0,0 +1,83 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   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 */