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authorK. Richard Pixley <rich@cygnus>1993-08-31 22:13:29 +0000
committerK. Richard Pixley <rich@cygnus>1993-08-31 22:13:29 +0000
commit755892d6ff13e99b7cb12f349c05345da4befcb4 (patch)
tree5f8912bde3cf922710793455434f0b95b7f1ed7e /gdb/dcache.c
parentbf9d25378e65e0c5b96cc0f4cbbaa485b98913ba (diff)
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break dcache code out of remote-bug.c
Diffstat (limited to 'gdb/dcache.c')
-rw-r--r--gdb/dcache.c189
1 files changed, 189 insertions, 0 deletions
diff --git a/gdb/dcache.c b/gdb/dcache.c
new file mode 100644
index 0000000..498c22e
--- /dev/null
+++ b/gdb/dcache.c
@@ -0,0 +1,189 @@
+/* Caching code. Typically used by remote back ends for
+ caching remote memory.
+
+ Copyright 1992, 1993 Free Software Foundation, Inc.
+
+This file is part of GDB.
+
+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 program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
+
+#include "defs.h"
+#include "dcache.h"
+
+extern int insque();
+extern int remque();
+
+/* The data cache records all the data read from the remote machine
+ since the last time it stopped.
+
+ Each cache block holds line_size bytes of data
+ starting at a multiple-of-line_size address. */
+
+#define LINE_SIZE_MASK ((LINE_SIZE - 1)) /* eg 7*2+1= 111*/
+#define XFORM(x) (((x) & LINE_SIZE_MASK) >> 2)
+
+/* Free all the data cache blocks, thus discarding all cached data. */
+void
+dcache_flush (dcache)
+ DCACHE *dcache;
+{
+ register struct dcache_block *db;
+
+ while ((db = dcache->dcache_valid.next) != &dcache->dcache_valid)
+ {
+ remque (db);
+ insque (db, &dcache->dcache_free);
+ }
+}
+
+/*
+ * If addr is present in the dcache, return the address of the block
+ * containing it.
+ */
+struct dcache_block *
+dcache_hit (dcache, addr)
+ DCACHE *dcache;
+ unsigned int addr;
+{
+ register struct dcache_block *db;
+
+ if (addr & 3)
+ abort ();
+
+ /* Search all cache blocks for one that is at this address. */
+ db = dcache->dcache_valid.next;
+ while (db != &dcache->dcache_valid)
+ {
+ if ((addr & ~LINE_SIZE_MASK) == db->addr)
+ return db;
+ db = db->next;
+ }
+ return NULL;
+}
+
+/* Return the int data at address ADDR in dcache block DC. */
+int
+dcache_value (db, addr)
+ struct dcache_block *db;
+ unsigned int addr;
+{
+ if (addr & 3)
+ abort ();
+ return (db->data[XFORM (addr)]);
+}
+
+/* Get a free cache block, put or keep it on the valid list,
+ and return its address. The caller should store into the block
+ the address and data that it describes, then remque it from the
+ free list and insert it into the valid list. This procedure
+ prevents errors from creeping in if a ninMemGet is interrupted
+ (which used to put garbage blocks in the valid list...). */
+struct dcache_block *
+dcache_alloc (dcache)
+ DCACHE *dcache;
+{
+ register struct dcache_block *db;
+
+ if ((db = dcache->dcache_free.next) == &dcache->dcache_free)
+ {
+ /* If we can't get one from the free list, take last valid and put
+ it on the free list. */
+ db = dcache->dcache_valid.last;
+ remque (db);
+ insque (db, &dcache->dcache_free);
+ }
+
+ remque (db);
+ insque (db, &dcache->dcache_valid);
+ return (db);
+}
+
+/* Return the contents of the word at address ADDR in the remote machine,
+ using the data cache. */
+int
+dcache_fetch (dcache, addr)
+ DCACHE *dcache;
+ CORE_ADDR addr;
+{
+ register struct dcache_block *db;
+
+ db = dcache_hit (dcache, addr);
+ if (db == 0)
+ {
+ db = dcache_alloc (dcache);
+ immediate_quit++;
+ (*dcache->read_memory) (addr & ~LINE_SIZE_MASK, (unsigned char *) db->data, LINE_SIZE);
+ immediate_quit--;
+ db->addr = addr & ~LINE_SIZE_MASK;
+ remque (db); /* Off the free list */
+ insque (db, &dcache->dcache_valid); /* On the valid list */
+ }
+ return (dcache_value (db, addr));
+}
+
+/* Write the word at ADDR both in the data cache and in the remote machine. */
+void
+dcache_poke (dcache, addr, data)
+ DCACHE *dcache;
+ CORE_ADDR addr;
+ int data;
+{
+ register struct dcache_block *db;
+
+ /* First make sure the word is IN the cache. DB is its cache block. */
+ db = dcache_hit (dcache, addr);
+ if (db == 0)
+ {
+ db = dcache_alloc (dcache);
+ immediate_quit++;
+ (*dcache->write_memory) (addr & ~LINE_SIZE_MASK, (unsigned char *) db->data, LINE_SIZE);
+ immediate_quit--;
+ db->addr = addr & ~LINE_SIZE_MASK;
+ remque (db); /* Off the free list */
+ insque (db, &dcache->dcache_valid); /* On the valid list */
+ }
+
+ /* Modify the word in the cache. */
+ db->data[XFORM (addr)] = data;
+
+ /* Send the changed word. */
+ immediate_quit++;
+ (*dcache->write_memory) (addr, (unsigned char *) &data, 4);
+ immediate_quit--;
+}
+
+/* Initialize the data cache. */
+DCACHE *
+dcache_init (reading, writing)
+ memxferfunc reading;
+ memxferfunc writing;
+{
+ register i;
+ register struct dcache_block *db;
+ DCACHE *dcache;
+
+ dcache = xmalloc(sizeof(*dcache));
+ dcache->read_memory = reading;
+ dcache->write_memory = writing;
+ dcache->the_cache = xmalloc(sizeof(*dcache->the_cache) * DCACHE_SIZE);
+
+ dcache->dcache_free.next = dcache->dcache_free.last = &dcache->dcache_free;
+ dcache->dcache_valid.next = dcache->dcache_valid.last = &dcache->dcache_valid;
+ for (db = dcache->the_cache, i = 0; i < DCACHE_SIZE; i++, db++)
+ insque (db, &dcache->dcache_free);
+
+ return(dcache);
+}
+