235 lines
6.2 KiB
C
235 lines
6.2 KiB
C
/* Caching code. Typically used by remote back ends for
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caching remote memory.
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Copyright 1992, 1993 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
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#include "defs.h"
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#include "dcache.h"
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#include "gdbcmd.h"
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extern int insque();
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extern int remque();
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int remote_dcache = 0;
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/* The data cache records all the data read from the remote machine
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since the last time it stopped.
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Each cache block holds LINE_SIZE bytes of data
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starting at a multiple-of-LINE_SIZE address. */
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#define LINE_SIZE_MASK ((LINE_SIZE - 1)) /* eg 7*2+1= 111*/
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#define XFORM(x) (((x) & LINE_SIZE_MASK) >> 2)
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/* Free all the data cache blocks, thus discarding all cached data. */
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void
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dcache_flush (dcache)
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DCACHE *dcache;
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{
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register struct dcache_block *db;
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if (remote_dcache > 0)
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while ((db = dcache->dcache_valid.next) != &dcache->dcache_valid)
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{
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remque (db);
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insque (db, &dcache->dcache_free);
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}
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return;
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}
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/*
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* If addr is present in the dcache, return the address of the block
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* containing it.
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*/
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static
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struct dcache_block *
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dcache_hit (dcache, addr)
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DCACHE *dcache;
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unsigned int addr;
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{
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register struct dcache_block *db;
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if (addr & 3
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|| remote_dcache == 0)
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abort ();
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/* Search all cache blocks for one that is at this address. */
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db = dcache->dcache_valid.next;
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while (db != &dcache->dcache_valid)
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{
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if ((addr & ~LINE_SIZE_MASK) == db->addr)
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return db;
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db = db->next;
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}
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return NULL;
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}
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/* Return the int data at address ADDR in dcache block DC. */
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static
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int
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dcache_value (db, addr)
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struct dcache_block *db;
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unsigned int addr;
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{
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if (addr & 3
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|| remote_dcache == 0)
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abort ();
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return (db->data[XFORM (addr)]);
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}
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/* Get a free cache block, put or keep it on the valid list,
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and return its address. The caller should store into the block
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the address and data that it describes, then remque it from the
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free list and insert it into the valid list. This procedure
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prevents errors from creeping in if a memory retrieval is
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interrupted (which used to put garbage blocks in the valid
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list...). */
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static
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struct dcache_block *
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dcache_alloc (dcache)
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DCACHE *dcache;
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{
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register struct dcache_block *db;
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if (remote_dcache == 0)
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abort();
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if ((db = dcache->dcache_free.next) == &dcache->dcache_free)
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{
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/* If we can't get one from the free list, take last valid and put
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it on the free list. */
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db = dcache->dcache_valid.last;
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remque (db);
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insque (db, &dcache->dcache_free);
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}
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remque (db);
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insque (db, &dcache->dcache_valid);
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return (db);
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}
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/* Using the data cache DCACHE return the contents of the word at
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address ADDR in the remote machine. */
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int
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dcache_fetch (dcache, addr)
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DCACHE *dcache;
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CORE_ADDR addr;
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{
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register struct dcache_block *db;
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if (remote_dcache == 0)
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{
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int i;
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(*dcache->read_memory) (addr, (unsigned char *) &i, 4);
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return(i);
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}
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db = dcache_hit (dcache, addr);
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if (db == 0)
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{
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db = dcache_alloc (dcache);
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immediate_quit++;
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(*dcache->read_memory) (addr & ~LINE_SIZE_MASK, (unsigned char *) db->data, LINE_SIZE);
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immediate_quit--;
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db->addr = addr & ~LINE_SIZE_MASK;
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remque (db); /* Off the free list */
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insque (db, &dcache->dcache_valid); /* On the valid list */
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}
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return (dcache_value (db, addr));
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}
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/* Write the word at ADDR both in the data cache and in the remote machine. */
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void
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dcache_poke (dcache, addr, data)
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DCACHE *dcache;
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CORE_ADDR addr;
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int data;
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{
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register struct dcache_block *db;
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if (remote_dcache == 0)
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{
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(*dcache->write_memory) (addr, (unsigned char *) &data, 4);
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return;
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}
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/* First make sure the word is IN the cache. DB is its cache block. */
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db = dcache_hit (dcache, addr);
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if (db == 0)
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{
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db = dcache_alloc (dcache);
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immediate_quit++;
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(*dcache->write_memory) (addr & ~LINE_SIZE_MASK, (unsigned char *) db->data, LINE_SIZE);
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immediate_quit--;
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db->addr = addr & ~LINE_SIZE_MASK;
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remque (db); /* Off the free list */
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insque (db, &dcache->dcache_valid); /* On the valid list */
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}
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/* Modify the word in the cache. */
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db->data[XFORM (addr)] = data;
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/* Send the changed word. */
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immediate_quit++;
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(*dcache->write_memory) (addr, (unsigned char *) &data, 4);
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immediate_quit--;
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}
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/* Initialize the data cache. */
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DCACHE *
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dcache_init (reading, writing)
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memxferfunc reading;
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memxferfunc writing;
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{
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register i;
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register struct dcache_block *db;
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DCACHE *dcache;
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dcache = xmalloc(sizeof(*dcache));
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dcache->read_memory = reading;
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dcache->write_memory = writing;
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dcache->the_cache = xmalloc(sizeof(*dcache->the_cache) * DCACHE_SIZE);
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dcache->dcache_free.next = dcache->dcache_free.last = &dcache->dcache_free;
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dcache->dcache_valid.next = dcache->dcache_valid.last = &dcache->dcache_valid;
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for (db = dcache->the_cache, i = 0; i < DCACHE_SIZE; i++, db++)
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insque (db, &dcache->dcache_free);
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return(dcache);
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}
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void
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_initialitize_dcache ()
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{
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add_show_from_set
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(add_set_cmd ("remotecache", class_support, var_boolean,
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(char *) &remote_dcache,
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"\
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Set cache use for remote targets.\n\
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When on, use data caching for remote targets. For many remote targets\n\
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this option can offer better throughput for reading target memory.\n\
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Unfortunately, gdb does not currently know anything about volatile\n\
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registers and thus data caching will produce incorrect results with\n\
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volatile registers are in use. By default, this option is off.",
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&setlist),
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&showlist);
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}
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