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git.ipfire.org Git - thirdparty/binutils-gdb.git/blob - gdb/dcache.c
1 /* Caching code. Typically used by remote back ends for
4 Copyright 1992, 1993 Free Software Foundation, Inc.
6 This file is part of GDB.
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2 of the License, or
11 (at your option) any later version.
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with this program; if not, write to the Free Software
20 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
26 #if defined(__STDC__) && defined(__linux__)
27 /* In case the system header files define a prototype for insque and
28 remque that uses a pointer to a struct qelem, silence the warnings */
30 #define insque(a,b) (insque)((struct qelem *)(a), (struct qelem *)(b))
31 #define remque(a) (remque)((struct qelem *)(a))
38 int remote_dcache
= 0;
40 /* The data cache records all the data read from the remote machine
41 since the last time it stopped.
43 Each cache block holds LINE_SIZE bytes of data
44 starting at a multiple-of-LINE_SIZE address. */
46 #define LINE_SIZE_MASK ((LINE_SIZE - 1)) /* eg 7*2+1= 111*/
47 #define XFORM(x) (((x) & LINE_SIZE_MASK) >> 2)
49 /* Free all the data cache blocks, thus discarding all cached data. */
54 register struct dcache_block
*db
;
56 if (remote_dcache
> 0)
57 while ((db
= dcache
->dcache_valid
.next
) != &dcache
->dcache_valid
)
60 insque (db
, &dcache
->dcache_free
);
67 * If addr is present in the dcache, return the address of the block
72 dcache_hit (dcache
, addr
)
76 register struct dcache_block
*db
;
79 || remote_dcache
== 0)
82 /* Search all cache blocks for one that is at this address. */
83 db
= dcache
->dcache_valid
.next
;
84 while (db
!= &dcache
->dcache_valid
)
86 if ((addr
& ~LINE_SIZE_MASK
) == db
->addr
)
94 /* Return the int data at address ADDR in dcache block DC. */
97 dcache_value (db
, addr
)
98 struct dcache_block
*db
;
102 || remote_dcache
== 0)
104 return (db
->data
[XFORM (addr
)]);
107 /* Get a free cache block, put or keep it on the valid list,
108 and return its address. The caller should store into the block
109 the address and data that it describes, then remque it from the
110 free list and insert it into the valid list. This procedure
111 prevents errors from creeping in if a memory retrieval is
112 interrupted (which used to put garbage blocks in the valid
115 struct dcache_block
*
116 dcache_alloc (dcache
)
119 register struct dcache_block
*db
;
121 if (remote_dcache
== 0)
124 if ((db
= dcache
->dcache_free
.next
) == &dcache
->dcache_free
)
126 /* If we can't get one from the free list, take last valid and put
127 it on the free list. */
128 db
= dcache
->dcache_valid
.last
;
130 insque (db
, &dcache
->dcache_free
);
134 insque (db
, &dcache
->dcache_valid
);
138 /* Using the data cache DCACHE return the contents of the word at
139 address ADDR in the remote machine. */
141 dcache_fetch (dcache
, addr
)
145 register struct dcache_block
*db
;
147 if (remote_dcache
== 0)
151 (*dcache
->read_memory
) (addr
, (unsigned char *) &i
, 4);
155 db
= dcache_hit (dcache
, addr
);
158 db
= dcache_alloc (dcache
);
160 (*dcache
->read_memory
) (addr
& ~LINE_SIZE_MASK
, (unsigned char *) db
->data
, LINE_SIZE
);
162 db
->addr
= addr
& ~LINE_SIZE_MASK
;
163 remque (db
); /* Off the free list */
164 insque (db
, &dcache
->dcache_valid
); /* On the valid list */
166 return (dcache_value (db
, addr
));
169 /* Write the word at ADDR both in the data cache and in the remote machine. */
171 dcache_poke (dcache
, addr
, data
)
176 register struct dcache_block
*db
;
178 if (remote_dcache
== 0)
180 (*dcache
->write_memory
) (addr
, (unsigned char *) &data
, 4);
184 /* First make sure the word is IN the cache. DB is its cache block. */
185 db
= dcache_hit (dcache
, addr
);
188 db
= dcache_alloc (dcache
);
190 (*dcache
->write_memory
) (addr
& ~LINE_SIZE_MASK
, (unsigned char *) db
->data
, LINE_SIZE
);
192 db
->addr
= addr
& ~LINE_SIZE_MASK
;
193 remque (db
); /* Off the free list */
194 insque (db
, &dcache
->dcache_valid
); /* On the valid list */
197 /* Modify the word in the cache. */
198 db
->data
[XFORM (addr
)] = data
;
200 /* Send the changed word. */
202 (*dcache
->write_memory
) (addr
, (unsigned char *) &data
, 4);
206 /* Initialize the data cache. */
208 dcache_init (reading
, writing
)
213 register struct dcache_block
*db
;
216 dcache
= (DCACHE
*) xmalloc (sizeof (*dcache
));
217 dcache
->read_memory
= reading
;
218 dcache
->write_memory
= writing
;
219 dcache
->the_cache
= (struct dcache_block
*)
220 xmalloc (sizeof (*dcache
->the_cache
) * DCACHE_SIZE
);
222 dcache
->dcache_free
.next
= dcache
->dcache_free
.last
= &dcache
->dcache_free
;
223 dcache
->dcache_valid
.next
= dcache
->dcache_valid
.last
= &dcache
->dcache_valid
;
224 for (db
= dcache
->the_cache
, i
= 0; i
< DCACHE_SIZE
; i
++, db
++)
225 insque (db
, &dcache
->dcache_free
);
231 _initialitize_dcache ()
234 (add_set_cmd ("remotecache", class_support
, var_boolean
,
235 (char *) &remote_dcache
,
237 Set cache use for remote targets.\n\
238 When on, use data caching for remote targets. For many remote targets\n\
239 this option can offer better throughput for reading target memory.\n\
240 Unfortunately, gdb does not currently know anything about volatile\n\
241 registers and thus data caching will produce incorrect results with\n\
242 volatile registers are in use. By default, this option is off.",