| 1 | /* Caching code. Typically used by remote back ends for |
| 2 | caching remote memory. |
| 3 | |
| 4 | Copyright 1992, 1993 Free Software Foundation, Inc. |
| 5 | |
| 6 | This file is part of GDB. |
| 7 | |
| 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. |
| 12 | |
| 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. |
| 17 | |
| 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. */ |
| 21 | |
| 22 | #include "defs.h" |
| 23 | #include "dcache.h" |
| 24 | #include "gdbcmd.h" |
| 25 | |
| 26 | extern int insque(); |
| 27 | extern int remque(); |
| 28 | |
| 29 | int remote_dcache = 0; |
| 30 | |
| 31 | /* The data cache records all the data read from the remote machine |
| 32 | since the last time it stopped. |
| 33 | |
| 34 | Each cache block holds LINE_SIZE bytes of data |
| 35 | starting at a multiple-of-LINE_SIZE address. */ |
| 36 | |
| 37 | #define LINE_SIZE_MASK ((LINE_SIZE - 1)) /* eg 7*2+1= 111*/ |
| 38 | #define XFORM(x) (((x) & LINE_SIZE_MASK) >> 2) |
| 39 | |
| 40 | /* Free all the data cache blocks, thus discarding all cached data. */ |
| 41 | void |
| 42 | dcache_flush (dcache) |
| 43 | DCACHE *dcache; |
| 44 | { |
| 45 | register struct dcache_block *db; |
| 46 | |
| 47 | if (remote_dcache > 0) |
| 48 | while ((db = dcache->dcache_valid.next) != &dcache->dcache_valid) |
| 49 | { |
| 50 | remque (db); |
| 51 | insque (db, &dcache->dcache_free); |
| 52 | } |
| 53 | |
| 54 | return; |
| 55 | } |
| 56 | |
| 57 | /* |
| 58 | * If addr is present in the dcache, return the address of the block |
| 59 | * containing it. |
| 60 | */ |
| 61 | static |
| 62 | struct dcache_block * |
| 63 | dcache_hit (dcache, addr) |
| 64 | DCACHE *dcache; |
| 65 | unsigned int addr; |
| 66 | { |
| 67 | register struct dcache_block *db; |
| 68 | |
| 69 | if (addr & 3 |
| 70 | || remote_dcache == 0) |
| 71 | abort (); |
| 72 | |
| 73 | /* Search all cache blocks for one that is at this address. */ |
| 74 | db = dcache->dcache_valid.next; |
| 75 | while (db != &dcache->dcache_valid) |
| 76 | { |
| 77 | if ((addr & ~LINE_SIZE_MASK) == db->addr) |
| 78 | return db; |
| 79 | db = db->next; |
| 80 | } |
| 81 | |
| 82 | return NULL; |
| 83 | } |
| 84 | |
| 85 | /* Return the int data at address ADDR in dcache block DC. */ |
| 86 | static |
| 87 | int |
| 88 | dcache_value (db, addr) |
| 89 | struct dcache_block *db; |
| 90 | unsigned int addr; |
| 91 | { |
| 92 | if (addr & 3 |
| 93 | || remote_dcache == 0) |
| 94 | abort (); |
| 95 | return (db->data[XFORM (addr)]); |
| 96 | } |
| 97 | |
| 98 | /* Get a free cache block, put or keep it on the valid list, |
| 99 | and return its address. The caller should store into the block |
| 100 | the address and data that it describes, then remque it from the |
| 101 | free list and insert it into the valid list. This procedure |
| 102 | prevents errors from creeping in if a memory retrieval is |
| 103 | interrupted (which used to put garbage blocks in the valid |
| 104 | list...). */ |
| 105 | static |
| 106 | struct dcache_block * |
| 107 | dcache_alloc (dcache) |
| 108 | DCACHE *dcache; |
| 109 | { |
| 110 | register struct dcache_block *db; |
| 111 | |
| 112 | if (remote_dcache == 0) |
| 113 | abort(); |
| 114 | |
| 115 | if ((db = dcache->dcache_free.next) == &dcache->dcache_free) |
| 116 | { |
| 117 | /* If we can't get one from the free list, take last valid and put |
| 118 | it on the free list. */ |
| 119 | db = dcache->dcache_valid.last; |
| 120 | remque (db); |
| 121 | insque (db, &dcache->dcache_free); |
| 122 | } |
| 123 | |
| 124 | remque (db); |
| 125 | insque (db, &dcache->dcache_valid); |
| 126 | return (db); |
| 127 | } |
| 128 | |
| 129 | /* Using the data cache DCACHE return the contents of the word at |
| 130 | address ADDR in the remote machine. */ |
| 131 | int |
| 132 | dcache_fetch (dcache, addr) |
| 133 | DCACHE *dcache; |
| 134 | CORE_ADDR addr; |
| 135 | { |
| 136 | register struct dcache_block *db; |
| 137 | |
| 138 | if (remote_dcache == 0) |
| 139 | { |
| 140 | int i; |
| 141 | |
| 142 | (*dcache->read_memory) (addr, (unsigned char *) &i, 4); |
| 143 | return(i); |
| 144 | } |
| 145 | |
| 146 | db = dcache_hit (dcache, addr); |
| 147 | if (db == 0) |
| 148 | { |
| 149 | db = dcache_alloc (dcache); |
| 150 | immediate_quit++; |
| 151 | (*dcache->read_memory) (addr & ~LINE_SIZE_MASK, (unsigned char *) db->data, LINE_SIZE); |
| 152 | immediate_quit--; |
| 153 | db->addr = addr & ~LINE_SIZE_MASK; |
| 154 | remque (db); /* Off the free list */ |
| 155 | insque (db, &dcache->dcache_valid); /* On the valid list */ |
| 156 | } |
| 157 | return (dcache_value (db, addr)); |
| 158 | } |
| 159 | |
| 160 | /* Write the word at ADDR both in the data cache and in the remote machine. */ |
| 161 | void |
| 162 | dcache_poke (dcache, addr, data) |
| 163 | DCACHE *dcache; |
| 164 | CORE_ADDR addr; |
| 165 | int data; |
| 166 | { |
| 167 | register struct dcache_block *db; |
| 168 | |
| 169 | if (remote_dcache == 0) |
| 170 | { |
| 171 | (*dcache->write_memory) (addr, (unsigned char *) &data, 4); |
| 172 | return; |
| 173 | } |
| 174 | |
| 175 | /* First make sure the word is IN the cache. DB is its cache block. */ |
| 176 | db = dcache_hit (dcache, addr); |
| 177 | if (db == 0) |
| 178 | { |
| 179 | db = dcache_alloc (dcache); |
| 180 | immediate_quit++; |
| 181 | (*dcache->write_memory) (addr & ~LINE_SIZE_MASK, (unsigned char *) db->data, LINE_SIZE); |
| 182 | immediate_quit--; |
| 183 | db->addr = addr & ~LINE_SIZE_MASK; |
| 184 | remque (db); /* Off the free list */ |
| 185 | insque (db, &dcache->dcache_valid); /* On the valid list */ |
| 186 | } |
| 187 | |
| 188 | /* Modify the word in the cache. */ |
| 189 | db->data[XFORM (addr)] = data; |
| 190 | |
| 191 | /* Send the changed word. */ |
| 192 | immediate_quit++; |
| 193 | (*dcache->write_memory) (addr, (unsigned char *) &data, 4); |
| 194 | immediate_quit--; |
| 195 | } |
| 196 | |
| 197 | /* Initialize the data cache. */ |
| 198 | DCACHE * |
| 199 | dcache_init (reading, writing) |
| 200 | memxferfunc reading; |
| 201 | memxferfunc writing; |
| 202 | { |
| 203 | register i; |
| 204 | register struct dcache_block *db; |
| 205 | DCACHE *dcache; |
| 206 | |
| 207 | dcache = (DCACHE *) xmalloc (sizeof (*dcache)); |
| 208 | dcache->read_memory = reading; |
| 209 | dcache->write_memory = writing; |
| 210 | dcache->the_cache = (struct dcache_block *) |
| 211 | xmalloc (sizeof (*dcache->the_cache) * DCACHE_SIZE); |
| 212 | |
| 213 | dcache->dcache_free.next = dcache->dcache_free.last = &dcache->dcache_free; |
| 214 | dcache->dcache_valid.next = dcache->dcache_valid.last = &dcache->dcache_valid; |
| 215 | for (db = dcache->the_cache, i = 0; i < DCACHE_SIZE; i++, db++) |
| 216 | insque (db, &dcache->dcache_free); |
| 217 | |
| 218 | return(dcache); |
| 219 | } |
| 220 | |
| 221 | void |
| 222 | _initialitize_dcache () |
| 223 | { |
| 224 | add_show_from_set |
| 225 | (add_set_cmd ("remotecache", class_support, var_boolean, |
| 226 | (char *) &remote_dcache, |
| 227 | "\ |
| 228 | Set cache use for remote targets.\n\ |
| 229 | When on, use data caching for remote targets. For many remote targets\n\ |
| 230 | this option can offer better throughput for reading target memory.\n\ |
| 231 | Unfortunately, gdb does not currently know anything about volatile\n\ |
| 232 | registers and thus data caching will produce incorrect results with\n\ |
| 233 | volatile registers are in use. By default, this option is off.", |
| 234 | &setlist), |
| 235 | &showlist); |
| 236 | } |