gdb/dcache.h

   1 /* Declarations for caching.  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 #ifndef DCACHE_H
  23 #define DCACHE_H
  24
  25 /* The data cache leads to incorrect results because it doesn't know about
  26    volatile variables, thus making it impossible to debug functions which
  27    use hardware registers.  Therefore it is #if 0'd out.  Effect on
  28    performance is some, for backtraces of functions with a few
  29    arguments each.  For functions with many arguments, the stack
  30    frames don't fit in the cache blocks, which makes the cache less
  31    helpful.  Disabling the cache is a big performance win for fetching
  32    large structures, because the cache code fetched data in 16-byte
  33    chunks.  */
  34
  35 #define LINE_SIZE_POWER (4)
  36 /* eg 1<<3 == 8 */
  37 #define LINE_SIZE (1 << LINE_SIZE_POWER)
  38 /* Number of cache blocks */
  39 #define DCACHE_SIZE (64)
  40
  41 struct dcache_block
  42 {
  43   struct dcache_block *next, *last;
  44   unsigned int addr; /* Address for which data is recorded.  */
  45   int data[LINE_SIZE / sizeof (int)];
  46 };
  47
  48 typedef int (*memxferfunc) PARAMS((CORE_ADDR memaddr,
  49                              unsigned char *myaddr,
  50                              int len));
  51
  52 typedef struct {
  53   /* Function to actually read the target memory. */
  54   memxferfunc read_memory;
  55
  56   /* Function to actually write the target memory */
  57   memxferfunc write_memory;
  58
  59   /* free list */
  60   struct dcache_block dcache_free;
  61
  62   /* in use list */
  63   struct dcache_block dcache_valid;
  64
  65   /* The cache itself. */
  66   struct dcache_block *the_cache;
  67
  68 } DCACHE;
  69
  70 /* Using the data cache DCACHE return the contents of the word at
  71    address ADDR in the remote machine.  */
  72 int dcache_fetch PARAMS((DCACHE *dcache, CORE_ADDR addr));
  73
  74 /* Flush DCACHE. */
  75 void dcache_flush PARAMS((DCACHE *dcache));
  76
  77 /* Initialize DCACHE. */
  78 DCACHE *dcache_init PARAMS((memxferfunc reading, memxferfunc writing));
  79
  80 /* Write the word at ADDR both in the data cache and in the remote machine.  */
  81 void dcache_poke PARAMS((DCACHE *dcache, CORE_ADDR addr, int data));
  82
  83 #endif /* DCACHE_H */