gdb/target-descriptions.c

   1 /* Target description support for GDB.
   2
   3    Copyright (C) 2006
   4    Free Software Foundation, Inc.
   5
   6    Contributed by CodeSourcery.
   7
   8    This file is part of GDB.
   9
  10    This program is free software; you can redistribute it and/or modify
  11    it under the terms of the GNU General Public License as published by
  12    the Free Software Foundation; either version 2 of the License, or
  13    (at your option) any later version.
  14
  15    This program is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18    GNU General Public License for more details.
  19
  20    You should have received a copy of the GNU General Public License
  21    along with this program; if not, write to the Free Software
  22    Foundation, Inc., 51 Franklin Street, Fifth Floor,
  23    Boston, MA 02110-1301, USA.  */
  24
  25 #include "defs.h"
  26 #include "arch-utils.h"
  27 #include "target.h"
  28 #include "target-descriptions.h"
  29
  30 #include "gdb_assert.h"
  31
  32 /* Types.  */
  33
  34 struct target_desc
  35 {
  36 };
  37
  38 /* Global state.  These variables are associated with the current
  39    target; if GDB adds support for multiple simultaneous targets, then
  40    these variables should become target-specific data.  */
  41
  42 /* A flag indicating that a description has already been fetched from
  43    the current target, so it should not be queried again.  */
  44
  45 static int target_desc_fetched;
  46
  47 /* The description fetched from the current target, or NULL if the
  48    current target did not supply any description.  Only valid when
  49    target_desc_fetched is set.  Only the description initialization
  50    code should access this; normally, the description should be
  51    accessed through the gdbarch object.  */
  52
  53 static const struct target_desc *current_target_desc;
  54
  55 /* Fetch the current target's description, and switch the current
  56    architecture to one which incorporates that description.  */
  57
  58 void
  59 target_find_description (void)
  60 {
  61   /* If we've already fetched a description from the target, don't do
  62      it again.  This allows a target to fetch the description early,
  63      during its to_open or to_create_inferior, if it needs extra
  64      information about the target to initialize.  */
  65   if (target_desc_fetched)
  66     return;
  67
  68   /* The current architecture should not have any target description
  69      specified.  It should have been cleared, e.g. when we
  70      disconnected from the previous target.  */
  71   gdb_assert (gdbarch_target_desc (current_gdbarch) == NULL);
  72
  73   current_target_desc = target_read_description (&current_target);
  74
  75   /* If a non-NULL description was returned, then update the current
  76      architecture.  */
  77   if (current_target_desc)
  78     {
  79       struct gdbarch_info info;
  80
  81       gdbarch_info_init (&info);
  82       info.target_desc = current_target_desc;
  83       if (!gdbarch_update_p (info))
  84         warning (_("Could not use target-supplied description"));
  85     }
  86
  87   /* Now that we know this description is usable, record that we
  88      fetched it.  */
  89   target_desc_fetched = 1;
  90 }
  91
  92 /* Discard any description fetched from the current target, and switch
  93    the current architecture to one with no target description.  */
  94
  95 void
  96 target_clear_description (void)
  97 {
  98   struct gdbarch_info info;
  99
 100   if (!target_desc_fetched)
 101     return;
 102
 103   target_desc_fetched = 0;
 104   current_target_desc = NULL;
 105
 106   gdbarch_info_init (&info);
 107   if (!gdbarch_update_p (info))
 108     internal_error (__FILE__, __LINE__,
 109                     _("Could not remove target-supplied description"));
 110 }
 111
 112 /* Return the global current target description.  This should only be
 113    used by gdbarch initialization code; most access should be through
 114    an existing gdbarch.  */
 115
 116 const struct target_desc *
 117 target_current_description (void)
 118 {
 119   if (target_desc_fetched)
 120     return current_target_desc;
 121
 122   return NULL;
 123 }
 124
 125 /* Methods for constructing a target description.  */
 126
 127 struct target_desc *
 128 allocate_target_description (void)
 129 {
 130   return XZALLOC (struct target_desc);
 131 }