1/* Code dealing with register stack frames, for GDB, the GNU debugger.
2
3   Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
4   1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002 Free Software
5   Foundation, Inc.
6
7   This file is part of GDB.
8
9   This program is free software; you can redistribute it and/or modify
10   it under the terms of the GNU General Public License as published by
11   the Free Software Foundation; either version 2 of the License, or
12   (at your option) any later version.
13
14   This program is distributed in the hope that it will be useful,
15   but WITHOUT ANY WARRANTY; without even the implied warranty of
16   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17   GNU General Public License for more details.
18
19   You should have received a copy of the GNU General Public License
20   along with this program; if not, write to the Free Software
21   Foundation, Inc., 59 Temple Place - Suite 330,
22   Boston, MA 02111-1307, USA.  */
23
24
25#include "defs.h"
26#include "regcache.h"
27#include "sentinel-frame.h"
28#include "inferior.h"
29#include "frame-unwind.h"
30
31struct frame_unwind_cache
32{
33  struct regcache *regcache;
34};
35
36void *
37sentinel_frame_cache (struct regcache *regcache)
38{
39  struct frame_unwind_cache *cache =
40    FRAME_OBSTACK_ZALLOC (struct frame_unwind_cache);
41  cache->regcache = regcache;
42  return cache;
43}
44
45/* Here the register value is taken direct from the register cache.  */
46
47static void
48sentinel_frame_prev_register (struct frame_info *next_frame,
49			      void **this_prologue_cache,
50			      int regnum, int *optimized,
51			      enum lval_type *lvalp, CORE_ADDR *addrp,
52			      int *realnum, void *bufferp)
53{
54  struct frame_unwind_cache *cache = *this_prologue_cache;
55  /* Describe the register's location.  A reg-frame maps all registers
56     onto the corresponding hardware register.  */
57  *optimized = 0;
58  *lvalp = lval_register;
59  *addrp = register_offset_hack (current_gdbarch, regnum);
60  *realnum = regnum;
61
62  /* If needed, find and return the value of the register.  */
63  if (bufferp != NULL)
64    {
65      /* Return the actual value.  */
66      /* Use the regcache_cooked_read() method so that it, on the fly,
67         constructs either a raw or pseudo register from the raw
68         register cache.  */
69      regcache_cooked_read (cache->regcache, regnum, bufferp);
70    }
71}
72
73static void
74sentinel_frame_this_id (struct frame_info *next_frame,
75			void **this_prologue_cache,
76			struct frame_id *this_id)
77{
78  /* The sentinel frame is used as a starting point for creating the
79     previous (inner most) frame.  That frame's THIS_ID method will be
80     called to determine the inner most frame's ID.  Not this one.  */
81  internal_error (__FILE__, __LINE__, "sentinel_frame_this_id called");
82}
83
84const struct frame_unwind sentinel_frame_unwinder =
85{
86  SENTINEL_FRAME,
87  sentinel_frame_this_id,
88  sentinel_frame_prev_register
89};
90
91const struct frame_unwind *const sentinel_frame_unwind = &sentinel_frame_unwinder;
92