1/* Unaligned memory access functionality.
2   Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005 Red Hat, Inc.
3   This file is part of Red Hat elfutils.
4   Written by Ulrich Drepper <drepper@redhat.com>, 2001.
5
6   Red Hat elfutils is free software; you can redistribute it and/or modify
7   it under the terms of the GNU General Public License as published by the
8   Free Software Foundation; version 2 of the License.
9
10   Red Hat elfutils is distributed in the hope that it will be useful, but
11   WITHOUT ANY WARRANTY; without even the implied warranty of
12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13   General Public License for more details.
14
15   You should have received a copy of the GNU General Public License along
16   with Red Hat elfutils; if not, write to the Free Software Foundation,
17   Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
18
19   In addition, as a special exception, Red Hat, Inc. gives You the
20   additional right to link the code of Red Hat elfutils with code licensed
21   under any Open Source Initiative certified open source license
22   (http://www.opensource.org/licenses/index.php) which requires the
23   distribution of source code with any binary distribution and to
24   distribute linked combinations of the two.  Non-GPL Code permitted under
25   this exception must only link to the code of Red Hat elfutils through
26   those well defined interfaces identified in the file named EXCEPTION
27   found in the source code files (the "Approved Interfaces").  The files
28   of Non-GPL Code may instantiate templates or use macros or inline
29   functions from the Approved Interfaces without causing the resulting
30   work to be covered by the GNU General Public License.  Only Red Hat,
31   Inc. may make changes or additions to the list of Approved Interfaces.
32   Red Hat's grant of this exception is conditioned upon your not adding
33   any new exceptions.  If you wish to add a new Approved Interface or
34   exception, please contact Red Hat.  You must obey the GNU General Public
35   License in all respects for all of the Red Hat elfutils code and other
36   code used in conjunction with Red Hat elfutils except the Non-GPL Code
37   covered by this exception.  If you modify this file, you may extend this
38   exception to your version of the file, but you are not obligated to do
39   so.  If you do not wish to provide this exception without modification,
40   you must delete this exception statement from your version and license
41   this file solely under the GPL without exception.
42
43   Red Hat elfutils is an included package of the Open Invention Network.
44   An included package of the Open Invention Network is a package for which
45   Open Invention Network licensees cross-license their patents.  No patent
46   license is granted, either expressly or impliedly, by designation as an
47   included package.  Should you wish to participate in the Open Invention
48   Network licensing program, please visit www.openinventionnetwork.com
49   <http://www.openinventionnetwork.com>.  */
50
51#ifndef _MEMORY_ACCESS_H
52#define _MEMORY_ACCESS_H 1
53
54#include <byteswap.h>
55#include <limits.h>
56#include <stdint.h>
57
58
59/* Number decoding macros.  See 7.6 Variable Length Data.  */
60
61#define get_uleb128_step(var, addr, nth, break)				      \
62    __b = *(addr)++;							      \
63    var |= (uintmax_t) (__b & 0x7f) << (nth * 7);			      \
64    if (likely ((__b & 0x80) == 0))					      \
65      break
66
67#define get_uleb128(var, addr)						      \
68  do {									      \
69    unsigned char __b;							      \
70    var = 0;								      \
71    get_uleb128_step (var, addr, 0, break);				      \
72    var = __libdw_get_uleb128 (var, 1, &(addr));			      \
73  } while (0)
74
75#define get_uleb128_rest_return(var, i, addrp)				      \
76  do {									      \
77    for (; i < 10; ++i)							      \
78      {									      \
79	get_uleb128_step (var, *addrp, i, return var);			      \
80      }									      \
81    /* Other implementations set VALUE to UINT_MAX in this		      \
82       case.  So we better do this as well.  */				      \
83    return UINT64_MAX;							      \
84  } while (0)
85
86/* The signed case is similar, but we sign-extend the result.  */
87
88#define get_sleb128_step(var, addr, nth, break)				      \
89    __b = *(addr)++;							      \
90    _v |= (uint64_t) (__b & 0x7f) << (nth * 7);				      \
91    if (likely ((__b & 0x80) == 0))					      \
92      {									      \
93	var = (_v << (64 - (nth * 7) - 7) >> (64 - (nth * 7) - 7));	      \
94        break;					 			      \
95      }									      \
96    else do {} while (0)
97
98#define get_sleb128(var, addr)						      \
99  do {									      \
100    unsigned char __b;							      \
101    int64_t _v = 0;							      \
102    get_sleb128_step (var, addr, 0, break);				      \
103    var = __libdw_get_sleb128 (_v, 1, &(addr));				      \
104  } while (0)
105
106#define get_sleb128_rest_return(var, i, addrp)				      \
107  do {									      \
108    for (; i < 9; ++i)							      \
109      {									      \
110	get_sleb128_step (var, *addrp, i, return var);			      \
111      }									      \
112    /* Other implementations set VALUE to INT_MAX in this		      \
113       case.  So we better do this as well.  */				      \
114    return INT64_MAX;							      \
115  } while (0)
116
117#ifdef IS_LIBDW
118extern uint64_t __libdw_get_uleb128 (uint64_t acc, unsigned int i,
119				     const unsigned char **addrp)
120     internal_function attribute_hidden;
121extern int64_t __libdw_get_sleb128 (int64_t acc, unsigned int i,
122				    const unsigned char **addrp)
123     internal_function attribute_hidden;
124#else
125static uint64_t
126__attribute__ ((unused))
127__libdw_get_uleb128 (uint64_t acc, unsigned int i, const unsigned char **addrp)
128{
129  unsigned char __b;
130  get_uleb128_rest_return (acc, i, addrp);
131}
132static int64_t
133__attribute__ ((unused))
134__libdw_get_sleb128 (int64_t acc, unsigned int i, const unsigned char **addrp)
135{
136  unsigned char __b;
137  int64_t _v = acc;
138  get_sleb128_rest_return (acc, i, addrp);
139}
140#endif
141
142
143/* We use simple memory access functions in case the hardware allows it.
144   The caller has to make sure we don't have alias problems.  */
145#if ALLOW_UNALIGNED
146
147# define read_2ubyte_unaligned(Dbg, Addr) \
148  (unlikely ((Dbg)->other_byte_order)					      \
149   ? bswap_16 (*((const uint16_t *) (Addr)))				      \
150   : *((const uint16_t *) (Addr)))
151# define read_2sbyte_unaligned(Dbg, Addr) \
152  (unlikely ((Dbg)->other_byte_order)					      \
153   ? (int16_t) bswap_16 (*((const int16_t *) (Addr)))			      \
154   : *((const int16_t *) (Addr)))
155
156# define read_4ubyte_unaligned_noncvt(Addr) \
157   *((const uint32_t *) (Addr))
158# define read_4ubyte_unaligned(Dbg, Addr) \
159  (unlikely ((Dbg)->other_byte_order)					      \
160   ? bswap_32 (*((const uint32_t *) (Addr)))				      \
161   : *((const uint32_t *) (Addr)))
162# define read_4sbyte_unaligned(Dbg, Addr) \
163  (unlikely ((Dbg)->other_byte_order)					      \
164   ? (int32_t) bswap_32 (*((const int32_t *) (Addr)))			      \
165   : *((const int32_t *) (Addr)))
166
167# define read_8ubyte_unaligned(Dbg, Addr) \
168  (unlikely ((Dbg)->other_byte_order)					      \
169   ? bswap_64 (*((const uint64_t *) (Addr)))				      \
170   : *((const uint64_t *) (Addr)))
171# define read_8sbyte_unaligned(Dbg, Addr) \
172  (unlikely ((Dbg)->other_byte_order)					      \
173   ? (int64_t) bswap_64 (*((const int64_t *) (Addr)))			      \
174   : *((const int64_t *) (Addr)))
175
176#else
177
178union unaligned
179  {
180    void *p;
181    uint16_t u2;
182    uint32_t u4;
183    uint64_t u8;
184    int16_t s2;
185    int32_t s4;
186    int64_t s8;
187  } __attribute__ ((packed));
188
189static inline uint16_t
190read_2ubyte_unaligned (Dwarf *dbg, const void *p)
191{
192  const union unaligned *up = p;
193  if (dbg->other_byte_order)
194    return bswap_16 (up->u2);
195  return up->u2;
196}
197static inline int16_t
198read_2sbyte_unaligned (Dwarf *dbg, const void *p)
199{
200  const union unaligned *up = p;
201  if (dbg->other_byte_order)
202    return (int16_t) bswap_16 (up->u2);
203  return up->s2;
204}
205
206static inline uint32_t
207read_4ubyte_unaligned_noncvt (const void *p)
208{
209  const union unaligned *up = p;
210  return up->u4;
211}
212static inline uint32_t
213read_4ubyte_unaligned (Dwarf *dbg, const void *p)
214{
215  const union unaligned *up = p;
216  if (dbg->other_byte_order)
217    return bswap_32 (up->u4);
218  return up->u4;
219}
220static inline int32_t
221read_4sbyte_unaligned (Dwarf *dbg, const void *p)
222{
223  const union unaligned *up = p;
224  if (dbg->other_byte_order)
225    return (int32_t) bswap_32 (up->u4);
226  return up->s4;
227}
228
229static inline uint64_t
230read_8ubyte_unaligned (Dwarf *dbg, const void *p)
231{
232  const union unaligned *up = p;
233  if (dbg->other_byte_order)
234    return bswap_64 (up->u8);
235  return up->u8;
236}
237static inline int64_t
238read_8sbyte_unaligned (Dwarf *dbg, const void *p)
239{
240  const union unaligned *up = p;
241  if (dbg->other_byte_order)
242    return (int64_t) bswap_64 (up->u8);
243  return up->s8;
244}
245
246#endif	/* allow unaligned */
247
248
249#define read_2ubyte_unaligned_inc(Dbg, Addr) \
250  ({ uint16_t t_ = read_2ubyte_unaligned (Dbg, Addr);			      \
251     Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 2);		      \
252     t_; })
253#define read_2sbyte_unaligned_inc(Dbg, Addr) \
254  ({ int16_t t_ = read_2sbyte_unaligned (Dbg, Addr);			      \
255     Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 2);		      \
256     t_; })
257
258#define read_4ubyte_unaligned_inc(Dbg, Addr) \
259  ({ uint32_t t_ = read_4ubyte_unaligned (Dbg, Addr);			      \
260     Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 4);		      \
261     t_; })
262#define read_4sbyte_unaligned_inc(Dbg, Addr) \
263  ({ int32_t t_ = read_4sbyte_unaligned (Dbg, Addr);			      \
264     Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 4);		      \
265     t_; })
266
267#define read_8ubyte_unaligned_inc(Dbg, Addr) \
268  ({ uint64_t t_ = read_8ubyte_unaligned (Dbg, Addr);			      \
269     Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 8);		      \
270     t_; })
271#define read_8sbyte_unaligned_inc(Dbg, Addr) \
272  ({ int64_t t_ = read_8sbyte_unaligned (Dbg, Addr);			      \
273     Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 8);		      \
274     t_; })
275
276#endif	/* memory-access.h */
277