1/* Unaligned memory access functionality.
2   Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2008 Red Hat, Inc.
3   Written by Ulrich Drepper <drepper@redhat.com>, 2001.
4
5   This file is free software; you can redistribute it and/or modify
6   it under the terms of either
7
8     * the GNU Lesser General Public License as published by the Free
9       Software Foundation; either version 3 of the License, or (at
10       your option) any later version
11
12   or
13
14     * the GNU General Public License as published by the Free
15       Software Foundation; either version 2 of the License, or (at
16       your option) any later version
17
18   or both in parallel, as here.
19
20   elfutils is distributed in the hope that it will be useful, but
21   WITHOUT ANY WARRANTY; without even the implied warranty of
22   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
23   General Public License for more details.
24
25   You should have received copies of the GNU General Public License and
26   the GNU Lesser General Public License along with this program.  If
27   not, see <http://www.gnu.org/licenses/>.  */
28
29#ifndef _MEMORY_ACCESS_H
30#define _MEMORY_ACCESS_H 1
31
32#include <limits.h>
33#include <stdint.h>
34
35#include <system.h>
36
37/* When loading this file we require the macro MACHINE_ENCODING to be
38   defined to signal the endianness of the architecture which is
39   defined.  */
40#ifndef MACHINE_ENCODING
41# error "MACHINE_ENCODING needs to be defined"
42#endif
43#if MACHINE_ENCODING != BIG_ENDIAN && MACHINE_ENCODING != LITTLE_ENDIAN
44# error "MACHINE_ENCODING must signal either big or little endian"
45#endif
46
47
48/* We use simple memory access functions in case the hardware allows it.
49   The caller has to make sure we don't have alias problems.  */
50#if ALLOW_UNALIGNED
51
52# define read_2ubyte_unaligned(Addr) \
53  (unlikely (MACHINE_ENCODING != BYTE_ORDER)				      \
54   ? bswap_16 (*((const uint16_t *) (Addr)))				      \
55   : *((const uint16_t *) (Addr)))
56# define read_2sbyte_unaligned(Addr) \
57  (unlikely (MACHINE_ENCODING != BYTE_ORDER)				      \
58   ? (int16_t) bswap_16 (*((const int16_t *) (Addr)))			      \
59   : *((const int16_t *) (Addr)))
60
61# define read_4ubyte_unaligned_noncvt(Addr) \
62   *((const uint32_t *) (Addr))
63# define read_4ubyte_unaligned(Addr) \
64  (unlikely (MACHINE_ENCODING != BYTE_ORDER)				      \
65   ? bswap_32 (*((const uint32_t *) (Addr)))				      \
66   : *((const uint32_t *) (Addr)))
67# define read_4sbyte_unaligned(Addr) \
68  (unlikely (MACHINE_ENCODING != BYTE_ORDER)				      \
69   ? (int32_t) bswap_32 (*((const int32_t *) (Addr)))			      \
70   : *((const int32_t *) (Addr)))
71
72# define read_8ubyte_unaligned(Addr) \
73  (unlikely (MACHINE_ENCODING != BYTE_ORDER)				      \
74   ? bswap_64 (*((const uint64_t *) (Addr)))				      \
75   : *((const uint64_t *) (Addr)))
76# define read_8sbyte_unaligned(Addr) \
77  (unlikely (MACHINE_ENCODING != BYTE_ORDER)				      \
78   ? (int64_t) bswap_64 (*((const int64_t *) (Addr)))			      \
79   : *((const int64_t *) (Addr)))
80
81#else
82
83union unaligned
84  {
85    void *p;
86    uint16_t u2;
87    uint32_t u4;
88    uint64_t u8;
89    int16_t s2;
90    int32_t s4;
91    int64_t s8;
92  } attribute_packed;
93
94static inline uint16_t
95read_2ubyte_unaligned (const void *p)
96{
97  const union unaligned *up = p;
98  if (MACHINE_ENCODING != BYTE_ORDER)
99    return bswap_16 (up->u2);
100  return up->u2;
101}
102static inline int16_t
103read_2sbyte_unaligned (const void *p)
104{
105  const union unaligned *up = p;
106  if (MACHINE_ENCODING != BYTE_ORDER)
107    return (int16_t) bswap_16 (up->u2);
108  return up->s2;
109}
110
111static inline uint32_t
112read_4ubyte_unaligned_noncvt (const void *p)
113{
114  const union unaligned *up = p;
115  return up->u4;
116}
117static inline uint32_t
118read_4ubyte_unaligned (const void *p)
119{
120  const union unaligned *up = p;
121  if (MACHINE_ENCODING != BYTE_ORDER)
122    return bswap_32 (up->u4);
123  return up->u4;
124}
125static inline int32_t
126read_4sbyte_unaligned (const void *p)
127{
128  const union unaligned *up = p;
129  if (MACHINE_ENCODING != BYTE_ORDER)
130    return (int32_t) bswap_32 (up->u4);
131  return up->s4;
132}
133
134static inline uint64_t
135read_8ubyte_unaligned (const void *p)
136{
137  const union unaligned *up = p;
138  if (MACHINE_ENCODING != BYTE_ORDER)
139    return bswap_64 (up->u8);
140  return up->u8;
141}
142static inline int64_t
143read_8sbyte_unaligned (const void *p)
144{
145  const union unaligned *up = p;
146  if (MACHINE_ENCODING != BYTE_ORDER)
147    return (int64_t) bswap_64 (up->u8);
148  return up->s8;
149}
150
151#endif	/* allow unaligned */
152
153
154#define read_2ubyte_unaligned_inc(Addr) \
155  ({ uint16_t t_ = read_2ubyte_unaligned (Addr);			      \
156     Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 2);		      \
157     t_; })
158#define read_2sbyte_unaligned_inc(Addr) \
159  ({ int16_t t_ = read_2sbyte_unaligned (Addr);				      \
160     Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 2);		      \
161     t_; })
162
163#define read_4ubyte_unaligned_inc(Addr) \
164  ({ uint32_t t_ = read_4ubyte_unaligned (Addr);			      \
165     Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 4);		      \
166     t_; })
167#define read_4sbyte_unaligned_inc(Addr) \
168  ({ int32_t t_ = read_4sbyte_unaligned (Addr);				      \
169     Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 4);		      \
170     t_; })
171
172#define read_8ubyte_unaligned_inc(Addr) \
173  ({ uint64_t t_ = read_8ubyte_unaligned (Addr);			      \
174     Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 8);		      \
175     t_; })
176#define read_8sbyte_unaligned_inc(Addr) \
177  ({ int64_t t_ = read_8sbyte_unaligned (Addr);				      \
178     Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 8);		      \
179     t_; })
180
181#endif	/* memory-access.h */
182