fixed merge bug
[linux-2.6.git] / include / asm-arm / unaligned.h
1 #ifndef __ASM_ARM_UNALIGNED_H
2 #define __ASM_ARM_UNALIGNED_H
3
4 #include <asm/types.h>
5
6 extern int __bug_unaligned_x(void *ptr);
7
8 /*
9  * What is the most efficient way of loading/storing an unaligned value?
10  *
11  * That is the subject of this file.  Efficiency here is defined as
12  * minimum code size with minimum register usage for the common cases.
13  * It is currently not believed that long longs are common, so we
14  * trade efficiency for the chars, shorts and longs against the long
15  * longs.
16  *
17  * Current stats with gcc 2.7.2.2 for these functions:
18  *
19  *      ptrsize get:    code    regs    put:    code    regs
20  *      1               1       1               1       2
21  *      2               3       2               3       2
22  *      4               7       3               7       3
23  *      8               20      6               16      6
24  *
25  * gcc 2.95.1 seems to code differently:
26  *
27  *      ptrsize get:    code    regs    put:    code    regs
28  *      1               1       1               1       2
29  *      2               3       2               3       2
30  *      4               7       4               7       4
31  *      8               19      8               15      6
32  *
33  * which may or may not be more efficient (depending upon whether
34  * you can afford the extra registers).  Hopefully the gcc 2.95
35  * is inteligent enough to decide if it is better to use the
36  * extra register, but evidence so far seems to suggest otherwise.
37  *
38  * Unfortunately, gcc is not able to optimise the high word
39  * out of long long >> 32, or the low word from long long << 32
40  */
41
42 #define __get_unaligned_2_le(__p)                                       \
43         (__p[0] | __p[1] << 8)
44
45 #define __get_unaligned_2_be(__p)                                       \
46         (__p[0] << 8 | __p[1])
47
48 #define __get_unaligned_4_le(__p)                                       \
49         (__p[0] | __p[1] << 8 | __p[2] << 16 | __p[3] << 24)
50
51 #define __get_unaligned_4_be(__p)                                       \
52         (__p[0] << 24 | __p[1] << 16 | __p[2] << 8 | __p[3])
53
54 #define __get_unaligned_le(ptr)                                 \
55         ({                                                      \
56                 __typeof__(*(ptr)) __v;                         \
57                 __u8 *__p = (__u8 *)(ptr);                      \
58                 switch (sizeof(*(ptr))) {                       \
59                 case 1: __v = *(ptr);                   break;  \
60                 case 2: __v = __get_unaligned_2_le(__p);        break;  \
61                 case 4: __v = __get_unaligned_4_le(__p);        break;  \
62                 case 8: {                                       \
63                                 unsigned int __v1, __v2;        \
64                                 __v2 = __get_unaligned_4_le((__p+4)); \
65                                 __v1 = __get_unaligned_4_le(__p);       \
66                                 __v = ((unsigned long long)__v2 << 32 | __v1);  \
67                         }                                       \
68                         break;                                  \
69                 default: __v = __bug_unaligned_x(__p);  break;  \
70                 }                                               \
71                 __v;                                            \
72         })
73
74 #define __get_unaligned_be(ptr)                                 \
75         ({                                                      \
76                 __typeof__(*(ptr)) __v;                         \
77                 __u8 *__p = (__u8 *)(ptr);                      \
78                 switch (sizeof(*(ptr))) {                       \
79                 case 1: __v = *(ptr);                   break;  \
80                 case 2: __v = __get_unaligned_2_be(__p);        break;  \
81                 case 4: __v = __get_unaligned_4_be(__p);        break;  \
82                 case 8: {                                       \
83                                 unsigned int __v1, __v2;        \
84                                 __v2 = __get_unaligned_4_be(__p); \
85                                 __v1 = __get_unaligned_4_be((__p+4));   \
86                                 __v = ((unsigned long long)__v2 << 32 | __v1);  \
87                         }                                       \
88                         break;                                  \
89                 default: __v = __bug_unaligned_x(__p);  break;  \
90                 }                                               \
91                 __v;                                            \
92         })
93
94
95 static inline void __put_unaligned_2_le(__u32 __v, register __u8 *__p)
96 {
97         *__p++ = __v;
98         *__p++ = __v >> 8;
99 }
100
101 static inline void __put_unaligned_2_be(__u32 __v, register __u8 *__p)
102 {
103         *__p++ = __v >> 8;
104         *__p++ = __v;
105 }
106
107 static inline void __put_unaligned_4_le(__u32 __v, register __u8 *__p)
108 {
109         __put_unaligned_2_le(__v >> 16, __p + 2);
110         __put_unaligned_2_le(__v, __p);
111 }
112
113 static inline void __put_unaligned_4_be(__u32 __v, register __u8 *__p)
114 {
115         __put_unaligned_2_be(__v >> 16, __p);
116         __put_unaligned_2_be(__v, __p + 2);
117 }
118
119 static inline void __put_unaligned_8_le(const unsigned long long __v, register __u8 *__p)
120 {
121         /*
122          * tradeoff: 8 bytes of stack for all unaligned puts (2
123          * instructions), or an extra register in the long long
124          * case - go for the extra register.
125          */
126         __put_unaligned_4_le(__v >> 32, __p+4);
127         __put_unaligned_4_le(__v, __p);
128 }
129
130 static inline void __put_unaligned_8_be(const unsigned long long __v, register __u8 *__p)
131 {
132         /*
133          * tradeoff: 8 bytes of stack for all unaligned puts (2
134          * instructions), or an extra register in the long long
135          * case - go for the extra register.
136          */
137         __put_unaligned_4_be(__v >> 32, __p);
138         __put_unaligned_4_be(__v, __p+4);
139 }
140
141 /*
142  * Try to store an unaligned value as efficiently as possible.
143  */
144 #define __put_unaligned_le(val,ptr)                                     \
145         ({                                                      \
146                 switch (sizeof(*(ptr))) {                       \
147                 case 1:                                         \
148                         *(ptr) = (val);                         \
149                         break;                                  \
150                 case 2: __put_unaligned_2_le((val),(__u8 *)(ptr));      \
151                         break;                                  \
152                 case 4: __put_unaligned_4_le((val),(__u8 *)(ptr));      \
153                         break;                                  \
154                 case 8: __put_unaligned_8_le((val),(__u8 *)(ptr)); \
155                         break;                                  \
156                 default: __bug_unaligned_x(ptr);                \
157                         break;                                  \
158                 }                                               \
159                 (void) 0;                                       \
160         })
161
162 #define __put_unaligned_be(val,ptr)                                     \
163         ({                                                      \
164                 switch (sizeof(*(ptr))) {                       \
165                 case 1:                                         \
166                         *(ptr) = (val);                         \
167                         break;                                  \
168                 case 2: __put_unaligned_2_be((val),(__u8 *)(ptr));      \
169                         break;                                  \
170                 case 4: __put_unaligned_4_be((val),(__u8 *)(ptr));      \
171                         break;                                  \
172                 case 8: __put_unaligned_8_be((val),(__u8 *)(ptr)); \
173                         break;                                  \
174                 default: __bug_unaligned_x(ptr);                \
175                         break;                                  \
176                 }                                               \
177                 (void) 0;                                       \
178         })
179
180 /*
181  * Select endianness
182  */
183 #ifndef __ARMEB__
184 #define get_unaligned   __get_unaligned_le
185 #define put_unaligned   __put_unaligned_le
186 #else
187 #define get_unaligned   __get_unaligned_be
188 #define put_unaligned   __put_unaligned_be
189 #endif
190
191 #endif