1 #ifndef __ASM_ARM_UNALIGNED_H
2 #define __ASM_ARM_UNALIGNED_H
6 extern int __bug_unaligned_x(const void *ptr
);
9 * What is the most efficient way of loading/storing an unaligned value?
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
17 * Current stats with gcc 2.7.2.2 for these functions:
19 * ptrsize get: code regs put: code regs
25 * gcc 2.95.1 seems to code differently:
27 * ptrsize get: code regs put: code regs
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.
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
42 #define __get_unaligned_2_le(__p) \
43 (__p[0] | __p[1] << 8)
45 #define __get_unaligned_2_be(__p) \
46 (__p[0] << 8 | __p[1])
48 #define __get_unaligned_4_le(__p) \
49 (__p[0] | __p[1] << 8 | __p[2] << 16 | __p[3] << 24)
51 #define __get_unaligned_4_be(__p) \
52 (__p[0] << 24 | __p[1] << 16 | __p[2] << 8 | __p[3])
54 #define __get_unaligned_8_le(__p) \
55 ((unsigned long long)__get_unaligned_4_le((__p+4)) << 32 | \
56 __get_unaligned_4_le(__p))
58 #define __get_unaligned_8_be(__p) \
59 ((unsigned long long)__get_unaligned_4_be(__p) << 32 | \
60 __get_unaligned_4_be((__p+4)))
62 #if 0 // mask by Victor Yu. 02-12-2007
63 #define __get_unaligned_le(ptr) \
65 const __u8 *__p = (const __u8 *)(ptr); \
66 __builtin_choose_expr(sizeof(*(ptr)) == 1, *__p, \
67 __builtin_choose_expr(sizeof(*(ptr)) == 2, __get_unaligned_2_le(__p), \
68 __builtin_choose_expr(sizeof(*(ptr)) == 4, __get_unaligned_4_le(__p), \
69 __builtin_choose_expr(sizeof(*(ptr)) == 8, __get_unaligned_8_le(__p), \
70 (void)__bug_unaligned_x(__p))))); \
73 #define __get_unaligned_le(ptr) \
75 __typeof__(*(ptr)) __v; \
76 __u8 *__p = (__u8 *)(ptr); \
77 switch (sizeof(*(ptr))) { \
78 case 1: __v = *(ptr); break; \
79 case 2: __v = __get_unaligned_2_le(__p); break; \
80 case 4: __v = __get_unaligned_4_le(__p); break; \
82 unsigned int __v1, __v2; \
83 __v2 = __get_unaligned_4_le((__p+4)); \
84 __v1 = __get_unaligned_4_le(__p); \
85 __v = ((unsigned long long)__v2 << 32 | __v1); \
88 default: __v = __bug_unaligned_x(__p); break; \
94 #define __get_unaligned_be(ptr) \
96 const __u8 *__p = (const __u8 *)(ptr); \
97 __builtin_choose_expr(sizeof(*(ptr)) == 1, *__p, \
98 __builtin_choose_expr(sizeof(*(ptr)) == 2, __get_unaligned_2_be(__p), \
99 __builtin_choose_expr(sizeof(*(ptr)) == 4, __get_unaligned_4_be(__p), \
100 __builtin_choose_expr(sizeof(*(ptr)) == 8, __get_unaligned_8_be(__p), \
101 (void)__bug_unaligned_x(__p))))); \
105 static inline void __put_unaligned_2_le(__u32 __v
, register __u8
*__p
)
111 static inline void __put_unaligned_2_be(__u32 __v
, register __u8
*__p
)
117 static inline void __put_unaligned_4_le(__u32 __v
, register __u8
*__p
)
119 __put_unaligned_2_le(__v
>> 16, __p
+ 2);
120 __put_unaligned_2_le(__v
, __p
);
123 static inline void __put_unaligned_4_be(__u32 __v
, register __u8
*__p
)
125 __put_unaligned_2_be(__v
>> 16, __p
);
126 __put_unaligned_2_be(__v
, __p
+ 2);
129 static inline void __put_unaligned_8_le(const unsigned long long __v
, register __u8
*__p
)
132 * tradeoff: 8 bytes of stack for all unaligned puts (2
133 * instructions), or an extra register in the long long
134 * case - go for the extra register.
136 __put_unaligned_4_le(__v
>> 32, __p
+4);
137 __put_unaligned_4_le(__v
, __p
);
140 static inline void __put_unaligned_8_be(const unsigned long long __v
, register __u8
*__p
)
143 * tradeoff: 8 bytes of stack for all unaligned puts (2
144 * instructions), or an extra register in the long long
145 * case - go for the extra register.
147 __put_unaligned_4_be(__v
>> 32, __p
);
148 __put_unaligned_4_be(__v
, __p
+4);
152 * Try to store an unaligned value as efficiently as possible.
154 #define __put_unaligned_le(val,ptr) \
156 switch (sizeof(*(ptr))) { \
160 case 2: __put_unaligned_2_le((val),(__u8 *)(ptr)); \
162 case 4: __put_unaligned_4_le((val),(__u8 *)(ptr)); \
164 case 8: __put_unaligned_8_le((val),(__u8 *)(ptr)); \
166 default: __bug_unaligned_x(ptr); \
172 #define __put_unaligned_be(val,ptr) \
174 switch (sizeof(*(ptr))) { \
178 case 2: __put_unaligned_2_be((val),(__u8 *)(ptr)); \
180 case 4: __put_unaligned_4_be((val),(__u8 *)(ptr)); \
182 case 8: __put_unaligned_8_be((val),(__u8 *)(ptr)); \
184 default: __bug_unaligned_x(ptr); \
194 #define get_unaligned __get_unaligned_le
195 #define put_unaligned __put_unaligned_le
197 #define get_unaligned __get_unaligned_be
198 #define put_unaligned __put_unaligned_be