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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 |