Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/include/asm-arm/unaligned.h
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Wed Mar 4 11:03:09 2009 UTC (15 years, 3 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 3 months ago) by niro
File MIME type: text/plain
File size: 5049 byte(s)
Tag kernel26-2.6.12-alx-r9
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 |