1#ifndef __ASM_ARM_UNALIGNED_H
2#define __ASM_ARM_UNALIGNED_H
3
4#include <asm/types.h>
5
6extern 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
95static inline void __put_unaligned_2_le(__u32 __v, register __u8 *__p)
96{
97	*__p++ = __v;
98	*__p++ = __v >> 8;
99}
100
101static inline void __put_unaligned_2_be(__u32 __v, register __u8 *__p)
102{
103	*__p++ = __v >> 8;
104	*__p++ = __v;
105}
106
107static 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
113static 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
119static 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
130static 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
192