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1#ifndef _LINUX_BYTEORDER_SWAB_H
2#define _LINUX_BYTEORDER_SWAB_H
3
4/*
5 * linux/byteorder/swab.h
6 * Byte-swapping, independently from CPU endianness
7 * swabXX[ps]?(foo)
8 *
9 * Francois-Rene Rideau <fare@tunes.org> 19971205
10 * separated swab functions from cpu_to_XX,
11 * to clean up support for bizarre-endian architectures.
12 *
13 * Trent Piepho <xyzzy@speakeasy.org> 2007114
14 * make constant-folding work, provide C versions that
15 * gcc can optimize better, explain different versions
16 *
17 * See asm-i386/byteorder.h and suches for examples of how to provide
18 * architecture-dependent optimized versions
19 *
20 */
21
22#include <linux/compiler.h>
23
24/* Functions/macros defined, there are a lot:
25 *
26 * ___swabXX
27 * Generic C versions of the swab functions.
28 *
29 * ___constant_swabXX
30 * C versions that gcc can fold into a compile-time constant when
31 * the argument is a compile-time constant.
32 *
33 * __arch__swabXX[sp]?
34 * Architecture optimized versions of all the swab functions
35 * (including the s and p versions). These can be defined in
36 * asm-arch/byteorder.h. Any which are not, are defined here.
37 * __arch__swabXXs() is defined in terms of __arch__swabXXp(), which
38 * is defined in terms of __arch__swabXX(), which is in turn defined
39 * in terms of ___swabXX(x).
40 * These must be macros. They may be unsafe for arguments with
41 * side-effects.
42 *
43 * __fswabXX
44 * Inline function versions of the __arch__ macros. These _are_ safe
45 * if the arguments have side-effects. Note there are no s and p
46 * versions of these.
47 *
48 * __swabXX[sb]
49 * There are the ones you should actually use. The __swabXX versions
50 * will be a constant given a constant argument and use the arch
51 * specific code (if any) for non-constant arguments. The s and p
52 * versions always use the arch specific code (constant folding
53 * doesn't apply). They are safe to use with arguments with
54 * side-effects.
55 *
56 * swabXX[sb]
57 * Nicknames for __swabXX[sb] to use in the kernel.
58 */
59
60/* casts are necessary for constants, because we never know how for sure
61 * how U/UL/ULL map to __u16, __u32, __u64. At least not in a portable way.
62 */
63
64static __inline__ __attribute_const__ __u16 ___swab16(__u16 x)
65{
66 return x<<8 | x>>8;
67}
68static __inline__ __attribute_const__ __u32 ___swab32(__u32 x)
69{
70 return x<<24 | x>>24 |
71 (x & (__u32)0x0000ff00UL)<<8 |
72 (x & (__u32)0x00ff0000UL)>>8;
73}
74static __inline__ __attribute_const__ __u64 ___swab64(__u64 x)
75{
76 return x<<56 | x>>56 |
77 (x & (__u64)0x000000000000ff00ULL)<<40 |
78 (x & (__u64)0x0000000000ff0000ULL)<<24 |
79 (x & (__u64)0x00000000ff000000ULL)<< 8 |
80 (x & (__u64)0x000000ff00000000ULL)>> 8 |
81 (x & (__u64)0x0000ff0000000000ULL)>>24 |
82 (x & (__u64)0x00ff000000000000ULL)>>40;
83}
84
85#define ___constant_swab16(x) \
86 ((__u16)( \
87 (((__u16)(x) & (__u16)0x00ffU) << 8) | \
88 (((__u16)(x) & (__u16)0xff00U) >> 8) ))
89#define ___constant_swab32(x) \
90 ((__u32)( \
91 (((__u32)(x) & (__u32)0x000000ffUL) << 24) | \
92 (((__u32)(x) & (__u32)0x0000ff00UL) << 8) | \
93 (((__u32)(x) & (__u32)0x00ff0000UL) >> 8) | \
94 (((__u32)(x) & (__u32)0xff000000UL) >> 24) ))
95#define ___constant_swab64(x) \
96 ((__u64)( \
97 (__u64)(((__u64)(x) & (__u64)0x00000000000000ffULL) << 56) | \
98 (__u64)(((__u64)(x) & (__u64)0x000000000000ff00ULL) << 40) | \
99 (__u64)(((__u64)(x) & (__u64)0x0000000000ff0000ULL) << 24) | \
100 (__u64)(((__u64)(x) & (__u64)0x00000000ff000000ULL) << 8) | \
101 (__u64)(((__u64)(x) & (__u64)0x000000ff00000000ULL) >> 8) | \
102 (__u64)(((__u64)(x) & (__u64)0x0000ff0000000000ULL) >> 24) | \
103 (__u64)(((__u64)(x) & (__u64)0x00ff000000000000ULL) >> 40) | \
104 (__u64)(((__u64)(x) & (__u64)0xff00000000000000ULL) >> 56) ))
105
106/*
107 * provide defaults when no architecture-specific optimization is detected
108 */
109#ifndef __arch__swab16
110# define __arch__swab16(x) ___swab16(x)
111#endif
112#ifndef __arch__swab32
113# define __arch__swab32(x) ___swab32(x)
114#endif
115#ifndef __arch__swab64
116# define __arch__swab64(x) ___swab64(x)
117#endif
118
119#ifndef __arch__swab16p
120# define __arch__swab16p(x) __arch__swab16(*(x))
121#endif
122#ifndef __arch__swab32p
123# define __arch__swab32p(x) __arch__swab32(*(x))
124#endif
125#ifndef __arch__swab64p
126# define __arch__swab64p(x) __arch__swab64(*(x))
127#endif
128
129#ifndef __arch__swab16s
130# define __arch__swab16s(x) ((void)(*(x) = __arch__swab16p(x)))
131#endif
132#ifndef __arch__swab32s
133# define __arch__swab32s(x) ((void)(*(x) = __arch__swab32p(x)))
134#endif
135#ifndef __arch__swab64s
136# define __arch__swab64s(x) ((void)(*(x) = __arch__swab64p(x)))
137#endif
138
139
140/*
141 * Allow constant folding
142 */
143#if defined(__GNUC__) && defined(__OPTIMIZE__)
144# define __swab16(x) \
145(__builtin_constant_p((__u16)(x)) ? \
146 ___constant_swab16((x)) : \
147 __fswab16((x)))
148# define __swab32(x) \
149(__builtin_constant_p((__u32)(x)) ? \
150 ___constant_swab32((x)) : \
151 __fswab32((x)))
152# define __swab64(x) \
153(__builtin_constant_p((__u64)(x)) ? \
154 ___constant_swab64((x)) : \
155 __fswab64((x)))
156#else
157# define __swab16(x) __fswab16(x)
158# define __swab32(x) __fswab32(x)
159# define __swab64(x) __fswab64(x)
160#endif /* OPTIMIZE */
161
162
163static __inline__ __attribute_const__ __u16 __fswab16(__u16 x)
164{
165 return __arch__swab16(x);
166}
167static __inline__ __u16 __swab16p(const __u16 *x)
168{
169 return __arch__swab16p(x);
170}
171static __inline__ void __swab16s(__u16 *addr)
172{
173 __arch__swab16s(addr);
174}
175
176static __inline__ __attribute_const__ __u32 __fswab32(__u32 x)
177{
178 return __arch__swab32(x);
179}
180static __inline__ __u32 __swab32p(const __u32 *x)
181{
182 return __arch__swab32p(x);
183}
184static __inline__ void __swab32s(__u32 *addr)
185{
186 __arch__swab32s(addr);
187}
188
189#ifdef __BYTEORDER_HAS_U64__
190static __inline__ __attribute_const__ __u64 __fswab64(__u64 x)
191{
192# ifdef __SWAB_64_THRU_32__
193 __u32 h = x >> 32;
194 __u32 l = x & ((1ULL<<32)-1);
195 return (((__u64)__swab32(l)) << 32) | ((__u64)(__swab32(h)));
196# else
197 return __arch__swab64(x);
198# endif
199}
200static __inline__ __u64 __swab64p(const __u64 *x)
201{
202 return __arch__swab64p(x);
203}
204static __inline__ void __swab64s(__u64 *addr)
205{
206 __arch__swab64s(addr);
207}
208#endif /* __BYTEORDER_HAS_U64__ */
209
210#if defined(__KERNEL__)
211#define swab16 __swab16
212#define swab32 __swab32
213#define swab64 __swab64
214#define swab16p __swab16p
215#define swab32p __swab32p
216#define swab64p __swab64p
217#define swab16s __swab16s
218#define swab32s __swab32s
219#define swab64s __swab64s
220#endif
221
222#endif /* _LINUX_BYTEORDER_SWAB_H */