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