1/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2#ifndef _LINUX_SWAB_H
3#define _LINUX_SWAB_H
4
5#include <linux/types.h>
6
7#include <asm/bitsperlong.h>
8#include <asm/swab.h>
9
10/*
11 * casts are necessary for constants, because we never know how for sure
12 * how U/UL/ULL map to __u16, __u32, __u64. At least not in a portable way.
13 */
14#define ___constant_swab16(x) ((__u16)( \
15 (((__u16)(x) & (__u16)0x00ffU) << 8) | \
16 (((__u16)(x) & (__u16)0xff00U) >> 8)))
17
18#define ___constant_swab32(x) ((__u32)( \
19 (((__u32)(x) & (__u32)0x000000ffUL) << 24) | \
20 (((__u32)(x) & (__u32)0x0000ff00UL) << 8) | \
21 (((__u32)(x) & (__u32)0x00ff0000UL) >> 8) | \
22 (((__u32)(x) & (__u32)0xff000000UL) >> 24)))
23
24#define ___constant_swab64(x) ((__u64)( \
25 (((__u64)(x) & (__u64)0x00000000000000ffULL) << 56) | \
26 (((__u64)(x) & (__u64)0x000000000000ff00ULL) << 40) | \
27 (((__u64)(x) & (__u64)0x0000000000ff0000ULL) << 24) | \
28 (((__u64)(x) & (__u64)0x00000000ff000000ULL) << 8) | \
29 (((__u64)(x) & (__u64)0x000000ff00000000ULL) >> 8) | \
30 (((__u64)(x) & (__u64)0x0000ff0000000000ULL) >> 24) | \
31 (((__u64)(x) & (__u64)0x00ff000000000000ULL) >> 40) | \
32 (((__u64)(x) & (__u64)0xff00000000000000ULL) >> 56)))
33
34#define ___constant_swahw32(x) ((__u32)( \
35 (((__u32)(x) & (__u32)0x0000ffffUL) << 16) | \
36 (((__u32)(x) & (__u32)0xffff0000UL) >> 16)))
37
38#define ___constant_swahb32(x) ((__u32)( \
39 (((__u32)(x) & (__u32)0x00ff00ffUL) << 8) | \
40 (((__u32)(x) & (__u32)0xff00ff00UL) >> 8)))
41
42/*
43 * Implement the following as inlines, but define the interface using
44 * macros to allow constant folding when possible:
45 * ___swab16, ___swab32, ___swab64, ___swahw32, ___swahb32
46 */
47
48static __inline__ __u16 __fswab16(__u16 val)
49{
50#if defined (__arch_swab16)
51 return __arch_swab16(val);
52#else
53 return ___constant_swab16(val);
54#endif
55}
56
57static __inline__ __u32 __fswab32(__u32 val)
58{
59#if defined(__arch_swab32)
60 return __arch_swab32(val);
61#else
62 return ___constant_swab32(val);
63#endif
64}
65
66static __inline__ __u64 __fswab64(__u64 val)
67{
68#if defined (__arch_swab64)
69 return __arch_swab64(val);
70#elif defined(__SWAB_64_THRU_32__)
71 __u32 h = val >> 32;
72 __u32 l = val & ((1ULL << 32) - 1);
73 return (((__u64)__fswab32(l)) << 32) | ((__u64)(__fswab32(h)));
74#else
75 return ___constant_swab64(val);
76#endif
77}
78
79static __inline__ __u32 __fswahw32(__u32 val)
80{
81#ifdef __arch_swahw32
82 return __arch_swahw32(val);
83#else
84 return ___constant_swahw32(val);
85#endif
86}
87
88static __inline__ __u32 __fswahb32(__u32 val)
89{
90#ifdef __arch_swahb32
91 return __arch_swahb32(val);
92#else
93 return ___constant_swahb32(val);
94#endif
95}
96
97/**
98 * __swab16 - return a byteswapped 16-bit value
99 * @x: value to byteswap
100 */
101#ifdef __HAVE_BUILTIN_BSWAP16__
102#define __swab16(x) (__u16)__builtin_bswap16((__u16)(x))
103#else
104#define __swab16(x) \
105 (__builtin_constant_p((__u16)(x)) ? \
106 ___constant_swab16(x) : \
107 __fswab16(x))
108#endif
109
110/**
111 * __swab32 - return a byteswapped 32-bit value
112 * @x: value to byteswap
113 */
114#ifdef __HAVE_BUILTIN_BSWAP32__
115#define __swab32(x) (__u32)__builtin_bswap32((__u32)(x))
116#else
117#define __swab32(x) \
118 (__builtin_constant_p((__u32)(x)) ? \
119 ___constant_swab32(x) : \
120 __fswab32(x))
121#endif
122
123/**
124 * __swab64 - return a byteswapped 64-bit value
125 * @x: value to byteswap
126 */
127#ifdef __HAVE_BUILTIN_BSWAP64__
128#define __swab64(x) (__u64)__builtin_bswap64((__u64)(x))
129#else
130#define __swab64(x) \
131 (__builtin_constant_p((__u64)(x)) ? \
132 ___constant_swab64(x) : \
133 __fswab64(x))
134#endif
135
136static __always_inline unsigned long __swab(const unsigned long y)
137{
138#if __BITS_PER_LONG == 64
139 return __swab64(y);
140#else /* __BITS_PER_LONG == 32 */
141 return __swab32(y);
142#endif
143}
144
145/**
146 * __swahw32 - return a word-swapped 32-bit value
147 * @x: value to wordswap
148 *
149 * __swahw32(0x12340000) is 0x00001234
150 */
151#define __swahw32(x) \
152 (__builtin_constant_p((__u32)(x)) ? \
153 ___constant_swahw32(x) : \
154 __fswahw32(x))
155
156/**
157 * __swahb32 - return a high and low byte-swapped 32-bit value
158 * @x: value to byteswap
159 *
160 * __swahb32(0x12345678) is 0x34127856
161 */
162#define __swahb32(x) \
163 (__builtin_constant_p((__u32)(x)) ? \
164 ___constant_swahb32(x) : \
165 __fswahb32(x))
166
167/**
168 * __swab16p - return a byteswapped 16-bit value from a pointer
169 * @p: pointer to a naturally-aligned 16-bit value
170 */
171static __always_inline __u16 __swab16p(const __u16 *p)
172{
173#ifdef __arch_swab16p
174 return __arch_swab16p(p);
175#else
176 return __swab16(*p);
177#endif
178}
179
180/**
181 * __swab32p - return a byteswapped 32-bit value from a pointer
182 * @p: pointer to a naturally-aligned 32-bit value
183 */
184static __always_inline __u32 __swab32p(const __u32 *p)
185{
186#ifdef __arch_swab32p
187 return __arch_swab32p(p);
188#else
189 return __swab32(*p);
190#endif
191}
192
193/**
194 * __swab64p - return a byteswapped 64-bit value from a pointer
195 * @p: pointer to a naturally-aligned 64-bit value
196 */
197static __always_inline __u64 __swab64p(const __u64 *p)
198{
199#ifdef __arch_swab64p
200 return __arch_swab64p(p);
201#else
202 return __swab64(*p);
203#endif
204}
205
206/**
207 * __swahw32p - return a wordswapped 32-bit value from a pointer
208 * @p: pointer to a naturally-aligned 32-bit value
209 *
210 * See __swahw32() for details of wordswapping.
211 */
212static __inline__ __u32 __swahw32p(const __u32 *p)
213{
214#ifdef __arch_swahw32p
215 return __arch_swahw32p(p);
216#else
217 return __swahw32(*p);
218#endif
219}
220
221/**
222 * __swahb32p - return a high and low byteswapped 32-bit value from a pointer
223 * @p: pointer to a naturally-aligned 32-bit value
224 *
225 * See __swahb32() for details of high/low byteswapping.
226 */
227static __inline__ __u32 __swahb32p(const __u32 *p)
228{
229#ifdef __arch_swahb32p
230 return __arch_swahb32p(p);
231#else
232 return __swahb32(*p);
233#endif
234}
235
236/**
237 * __swab16s - byteswap a 16-bit value in-place
238 * @p: pointer to a naturally-aligned 16-bit value
239 */
240static __inline__ void __swab16s(__u16 *p)
241{
242#ifdef __arch_swab16s
243 __arch_swab16s(p);
244#else
245 *p = __swab16p(p);
246#endif
247}
248/**
249 * __swab32s - byteswap a 32-bit value in-place
250 * @p: pointer to a naturally-aligned 32-bit value
251 */
252static __always_inline void __swab32s(__u32 *p)
253{
254#ifdef __arch_swab32s
255 __arch_swab32s(p);
256#else
257 *p = __swab32p(p);
258#endif
259}
260
261/**
262 * __swab64s - byteswap a 64-bit value in-place
263 * @p: pointer to a naturally-aligned 64-bit value
264 */
265static __always_inline void __swab64s(__u64 *p)
266{
267#ifdef __arch_swab64s
268 __arch_swab64s(p);
269#else
270 *p = __swab64p(p);
271#endif
272}
273
274/**
275 * __swahw32s - wordswap a 32-bit value in-place
276 * @p: pointer to a naturally-aligned 32-bit value
277 *
278 * See __swahw32() for details of wordswapping
279 */
280static __inline__ void __swahw32s(__u32 *p)
281{
282#ifdef __arch_swahw32s
283 __arch_swahw32s(p);
284#else
285 *p = __swahw32p(p);
286#endif
287}
288
289/**
290 * __swahb32s - high and low byteswap a 32-bit value in-place
291 * @p: pointer to a naturally-aligned 32-bit value
292 *
293 * See __swahb32() for details of high and low byte swapping
294 */
295static __inline__ void __swahb32s(__u32 *p)
296{
297#ifdef __arch_swahb32s
298 __arch_swahb32s(p);
299#else
300 *p = __swahb32p(p);
301#endif
302}
303
304
305#endif /* _LINUX_SWAB_H */
306

source code of include/linux/swab.h