Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_BITOPS_H
3#define _LINUX_BITOPS_H
4
5#include <asm/types.h>
6#include <linux/bits.h>
7#include <linux/typecheck.h>
8
9#include <uapi/linux/kernel.h>
10
11#define BITS_TO_LONGS(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(long))
12#define BITS_TO_U64(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(u64))
13#define BITS_TO_U32(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(u32))
14#define BITS_TO_BYTES(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(char))
15
16#define BYTES_TO_BITS(nb) ((nb) * BITS_PER_BYTE)
17
18extern unsigned int __sw_hweight8(unsigned int w);
19extern unsigned int __sw_hweight16(unsigned int w);
20extern unsigned int __sw_hweight32(unsigned int w);
21extern unsigned long __sw_hweight64(__u64 w);
22
23/*
24 * Defined here because those may be needed by architecture-specific static
25 * inlines.
26 */
27
28#include <asm-generic/bitops/generic-non-atomic.h>
29
30/*
31 * Many architecture-specific non-atomic bitops contain inline asm code and due
32 * to that the compiler can't optimize them to compile-time expressions or
33 * constants. In contrary, generic_*() helpers are defined in pure C and
34 * compilers optimize them just well.
35 * Therefore, to make `unsigned long foo = 0; __set_bit(BAR, &foo)` effectively
36 * equal to `unsigned long foo = BIT(BAR)`, pick the generic C alternative when
37 * the arguments can be resolved at compile time. That expression itself is a
38 * constant and doesn't bring any functional changes to the rest of cases.
39 * The casts to `uintptr_t` are needed to mitigate `-Waddress` warnings when
40 * passing a bitmap from .bss or .data (-> `!!addr` is always true).
41 */
42#define bitop(op, nr, addr) \
43 ((__builtin_constant_p(nr) && \
44 __builtin_constant_p((uintptr_t)(addr) != (uintptr_t)NULL) && \
45 (uintptr_t)(addr) != (uintptr_t)NULL && \
46 __builtin_constant_p(*(const unsigned long *)(addr))) ? \
47 const##op(nr, addr) : op(nr, addr))
48
49/*
50 * The following macros are non-atomic versions of their non-underscored
51 * counterparts.
52 */
53#define __set_bit(nr, addr) bitop(___set_bit, nr, addr)
54#define __clear_bit(nr, addr) bitop(___clear_bit, nr, addr)
55#define __change_bit(nr, addr) bitop(___change_bit, nr, addr)
56#define __test_and_set_bit(nr, addr) bitop(___test_and_set_bit, nr, addr)
57#define __test_and_clear_bit(nr, addr) bitop(___test_and_clear_bit, nr, addr)
58#define __test_and_change_bit(nr, addr) bitop(___test_and_change_bit, nr, addr)
59
60#define test_bit(nr, addr) bitop(_test_bit, nr, addr)
61#define test_bit_acquire(nr, addr) bitop(_test_bit_acquire, nr, addr)
62
63/*
64 * Include this here because some architectures need generic_ffs/fls in
65 * scope
66 */
67#include <asm/bitops.h>
68
69/* Check that the bitops prototypes are sane */
70#define __check_bitop_pr(name) \
71 static_assert(__same_type(arch_##name, generic_##name) && \
72 __same_type(const_##name, generic_##name) && \
73 __same_type(_##name, generic_##name))
74
75__check_bitop_pr(__set_bit);
76__check_bitop_pr(__clear_bit);
77__check_bitop_pr(__change_bit);
78__check_bitop_pr(__test_and_set_bit);
79__check_bitop_pr(__test_and_clear_bit);
80__check_bitop_pr(__test_and_change_bit);
81__check_bitop_pr(test_bit);
82__check_bitop_pr(test_bit_acquire);
83
84#undef __check_bitop_pr
85
86static inline int get_bitmask_order(unsigned int count)
87{
88 int order;
89
90 order = fls(count);
91 return order; /* We could be slightly more clever with -1 here... */
92}
93
94static __always_inline unsigned long hweight_long(unsigned long w)
95{
96 return sizeof(w) == 4 ? hweight32(w) : hweight64((__u64)w);
97}
98
99/**
100 * rol64 - rotate a 64-bit value left
101 * @word: value to rotate
102 * @shift: bits to roll
103 */
104static inline __u64 rol64(__u64 word, unsigned int shift)
105{
106 return (word << (shift & 63)) | (word >> ((-shift) & 63));
107}
108
109/**
110 * ror64 - rotate a 64-bit value right
111 * @word: value to rotate
112 * @shift: bits to roll
113 */
114static inline __u64 ror64(__u64 word, unsigned int shift)
115{
116 return (word >> (shift & 63)) | (word << ((-shift) & 63));
117}
118
119/**
120 * rol32 - rotate a 32-bit value left
121 * @word: value to rotate
122 * @shift: bits to roll
123 */
124static inline __u32 rol32(__u32 word, unsigned int shift)
125{
126 return (word << (shift & 31)) | (word >> ((-shift) & 31));
127}
128
129/**
130 * ror32 - rotate a 32-bit value right
131 * @word: value to rotate
132 * @shift: bits to roll
133 */
134static inline __u32 ror32(__u32 word, unsigned int shift)
135{
136 return (word >> (shift & 31)) | (word << ((-shift) & 31));
137}
138
139/**
140 * rol16 - rotate a 16-bit value left
141 * @word: value to rotate
142 * @shift: bits to roll
143 */
144static inline __u16 rol16(__u16 word, unsigned int shift)
145{
146 return (word << (shift & 15)) | (word >> ((-shift) & 15));
147}
148
149/**
150 * ror16 - rotate a 16-bit value right
151 * @word: value to rotate
152 * @shift: bits to roll
153 */
154static inline __u16 ror16(__u16 word, unsigned int shift)
155{
156 return (word >> (shift & 15)) | (word << ((-shift) & 15));
157}
158
159/**
160 * rol8 - rotate an 8-bit value left
161 * @word: value to rotate
162 * @shift: bits to roll
163 */
164static inline __u8 rol8(__u8 word, unsigned int shift)
165{
166 return (word << (shift & 7)) | (word >> ((-shift) & 7));
167}
168
169/**
170 * ror8 - rotate an 8-bit value right
171 * @word: value to rotate
172 * @shift: bits to roll
173 */
174static inline __u8 ror8(__u8 word, unsigned int shift)
175{
176 return (word >> (shift & 7)) | (word << ((-shift) & 7));
177}
178
179/**
180 * sign_extend32 - sign extend a 32-bit value using specified bit as sign-bit
181 * @value: value to sign extend
182 * @index: 0 based bit index (0 <= index < 32) to sign bit
183 *
184 * This is safe to use for 16- and 8-bit types as well.
185 *
186 * Return: 32-bit sign extended value
187 */
188static __always_inline __s32 sign_extend32(__u32 value, int index)
189{
190 __u8 shift = 31 - index;
191 return (__s32)(value << shift) >> shift;
192}
193
194/**
195 * sign_extend64 - sign extend a 64-bit value using specified bit as sign-bit
196 * @value: value to sign extend
197 * @index: 0 based bit index (0 <= index < 64) to sign bit
198 *
199 * This is safe to use for 32-, 16- and 8-bit types as well.
200 *
201 * Return: 64-bit sign extended value
202 */
203static __always_inline __s64 sign_extend64(__u64 value, int index)
204{
205 __u8 shift = 63 - index;
206 return (__s64)(value << shift) >> shift;
207}
208
209static inline unsigned int fls_long(unsigned long l)
210{
211 if (sizeof(l) == 4)
212 return fls(l);
213 return fls64(l);
214}
215
216static inline int get_count_order(unsigned int count)
217{
218 if (count == 0)
219 return -1;
220
221 return fls(--count);
222}
223
224/**
225 * get_count_order_long - get order after rounding @l up to power of 2
226 * @l: parameter
227 *
228 * it is same as get_count_order() but with long type parameter
229 */
230static inline int get_count_order_long(unsigned long l)
231{
232 if (l == 0UL)
233 return -1;
234 return (int)fls_long(--l);
235}
236
237/**
238 * parity8 - get the parity of an u8 value
239 * @val: the value to be examined
240 *
241 * Determine the parity of the u8 argument.
242 *
243 * Returns:
244 * 0 for even parity, 1 for odd parity
245 *
246 * Note: This function informs you about the current parity. Example to bail
247 * out when parity is odd:
248 *
249 * if (parity8(val) == 1)
250 * return -EBADMSG;
251 *
252 * If you need to calculate a parity bit, you need to draw the conclusion from
253 * this result yourself. Example to enforce odd parity, parity bit is bit 7:
254 *
255 * if (parity8(val) == 0)
256 * val ^= BIT(7);
257 */
258static inline int parity8(u8 val)
259{
260 /*
261 * One explanation of this algorithm:
262 * https://funloop.org/codex/problem/parity/README.html
263 */
264 val ^= val >> 4;
265 return (0x6996 >> (val & 0xf)) & 1;
266}
267
268/**
269 * __ffs64 - find first set bit in a 64 bit word
270 * @word: The 64 bit word
271 *
272 * On 64 bit arches this is a synonym for __ffs
273 * The result is not defined if no bits are set, so check that @word
274 * is non-zero before calling this.
275 */
276static inline __attribute_const__ unsigned int __ffs64(u64 word)
277{
278#if BITS_PER_LONG == 32
279 if (((u32)word) == 0UL)
280 return __ffs((u32)(word >> 32)) + 32;
281#elif BITS_PER_LONG != 64
282#error BITS_PER_LONG not 32 or 64
283#endif
284 return __ffs((unsigned long)word);
285}
286
287/**
288 * fns - find N'th set bit in a word
289 * @word: The word to search
290 * @n: Bit to find
291 */
292static inline unsigned int fns(unsigned long word, unsigned int n)
293{
294 while (word && n--)
295 word &= word - 1;
296
297 return word ? __ffs(word) : BITS_PER_LONG;
298}
299
300/**
301 * assign_bit - Assign value to a bit in memory
302 * @nr: the bit to set
303 * @addr: the address to start counting from
304 * @value: the value to assign
305 */
306#define assign_bit(nr, addr, value) \
307 ((value) ? set_bit((nr), (addr)) : clear_bit((nr), (addr)))
308
309#define __assign_bit(nr, addr, value) \
310 ((value) ? __set_bit((nr), (addr)) : __clear_bit((nr), (addr)))
311
312/**
313 * __ptr_set_bit - Set bit in a pointer's value
314 * @nr: the bit to set
315 * @addr: the address of the pointer variable
316 *
317 * Example:
318 * void *p = foo();
319 * __ptr_set_bit(bit, &p);
320 */
321#define __ptr_set_bit(nr, addr) \
322 ({ \
323 typecheck_pointer(*(addr)); \
324 __set_bit(nr, (unsigned long *)(addr)); \
325 })
326
327/**
328 * __ptr_clear_bit - Clear bit in a pointer's value
329 * @nr: the bit to clear
330 * @addr: the address of the pointer variable
331 *
332 * Example:
333 * void *p = foo();
334 * __ptr_clear_bit(bit, &p);
335 */
336#define __ptr_clear_bit(nr, addr) \
337 ({ \
338 typecheck_pointer(*(addr)); \
339 __clear_bit(nr, (unsigned long *)(addr)); \
340 })
341
342/**
343 * __ptr_test_bit - Test bit in a pointer's value
344 * @nr: the bit to test
345 * @addr: the address of the pointer variable
346 *
347 * Example:
348 * void *p = foo();
349 * if (__ptr_test_bit(bit, &p)) {
350 * ...
351 * } else {
352 * ...
353 * }
354 */
355#define __ptr_test_bit(nr, addr) \
356 ({ \
357 typecheck_pointer(*(addr)); \
358 test_bit(nr, (unsigned long *)(addr)); \
359 })
360
361#ifdef __KERNEL__
362
363#ifndef set_mask_bits
364#define set_mask_bits(ptr, mask, bits) \
365({ \
366 const typeof(*(ptr)) mask__ = (mask), bits__ = (bits); \
367 typeof(*(ptr)) old__, new__; \
368 \
369 old__ = READ_ONCE(*(ptr)); \
370 do { \
371 new__ = (old__ & ~mask__) | bits__; \
372 } while (!try_cmpxchg(ptr, &old__, new__)); \
373 \
374 old__; \
375})
376#endif
377
378#ifndef bit_clear_unless
379#define bit_clear_unless(ptr, clear, test) \
380({ \
381 const typeof(*(ptr)) clear__ = (clear), test__ = (test);\
382 typeof(*(ptr)) old__, new__; \
383 \
384 old__ = READ_ONCE(*(ptr)); \
385 do { \
386 if (old__ & test__) \
387 break; \
388 new__ = old__ & ~clear__; \
389 } while (!try_cmpxchg(ptr, &old__, new__)); \
390 \
391 !(old__ & test__); \
392})
393#endif
394
395#endif /* __KERNEL__ */
396#endif