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/* Set bits in the first 'n' bytes when loaded from memory */
12#ifdef __LITTLE_ENDIAN
13# define aligned_byte_mask(n) ((1UL << 8*(n))-1)
14#else
15# define aligned_byte_mask(n) (~0xffUL << (BITS_PER_LONG - 8 - 8*(n)))
16#endif
17
18#define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE)
19#define BITS_TO_LONGS(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(long))
20#define BITS_TO_U64(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(u64))
21#define BITS_TO_U32(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(u32))
22#define BITS_TO_BYTES(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(char))
23
24extern unsigned int __sw_hweight8(unsigned int w);
25extern unsigned int __sw_hweight16(unsigned int w);
26extern unsigned int __sw_hweight32(unsigned int w);
27extern unsigned long __sw_hweight64(__u64 w);
28
29/*
30 * Defined here because those may be needed by architecture-specific static
31 * inlines.
32 */
33
34#include <asm-generic/bitops/generic-non-atomic.h>
35
36/*
37 * Many architecture-specific non-atomic bitops contain inline asm code and due
38 * to that the compiler can't optimize them to compile-time expressions or
39 * constants. In contrary, generic_*() helpers are defined in pure C and
40 * compilers optimize them just well.
41 * Therefore, to make `unsigned long foo = 0; __set_bit(BAR, &foo)` effectively
42 * equal to `unsigned long foo = BIT(BAR)`, pick the generic C alternative when
43 * the arguments can be resolved at compile time. That expression itself is a
44 * constant and doesn't bring any functional changes to the rest of cases.
45 * The casts to `uintptr_t` are needed to mitigate `-Waddress` warnings when
46 * passing a bitmap from .bss or .data (-> `!!addr` is always true).
47 */
48#define bitop(op, nr, addr) \
49 ((__builtin_constant_p(nr) && \
50 __builtin_constant_p((uintptr_t)(addr) != (uintptr_t)NULL) && \
51 (uintptr_t)(addr) != (uintptr_t)NULL && \
52 __builtin_constant_p(*(const unsigned long *)(addr))) ? \
53 const##op(nr, addr) : op(nr, addr))
54
55#define __set_bit(nr, addr) bitop(___set_bit, nr, addr)
56#define __clear_bit(nr, addr) bitop(___clear_bit, nr, addr)
57#define __change_bit(nr, addr) bitop(___change_bit, nr, addr)
58#define __test_and_set_bit(nr, addr) bitop(___test_and_set_bit, nr, addr)
59#define __test_and_clear_bit(nr, addr) bitop(___test_and_clear_bit, nr, addr)
60#define __test_and_change_bit(nr, addr) bitop(___test_and_change_bit, nr, addr)
61#define test_bit(nr, addr) bitop(_test_bit, nr, addr)
62#define test_bit_acquire(nr, addr) bitop(_test_bit_acquire, nr, addr)
63
64/*
65 * Include this here because some architectures need generic_ffs/fls in
66 * scope
67 */
68#include <asm/bitops.h>
69
70/* Check that the bitops prototypes are sane */
71#define __check_bitop_pr(name) \
72 static_assert(__same_type(arch_##name, generic_##name) && \
73 __same_type(const_##name, generic_##name) && \
74 __same_type(_##name, generic_##name))
75
76__check_bitop_pr(__set_bit);
77__check_bitop_pr(__clear_bit);
78__check_bitop_pr(__change_bit);
79__check_bitop_pr(__test_and_set_bit);
80__check_bitop_pr(__test_and_clear_bit);
81__check_bitop_pr(__test_and_change_bit);
82__check_bitop_pr(test_bit);
83
84#undef __check_bitop_pr
85
86static inline int get_bitmask_order(unsigned int count)
87{
88 int order;
89
90 order = fls(x: 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 */
186static __always_inline __s32 sign_extend32(__u32 value, int index)
187{
188 __u8 shift = 31 - index;
189 return (__s32)(value << shift) >> shift;
190}
191
192/**
193 * sign_extend64 - sign extend a 64-bit value using specified bit as sign-bit
194 * @value: value to sign extend
195 * @index: 0 based bit index (0<=index<64) to sign bit
196 */
197static __always_inline __s64 sign_extend64(__u64 value, int index)
198{
199 __u8 shift = 63 - index;
200 return (__s64)(value << shift) >> shift;
201}
202
203static inline unsigned fls_long(unsigned long l)
204{
205 if (sizeof(l) == 4)
206 return fls(x: l);
207 return fls64(x: l);
208}
209
210static inline int get_count_order(unsigned int count)
211{
212 if (count == 0)
213 return -1;
214
215 return fls(x: --count);
216}
217
218/**
219 * get_count_order_long - get order after rounding @l up to power of 2
220 * @l: parameter
221 *
222 * it is same as get_count_order() but with long type parameter
223 */
224static inline int get_count_order_long(unsigned long l)
225{
226 if (l == 0UL)
227 return -1;
228 return (int)fls_long(l: --l);
229}
230
231/**
232 * __ffs64 - find first set bit in a 64 bit word
233 * @word: The 64 bit word
234 *
235 * On 64 bit arches this is a synonym for __ffs
236 * The result is not defined if no bits are set, so check that @word
237 * is non-zero before calling this.
238 */
239static inline unsigned long __ffs64(u64 word)
240{
241#if BITS_PER_LONG == 32
242 if (((u32)word) == 0UL)
243 return __ffs((u32)(word >> 32)) + 32;
244#elif BITS_PER_LONG != 64
245#error BITS_PER_LONG not 32 or 64
246#endif
247 return __ffs((unsigned long)word);
248}
249
250/**
251 * fns - find N'th set bit in a word
252 * @word: The word to search
253 * @n: Bit to find
254 */
255static inline unsigned long fns(unsigned long word, unsigned int n)
256{
257 unsigned int bit;
258
259 while (word) {
260 bit = __ffs(word);
261 if (n-- == 0)
262 return bit;
263 __clear_bit(bit, &word);
264 }
265
266 return BITS_PER_LONG;
267}
268
269/**
270 * assign_bit - Assign value to a bit in memory
271 * @nr: the bit to set
272 * @addr: the address to start counting from
273 * @value: the value to assign
274 */
275static __always_inline void assign_bit(long nr, volatile unsigned long *addr,
276 bool value)
277{
278 if (value)
279 set_bit(nr, addr);
280 else
281 clear_bit(nr, addr);
282}
283
284static __always_inline void __assign_bit(long nr, volatile unsigned long *addr,
285 bool value)
286{
287 if (value)
288 __set_bit(nr, addr);
289 else
290 __clear_bit(nr, addr);
291}
292
293/**
294 * __ptr_set_bit - Set bit in a pointer's value
295 * @nr: the bit to set
296 * @addr: the address of the pointer variable
297 *
298 * Example:
299 * void *p = foo();
300 * __ptr_set_bit(bit, &p);
301 */
302#define __ptr_set_bit(nr, addr) \
303 ({ \
304 typecheck_pointer(*(addr)); \
305 __set_bit(nr, (unsigned long *)(addr)); \
306 })
307
308/**
309 * __ptr_clear_bit - Clear bit in a pointer's value
310 * @nr: the bit to clear
311 * @addr: the address of the pointer variable
312 *
313 * Example:
314 * void *p = foo();
315 * __ptr_clear_bit(bit, &p);
316 */
317#define __ptr_clear_bit(nr, addr) \
318 ({ \
319 typecheck_pointer(*(addr)); \
320 __clear_bit(nr, (unsigned long *)(addr)); \
321 })
322
323/**
324 * __ptr_test_bit - Test bit in a pointer's value
325 * @nr: the bit to test
326 * @addr: the address of the pointer variable
327 *
328 * Example:
329 * void *p = foo();
330 * if (__ptr_test_bit(bit, &p)) {
331 * ...
332 * } else {
333 * ...
334 * }
335 */
336#define __ptr_test_bit(nr, addr) \
337 ({ \
338 typecheck_pointer(*(addr)); \
339 test_bit(nr, (unsigned long *)(addr)); \
340 })
341
342#ifdef __KERNEL__
343
344#ifndef set_mask_bits
345#define set_mask_bits(ptr, mask, bits) \
346({ \
347 const typeof(*(ptr)) mask__ = (mask), bits__ = (bits); \
348 typeof(*(ptr)) old__, new__; \
349 \
350 old__ = READ_ONCE(*(ptr)); \
351 do { \
352 new__ = (old__ & ~mask__) | bits__; \
353 } while (!try_cmpxchg(ptr, &old__, new__)); \
354 \
355 old__; \
356})
357#endif
358
359#ifndef bit_clear_unless
360#define bit_clear_unless(ptr, clear, test) \
361({ \
362 const typeof(*(ptr)) clear__ = (clear), test__ = (test);\
363 typeof(*(ptr)) old__, new__; \
364 \
365 old__ = READ_ONCE(*(ptr)); \
366 do { \
367 if (old__ & test__) \
368 break; \
369 new__ = old__ & ~clear__; \
370 } while (!try_cmpxchg(ptr, &old__, new__)); \
371 \
372 !(old__ & test__); \
373})
374#endif
375
376#endif /* __KERNEL__ */
377#endif
378

source code of linux/include/linux/bitops.h