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
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
83#undef __check_bitop_pr
84
85static inline int get_bitmask_order(unsigned int count)
86{
87 int order;
88
89 order = fls(count);
90 return order; /* We could be slightly more clever with -1 here... */
91}
92
93static __always_inline unsigned long hweight_long(unsigned long w)
94{
95 return sizeof(w) == 4 ? hweight32(w) : hweight64((__u64)w);
96}
97
98/**
99 * rol64 - rotate a 64-bit value left
100 * @word: value to rotate
101 * @shift: bits to roll
102 */
103static inline __u64 rol64(__u64 word, unsigned int shift)
104{
105 return (word << (shift & 63)) | (word >> ((-shift) & 63));
106}
107
108/**
109 * ror64 - rotate a 64-bit value right
110 * @word: value to rotate
111 * @shift: bits to roll
112 */
113static inline __u64 ror64(__u64 word, unsigned int shift)
114{
115 return (word >> (shift & 63)) | (word << ((-shift) & 63));
116}
117
118/**
119 * rol32 - rotate a 32-bit value left
120 * @word: value to rotate
121 * @shift: bits to roll
122 */
123static inline __u32 rol32(__u32 word, unsigned int shift)
124{
125 return (word << (shift & 31)) | (word >> ((-shift) & 31));
126}
127
128/**
129 * ror32 - rotate a 32-bit value right
130 * @word: value to rotate
131 * @shift: bits to roll
132 */
133static inline __u32 ror32(__u32 word, unsigned int shift)
134{
135 return (word >> (shift & 31)) | (word << ((-shift) & 31));
136}
137
138/**
139 * rol16 - rotate a 16-bit value left
140 * @word: value to rotate
141 * @shift: bits to roll
142 */
143static inline __u16 rol16(__u16 word, unsigned int shift)
144{
145 return (word << (shift & 15)) | (word >> ((-shift) & 15));
146}
147
148/**
149 * ror16 - rotate a 16-bit value right
150 * @word: value to rotate
151 * @shift: bits to roll
152 */
153static inline __u16 ror16(__u16 word, unsigned int shift)
154{
155 return (word >> (shift & 15)) | (word << ((-shift) & 15));
156}
157
158/**
159 * rol8 - rotate an 8-bit value left
160 * @word: value to rotate
161 * @shift: bits to roll
162 */
163static inline __u8 rol8(__u8 word, unsigned int shift)
164{
165 return (word << (shift & 7)) | (word >> ((-shift) & 7));
166}
167
168/**
169 * ror8 - rotate an 8-bit value right
170 * @word: value to rotate
171 * @shift: bits to roll
172 */
173static inline __u8 ror8(__u8 word, unsigned int shift)
174{
175 return (word >> (shift & 7)) | (word << ((-shift) & 7));
176}
177
178/**
179 * sign_extend32 - sign extend a 32-bit value using specified bit as sign-bit
180 * @value: value to sign extend
181 * @index: 0 based bit index (0<=index<32) to sign bit
182 *
183 * This is safe to use for 16- and 8-bit types as well.
184 */
185static __always_inline __s32 sign_extend32(__u32 value, int index)
186{
187 __u8 shift = 31 - index;
188 return (__s32)(value << shift) >> shift;
189}
190
191/**
192 * sign_extend64 - sign extend a 64-bit value using specified bit as sign-bit
193 * @value: value to sign extend
194 * @index: 0 based bit index (0<=index<64) to sign bit
195 */
196static __always_inline __s64 sign_extend64(__u64 value, int index)
197{
198 __u8 shift = 63 - index;
199 return (__s64)(value << shift) >> shift;
200}
201
202static inline unsigned fls_long(unsigned long l)
203{
204 if (sizeof(l) == 4)
205 return fls(l);
206 return fls64(l);
207}
208
209static inline int get_count_order(unsigned int count)
210{
211 if (count == 0)
212 return -1;
213
214 return fls(--count);
215}
216
217/**
218 * get_count_order_long - get order after rounding @l up to power of 2
219 * @l: parameter
220 *
221 * it is same as get_count_order() but with long type parameter
222 */
223static inline int get_count_order_long(unsigned long l)
224{
225 if (l == 0UL)
226 return -1;
227 return (int)fls_long(--l);
228}
229
230/**
231 * __ffs64 - find first set bit in a 64 bit word
232 * @word: The 64 bit word
233 *
234 * On 64 bit arches this is a synonym for __ffs
235 * The result is not defined if no bits are set, so check that @word
236 * is non-zero before calling this.
237 */
238static inline unsigned long __ffs64(u64 word)
239{
240#if BITS_PER_LONG == 32
241 if (((u32)word) == 0UL)
242 return __ffs((u32)(word >> 32)) + 32;
243#elif BITS_PER_LONG != 64
244#error BITS_PER_LONG not 32 or 64
245#endif
246 return __ffs((unsigned long)word);
247}
248
249/**
250 * assign_bit - Assign value to a bit in memory
251 * @nr: the bit to set
252 * @addr: the address to start counting from
253 * @value: the value to assign
254 */
255static __always_inline void assign_bit(long nr, volatile unsigned long *addr,
256 bool value)
257{
258 if (value)
259 set_bit(nr, addr);
260 else
261 clear_bit(nr, addr);
262}
263
264static __always_inline void __assign_bit(long nr, volatile unsigned long *addr,
265 bool value)
266{
267 if (value)
268 __set_bit(nr, addr);
269 else
270 __clear_bit(nr, addr);
271}
272
273/**
274 * __ptr_set_bit - Set bit in a pointer's value
275 * @nr: the bit to set
276 * @addr: the address of the pointer variable
277 *
278 * Example:
279 * void *p = foo();
280 * __ptr_set_bit(bit, &p);
281 */
282#define __ptr_set_bit(nr, addr) \
283 ({ \
284 typecheck_pointer(*(addr)); \
285 __set_bit(nr, (unsigned long *)(addr)); \
286 })
287
288/**
289 * __ptr_clear_bit - Clear bit in a pointer's value
290 * @nr: the bit to clear
291 * @addr: the address of the pointer variable
292 *
293 * Example:
294 * void *p = foo();
295 * __ptr_clear_bit(bit, &p);
296 */
297#define __ptr_clear_bit(nr, addr) \
298 ({ \
299 typecheck_pointer(*(addr)); \
300 __clear_bit(nr, (unsigned long *)(addr)); \
301 })
302
303/**
304 * __ptr_test_bit - Test bit in a pointer's value
305 * @nr: the bit to test
306 * @addr: the address of the pointer variable
307 *
308 * Example:
309 * void *p = foo();
310 * if (__ptr_test_bit(bit, &p)) {
311 * ...
312 * } else {
313 * ...
314 * }
315 */
316#define __ptr_test_bit(nr, addr) \
317 ({ \
318 typecheck_pointer(*(addr)); \
319 test_bit(nr, (unsigned long *)(addr)); \
320 })
321
322#ifdef __KERNEL__
323
324#ifndef set_mask_bits
325#define set_mask_bits(ptr, mask, bits) \
326({ \
327 const typeof(*(ptr)) mask__ = (mask), bits__ = (bits); \
328 typeof(*(ptr)) old__, new__; \
329 \
330 do { \
331 old__ = READ_ONCE(*(ptr)); \
332 new__ = (old__ & ~mask__) | bits__; \
333 } while (cmpxchg(ptr, old__, new__) != old__); \
334 \
335 old__; \
336})
337#endif
338
339#ifndef bit_clear_unless
340#define bit_clear_unless(ptr, clear, test) \
341({ \
342 const typeof(*(ptr)) clear__ = (clear), test__ = (test);\
343 typeof(*(ptr)) old__, new__; \
344 \
345 do { \
346 old__ = READ_ONCE(*(ptr)); \
347 new__ = old__ & ~clear__; \
348 } while (!(old__ & test__) && \
349 cmpxchg(ptr, old__, new__) != old__); \
350 \
351 !(old__ & test__); \
352})
353#endif
354
355#endif /* __KERNEL__ */
356#endif
357

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