xref: /linux/include/linux/bitops.h (revision 9d5db4e3fcb10900d828826418a83dfba9318277)
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_PER_TYPE(type)	(sizeof(type) * BITS_PER_BYTE)
12 #define BITS_TO_LONGS(nr)	__KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(long))
13 #define BITS_TO_U64(nr)		__KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(u64))
14 #define BITS_TO_U32(nr)		__KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(u32))
15 #define BITS_TO_BYTES(nr)	__KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(char))
16 
17 #define BYTES_TO_BITS(nb)	((nb) * BITS_PER_BYTE)
18 
19 extern unsigned int __sw_hweight8(unsigned int w);
20 extern unsigned int __sw_hweight16(unsigned int w);
21 extern unsigned int __sw_hweight32(unsigned int w);
22 extern unsigned long __sw_hweight64(__u64 w);
23 
24 /*
25  * Defined here because those may be needed by architecture-specific static
26  * inlines.
27  */
28 
29 #include <asm-generic/bitops/generic-non-atomic.h>
30 
31 /*
32  * Many architecture-specific non-atomic bitops contain inline asm code and due
33  * to that the compiler can't optimize them to compile-time expressions or
34  * constants. In contrary, generic_*() helpers are defined in pure C and
35  * compilers optimize them just well.
36  * Therefore, to make `unsigned long foo = 0; __set_bit(BAR, &foo)` effectively
37  * equal to `unsigned long foo = BIT(BAR)`, pick the generic C alternative when
38  * the arguments can be resolved at compile time. That expression itself is a
39  * constant and doesn't bring any functional changes to the rest of cases.
40  * The casts to `uintptr_t` are needed to mitigate `-Waddress` warnings when
41  * passing a bitmap from .bss or .data (-> `!!addr` is always true).
42  */
43 #define bitop(op, nr, addr)						\
44 	((__builtin_constant_p(nr) &&					\
45 	  __builtin_constant_p((uintptr_t)(addr) != (uintptr_t)NULL) &&	\
46 	  (uintptr_t)(addr) != (uintptr_t)NULL &&			\
47 	  __builtin_constant_p(*(const unsigned long *)(addr))) ?	\
48 	 const##op(nr, addr) : op(nr, addr))
49 
50 /*
51  * The following macros are non-atomic versions of their non-underscored
52  * counterparts.
53  */
54 #define __set_bit(nr, addr)		bitop(___set_bit, nr, addr)
55 #define __clear_bit(nr, addr)		bitop(___clear_bit, nr, addr)
56 #define __change_bit(nr, addr)		bitop(___change_bit, nr, addr)
57 #define __test_and_set_bit(nr, addr)	bitop(___test_and_set_bit, nr, addr)
58 #define __test_and_clear_bit(nr, addr)	bitop(___test_and_clear_bit, nr, addr)
59 #define __test_and_change_bit(nr, addr)	bitop(___test_and_change_bit, nr, addr)
60 
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 __check_bitop_pr(test_bit_acquire);
84 
85 #undef __check_bitop_pr
86 
87 static inline int get_bitmask_order(unsigned int count)
88 {
89 	int order;
90 
91 	order = fls(count);
92 	return order;	/* We could be slightly more clever with -1 here... */
93 }
94 
95 static __always_inline unsigned long hweight_long(unsigned long w)
96 {
97 	return sizeof(w) == 4 ? hweight32(w) : hweight64((__u64)w);
98 }
99 
100 /**
101  * rol64 - rotate a 64-bit value left
102  * @word: value to rotate
103  * @shift: bits to roll
104  */
105 static inline __u64 rol64(__u64 word, unsigned int shift)
106 {
107 	return (word << (shift & 63)) | (word >> ((-shift) & 63));
108 }
109 
110 /**
111  * ror64 - rotate a 64-bit value right
112  * @word: value to rotate
113  * @shift: bits to roll
114  */
115 static inline __u64 ror64(__u64 word, unsigned int shift)
116 {
117 	return (word >> (shift & 63)) | (word << ((-shift) & 63));
118 }
119 
120 /**
121  * rol32 - rotate a 32-bit value left
122  * @word: value to rotate
123  * @shift: bits to roll
124  */
125 static inline __u32 rol32(__u32 word, unsigned int shift)
126 {
127 	return (word << (shift & 31)) | (word >> ((-shift) & 31));
128 }
129 
130 /**
131  * ror32 - rotate a 32-bit value right
132  * @word: value to rotate
133  * @shift: bits to roll
134  */
135 static inline __u32 ror32(__u32 word, unsigned int shift)
136 {
137 	return (word >> (shift & 31)) | (word << ((-shift) & 31));
138 }
139 
140 /**
141  * rol16 - rotate a 16-bit value left
142  * @word: value to rotate
143  * @shift: bits to roll
144  */
145 static inline __u16 rol16(__u16 word, unsigned int shift)
146 {
147 	return (word << (shift & 15)) | (word >> ((-shift) & 15));
148 }
149 
150 /**
151  * ror16 - rotate a 16-bit value right
152  * @word: value to rotate
153  * @shift: bits to roll
154  */
155 static inline __u16 ror16(__u16 word, unsigned int shift)
156 {
157 	return (word >> (shift & 15)) | (word << ((-shift) & 15));
158 }
159 
160 /**
161  * rol8 - rotate an 8-bit value left
162  * @word: value to rotate
163  * @shift: bits to roll
164  */
165 static inline __u8 rol8(__u8 word, unsigned int shift)
166 {
167 	return (word << (shift & 7)) | (word >> ((-shift) & 7));
168 }
169 
170 /**
171  * ror8 - rotate an 8-bit value right
172  * @word: value to rotate
173  * @shift: bits to roll
174  */
175 static inline __u8 ror8(__u8 word, unsigned int shift)
176 {
177 	return (word >> (shift & 7)) | (word << ((-shift) & 7));
178 }
179 
180 /**
181  * sign_extend32 - sign extend a 32-bit value using specified bit as sign-bit
182  * @value: value to sign extend
183  * @index: 0 based bit index (0<=index<32) to sign bit
184  *
185  * This is safe to use for 16- and 8-bit types as well.
186  */
187 static __always_inline __s32 sign_extend32(__u32 value, int index)
188 {
189 	__u8 shift = 31 - index;
190 	return (__s32)(value << shift) >> shift;
191 }
192 
193 /**
194  * sign_extend64 - sign extend a 64-bit value using specified bit as sign-bit
195  * @value: value to sign extend
196  * @index: 0 based bit index (0<=index<64) to sign bit
197  */
198 static __always_inline __s64 sign_extend64(__u64 value, int index)
199 {
200 	__u8 shift = 63 - index;
201 	return (__s64)(value << shift) >> shift;
202 }
203 
204 static inline unsigned int fls_long(unsigned long l)
205 {
206 	if (sizeof(l) == 4)
207 		return fls(l);
208 	return fls64(l);
209 }
210 
211 static inline int get_count_order(unsigned int count)
212 {
213 	if (count == 0)
214 		return -1;
215 
216 	return fls(--count);
217 }
218 
219 /**
220  * get_count_order_long - get order after rounding @l up to power of 2
221  * @l: parameter
222  *
223  * it is same as get_count_order() but with long type parameter
224  */
225 static inline int get_count_order_long(unsigned long l)
226 {
227 	if (l == 0UL)
228 		return -1;
229 	return (int)fls_long(--l);
230 }
231 
232 /**
233  * parity8 - get the parity of an u8 value
234  * @value: the value to be examined
235  *
236  * Determine the parity of the u8 argument.
237  *
238  * Returns:
239  * 0 for even parity, 1 for odd parity
240  *
241  * Note: This function informs you about the current parity. Example to bail
242  * out when parity is odd:
243  *
244  *	if (parity8(val) == 1)
245  *		return -EBADMSG;
246  *
247  * If you need to calculate a parity bit, you need to draw the conclusion from
248  * this result yourself. Example to enforce odd parity, parity bit is bit 7:
249  *
250  *	if (parity8(val) == 0)
251  *		val ^= BIT(7);
252  */
253 static inline int parity8(u8 val)
254 {
255 	/*
256 	 * One explanation of this algorithm:
257 	 * https://funloop.org/codex/problem/parity/README.html
258 	 */
259 	val ^= val >> 4;
260 	return (0x6996 >> (val & 0xf)) & 1;
261 }
262 
263 /**
264  * __ffs64 - find first set bit in a 64 bit word
265  * @word: The 64 bit word
266  *
267  * On 64 bit arches this is a synonym for __ffs
268  * The result is not defined if no bits are set, so check that @word
269  * is non-zero before calling this.
270  */
271 static inline unsigned int __ffs64(u64 word)
272 {
273 #if BITS_PER_LONG == 32
274 	if (((u32)word) == 0UL)
275 		return __ffs((u32)(word >> 32)) + 32;
276 #elif BITS_PER_LONG != 64
277 #error BITS_PER_LONG not 32 or 64
278 #endif
279 	return __ffs((unsigned long)word);
280 }
281 
282 /**
283  * fns - find N'th set bit in a word
284  * @word: The word to search
285  * @n: Bit to find
286  */
287 static inline unsigned int fns(unsigned long word, unsigned int n)
288 {
289 	while (word && n--)
290 		word &= word - 1;
291 
292 	return word ? __ffs(word) : BITS_PER_LONG;
293 }
294 
295 /**
296  * assign_bit - Assign value to a bit in memory
297  * @nr: the bit to set
298  * @addr: the address to start counting from
299  * @value: the value to assign
300  */
301 #define assign_bit(nr, addr, value)					\
302 	((value) ? set_bit((nr), (addr)) : clear_bit((nr), (addr)))
303 
304 #define __assign_bit(nr, addr, value)					\
305 	((value) ? __set_bit((nr), (addr)) : __clear_bit((nr), (addr)))
306 
307 /**
308  * __ptr_set_bit - Set bit in a pointer's value
309  * @nr: the bit to set
310  * @addr: the address of the pointer variable
311  *
312  * Example:
313  *	void *p = foo();
314  *	__ptr_set_bit(bit, &p);
315  */
316 #define __ptr_set_bit(nr, addr)                         \
317 	({                                              \
318 		typecheck_pointer(*(addr));             \
319 		__set_bit(nr, (unsigned long *)(addr)); \
320 	})
321 
322 /**
323  * __ptr_clear_bit - Clear bit in a pointer's value
324  * @nr: the bit to clear
325  * @addr: the address of the pointer variable
326  *
327  * Example:
328  *	void *p = foo();
329  *	__ptr_clear_bit(bit, &p);
330  */
331 #define __ptr_clear_bit(nr, addr)                         \
332 	({                                                \
333 		typecheck_pointer(*(addr));               \
334 		__clear_bit(nr, (unsigned long *)(addr)); \
335 	})
336 
337 /**
338  * __ptr_test_bit - Test bit in a pointer's value
339  * @nr: the bit to test
340  * @addr: the address of the pointer variable
341  *
342  * Example:
343  *	void *p = foo();
344  *	if (__ptr_test_bit(bit, &p)) {
345  *	        ...
346  *	} else {
347  *		...
348  *	}
349  */
350 #define __ptr_test_bit(nr, addr)                       \
351 	({                                             \
352 		typecheck_pointer(*(addr));            \
353 		test_bit(nr, (unsigned long *)(addr)); \
354 	})
355 
356 #ifdef __KERNEL__
357 
358 #ifndef set_mask_bits
359 #define set_mask_bits(ptr, mask, bits)	\
360 ({								\
361 	const typeof(*(ptr)) mask__ = (mask), bits__ = (bits);	\
362 	typeof(*(ptr)) old__, new__;				\
363 								\
364 	old__ = READ_ONCE(*(ptr));				\
365 	do {							\
366 		new__ = (old__ & ~mask__) | bits__;		\
367 	} while (!try_cmpxchg(ptr, &old__, new__));		\
368 								\
369 	old__;							\
370 })
371 #endif
372 
373 #ifndef bit_clear_unless
374 #define bit_clear_unless(ptr, clear, test)	\
375 ({								\
376 	const typeof(*(ptr)) clear__ = (clear), test__ = (test);\
377 	typeof(*(ptr)) old__, new__;				\
378 								\
379 	old__ = READ_ONCE(*(ptr));				\
380 	do {							\
381 		if (old__ & test__)				\
382 			break;					\
383 		new__ = old__ & ~clear__;			\
384 	} while (!try_cmpxchg(ptr, &old__, new__));		\
385 								\
386 	!(old__ & test__);					\
387 })
388 #endif
389 
390 #endif /* __KERNEL__ */
391 #endif
392