1 #ifndef _ASM_X86_BITOPS_H
2 #define _ASM_X86_BITOPS_H
5 * Copyright 1992, Linus Torvalds.
7 * Note: inlines with more than a single statement should be marked
8 * __always_inline to avoid problems with older gcc's inlining heuristics.
11 #ifndef _LINUX_BITOPS_H
12 #error only <linux/bitops.h> can be included directly
15 #include <linux/compiler.h>
16 #include <asm/alternative.h>
19 * These have to be done with inline assembly: that way the bit-setting
20 * is guaranteed to be atomic. All bit operations return 0 if the bit
21 * was cleared before the operation and != 0 if it was not.
23 * bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
26 #if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 1)
27 /* Technically wrong, but this avoids compilation errors on some gcc
29 #define BITOP_ADDR(x) "=m" (*(volatile long *) (x))
31 #define BITOP_ADDR(x) "+m" (*(volatile long *) (x))
34 #define ADDR BITOP_ADDR(addr)
37 * We do the locked ops that don't return the old value as
38 * a mask operation on a byte.
40 #define IS_IMMEDIATE(nr) (__builtin_constant_p(nr))
41 #define CONST_MASK_ADDR(nr, addr) BITOP_ADDR((void *)(addr) + ((nr)>>3))
42 #define CONST_MASK(nr) (1 << ((nr) & 7))
45 * set_bit - Atomically set a bit in memory
47 * @addr: the address to start counting from
49 * This function is atomic and may not be reordered. See __set_bit()
50 * if you do not require the atomic guarantees.
52 * Note: there are no guarantees that this function will not be reordered
53 * on non x86 architectures, so if you are writing portable code,
54 * make sure not to rely on its reordering guarantees.
56 * Note that @nr may be almost arbitrarily large; this function is not
57 * restricted to acting on a single-word quantity.
59 static __always_inline
void
60 set_bit(unsigned int nr
, volatile unsigned long *addr
)
62 if (IS_IMMEDIATE(nr
)) {
63 asm volatile(LOCK_PREFIX
"orb %1,%0"
64 : CONST_MASK_ADDR(nr
, addr
)
65 : "iq" ((u8
)CONST_MASK(nr
))
68 asm volatile(LOCK_PREFIX
"bts %1,%0"
69 : BITOP_ADDR(addr
) : "Ir" (nr
) : "memory");
74 * __set_bit - Set a bit in memory
76 * @addr: the address to start counting from
78 * Unlike set_bit(), this function is non-atomic and may be reordered.
79 * If it's called on the same region of memory simultaneously, the effect
80 * may be that only one operation succeeds.
82 static inline void __set_bit(int nr
, volatile unsigned long *addr
)
84 asm volatile("bts %1,%0" : ADDR
: "Ir" (nr
) : "memory");
88 * clear_bit - Clears a bit in memory
90 * @addr: Address to start counting from
92 * clear_bit() is atomic and may not be reordered. However, it does
93 * not contain a memory barrier, so if it is used for locking purposes,
94 * you should call smp_mb__before_clear_bit() and/or smp_mb__after_clear_bit()
95 * in order to ensure changes are visible on other processors.
97 static __always_inline
void
98 clear_bit(int nr
, volatile unsigned long *addr
)
100 if (IS_IMMEDIATE(nr
)) {
101 asm volatile(LOCK_PREFIX
"andb %1,%0"
102 : CONST_MASK_ADDR(nr
, addr
)
103 : "iq" ((u8
)~CONST_MASK(nr
)));
105 asm volatile(LOCK_PREFIX
"btr %1,%0"
112 * clear_bit_unlock - Clears a bit in memory
114 * @addr: Address to start counting from
116 * clear_bit() is atomic and implies release semantics before the memory
117 * operation. It can be used for an unlock.
119 static inline void clear_bit_unlock(unsigned nr
, volatile unsigned long *addr
)
125 static inline void __clear_bit(int nr
, volatile unsigned long *addr
)
127 asm volatile("btr %1,%0" : ADDR
: "Ir" (nr
));
131 * __clear_bit_unlock - Clears a bit in memory
133 * @addr: Address to start counting from
135 * __clear_bit() is non-atomic and implies release semantics before the memory
136 * operation. It can be used for an unlock if no other CPUs can concurrently
137 * modify other bits in the word.
139 * No memory barrier is required here, because x86 cannot reorder stores past
140 * older loads. Same principle as spin_unlock.
142 static inline void __clear_bit_unlock(unsigned nr
, volatile unsigned long *addr
)
145 __clear_bit(nr
, addr
);
148 #define smp_mb__before_clear_bit() barrier()
149 #define smp_mb__after_clear_bit() barrier()
152 * __change_bit - Toggle a bit in memory
153 * @nr: the bit to change
154 * @addr: the address to start counting from
156 * Unlike change_bit(), this function is non-atomic and may be reordered.
157 * If it's called on the same region of memory simultaneously, the effect
158 * may be that only one operation succeeds.
160 static inline void __change_bit(int nr
, volatile unsigned long *addr
)
162 asm volatile("btc %1,%0" : ADDR
: "Ir" (nr
));
166 * change_bit - Toggle a bit in memory
168 * @addr: Address to start counting from
170 * change_bit() is atomic and may not be reordered.
171 * Note that @nr may be almost arbitrarily large; this function is not
172 * restricted to acting on a single-word quantity.
174 static inline void change_bit(int nr
, volatile unsigned long *addr
)
176 if (IS_IMMEDIATE(nr
)) {
177 asm volatile(LOCK_PREFIX
"xorb %1,%0"
178 : CONST_MASK_ADDR(nr
, addr
)
179 : "iq" ((u8
)CONST_MASK(nr
)));
181 asm volatile(LOCK_PREFIX
"btc %1,%0"
188 * test_and_set_bit - Set a bit and return its old value
190 * @addr: Address to count from
192 * This operation is atomic and cannot be reordered.
193 * It also implies a memory barrier.
195 static inline int test_and_set_bit(int nr
, volatile unsigned long *addr
)
199 asm volatile(LOCK_PREFIX
"bts %2,%1\n\t"
200 "sbb %0,%0" : "=r" (oldbit
), ADDR
: "Ir" (nr
) : "memory");
206 * test_and_set_bit_lock - Set a bit and return its old value for lock
208 * @addr: Address to count from
210 * This is the same as test_and_set_bit on x86.
212 static __always_inline
int
213 test_and_set_bit_lock(int nr
, volatile unsigned long *addr
)
215 return test_and_set_bit(nr
, addr
);
219 * __test_and_set_bit - Set a bit and return its old value
221 * @addr: Address to count from
223 * This operation is non-atomic and can be reordered.
224 * If two examples of this operation race, one can appear to succeed
225 * but actually fail. You must protect multiple accesses with a lock.
227 static inline int __test_and_set_bit(int nr
, volatile unsigned long *addr
)
233 : "=r" (oldbit
), ADDR
239 * test_and_clear_bit - Clear a bit and return its old value
241 * @addr: Address to count from
243 * This operation is atomic and cannot be reordered.
244 * It also implies a memory barrier.
246 static inline int test_and_clear_bit(int nr
, volatile unsigned long *addr
)
250 asm volatile(LOCK_PREFIX
"btr %2,%1\n\t"
252 : "=r" (oldbit
), ADDR
: "Ir" (nr
) : "memory");
258 * __test_and_clear_bit - Clear a bit and return its old value
260 * @addr: Address to count from
262 * This operation is non-atomic and can be reordered.
263 * If two examples of this operation race, one can appear to succeed
264 * but actually fail. You must protect multiple accesses with a lock.
266 static inline int __test_and_clear_bit(int nr
, volatile unsigned long *addr
)
270 asm volatile("btr %2,%1\n\t"
272 : "=r" (oldbit
), ADDR
277 /* WARNING: non atomic and it can be reordered! */
278 static inline int __test_and_change_bit(int nr
, volatile unsigned long *addr
)
282 asm volatile("btc %2,%1\n\t"
284 : "=r" (oldbit
), ADDR
285 : "Ir" (nr
) : "memory");
291 * test_and_change_bit - Change a bit and return its old value
293 * @addr: Address to count from
295 * This operation is atomic and cannot be reordered.
296 * It also implies a memory barrier.
298 static inline int test_and_change_bit(int nr
, volatile unsigned long *addr
)
302 asm volatile(LOCK_PREFIX
"btc %2,%1\n\t"
304 : "=r" (oldbit
), ADDR
: "Ir" (nr
) : "memory");
309 static __always_inline
int constant_test_bit(unsigned int nr
, const volatile unsigned long *addr
)
311 return ((1UL << (nr
% BITS_PER_LONG
)) &
312 (((unsigned long *)addr
)[nr
/ BITS_PER_LONG
])) != 0;
315 static inline int variable_test_bit(int nr
, volatile const unsigned long *addr
)
319 asm volatile("bt %2,%1\n\t"
322 : "m" (*(unsigned long *)addr
), "Ir" (nr
));
327 #if 0 /* Fool kernel-doc since it doesn't do macros yet */
329 * test_bit - Determine whether a bit is set
330 * @nr: bit number to test
331 * @addr: Address to start counting from
333 static int test_bit(int nr
, const volatile unsigned long *addr
);
336 #define test_bit(nr, addr) \
337 (__builtin_constant_p((nr)) \
338 ? constant_test_bit((nr), (addr)) \
339 : variable_test_bit((nr), (addr)))
342 * __ffs - find first set bit in word
343 * @word: The word to search
345 * Undefined if no bit exists, so code should check against 0 first.
347 static inline unsigned long __ffs(unsigned long word
)
356 * ffz - find first zero bit in word
357 * @word: The word to search
359 * Undefined if no zero exists, so code should check against ~0UL first.
361 static inline unsigned long ffz(unsigned long word
)
370 * __fls: find last set bit in word
371 * @word: The word to search
373 * Undefined if no set bit exists, so code should check against 0 first.
375 static inline unsigned long __fls(unsigned long word
)
385 * ffs - find first set bit in word
386 * @x: the word to search
388 * This is defined the same way as the libc and compiler builtin ffs
389 * routines, therefore differs in spirit from the other bitops.
391 * ffs(value) returns 0 if value is 0 or the position of the first
392 * set bit if value is nonzero. The first (least significant) bit
395 static inline int ffs(int x
)
398 #ifdef CONFIG_X86_CMOV
401 : "=r" (r
) : "rm" (x
), "r" (-1));
406 "1:" : "=r" (r
) : "rm" (x
));
412 * fls - find last set bit in word
413 * @x: the word to search
415 * This is defined in a similar way as the libc and compiler builtin
416 * ffs, but returns the position of the most significant set bit.
418 * fls(value) returns 0 if value is 0 or the position of the last
419 * set bit if value is nonzero. The last (most significant) bit is
422 static inline int fls(int x
)
425 #ifdef CONFIG_X86_CMOV
428 : "=&r" (r
) : "rm" (x
), "rm" (-1));
433 "1:" : "=r" (r
) : "rm" (x
));
437 #endif /* __KERNEL__ */
443 #include <asm-generic/bitops/sched.h>
445 #define ARCH_HAS_FAST_MULTIPLIER 1
447 #include <asm-generic/bitops/hweight.h>
449 #endif /* __KERNEL__ */
451 #include <asm-generic/bitops/fls64.h>
455 #include <asm-generic/bitops/ext2-non-atomic.h>
457 #define ext2_set_bit_atomic(lock, nr, addr) \
458 test_and_set_bit((nr), (unsigned long *)(addr))
459 #define ext2_clear_bit_atomic(lock, nr, addr) \
460 test_and_clear_bit((nr), (unsigned long *)(addr))
462 #include <asm-generic/bitops/minix.h>
464 #endif /* __KERNEL__ */
465 #endif /* _ASM_X86_BITOPS_H */