5 * Copyright 1992, Linus Torvalds.
10 * These have to be done with inline assembly: that way the bit-setting
11 * is guaranteed to be atomic. All bit operations return 0 if the bit
12 * was cleared before the operation and != 0 if it was not.
14 * bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
17 #include <asm-generic/bitops/fls.h>
18 #include <asm-generic/bitops/__fls.h>
19 #include <asm-generic/bitops/fls64.h>
22 #define LOCK_PREFIX "lock ; "
24 #define LOCK_PREFIX ""
27 #define ADDR (*(volatile long *) addr)
30 * set_bit - Atomically set a bit in memory
32 * @addr: the address to start counting from
34 * This function is atomic and may not be reordered. See __set_bit()
35 * if you do not require the atomic guarantees.
36 * Note that @nr may be almost arbitrarily large; this function is not
37 * restricted to acting on a single-word quantity.
39 static __inline__ void set_bit(int nr, volatile void * addr)
41 __asm__ __volatile__( LOCK_PREFIX
48 * __set_bit - Set a bit in memory
50 * @addr: the address to start counting from
52 * Unlike set_bit(), this function is non-atomic and may be reordered.
53 * If it's called on the same region of memory simultaneously, the effect
54 * may be that only one operation succeeds.
56 static __inline__ void __set_bit(int nr, volatile void * addr)
64 #define PLATFORM__SET_BIT
67 * clear_bit - Clears a bit in memory
69 * @addr: Address to start counting from
71 * clear_bit() is atomic and may not be reordered. However, it does
72 * not contain a memory barrier, so if it is used for locking purposes,
73 * you should call smp_mb__before_clear_bit() and/or smp_mb__after_clear_bit()
74 * in order to ensure changes are visible on other processors.
76 static __inline__ void clear_bit(int nr, volatile void * addr)
78 __asm__ __volatile__( LOCK_PREFIX
83 #define smp_mb__before_clear_bit() barrier()
84 #define smp_mb__after_clear_bit() barrier()
87 * __change_bit - Toggle a bit in memory
89 * @addr: the address to start counting from
91 * Unlike change_bit(), this function is non-atomic and may be reordered.
92 * If it's called on the same region of memory simultaneously, the effect
93 * may be that only one operation succeeds.
95 static __inline__ void __change_bit(int nr, volatile void * addr)
104 * change_bit - Toggle a bit in memory
106 * @addr: Address to start counting from
108 * change_bit() is atomic and may not be reordered.
109 * Note that @nr may be almost arbitrarily large; this function is not
110 * restricted to acting on a single-word quantity.
112 static __inline__ void change_bit(int nr, volatile void * addr)
114 __asm__ __volatile__( LOCK_PREFIX
121 * test_and_set_bit - Set a bit and return its old value
123 * @addr: Address to count from
125 * This operation is atomic and cannot be reordered.
126 * It also implies a memory barrier.
128 static __inline__ int test_and_set_bit(int nr, volatile void * addr)
132 __asm__ __volatile__( LOCK_PREFIX
133 "btsl %2,%1\n\tsbbl %0,%0"
134 :"=r" (oldbit),"=m" (ADDR)
135 :"Ir" (nr) : "memory");
140 * __test_and_set_bit - Set a bit and return its old value
142 * @addr: Address to count from
144 * This operation is non-atomic and can be reordered.
145 * If two examples of this operation race, one can appear to succeed
146 * but actually fail. You must protect multiple accesses with a lock.
148 static __inline__ int __test_and_set_bit(int nr, volatile void * addr)
153 "btsl %2,%1\n\tsbbl %0,%0"
154 :"=r" (oldbit),"=m" (ADDR)
160 * test_and_clear_bit - Clear a bit and return its old value
162 * @addr: Address to count from
164 * This operation is atomic and cannot be reordered.
165 * It also implies a memory barrier.
167 static __inline__ int test_and_clear_bit(int nr, volatile void * addr)
171 __asm__ __volatile__( LOCK_PREFIX
172 "btrl %2,%1\n\tsbbl %0,%0"
173 :"=r" (oldbit),"=m" (ADDR)
174 :"Ir" (nr) : "memory");
179 * __test_and_clear_bit - Clear a bit and return its old value
181 * @addr: Address to count from
183 * This operation is non-atomic and can be reordered.
184 * If two examples of this operation race, one can appear to succeed
185 * but actually fail. You must protect multiple accesses with a lock.
187 static __inline__ int __test_and_clear_bit(int nr, volatile void * addr)
192 "btrl %2,%1\n\tsbbl %0,%0"
193 :"=r" (oldbit),"=m" (ADDR)
198 /* WARNING: non atomic and it can be reordered! */
199 static __inline__ int __test_and_change_bit(int nr, volatile void * addr)
203 __asm__ __volatile__(
204 "btcl %2,%1\n\tsbbl %0,%0"
205 :"=r" (oldbit),"=m" (ADDR)
206 :"Ir" (nr) : "memory");
211 * test_and_change_bit - Change a bit and return its new value
213 * @addr: Address to count from
215 * This operation is atomic and cannot be reordered.
216 * It also implies a memory barrier.
218 static __inline__ int test_and_change_bit(int nr, volatile void * addr)
222 __asm__ __volatile__( LOCK_PREFIX
223 "btcl %2,%1\n\tsbbl %0,%0"
224 :"=r" (oldbit),"=m" (ADDR)
225 :"Ir" (nr) : "memory");
229 #if 0 /* Fool kernel-doc since it doesn't do macros yet */
231 * test_bit - Determine whether a bit is set
232 * @nr: bit number to test
233 * @addr: Address to start counting from
235 static int test_bit(int nr, const volatile void * addr);
238 static __inline__ int constant_test_bit(int nr, const volatile void * addr)
240 return ((1UL << (nr & 31)) & (((const volatile unsigned int *) addr)[nr >> 5])) != 0;
243 static __inline__ int variable_test_bit(int nr, volatile void * addr)
247 __asm__ __volatile__(
248 "btl %2,%1\n\tsbbl %0,%0"
250 :"m" (ADDR),"Ir" (nr));
254 #define test_bit(nr,addr) \
255 (__builtin_constant_p(nr) ? \
256 constant_test_bit((nr),(addr)) : \
257 variable_test_bit((nr),(addr)))
260 * find_first_zero_bit - find the first zero bit in a memory region
261 * @addr: The address to start the search at
262 * @size: The maximum size to search
264 * Returns the bit-number of the first zero bit, not the number of the byte
267 static __inline__ int find_first_zero_bit(void * addr, unsigned size)
274 /* This looks at memory. Mark it volatile to tell gcc not to move it around */
275 __asm__ __volatile__(
277 "xorl %%edx,%%edx\n\t"
280 "xorl -4(%%edi),%%eax\n\t"
283 "1:\tsubl %%ebx,%%edi\n\t"
286 :"=d" (res), "=&c" (d0), "=&D" (d1), "=&a" (d2)
287 :"1" ((size + 31) >> 5), "2" (addr), "b" (addr));
292 * find_next_zero_bit - find the first zero bit in a memory region
293 * @addr: The address to base the search on
294 * @offset: The bitnumber to start searching at
295 * @size: The maximum size to search
297 static __inline__ int find_next_zero_bit (void * addr, int size, int offset)
299 unsigned long * p = ((unsigned long *) addr) + (offset >> 5);
300 int set = 0, bit = offset & 31, res;
304 * Look for zero in first byte
306 __asm__("bsfl %1,%0\n\t"
311 : "r" (~(*p >> bit)));
312 if (set < (32 - bit))
318 * No zero yet, search remaining full bytes for a zero
320 res = find_first_zero_bit (p, size - 32 * (p - (unsigned long *) addr));
321 return (offset + set + res);
325 * ffz - find first zero in word.
326 * @word: The word to search
328 * Undefined if no zero exists, so code should check against ~0UL first.
330 static __inline__ unsigned long ffz(unsigned long word)
341 * __ffs - find first set bit in word
342 * @word: The word to search
344 * Undefined if no bit exists, so code should check against 0 first.
346 static inline unsigned long __ffs(unsigned long word)
348 __asm__("rep; bsf %1,%0"
355 * ffs - find first bit set
356 * @x: the word to search
358 * This is defined the same way as
359 * the libc and compiler builtin ffs routines, therefore
360 * differs in spirit from the above ffz (man ffs).
362 static __inline__ int ffs(int x)
366 __asm__("bsfl %1,%0\n\t"
369 "1:" : "=r" (r) : "rm" (x));
375 static inline int __ilog2(unsigned int x)
377 return generic_fls(x) - 1;
381 * hweightN - returns the hamming weight of a N-bit word
382 * @x: the word to weigh
384 * The Hamming Weight of a number is the total number of bits set in it.
387 #define hweight32(x) generic_hweight32(x)
388 #define hweight16(x) generic_hweight16(x)
389 #define hweight8(x) generic_hweight8(x)
391 #endif /* __KERNEL__ */
395 #define ext2_set_bit __test_and_set_bit
396 #define ext2_clear_bit __test_and_clear_bit
397 #define ext2_test_bit test_bit
398 #define ext2_find_first_zero_bit find_first_zero_bit
399 #define ext2_find_next_zero_bit find_next_zero_bit
401 /* Bitmap functions for the minix filesystem. */
402 #define minix_test_and_set_bit(nr,addr) __test_and_set_bit(nr,addr)
403 #define minix_set_bit(nr,addr) __set_bit(nr,addr)
404 #define minix_test_and_clear_bit(nr,addr) __test_and_clear_bit(nr,addr)
405 #define minix_test_bit(nr,addr) test_bit(nr,addr)
406 #define minix_find_first_zero_bit(addr,size) find_first_zero_bit(addr,size)
408 #endif /* __KERNEL__ */
410 #endif /* _I386_BITOPS_H */