1 #ifndef _I386_BITOPS_H
2 #define _I386_BITOPS_H
3
4 /*
5 * Copyright 1992, Linus Torvalds.
6 */
7
8
9 /*
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.
13 *
14 * bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
15 */
16
17 #include <asm-generic/bitops/fls.h>
18 #include <asm-generic/bitops/__fls.h>
19 #include <asm-generic/bitops/fls64.h>
20
21 #ifdef CONFIG_SMP
22 #define LOCK_PREFIX "lock ; "
23 #else
24 #define LOCK_PREFIX ""
25 #endif
26
27 #define ADDR (*(volatile long *) addr)
28
29 /**
30 * set_bit - Atomically set a bit in memory
31 * @nr: the bit to set
32 * @addr: the address to start counting from
33 *
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.
38 */
set_bit(int nr,volatile void * addr)39 static __inline__ void set_bit(int nr, volatile void * addr)
40 {
41 __asm__ __volatile__( LOCK_PREFIX
42 "btsl %1,%0"
43 :"=m" (ADDR)
44 :"Ir" (nr));
45 }
46
47 /**
48 * __set_bit - Set a bit in memory
49 * @nr: the bit to set
50 * @addr: the address to start counting from
51 *
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.
55 */
__set_bit(int nr,volatile void * addr)56 static __inline__ void __set_bit(int nr, volatile void * addr)
57 {
58 __asm__(
59 "btsl %1,%0"
60 :"=m" (ADDR)
61 :"Ir" (nr));
62 }
63
64 /**
65 * clear_bit - Clears a bit in memory
66 * @nr: Bit to clear
67 * @addr: Address to start counting from
68 *
69 * clear_bit() is atomic and may not be reordered. However, it does
70 * not contain a memory barrier, so if it is used for locking purposes,
71 * you should call smp_mb__before_clear_bit() and/or smp_mb__after_clear_bit()
72 * in order to ensure changes are visible on other processors.
73 */
clear_bit(int nr,volatile void * addr)74 static __inline__ void clear_bit(int nr, volatile void * addr)
75 {
76 __asm__ __volatile__( LOCK_PREFIX
77 "btrl %1,%0"
78 :"=m" (ADDR)
79 :"Ir" (nr));
80 }
81 #define smp_mb__before_clear_bit() barrier()
82 #define smp_mb__after_clear_bit() barrier()
83
84 /**
85 * __change_bit - Toggle a bit in memory
86 * @nr: the bit to set
87 * @addr: the address to start counting from
88 *
89 * Unlike change_bit(), this function is non-atomic and may be reordered.
90 * If it's called on the same region of memory simultaneously, the effect
91 * may be that only one operation succeeds.
92 */
__change_bit(int nr,volatile void * addr)93 static __inline__ void __change_bit(int nr, volatile void * addr)
94 {
95 __asm__ __volatile__(
96 "btcl %1,%0"
97 :"=m" (ADDR)
98 :"Ir" (nr));
99 }
100
101 /**
102 * change_bit - Toggle a bit in memory
103 * @nr: Bit to clear
104 * @addr: Address to start counting from
105 *
106 * change_bit() is atomic and may not be reordered.
107 * Note that @nr may be almost arbitrarily large; this function is not
108 * restricted to acting on a single-word quantity.
109 */
change_bit(int nr,volatile void * addr)110 static __inline__ void change_bit(int nr, volatile void * addr)
111 {
112 __asm__ __volatile__( LOCK_PREFIX
113 "btcl %1,%0"
114 :"=m" (ADDR)
115 :"Ir" (nr));
116 }
117
118 /**
119 * test_and_set_bit - Set a bit and return its old value
120 * @nr: Bit to set
121 * @addr: Address to count from
122 *
123 * This operation is atomic and cannot be reordered.
124 * It also implies a memory barrier.
125 */
test_and_set_bit(int nr,volatile void * addr)126 static __inline__ int test_and_set_bit(int nr, volatile void * addr)
127 {
128 int oldbit;
129
130 __asm__ __volatile__( LOCK_PREFIX
131 "btsl %2,%1\n\tsbbl %0,%0"
132 :"=r" (oldbit),"=m" (ADDR)
133 :"Ir" (nr) : "memory");
134 return oldbit;
135 }
136
137 /**
138 * __test_and_set_bit - Set a bit and return its old value
139 * @nr: Bit to set
140 * @addr: Address to count from
141 *
142 * This operation is non-atomic and can be reordered.
143 * If two examples of this operation race, one can appear to succeed
144 * but actually fail. You must protect multiple accesses with a lock.
145 */
__test_and_set_bit(int nr,volatile void * addr)146 static __inline__ int __test_and_set_bit(int nr, volatile void * addr)
147 {
148 int oldbit;
149
150 __asm__(
151 "btsl %2,%1\n\tsbbl %0,%0"
152 :"=r" (oldbit),"=m" (ADDR)
153 :"Ir" (nr));
154 return oldbit;
155 }
156
157 /**
158 * test_and_clear_bit - Clear a bit and return its old value
159 * @nr: Bit to set
160 * @addr: Address to count from
161 *
162 * This operation is atomic and cannot be reordered.
163 * It also implies a memory barrier.
164 */
test_and_clear_bit(int nr,volatile void * addr)165 static __inline__ int test_and_clear_bit(int nr, volatile void * addr)
166 {
167 int oldbit;
168
169 __asm__ __volatile__( LOCK_PREFIX
170 "btrl %2,%1\n\tsbbl %0,%0"
171 :"=r" (oldbit),"=m" (ADDR)
172 :"Ir" (nr) : "memory");
173 return oldbit;
174 }
175
176 /**
177 * __test_and_clear_bit - Clear a bit and return its old value
178 * @nr: Bit to set
179 * @addr: Address to count from
180 *
181 * This operation is non-atomic and can be reordered.
182 * If two examples of this operation race, one can appear to succeed
183 * but actually fail. You must protect multiple accesses with a lock.
184 */
__test_and_clear_bit(int nr,volatile void * addr)185 static __inline__ int __test_and_clear_bit(int nr, volatile void * addr)
186 {
187 int oldbit;
188
189 __asm__(
190 "btrl %2,%1\n\tsbbl %0,%0"
191 :"=r" (oldbit),"=m" (ADDR)
192 :"Ir" (nr));
193 return oldbit;
194 }
195
196 /* WARNING: non atomic and it can be reordered! */
__test_and_change_bit(int nr,volatile void * addr)197 static __inline__ int __test_and_change_bit(int nr, volatile void * addr)
198 {
199 int oldbit;
200
201 __asm__ __volatile__(
202 "btcl %2,%1\n\tsbbl %0,%0"
203 :"=r" (oldbit),"=m" (ADDR)
204 :"Ir" (nr) : "memory");
205 return oldbit;
206 }
207
208 /**
209 * test_and_change_bit - Change a bit and return its new value
210 * @nr: Bit to set
211 * @addr: Address to count from
212 *
213 * This operation is atomic and cannot be reordered.
214 * It also implies a memory barrier.
215 */
test_and_change_bit(int nr,volatile void * addr)216 static __inline__ int test_and_change_bit(int nr, volatile void * addr)
217 {
218 int oldbit;
219
220 __asm__ __volatile__( LOCK_PREFIX
221 "btcl %2,%1\n\tsbbl %0,%0"
222 :"=r" (oldbit),"=m" (ADDR)
223 :"Ir" (nr) : "memory");
224 return oldbit;
225 }
226
227 #if 0 /* Fool kernel-doc since it doesn't do macros yet */
228 /**
229 * test_bit - Determine whether a bit is set
230 * @nr: bit number to test
231 * @addr: Address to start counting from
232 */
233 static int test_bit(int nr, const volatile void * addr);
234 #endif
235
constant_test_bit(int nr,const volatile void * addr)236 static __inline__ int constant_test_bit(int nr, const volatile void * addr)
237 {
238 return ((1UL << (nr & 31)) & (((const volatile unsigned int *) addr)[nr >> 5])) != 0;
239 }
240
variable_test_bit(int nr,volatile void * addr)241 static __inline__ int variable_test_bit(int nr, volatile void * addr)
242 {
243 int oldbit;
244
245 __asm__ __volatile__(
246 "btl %2,%1\n\tsbbl %0,%0"
247 :"=r" (oldbit)
248 :"m" (ADDR),"Ir" (nr));
249 return oldbit;
250 }
251
252 #define test_bit(nr,addr) \
253 (__builtin_constant_p(nr) ? \
254 constant_test_bit((nr),(addr)) : \
255 variable_test_bit((nr),(addr)))
256
257 /**
258 * find_first_zero_bit - find the first zero bit in a memory region
259 * @addr: The address to start the search at
260 * @size: The maximum size to search
261 *
262 * Returns the bit-number of the first zero bit, not the number of the byte
263 * containing a bit.
264 */
find_first_zero_bit(void * addr,unsigned size)265 static __inline__ int find_first_zero_bit(void * addr, unsigned size)
266 {
267 int d0, d1, d2;
268 int res;
269
270 if (!size)
271 return 0;
272 /* This looks at memory. Mark it volatile to tell gcc not to move it around */
273 __asm__ __volatile__(
274 "movl $-1,%%eax\n\t"
275 "xorl %%edx,%%edx\n\t"
276 "repe; scasl\n\t"
277 "je 1f\n\t"
278 "xorl -4(%%edi),%%eax\n\t"
279 "subl $4,%%edi\n\t"
280 "bsfl %%eax,%%edx\n"
281 "1:\tsubl %%ebx,%%edi\n\t"
282 "shll $3,%%edi\n\t"
283 "addl %%edi,%%edx"
284 :"=d" (res), "=&c" (d0), "=&D" (d1), "=&a" (d2)
285 :"1" ((size + 31) >> 5), "2" (addr), "b" (addr));
286 return res;
287 }
288
289 /**
290 * find_next_zero_bit - find the first zero bit in a memory region
291 * @addr: The address to base the search on
292 * @offset: The bitnumber to start searching at
293 * @size: The maximum size to search
294 */
find_next_zero_bit(void * addr,int size,int offset)295 static __inline__ int find_next_zero_bit (void * addr, int size, int offset)
296 {
297 unsigned long * p = ((unsigned long *) addr) + (offset >> 5);
298 int set = 0, bit = offset & 31, res;
299
300 if (bit) {
301 /*
302 * Look for zero in first byte
303 */
304 __asm__("bsfl %1,%0\n\t"
305 "jne 1f\n\t"
306 "movl $32, %0\n"
307 "1:"
308 : "=r" (set)
309 : "r" (~(*p >> bit)));
310 if (set < (32 - bit))
311 return set + offset;
312 set = 32 - bit;
313 p++;
314 }
315 /*
316 * No zero yet, search remaining full bytes for a zero
317 */
318 res = find_first_zero_bit (p, size - 32 * (p - (unsigned long *) addr));
319 return (offset + set + res);
320 }
321
322 /**
323 * ffz - find first zero in word.
324 * @word: The word to search
325 *
326 * Undefined if no zero exists, so code should check against ~0UL first.
327 */
ffz(unsigned long word)328 static __inline__ unsigned long ffz(unsigned long word)
329 {
330 __asm__("bsfl %1,%0"
331 :"=r" (word)
332 :"r" (~word));
333 return word;
334 }
335
336 #ifdef __KERNEL__
337
338 /**
339 * __ffs - find first set bit in word
340 * @word: The word to search
341 *
342 * Undefined if no bit exists, so code should check against 0 first.
343 */
__ffs(unsigned long word)344 static inline unsigned long __ffs(unsigned long word)
345 {
346 __asm__("rep; bsf %1,%0"
347 : "=r" (word)
348 : "rm" (word));
349 return word;
350 }
351
352 /**
353 * ffs - find first bit set
354 * @x: the word to search
355 *
356 * This is defined the same way as
357 * the libc and compiler builtin ffs routines, therefore
358 * differs in spirit from the above ffz (man ffs).
359 */
ffs(int x)360 static __inline__ int ffs(int x)
361 {
362 int r;
363
364 __asm__("bsfl %1,%0\n\t"
365 "jnz 1f\n\t"
366 "movl $-1,%0\n"
367 "1:" : "=r" (r) : "rm" (x));
368
369 return r+1;
370 }
371 #define PLATFORM_FFS
372
__ilog2(unsigned int x)373 static inline int __ilog2(unsigned int x)
374 {
375 return generic_fls(x) - 1;
376 }
377
378 /**
379 * hweightN - returns the hamming weight of a N-bit word
380 * @x: the word to weigh
381 *
382 * The Hamming Weight of a number is the total number of bits set in it.
383 */
384
385 #define hweight32(x) generic_hweight32(x)
386 #define hweight16(x) generic_hweight16(x)
387 #define hweight8(x) generic_hweight8(x)
388
389 #endif /* __KERNEL__ */
390
391 #ifdef __KERNEL__
392
393 #define ext2_set_bit __test_and_set_bit
394 #define ext2_clear_bit __test_and_clear_bit
395 #define ext2_test_bit test_bit
396 #define ext2_find_first_zero_bit find_first_zero_bit
397 #define ext2_find_next_zero_bit find_next_zero_bit
398
399 /* Bitmap functions for the minix filesystem. */
400 #define minix_test_and_set_bit(nr,addr) __test_and_set_bit(nr,addr)
401 #define minix_set_bit(nr,addr) __set_bit(nr,addr)
402 #define minix_test_and_clear_bit(nr,addr) __test_and_clear_bit(nr,addr)
403 #define minix_test_bit(nr,addr) test_bit(nr,addr)
404 #define minix_find_first_zero_bit(addr,size) find_first_zero_bit(addr,size)
405
406 #endif /* __KERNEL__ */
407
408 #endif /* _I386_BITOPS_H */
409