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Linux kernel mirror (for testing)
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linux
1/*
2 * Copyright 1995, Russell King.
3 * Various bits and pieces copyrights include:
4 * Linus Torvalds (test_bit).
5 * Big endian support: Copyright 2001, Nicolas Pitre
6 * reworked by rmk.
7 *
8 * bit 0 is the LSB of an "unsigned long" quantity.
9 *
10 * Please note that the code in this file should never be included
11 * from user space. Many of these are not implemented in assembler
12 * since they would be too costly. Also, they require privileged
13 * instructions (which are not available from user mode) to ensure
14 * that they are atomic.
15 */
16
17#ifndef __ASM_ARM_BITOPS_H
18#define __ASM_ARM_BITOPS_H
19
20#ifdef __KERNEL__
21
22#include <linux/compiler.h>
23#include <asm/system.h>
24
25#define smp_mb__before_clear_bit() mb()
26#define smp_mb__after_clear_bit() mb()
27
28/*
29 * These functions are the basis of our bit ops.
30 *
31 * First, the atomic bitops. These use native endian.
32 */
33static inline void ____atomic_set_bit(unsigned int bit, volatile unsigned long *p)
34{
35 unsigned long flags;
36 unsigned long mask = 1UL << (bit & 31);
37
38 p += bit >> 5;
39
40 local_irq_save(flags);
41 *p |= mask;
42 local_irq_restore(flags);
43}
44
45static inline void ____atomic_clear_bit(unsigned int bit, volatile unsigned long *p)
46{
47 unsigned long flags;
48 unsigned long mask = 1UL << (bit & 31);
49
50 p += bit >> 5;
51
52 local_irq_save(flags);
53 *p &= ~mask;
54 local_irq_restore(flags);
55}
56
57static inline void ____atomic_change_bit(unsigned int bit, volatile unsigned long *p)
58{
59 unsigned long flags;
60 unsigned long mask = 1UL << (bit & 31);
61
62 p += bit >> 5;
63
64 local_irq_save(flags);
65 *p ^= mask;
66 local_irq_restore(flags);
67}
68
69static inline int
70____atomic_test_and_set_bit(unsigned int bit, volatile unsigned long *p)
71{
72 unsigned long flags;
73 unsigned int res;
74 unsigned long mask = 1UL << (bit & 31);
75
76 p += bit >> 5;
77
78 local_irq_save(flags);
79 res = *p;
80 *p = res | mask;
81 local_irq_restore(flags);
82
83 return res & mask;
84}
85
86static inline int
87____atomic_test_and_clear_bit(unsigned int bit, volatile unsigned long *p)
88{
89 unsigned long flags;
90 unsigned int res;
91 unsigned long mask = 1UL << (bit & 31);
92
93 p += bit >> 5;
94
95 local_irq_save(flags);
96 res = *p;
97 *p = res & ~mask;
98 local_irq_restore(flags);
99
100 return res & mask;
101}
102
103static inline int
104____atomic_test_and_change_bit(unsigned int bit, volatile unsigned long *p)
105{
106 unsigned long flags;
107 unsigned int res;
108 unsigned long mask = 1UL << (bit & 31);
109
110 p += bit >> 5;
111
112 local_irq_save(flags);
113 res = *p;
114 *p = res ^ mask;
115 local_irq_restore(flags);
116
117 return res & mask;
118}
119
120/*
121 * Now the non-atomic variants. We let the compiler handle all
122 * optimisations for these. These are all _native_ endian.
123 */
124static inline void __set_bit(int nr, volatile unsigned long *p)
125{
126 p[nr >> 5] |= (1UL << (nr & 31));
127}
128
129static inline void __clear_bit(int nr, volatile unsigned long *p)
130{
131 p[nr >> 5] &= ~(1UL << (nr & 31));
132}
133
134static inline void __change_bit(int nr, volatile unsigned long *p)
135{
136 p[nr >> 5] ^= (1UL << (nr & 31));
137}
138
139static inline int __test_and_set_bit(int nr, volatile unsigned long *p)
140{
141 unsigned long oldval, mask = 1UL << (nr & 31);
142
143 p += nr >> 5;
144
145 oldval = *p;
146 *p = oldval | mask;
147 return oldval & mask;
148}
149
150static inline int __test_and_clear_bit(int nr, volatile unsigned long *p)
151{
152 unsigned long oldval, mask = 1UL << (nr & 31);
153
154 p += nr >> 5;
155
156 oldval = *p;
157 *p = oldval & ~mask;
158 return oldval & mask;
159}
160
161static inline int __test_and_change_bit(int nr, volatile unsigned long *p)
162{
163 unsigned long oldval, mask = 1UL << (nr & 31);
164
165 p += nr >> 5;
166
167 oldval = *p;
168 *p = oldval ^ mask;
169 return oldval & mask;
170}
171
172/*
173 * This routine doesn't need to be atomic.
174 */
175static inline int __test_bit(int nr, const volatile unsigned long * p)
176{
177 return (p[nr >> 5] >> (nr & 31)) & 1UL;
178}
179
180/*
181 * A note about Endian-ness.
182 * -------------------------
183 *
184 * When the ARM is put into big endian mode via CR15, the processor
185 * merely swaps the order of bytes within words, thus:
186 *
187 * ------------ physical data bus bits -----------
188 * D31 ... D24 D23 ... D16 D15 ... D8 D7 ... D0
189 * little byte 3 byte 2 byte 1 byte 0
190 * big byte 0 byte 1 byte 2 byte 3
191 *
192 * This means that reading a 32-bit word at address 0 returns the same
193 * value irrespective of the endian mode bit.
194 *
195 * Peripheral devices should be connected with the data bus reversed in
196 * "Big Endian" mode. ARM Application Note 61 is applicable, and is
197 * available from http://www.arm.com/.
198 *
199 * The following assumes that the data bus connectivity for big endian
200 * mode has been followed.
201 *
202 * Note that bit 0 is defined to be 32-bit word bit 0, not byte 0 bit 0.
203 */
204
205/*
206 * Little endian assembly bitops. nr = 0 -> byte 0 bit 0.
207 */
208extern void _set_bit_le(int nr, volatile unsigned long * p);
209extern void _clear_bit_le(int nr, volatile unsigned long * p);
210extern void _change_bit_le(int nr, volatile unsigned long * p);
211extern int _test_and_set_bit_le(int nr, volatile unsigned long * p);
212extern int _test_and_clear_bit_le(int nr, volatile unsigned long * p);
213extern int _test_and_change_bit_le(int nr, volatile unsigned long * p);
214extern int _find_first_zero_bit_le(const void * p, unsigned size);
215extern int _find_next_zero_bit_le(const void * p, int size, int offset);
216extern int _find_first_bit_le(const unsigned long *p, unsigned size);
217extern int _find_next_bit_le(const unsigned long *p, int size, int offset);
218
219/*
220 * Big endian assembly bitops. nr = 0 -> byte 3 bit 0.
221 */
222extern void _set_bit_be(int nr, volatile unsigned long * p);
223extern void _clear_bit_be(int nr, volatile unsigned long * p);
224extern void _change_bit_be(int nr, volatile unsigned long * p);
225extern int _test_and_set_bit_be(int nr, volatile unsigned long * p);
226extern int _test_and_clear_bit_be(int nr, volatile unsigned long * p);
227extern int _test_and_change_bit_be(int nr, volatile unsigned long * p);
228extern int _find_first_zero_bit_be(const void * p, unsigned size);
229extern int _find_next_zero_bit_be(const void * p, int size, int offset);
230extern int _find_first_bit_be(const unsigned long *p, unsigned size);
231extern int _find_next_bit_be(const unsigned long *p, int size, int offset);
232
233#ifndef CONFIG_SMP
234/*
235 * The __* form of bitops are non-atomic and may be reordered.
236 */
237#define ATOMIC_BITOP_LE(name,nr,p) \
238 (__builtin_constant_p(nr) ? \
239 ____atomic_##name(nr, p) : \
240 _##name##_le(nr,p))
241
242#define ATOMIC_BITOP_BE(name,nr,p) \
243 (__builtin_constant_p(nr) ? \
244 ____atomic_##name(nr, p) : \
245 _##name##_be(nr,p))
246#else
247#define ATOMIC_BITOP_LE(name,nr,p) _##name##_le(nr,p)
248#define ATOMIC_BITOP_BE(name,nr,p) _##name##_be(nr,p)
249#endif
250
251#define NONATOMIC_BITOP(name,nr,p) \
252 (____nonatomic_##name(nr, p))
253
254#ifndef __ARMEB__
255/*
256 * These are the little endian, atomic definitions.
257 */
258#define set_bit(nr,p) ATOMIC_BITOP_LE(set_bit,nr,p)
259#define clear_bit(nr,p) ATOMIC_BITOP_LE(clear_bit,nr,p)
260#define change_bit(nr,p) ATOMIC_BITOP_LE(change_bit,nr,p)
261#define test_and_set_bit(nr,p) ATOMIC_BITOP_LE(test_and_set_bit,nr,p)
262#define test_and_clear_bit(nr,p) ATOMIC_BITOP_LE(test_and_clear_bit,nr,p)
263#define test_and_change_bit(nr,p) ATOMIC_BITOP_LE(test_and_change_bit,nr,p)
264#define test_bit(nr,p) __test_bit(nr,p)
265#define find_first_zero_bit(p,sz) _find_first_zero_bit_le(p,sz)
266#define find_next_zero_bit(p,sz,off) _find_next_zero_bit_le(p,sz,off)
267#define find_first_bit(p,sz) _find_first_bit_le(p,sz)
268#define find_next_bit(p,sz,off) _find_next_bit_le(p,sz,off)
269
270#define WORD_BITOFF_TO_LE(x) ((x))
271
272#else
273
274/*
275 * These are the big endian, atomic definitions.
276 */
277#define set_bit(nr,p) ATOMIC_BITOP_BE(set_bit,nr,p)
278#define clear_bit(nr,p) ATOMIC_BITOP_BE(clear_bit,nr,p)
279#define change_bit(nr,p) ATOMIC_BITOP_BE(change_bit,nr,p)
280#define test_and_set_bit(nr,p) ATOMIC_BITOP_BE(test_and_set_bit,nr,p)
281#define test_and_clear_bit(nr,p) ATOMIC_BITOP_BE(test_and_clear_bit,nr,p)
282#define test_and_change_bit(nr,p) ATOMIC_BITOP_BE(test_and_change_bit,nr,p)
283#define test_bit(nr,p) __test_bit(nr,p)
284#define find_first_zero_bit(p,sz) _find_first_zero_bit_be(p,sz)
285#define find_next_zero_bit(p,sz,off) _find_next_zero_bit_be(p,sz,off)
286#define find_first_bit(p,sz) _find_first_bit_be(p,sz)
287#define find_next_bit(p,sz,off) _find_next_bit_be(p,sz,off)
288
289#define WORD_BITOFF_TO_LE(x) ((x) ^ 0x18)
290
291#endif
292
293#if __LINUX_ARM_ARCH__ < 5
294
295/*
296 * ffz = Find First Zero in word. Undefined if no zero exists,
297 * so code should check against ~0UL first..
298 */
299static inline unsigned long ffz(unsigned long word)
300{
301 int k;
302
303 word = ~word;
304 k = 31;
305 if (word & 0x0000ffff) { k -= 16; word <<= 16; }
306 if (word & 0x00ff0000) { k -= 8; word <<= 8; }
307 if (word & 0x0f000000) { k -= 4; word <<= 4; }
308 if (word & 0x30000000) { k -= 2; word <<= 2; }
309 if (word & 0x40000000) { k -= 1; }
310 return k;
311}
312
313/*
314 * ffz = Find First Zero in word. Undefined if no zero exists,
315 * so code should check against ~0UL first..
316 */
317static inline unsigned long __ffs(unsigned long word)
318{
319 int k;
320
321 k = 31;
322 if (word & 0x0000ffff) { k -= 16; word <<= 16; }
323 if (word & 0x00ff0000) { k -= 8; word <<= 8; }
324 if (word & 0x0f000000) { k -= 4; word <<= 4; }
325 if (word & 0x30000000) { k -= 2; word <<= 2; }
326 if (word & 0x40000000) { k -= 1; }
327 return k;
328}
329
330/*
331 * fls: find last bit set.
332 */
333
334#define fls(x) generic_fls(x)
335
336/*
337 * ffs: find first bit set. This is defined the same way as
338 * the libc and compiler builtin ffs routines, therefore
339 * differs in spirit from the above ffz (man ffs).
340 */
341
342#define ffs(x) generic_ffs(x)
343
344#else
345
346/*
347 * On ARMv5 and above those functions can be implemented around
348 * the clz instruction for much better code efficiency.
349 */
350
351#define fls(x) \
352 ( __builtin_constant_p(x) ? generic_fls(x) : \
353 ({ int __r; asm("clz\t%0, %1" : "=r"(__r) : "r"(x) : "cc"); 32-__r; }) )
354#define ffs(x) ({ unsigned long __t = (x); fls(__t & -__t); })
355#define __ffs(x) (ffs(x) - 1)
356#define ffz(x) __ffs( ~(x) )
357
358#endif
359
360/*
361 * Find first bit set in a 168-bit bitmap, where the first
362 * 128 bits are unlikely to be set.
363 */
364static inline int sched_find_first_bit(const unsigned long *b)
365{
366 unsigned long v;
367 unsigned int off;
368
369 for (off = 0; v = b[off], off < 4; off++) {
370 if (unlikely(v))
371 break;
372 }
373 return __ffs(v) + off * 32;
374}
375
376/*
377 * hweightN: returns the hamming weight (i.e. the number
378 * of bits set) of a N-bit word
379 */
380
381#define hweight32(x) generic_hweight32(x)
382#define hweight16(x) generic_hweight16(x)
383#define hweight8(x) generic_hweight8(x)
384
385/*
386 * Ext2 is defined to use little-endian byte ordering.
387 * These do not need to be atomic.
388 */
389#define ext2_set_bit(nr,p) \
390 __test_and_set_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
391#define ext2_set_bit_atomic(lock,nr,p) \
392 test_and_set_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
393#define ext2_clear_bit(nr,p) \
394 __test_and_clear_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
395#define ext2_clear_bit_atomic(lock,nr,p) \
396 test_and_clear_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
397#define ext2_test_bit(nr,p) \
398 __test_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
399#define ext2_find_first_zero_bit(p,sz) \
400 _find_first_zero_bit_le(p,sz)
401#define ext2_find_next_zero_bit(p,sz,off) \
402 _find_next_zero_bit_le(p,sz,off)
403
404/*
405 * Minix is defined to use little-endian byte ordering.
406 * These do not need to be atomic.
407 */
408#define minix_set_bit(nr,p) \
409 __set_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
410#define minix_test_bit(nr,p) \
411 __test_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
412#define minix_test_and_set_bit(nr,p) \
413 __test_and_set_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
414#define minix_test_and_clear_bit(nr,p) \
415 __test_and_clear_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
416#define minix_find_first_zero_bit(p,sz) \
417 _find_first_zero_bit_le(p,sz)
418
419#endif /* __KERNEL__ */
420
421#endif /* _ARM_BITOPS_H */