1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef __LINUX_BITMAP_H
3#define __LINUX_BITMAP_H
4
5#ifndef __ASSEMBLY__
6
7#include <linux/align.h>
8#include <linux/bitops.h>
9#include <linux/cleanup.h>
10#include <linux/errno.h>
11#include <linux/find.h>
12#include <linux/limits.h>
13#include <linux/string.h>
14#include <linux/types.h>
15#include <linux/bitmap-str.h>
16
17struct device;
18
19/*
20 * bitmaps provide bit arrays that consume one or more unsigned
21 * longs. The bitmap interface and available operations are listed
22 * here, in bitmap.h
23 *
24 * Function implementations generic to all architectures are in
25 * lib/bitmap.c. Functions implementations that are architecture
26 * specific are in various include/asm-<arch>/bitops.h headers
27 * and other arch/<arch> specific files.
28 *
29 * See lib/bitmap.c for more details.
30 */
31
32/**
33 * DOC: bitmap overview
34 *
35 * The available bitmap operations and their rough meaning in the
36 * case that the bitmap is a single unsigned long are thus:
37 *
38 * The generated code is more efficient when nbits is known at
39 * compile-time and at most BITS_PER_LONG.
40 *
41 * ::
42 *
43 * bitmap_zero(dst, nbits) *dst = 0UL
44 * bitmap_fill(dst, nbits) *dst = ~0UL
45 * bitmap_copy(dst, src, nbits) *dst = *src
46 * bitmap_and(dst, src1, src2, nbits) *dst = *src1 & *src2
47 * bitmap_or(dst, src1, src2, nbits) *dst = *src1 | *src2
48 * bitmap_xor(dst, src1, src2, nbits) *dst = *src1 ^ *src2
49 * bitmap_andnot(dst, src1, src2, nbits) *dst = *src1 & ~(*src2)
50 * bitmap_complement(dst, src, nbits) *dst = ~(*src)
51 * bitmap_equal(src1, src2, nbits) Are *src1 and *src2 equal?
52 * bitmap_intersects(src1, src2, nbits) Do *src1 and *src2 overlap?
53 * bitmap_subset(src1, src2, nbits) Is *src1 a subset of *src2?
54 * bitmap_empty(src, nbits) Are all bits zero in *src?
55 * bitmap_full(src, nbits) Are all bits set in *src?
56 * bitmap_weight(src, nbits) Hamming Weight: number set bits
57 * bitmap_weight_and(src1, src2, nbits) Hamming Weight of and'ed bitmap
58 * bitmap_weight_andnot(src1, src2, nbits) Hamming Weight of andnot'ed bitmap
59 * bitmap_set(dst, pos, nbits) Set specified bit area
60 * bitmap_clear(dst, pos, nbits) Clear specified bit area
61 * bitmap_find_next_zero_area(buf, len, pos, n, mask) Find bit free area
62 * bitmap_find_next_zero_area_off(buf, len, pos, n, mask, mask_off) as above
63 * bitmap_shift_right(dst, src, n, nbits) *dst = *src >> n
64 * bitmap_shift_left(dst, src, n, nbits) *dst = *src << n
65 * bitmap_cut(dst, src, first, n, nbits) Cut n bits from first, copy rest
66 * bitmap_replace(dst, old, new, mask, nbits) *dst = (*old & ~(*mask)) | (*new & *mask)
67 * bitmap_scatter(dst, src, mask, nbits) *dst = map(dense, sparse)(src)
68 * bitmap_gather(dst, src, mask, nbits) *dst = map(sparse, dense)(src)
69 * bitmap_remap(dst, src, old, new, nbits) *dst = map(old, new)(src)
70 * bitmap_bitremap(oldbit, old, new, nbits) newbit = map(old, new)(oldbit)
71 * bitmap_onto(dst, orig, relmap, nbits) *dst = orig relative to relmap
72 * bitmap_fold(dst, orig, sz, nbits) dst bits = orig bits mod sz
73 * bitmap_parse(buf, buflen, dst, nbits) Parse bitmap dst from kernel buf
74 * bitmap_parse_user(ubuf, ulen, dst, nbits) Parse bitmap dst from user buf
75 * bitmap_parselist(buf, dst, nbits) Parse bitmap dst from kernel buf
76 * bitmap_parselist_user(buf, dst, nbits) Parse bitmap dst from user buf
77 * bitmap_find_free_region(bitmap, bits, order) Find and allocate bit region
78 * bitmap_release_region(bitmap, pos, order) Free specified bit region
79 * bitmap_allocate_region(bitmap, pos, order) Allocate specified bit region
80 * bitmap_from_arr32(dst, buf, nbits) Copy nbits from u32[] buf to dst
81 * bitmap_from_arr64(dst, buf, nbits) Copy nbits from u64[] buf to dst
82 * bitmap_to_arr32(buf, src, nbits) Copy nbits from buf to u32[] dst
83 * bitmap_to_arr64(buf, src, nbits) Copy nbits from buf to u64[] dst
84 * bitmap_get_value8(map, start) Get 8bit value from map at start
85 * bitmap_set_value8(map, value, start) Set 8bit value to map at start
86 *
87 * Note, bitmap_zero() and bitmap_fill() operate over the region of
88 * unsigned longs, that is, bits behind bitmap till the unsigned long
89 * boundary will be zeroed or filled as well. Consider to use
90 * bitmap_clear() or bitmap_set() to make explicit zeroing or filling
91 * respectively.
92 */
93
94/**
95 * DOC: bitmap bitops
96 *
97 * Also the following operations in asm/bitops.h apply to bitmaps.::
98 *
99 * set_bit(bit, addr) *addr |= bit
100 * clear_bit(bit, addr) *addr &= ~bit
101 * change_bit(bit, addr) *addr ^= bit
102 * test_bit(bit, addr) Is bit set in *addr?
103 * test_and_set_bit(bit, addr) Set bit and return old value
104 * test_and_clear_bit(bit, addr) Clear bit and return old value
105 * test_and_change_bit(bit, addr) Change bit and return old value
106 * find_first_zero_bit(addr, nbits) Position first zero bit in *addr
107 * find_first_bit(addr, nbits) Position first set bit in *addr
108 * find_next_zero_bit(addr, nbits, bit)
109 * Position next zero bit in *addr >= bit
110 * find_next_bit(addr, nbits, bit) Position next set bit in *addr >= bit
111 * find_next_and_bit(addr1, addr2, nbits, bit)
112 * Same as find_next_bit, but in
113 * (*addr1 & *addr2)
114 *
115 */
116
117/**
118 * DOC: declare bitmap
119 * The DECLARE_BITMAP(name,bits) macro, in linux/types.h, can be used
120 * to declare an array named 'name' of just enough unsigned longs to
121 * contain all bit positions from 0 to 'bits' - 1.
122 */
123
124/*
125 * Allocation and deallocation of bitmap.
126 * Provided in lib/bitmap.c to avoid circular dependency.
127 */
128unsigned long *bitmap_alloc(unsigned int nbits, gfp_t flags);
129unsigned long *bitmap_zalloc(unsigned int nbits, gfp_t flags);
130unsigned long *bitmap_alloc_node(unsigned int nbits, gfp_t flags, int node);
131unsigned long *bitmap_zalloc_node(unsigned int nbits, gfp_t flags, int node);
132void bitmap_free(const unsigned long *bitmap);
133
134DEFINE_FREE(bitmap, unsigned long *, if (_T) bitmap_free(_T))
135
136/* Managed variants of the above. */
137unsigned long *devm_bitmap_alloc(struct device *dev,
138 unsigned int nbits, gfp_t flags);
139unsigned long *devm_bitmap_zalloc(struct device *dev,
140 unsigned int nbits, gfp_t flags);
141
142/*
143 * lib/bitmap.c provides these functions:
144 */
145
146bool __bitmap_equal(const unsigned long *bitmap1,
147 const unsigned long *bitmap2, unsigned int nbits);
148bool __pure __bitmap_or_equal(const unsigned long *src1,
149 const unsigned long *src2,
150 const unsigned long *src3,
151 unsigned int nbits);
152void __bitmap_complement(unsigned long *dst, const unsigned long *src,
153 unsigned int nbits);
154void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
155 unsigned int shift, unsigned int nbits);
156void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
157 unsigned int shift, unsigned int nbits);
158void bitmap_cut(unsigned long *dst, const unsigned long *src,
159 unsigned int first, unsigned int cut, unsigned int nbits);
160bool __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
161 const unsigned long *bitmap2, unsigned int nbits);
162void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
163 const unsigned long *bitmap2, unsigned int nbits);
164void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
165 const unsigned long *bitmap2, unsigned int nbits);
166bool __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
167 const unsigned long *bitmap2, unsigned int nbits);
168void __bitmap_replace(unsigned long *dst,
169 const unsigned long *old, const unsigned long *new,
170 const unsigned long *mask, unsigned int nbits);
171bool __bitmap_intersects(const unsigned long *bitmap1,
172 const unsigned long *bitmap2, unsigned int nbits);
173bool __bitmap_subset(const unsigned long *bitmap1,
174 const unsigned long *bitmap2, unsigned int nbits);
175unsigned int __bitmap_weight(const unsigned long *bitmap, unsigned int nbits);
176unsigned int __bitmap_weight_and(const unsigned long *bitmap1,
177 const unsigned long *bitmap2, unsigned int nbits);
178unsigned int __bitmap_weight_andnot(const unsigned long *bitmap1,
179 const unsigned long *bitmap2, unsigned int nbits);
180void __bitmap_set(unsigned long *map, unsigned int start, int len);
181void __bitmap_clear(unsigned long *map, unsigned int start, int len);
182
183unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
184 unsigned long size,
185 unsigned long start,
186 unsigned int nr,
187 unsigned long align_mask,
188 unsigned long align_offset);
189
190/**
191 * bitmap_find_next_zero_area - find a contiguous aligned zero area
192 * @map: The address to base the search on
193 * @size: The bitmap size in bits
194 * @start: The bitnumber to start searching at
195 * @nr: The number of zeroed bits we're looking for
196 * @align_mask: Alignment mask for zero area
197 *
198 * The @align_mask should be one less than a power of 2; the effect is that
199 * the bit offset of all zero areas this function finds is multiples of that
200 * power of 2. A @align_mask of 0 means no alignment is required.
201 */
202static inline unsigned long
203bitmap_find_next_zero_area(unsigned long *map,
204 unsigned long size,
205 unsigned long start,
206 unsigned int nr,
207 unsigned long align_mask)
208{
209 return bitmap_find_next_zero_area_off(map, size, start, nr,
210 align_mask, align_offset: 0);
211}
212
213void bitmap_remap(unsigned long *dst, const unsigned long *src,
214 const unsigned long *old, const unsigned long *new, unsigned int nbits);
215int bitmap_bitremap(int oldbit,
216 const unsigned long *old, const unsigned long *new, int bits);
217void bitmap_onto(unsigned long *dst, const unsigned long *orig,
218 const unsigned long *relmap, unsigned int bits);
219void bitmap_fold(unsigned long *dst, const unsigned long *orig,
220 unsigned int sz, unsigned int nbits);
221
222#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1)))
223#define BITMAP_LAST_WORD_MASK(nbits) (~0UL >> (-(nbits) & (BITS_PER_LONG - 1)))
224
225static inline void bitmap_zero(unsigned long *dst, unsigned int nbits)
226{
227 unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
228
229 if (small_const_nbits(nbits))
230 *dst = 0;
231 else
232 memset(dst, 0, len);
233}
234
235static inline void bitmap_fill(unsigned long *dst, unsigned int nbits)
236{
237 unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
238
239 if (small_const_nbits(nbits))
240 *dst = ~0UL;
241 else
242 memset(dst, 0xff, len);
243}
244
245static inline void bitmap_copy(unsigned long *dst, const unsigned long *src,
246 unsigned int nbits)
247{
248 unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
249
250 if (small_const_nbits(nbits))
251 *dst = *src;
252 else
253 memcpy(dst, src, len);
254}
255
256/*
257 * Copy bitmap and clear tail bits in last word.
258 */
259static inline void bitmap_copy_clear_tail(unsigned long *dst,
260 const unsigned long *src, unsigned int nbits)
261{
262 bitmap_copy(dst, src, nbits);
263 if (nbits % BITS_PER_LONG)
264 dst[nbits / BITS_PER_LONG] &= BITMAP_LAST_WORD_MASK(nbits);
265}
266
267/*
268 * On 32-bit systems bitmaps are represented as u32 arrays internally. On LE64
269 * machines the order of hi and lo parts of numbers match the bitmap structure.
270 * In both cases conversion is not needed when copying data from/to arrays of
271 * u32. But in LE64 case, typecast in bitmap_copy_clear_tail() may lead
272 * to out-of-bound access. To avoid that, both LE and BE variants of 64-bit
273 * architectures are not using bitmap_copy_clear_tail().
274 */
275#if BITS_PER_LONG == 64
276void bitmap_from_arr32(unsigned long *bitmap, const u32 *buf,
277 unsigned int nbits);
278void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap,
279 unsigned int nbits);
280#else
281#define bitmap_from_arr32(bitmap, buf, nbits) \
282 bitmap_copy_clear_tail((unsigned long *) (bitmap), \
283 (const unsigned long *) (buf), (nbits))
284#define bitmap_to_arr32(buf, bitmap, nbits) \
285 bitmap_copy_clear_tail((unsigned long *) (buf), \
286 (const unsigned long *) (bitmap), (nbits))
287#endif
288
289/*
290 * On 64-bit systems bitmaps are represented as u64 arrays internally. So,
291 * the conversion is not needed when copying data from/to arrays of u64.
292 */
293#if BITS_PER_LONG == 32
294void bitmap_from_arr64(unsigned long *bitmap, const u64 *buf, unsigned int nbits);
295void bitmap_to_arr64(u64 *buf, const unsigned long *bitmap, unsigned int nbits);
296#else
297#define bitmap_from_arr64(bitmap, buf, nbits) \
298 bitmap_copy_clear_tail((unsigned long *)(bitmap), (const unsigned long *)(buf), (nbits))
299#define bitmap_to_arr64(buf, bitmap, nbits) \
300 bitmap_copy_clear_tail((unsigned long *)(buf), (const unsigned long *)(bitmap), (nbits))
301#endif
302
303static inline bool bitmap_and(unsigned long *dst, const unsigned long *src1,
304 const unsigned long *src2, unsigned int nbits)
305{
306 if (small_const_nbits(nbits))
307 return (*dst = *src1 & *src2 & BITMAP_LAST_WORD_MASK(nbits)) != 0;
308 return __bitmap_and(dst, bitmap1: src1, bitmap2: src2, nbits);
309}
310
311static inline void bitmap_or(unsigned long *dst, const unsigned long *src1,
312 const unsigned long *src2, unsigned int nbits)
313{
314 if (small_const_nbits(nbits))
315 *dst = *src1 | *src2;
316 else
317 __bitmap_or(dst, bitmap1: src1, bitmap2: src2, nbits);
318}
319
320static inline void bitmap_xor(unsigned long *dst, const unsigned long *src1,
321 const unsigned long *src2, unsigned int nbits)
322{
323 if (small_const_nbits(nbits))
324 *dst = *src1 ^ *src2;
325 else
326 __bitmap_xor(dst, bitmap1: src1, bitmap2: src2, nbits);
327}
328
329static inline bool bitmap_andnot(unsigned long *dst, const unsigned long *src1,
330 const unsigned long *src2, unsigned int nbits)
331{
332 if (small_const_nbits(nbits))
333 return (*dst = *src1 & ~(*src2) & BITMAP_LAST_WORD_MASK(nbits)) != 0;
334 return __bitmap_andnot(dst, bitmap1: src1, bitmap2: src2, nbits);
335}
336
337static inline void bitmap_complement(unsigned long *dst, const unsigned long *src,
338 unsigned int nbits)
339{
340 if (small_const_nbits(nbits))
341 *dst = ~(*src);
342 else
343 __bitmap_complement(dst, src, nbits);
344}
345
346#ifdef __LITTLE_ENDIAN
347#define BITMAP_MEM_ALIGNMENT 8
348#else
349#define BITMAP_MEM_ALIGNMENT (8 * sizeof(unsigned long))
350#endif
351#define BITMAP_MEM_MASK (BITMAP_MEM_ALIGNMENT - 1)
352
353static inline bool bitmap_equal(const unsigned long *src1,
354 const unsigned long *src2, unsigned int nbits)
355{
356 if (small_const_nbits(nbits))
357 return !((*src1 ^ *src2) & BITMAP_LAST_WORD_MASK(nbits));
358 if (__builtin_constant_p(nbits & BITMAP_MEM_MASK) &&
359 IS_ALIGNED(nbits, BITMAP_MEM_ALIGNMENT))
360 return !memcmp(p: src1, q: src2, size: nbits / 8);
361 return __bitmap_equal(bitmap1: src1, bitmap2: src2, nbits);
362}
363
364/**
365 * bitmap_or_equal - Check whether the or of two bitmaps is equal to a third
366 * @src1: Pointer to bitmap 1
367 * @src2: Pointer to bitmap 2 will be or'ed with bitmap 1
368 * @src3: Pointer to bitmap 3. Compare to the result of *@src1 | *@src2
369 * @nbits: number of bits in each of these bitmaps
370 *
371 * Returns: True if (*@src1 | *@src2) == *@src3, false otherwise
372 */
373static inline bool bitmap_or_equal(const unsigned long *src1,
374 const unsigned long *src2,
375 const unsigned long *src3,
376 unsigned int nbits)
377{
378 if (!small_const_nbits(nbits))
379 return __bitmap_or_equal(src1, src2, src3, nbits);
380
381 return !(((*src1 | *src2) ^ *src3) & BITMAP_LAST_WORD_MASK(nbits));
382}
383
384static inline bool bitmap_intersects(const unsigned long *src1,
385 const unsigned long *src2,
386 unsigned int nbits)
387{
388 if (small_const_nbits(nbits))
389 return ((*src1 & *src2) & BITMAP_LAST_WORD_MASK(nbits)) != 0;
390 else
391 return __bitmap_intersects(bitmap1: src1, bitmap2: src2, nbits);
392}
393
394static inline bool bitmap_subset(const unsigned long *src1,
395 const unsigned long *src2, unsigned int nbits)
396{
397 if (small_const_nbits(nbits))
398 return ! ((*src1 & ~(*src2)) & BITMAP_LAST_WORD_MASK(nbits));
399 else
400 return __bitmap_subset(bitmap1: src1, bitmap2: src2, nbits);
401}
402
403static inline bool bitmap_empty(const unsigned long *src, unsigned nbits)
404{
405 if (small_const_nbits(nbits))
406 return ! (*src & BITMAP_LAST_WORD_MASK(nbits));
407
408 return find_first_bit(addr: src, size: nbits) == nbits;
409}
410
411static inline bool bitmap_full(const unsigned long *src, unsigned int nbits)
412{
413 if (small_const_nbits(nbits))
414 return ! (~(*src) & BITMAP_LAST_WORD_MASK(nbits));
415
416 return find_first_zero_bit(addr: src, size: nbits) == nbits;
417}
418
419static __always_inline
420unsigned int bitmap_weight(const unsigned long *src, unsigned int nbits)
421{
422 if (small_const_nbits(nbits))
423 return hweight_long(w: *src & BITMAP_LAST_WORD_MASK(nbits));
424 return __bitmap_weight(bitmap: src, nbits);
425}
426
427static __always_inline
428unsigned long bitmap_weight_and(const unsigned long *src1,
429 const unsigned long *src2, unsigned int nbits)
430{
431 if (small_const_nbits(nbits))
432 return hweight_long(w: *src1 & *src2 & BITMAP_LAST_WORD_MASK(nbits));
433 return __bitmap_weight_and(bitmap1: src1, bitmap2: src2, nbits);
434}
435
436static __always_inline
437unsigned long bitmap_weight_andnot(const unsigned long *src1,
438 const unsigned long *src2, unsigned int nbits)
439{
440 if (small_const_nbits(nbits))
441 return hweight_long(w: *src1 & ~(*src2) & BITMAP_LAST_WORD_MASK(nbits));
442 return __bitmap_weight_andnot(bitmap1: src1, bitmap2: src2, nbits);
443}
444
445static __always_inline void bitmap_set(unsigned long *map, unsigned int start,
446 unsigned int nbits)
447{
448 if (__builtin_constant_p(nbits) && nbits == 1)
449 __set_bit(start, map);
450 else if (small_const_nbits(start + nbits))
451 *map |= GENMASK(start + nbits - 1, start);
452 else if (__builtin_constant_p(start & BITMAP_MEM_MASK) &&
453 IS_ALIGNED(start, BITMAP_MEM_ALIGNMENT) &&
454 __builtin_constant_p(nbits & BITMAP_MEM_MASK) &&
455 IS_ALIGNED(nbits, BITMAP_MEM_ALIGNMENT))
456 memset((char *)map + start / 8, 0xff, nbits / 8);
457 else
458 __bitmap_set(map, start, len: nbits);
459}
460
461static __always_inline void bitmap_clear(unsigned long *map, unsigned int start,
462 unsigned int nbits)
463{
464 if (__builtin_constant_p(nbits) && nbits == 1)
465 __clear_bit(start, map);
466 else if (small_const_nbits(start + nbits))
467 *map &= ~GENMASK(start + nbits - 1, start);
468 else if (__builtin_constant_p(start & BITMAP_MEM_MASK) &&
469 IS_ALIGNED(start, BITMAP_MEM_ALIGNMENT) &&
470 __builtin_constant_p(nbits & BITMAP_MEM_MASK) &&
471 IS_ALIGNED(nbits, BITMAP_MEM_ALIGNMENT))
472 memset((char *)map + start / 8, 0, nbits / 8);
473 else
474 __bitmap_clear(map, start, len: nbits);
475}
476
477static inline void bitmap_shift_right(unsigned long *dst, const unsigned long *src,
478 unsigned int shift, unsigned int nbits)
479{
480 if (small_const_nbits(nbits))
481 *dst = (*src & BITMAP_LAST_WORD_MASK(nbits)) >> shift;
482 else
483 __bitmap_shift_right(dst, src, shift, nbits);
484}
485
486static inline void bitmap_shift_left(unsigned long *dst, const unsigned long *src,
487 unsigned int shift, unsigned int nbits)
488{
489 if (small_const_nbits(nbits))
490 *dst = (*src << shift) & BITMAP_LAST_WORD_MASK(nbits);
491 else
492 __bitmap_shift_left(dst, src, shift, nbits);
493}
494
495static inline void bitmap_replace(unsigned long *dst,
496 const unsigned long *old,
497 const unsigned long *new,
498 const unsigned long *mask,
499 unsigned int nbits)
500{
501 if (small_const_nbits(nbits))
502 *dst = (*old & ~(*mask)) | (*new & *mask);
503 else
504 __bitmap_replace(dst, old, new, mask, nbits);
505}
506
507/**
508 * bitmap_scatter - Scatter a bitmap according to the given mask
509 * @dst: scattered bitmap
510 * @src: gathered bitmap
511 * @mask: mask representing bits to assign to in the scattered bitmap
512 * @nbits: number of bits in each of these bitmaps
513 *
514 * Scatters bitmap with sequential bits according to the given @mask.
515 *
516 * Example:
517 * If @src bitmap = 0x005a, with @mask = 0x1313, @dst will be 0x0302.
518 *
519 * Or in binary form
520 * @src @mask @dst
521 * 0000000001011010 0001001100010011 0000001100000010
522 *
523 * (Bits 0, 1, 2, 3, 4, 5 are copied to the bits 0, 1, 4, 8, 9, 12)
524 *
525 * A more 'visual' description of the operation::
526 *
527 * src: 0000000001011010
528 * ||||||
529 * +------+|||||
530 * | +----+||||
531 * | |+----+|||
532 * | || +-+||
533 * | || | ||
534 * mask: ...v..vv...v..vv
535 * ...0..11...0..10
536 * dst: 0000001100000010
537 *
538 * A relationship exists between bitmap_scatter() and bitmap_gather().
539 * bitmap_gather() can be seen as the 'reverse' bitmap_scatter() operation.
540 * See bitmap_scatter() for details related to this relationship.
541 */
542static inline void bitmap_scatter(unsigned long *dst, const unsigned long *src,
543 const unsigned long *mask, unsigned int nbits)
544{
545 unsigned int n = 0;
546 unsigned int bit;
547
548 bitmap_zero(dst, nbits);
549
550 for_each_set_bit(bit, mask, nbits)
551 __assign_bit(nr: bit, addr: dst, test_bit(n++, src));
552}
553
554/**
555 * bitmap_gather - Gather a bitmap according to given mask
556 * @dst: gathered bitmap
557 * @src: scattered bitmap
558 * @mask: mask representing bits to extract from in the scattered bitmap
559 * @nbits: number of bits in each of these bitmaps
560 *
561 * Gathers bitmap with sparse bits according to the given @mask.
562 *
563 * Example:
564 * If @src bitmap = 0x0302, with @mask = 0x1313, @dst will be 0x001a.
565 *
566 * Or in binary form
567 * @src @mask @dst
568 * 0000001100000010 0001001100010011 0000000000011010
569 *
570 * (Bits 0, 1, 4, 8, 9, 12 are copied to the bits 0, 1, 2, 3, 4, 5)
571 *
572 * A more 'visual' description of the operation::
573 *
574 * mask: ...v..vv...v..vv
575 * src: 0000001100000010
576 * ^ ^^ ^ 0
577 * | || | 10
578 * | || > 010
579 * | |+--> 1010
580 * | +--> 11010
581 * +----> 011010
582 * dst: 0000000000011010
583 *
584 * A relationship exists between bitmap_gather() and bitmap_scatter(). See
585 * bitmap_scatter() for the bitmap scatter detailed operations.
586 * Suppose scattered computed using bitmap_scatter(scattered, src, mask, n).
587 * The operation bitmap_gather(result, scattered, mask, n) leads to a result
588 * equal or equivalent to src.
589 *
590 * The result can be 'equivalent' because bitmap_scatter() and bitmap_gather()
591 * are not bijective.
592 * The result and src values are equivalent in that sense that a call to
593 * bitmap_scatter(res, src, mask, n) and a call to
594 * bitmap_scatter(res, result, mask, n) will lead to the same res value.
595 */
596static inline void bitmap_gather(unsigned long *dst, const unsigned long *src,
597 const unsigned long *mask, unsigned int nbits)
598{
599 unsigned int n = 0;
600 unsigned int bit;
601
602 bitmap_zero(dst, nbits);
603
604 for_each_set_bit(bit, mask, nbits)
605 __assign_bit(nr: n++, addr: dst, test_bit(bit, src));
606}
607
608static inline void bitmap_next_set_region(unsigned long *bitmap,
609 unsigned int *rs, unsigned int *re,
610 unsigned int end)
611{
612 *rs = find_next_bit(addr: bitmap, size: end, offset: *rs);
613 *re = find_next_zero_bit(addr: bitmap, size: end, offset: *rs + 1);
614}
615
616/**
617 * bitmap_release_region - release allocated bitmap region
618 * @bitmap: array of unsigned longs corresponding to the bitmap
619 * @pos: beginning of bit region to release
620 * @order: region size (log base 2 of number of bits) to release
621 *
622 * This is the complement to __bitmap_find_free_region() and releases
623 * the found region (by clearing it in the bitmap).
624 */
625static inline void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order)
626{
627 bitmap_clear(map: bitmap, start: pos, BIT(order));
628}
629
630/**
631 * bitmap_allocate_region - allocate bitmap region
632 * @bitmap: array of unsigned longs corresponding to the bitmap
633 * @pos: beginning of bit region to allocate
634 * @order: region size (log base 2 of number of bits) to allocate
635 *
636 * Allocate (set bits in) a specified region of a bitmap.
637 *
638 * Returns: 0 on success, or %-EBUSY if specified region wasn't
639 * free (not all bits were zero).
640 */
641static inline int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order)
642{
643 unsigned int len = BIT(order);
644
645 if (find_next_bit(addr: bitmap, size: pos + len, offset: pos) < pos + len)
646 return -EBUSY;
647 bitmap_set(map: bitmap, start: pos, nbits: len);
648 return 0;
649}
650
651/**
652 * bitmap_find_free_region - find a contiguous aligned mem region
653 * @bitmap: array of unsigned longs corresponding to the bitmap
654 * @bits: number of bits in the bitmap
655 * @order: region size (log base 2 of number of bits) to find
656 *
657 * Find a region of free (zero) bits in a @bitmap of @bits bits and
658 * allocate them (set them to one). Only consider regions of length
659 * a power (@order) of two, aligned to that power of two, which
660 * makes the search algorithm much faster.
661 *
662 * Returns: the bit offset in bitmap of the allocated region,
663 * or -errno on failure.
664 */
665static inline int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order)
666{
667 unsigned int pos, end; /* scans bitmap by regions of size order */
668
669 for (pos = 0; (end = pos + BIT(order)) <= bits; pos = end) {
670 if (!bitmap_allocate_region(bitmap, pos, order))
671 return pos;
672 }
673 return -ENOMEM;
674}
675
676/**
677 * BITMAP_FROM_U64() - Represent u64 value in the format suitable for bitmap.
678 * @n: u64 value
679 *
680 * Linux bitmaps are internally arrays of unsigned longs, i.e. 32-bit
681 * integers in 32-bit environment, and 64-bit integers in 64-bit one.
682 *
683 * There are four combinations of endianness and length of the word in linux
684 * ABIs: LE64, BE64, LE32 and BE32.
685 *
686 * On 64-bit kernels 64-bit LE and BE numbers are naturally ordered in
687 * bitmaps and therefore don't require any special handling.
688 *
689 * On 32-bit kernels 32-bit LE ABI orders lo word of 64-bit number in memory
690 * prior to hi, and 32-bit BE orders hi word prior to lo. The bitmap on the
691 * other hand is represented as an array of 32-bit words and the position of
692 * bit N may therefore be calculated as: word #(N/32) and bit #(N%32) in that
693 * word. For example, bit #42 is located at 10th position of 2nd word.
694 * It matches 32-bit LE ABI, and we can simply let the compiler store 64-bit
695 * values in memory as it usually does. But for BE we need to swap hi and lo
696 * words manually.
697 *
698 * With all that, the macro BITMAP_FROM_U64() does explicit reordering of hi and
699 * lo parts of u64. For LE32 it does nothing, and for BE environment it swaps
700 * hi and lo words, as is expected by bitmap.
701 */
702#if __BITS_PER_LONG == 64
703#define BITMAP_FROM_U64(n) (n)
704#else
705#define BITMAP_FROM_U64(n) ((unsigned long) ((u64)(n) & ULONG_MAX)), \
706 ((unsigned long) ((u64)(n) >> 32))
707#endif
708
709/**
710 * bitmap_from_u64 - Check and swap words within u64.
711 * @mask: source bitmap
712 * @dst: destination bitmap
713 *
714 * In 32-bit Big Endian kernel, when using ``(u32 *)(&val)[*]``
715 * to read u64 mask, we will get the wrong word.
716 * That is ``(u32 *)(&val)[0]`` gets the upper 32 bits,
717 * but we expect the lower 32-bits of u64.
718 */
719static inline void bitmap_from_u64(unsigned long *dst, u64 mask)
720{
721 bitmap_from_arr64(dst, &mask, 64);
722}
723
724/**
725 * bitmap_get_value8 - get an 8-bit value within a memory region
726 * @map: address to the bitmap memory region
727 * @start: bit offset of the 8-bit value; must be a multiple of 8
728 *
729 * Returns the 8-bit value located at the @start bit offset within the @src
730 * memory region.
731 */
732static inline unsigned long bitmap_get_value8(const unsigned long *map,
733 unsigned long start)
734{
735 const size_t index = BIT_WORD(start);
736 const unsigned long offset = start % BITS_PER_LONG;
737
738 return (map[index] >> offset) & 0xFF;
739}
740
741/**
742 * bitmap_set_value8 - set an 8-bit value within a memory region
743 * @map: address to the bitmap memory region
744 * @value: the 8-bit value; values wider than 8 bits may clobber bitmap
745 * @start: bit offset of the 8-bit value; must be a multiple of 8
746 */
747static inline void bitmap_set_value8(unsigned long *map, unsigned long value,
748 unsigned long start)
749{
750 const size_t index = BIT_WORD(start);
751 const unsigned long offset = start % BITS_PER_LONG;
752
753 map[index] &= ~(0xFFUL << offset);
754 map[index] |= value << offset;
755}
756
757#endif /* __ASSEMBLY__ */
758
759#endif /* __LINUX_BITMAP_H */
760

source code of linux/include/linux/bitmap.h