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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * lib/bitmap.c
4 * Helper functions for bitmap.h.
5 */
6
7#include <linux/bitmap.h>
8#include <linux/bitops.h>
9#include <linux/ctype.h>
10#include <linux/device.h>
11#include <linux/export.h>
12#include <linux/slab.h>
13
14/**
15 * DOC: bitmap introduction
16 *
17 * bitmaps provide an array of bits, implemented using an
18 * array of unsigned longs. The number of valid bits in a
19 * given bitmap does _not_ need to be an exact multiple of
20 * BITS_PER_LONG.
21 *
22 * The possible unused bits in the last, partially used word
23 * of a bitmap are 'don't care'. The implementation makes
24 * no particular effort to keep them zero. It ensures that
25 * their value will not affect the results of any operation.
26 * The bitmap operations that return Boolean (bitmap_empty,
27 * for example) or scalar (bitmap_weight, for example) results
28 * carefully filter out these unused bits from impacting their
29 * results.
30 *
31 * The byte ordering of bitmaps is more natural on little
32 * endian architectures. See the big-endian headers
33 * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
34 * for the best explanations of this ordering.
35 */
36
37bool __bitmap_equal(const unsigned long *bitmap1,
38 const unsigned long *bitmap2, unsigned int bits)
39{
40 unsigned int k, lim = bits/BITS_PER_LONG;
41 for (k = 0; k < lim; ++k)
42 if (bitmap1[k] != bitmap2[k])
43 return false;
44
45 if (bits % BITS_PER_LONG)
46 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
47 return false;
48
49 return true;
50}
51EXPORT_SYMBOL(__bitmap_equal);
52
53bool __bitmap_or_equal(const unsigned long *bitmap1,
54 const unsigned long *bitmap2,
55 const unsigned long *bitmap3,
56 unsigned int bits)
57{
58 unsigned int k, lim = bits / BITS_PER_LONG;
59 unsigned long tmp;
60
61 for (k = 0; k < lim; ++k) {
62 if ((bitmap1[k] | bitmap2[k]) != bitmap3[k])
63 return false;
64 }
65
66 if (!(bits % BITS_PER_LONG))
67 return true;
68
69 tmp = (bitmap1[k] | bitmap2[k]) ^ bitmap3[k];
70 return (tmp & BITMAP_LAST_WORD_MASK(bits)) == 0;
71}
72EXPORT_SYMBOL(__bitmap_or_equal);
73
74void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits)
75{
76 unsigned int k, lim = BITS_TO_LONGS(bits);
77 for (k = 0; k < lim; ++k)
78 dst[k] = ~src[k];
79}
80EXPORT_SYMBOL(__bitmap_complement);
81
82/**
83 * __bitmap_shift_right - logical right shift of the bits in a bitmap
84 * @dst : destination bitmap
85 * @src : source bitmap
86 * @shift : shift by this many bits
87 * @nbits : bitmap size, in bits
88 *
89 * Shifting right (dividing) means moving bits in the MS -> LS bit
90 * direction. Zeros are fed into the vacated MS positions and the
91 * LS bits shifted off the bottom are lost.
92 */
93void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
94 unsigned shift, unsigned nbits)
95{
96 unsigned k, lim = BITS_TO_LONGS(nbits);
97 unsigned off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
98 unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);
99 for (k = 0; off + k < lim; ++k) {
100 unsigned long upper, lower;
101
102 /*
103 * If shift is not word aligned, take lower rem bits of
104 * word above and make them the top rem bits of result.
105 */
106 if (!rem || off + k + 1 >= lim)
107 upper = 0;
108 else {
109 upper = src[off + k + 1];
110 if (off + k + 1 == lim - 1)
111 upper &= mask;
112 upper <<= (BITS_PER_LONG - rem);
113 }
114 lower = src[off + k];
115 if (off + k == lim - 1)
116 lower &= mask;
117 lower >>= rem;
118 dst[k] = lower | upper;
119 }
120 if (off)
121 memset(&dst[lim - off], 0, off*sizeof(unsigned long));
122}
123EXPORT_SYMBOL(__bitmap_shift_right);
124
125
126/**
127 * __bitmap_shift_left - logical left shift of the bits in a bitmap
128 * @dst : destination bitmap
129 * @src : source bitmap
130 * @shift : shift by this many bits
131 * @nbits : bitmap size, in bits
132 *
133 * Shifting left (multiplying) means moving bits in the LS -> MS
134 * direction. Zeros are fed into the vacated LS bit positions
135 * and those MS bits shifted off the top are lost.
136 */
137
138void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
139 unsigned int shift, unsigned int nbits)
140{
141 int k;
142 unsigned int lim = BITS_TO_LONGS(nbits);
143 unsigned int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
144 for (k = lim - off - 1; k >= 0; --k) {
145 unsigned long upper, lower;
146
147 /*
148 * If shift is not word aligned, take upper rem bits of
149 * word below and make them the bottom rem bits of result.
150 */
151 if (rem && k > 0)
152 lower = src[k - 1] >> (BITS_PER_LONG - rem);
153 else
154 lower = 0;
155 upper = src[k] << rem;
156 dst[k + off] = lower | upper;
157 }
158 if (off)
159 memset(dst, 0, off*sizeof(unsigned long));
160}
161EXPORT_SYMBOL(__bitmap_shift_left);
162
163/**
164 * bitmap_cut() - remove bit region from bitmap and right shift remaining bits
165 * @dst: destination bitmap, might overlap with src
166 * @src: source bitmap
167 * @first: start bit of region to be removed
168 * @cut: number of bits to remove
169 * @nbits: bitmap size, in bits
170 *
171 * Set the n-th bit of @dst iff the n-th bit of @src is set and
172 * n is less than @first, or the m-th bit of @src is set for any
173 * m such that @first <= n < nbits, and m = n + @cut.
174 *
175 * In pictures, example for a big-endian 32-bit architecture:
176 *
177 * The @src bitmap is::
178 *
179 * 31 63
180 * | |
181 * 10000000 11000001 11110010 00010101 10000000 11000001 01110010 00010101
182 * | | | |
183 * 16 14 0 32
184 *
185 * if @cut is 3, and @first is 14, bits 14-16 in @src are cut and @dst is::
186 *
187 * 31 63
188 * | |
189 * 10110000 00011000 00110010 00010101 00010000 00011000 00101110 01000010
190 * | | |
191 * 14 (bit 17 0 32
192 * from @src)
193 *
194 * Note that @dst and @src might overlap partially or entirely.
195 *
196 * This is implemented in the obvious way, with a shift and carry
197 * step for each moved bit. Optimisation is left as an exercise
198 * for the compiler.
199 */
200void bitmap_cut(unsigned long *dst, const unsigned long *src,
201 unsigned int first, unsigned int cut, unsigned int nbits)
202{
203 unsigned int len = BITS_TO_LONGS(nbits);
204 unsigned long keep = 0, carry;
205 int i;
206
207 if (first % BITS_PER_LONG) {
208 keep = src[first / BITS_PER_LONG] &
209 (~0UL >> (BITS_PER_LONG - first % BITS_PER_LONG));
210 }
211
212 memmove(dst, src, len * sizeof(*dst));
213
214 while (cut--) {
215 for (i = first / BITS_PER_LONG; i < len; i++) {
216 if (i < len - 1)
217 carry = dst[i + 1] & 1UL;
218 else
219 carry = 0;
220
221 dst[i] = (dst[i] >> 1) | (carry << (BITS_PER_LONG - 1));
222 }
223 }
224
225 dst[first / BITS_PER_LONG] &= ~0UL << (first % BITS_PER_LONG);
226 dst[first / BITS_PER_LONG] |= keep;
227}
228EXPORT_SYMBOL(bitmap_cut);
229
230bool __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
231 const unsigned long *bitmap2, unsigned int bits)
232{
233 unsigned int k;
234 unsigned int lim = bits/BITS_PER_LONG;
235 unsigned long result = 0;
236
237 for (k = 0; k < lim; k++)
238 result |= (dst[k] = bitmap1[k] & bitmap2[k]);
239 if (bits % BITS_PER_LONG)
240 result |= (dst[k] = bitmap1[k] & bitmap2[k] &
241 BITMAP_LAST_WORD_MASK(bits));
242 return result != 0;
243}
244EXPORT_SYMBOL(__bitmap_and);
245
246void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
247 const unsigned long *bitmap2, unsigned int bits)
248{
249 unsigned int k;
250 unsigned int nr = BITS_TO_LONGS(bits);
251
252 for (k = 0; k < nr; k++)
253 dst[k] = bitmap1[k] | bitmap2[k];
254}
255EXPORT_SYMBOL(__bitmap_or);
256
257void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
258 const unsigned long *bitmap2, unsigned int bits)
259{
260 unsigned int k;
261 unsigned int nr = BITS_TO_LONGS(bits);
262
263 for (k = 0; k < nr; k++)
264 dst[k] = bitmap1[k] ^ bitmap2[k];
265}
266EXPORT_SYMBOL(__bitmap_xor);
267
268bool __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
269 const unsigned long *bitmap2, unsigned int bits)
270{
271 unsigned int k;
272 unsigned int lim = bits/BITS_PER_LONG;
273 unsigned long result = 0;
274
275 for (k = 0; k < lim; k++)
276 result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
277 if (bits % BITS_PER_LONG)
278 result |= (dst[k] = bitmap1[k] & ~bitmap2[k] &
279 BITMAP_LAST_WORD_MASK(bits));
280 return result != 0;
281}
282EXPORT_SYMBOL(__bitmap_andnot);
283
284void __bitmap_replace(unsigned long *dst,
285 const unsigned long *old, const unsigned long *new,
286 const unsigned long *mask, unsigned int nbits)
287{
288 unsigned int k;
289 unsigned int nr = BITS_TO_LONGS(nbits);
290
291 for (k = 0; k < nr; k++)
292 dst[k] = (old[k] & ~mask[k]) | (new[k] & mask[k]);
293}
294EXPORT_SYMBOL(__bitmap_replace);
295
296bool __bitmap_intersects(const unsigned long *bitmap1,
297 const unsigned long *bitmap2, unsigned int bits)
298{
299 unsigned int k, lim = bits/BITS_PER_LONG;
300 for (k = 0; k < lim; ++k)
301 if (bitmap1[k] & bitmap2[k])
302 return true;
303
304 if (bits % BITS_PER_LONG)
305 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
306 return true;
307 return false;
308}
309EXPORT_SYMBOL(__bitmap_intersects);
310
311bool __bitmap_subset(const unsigned long *bitmap1,
312 const unsigned long *bitmap2, unsigned int bits)
313{
314 unsigned int k, lim = bits/BITS_PER_LONG;
315 for (k = 0; k < lim; ++k)
316 if (bitmap1[k] & ~bitmap2[k])
317 return false;
318
319 if (bits % BITS_PER_LONG)
320 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
321 return false;
322 return true;
323}
324EXPORT_SYMBOL(__bitmap_subset);
325
326#define BITMAP_WEIGHT(FETCH, bits) \
327({ \
328 unsigned int __bits = (bits), idx, w = 0; \
329 \
330 for (idx = 0; idx < __bits / BITS_PER_LONG; idx++) \
331 w += hweight_long(FETCH); \
332 \
333 if (__bits % BITS_PER_LONG) \
334 w += hweight_long((FETCH) & BITMAP_LAST_WORD_MASK(__bits)); \
335 \
336 w; \
337})
338
339unsigned int __bitmap_weight(const unsigned long *bitmap, unsigned int bits)
340{
341 return BITMAP_WEIGHT(bitmap[idx], bits);
342}
343EXPORT_SYMBOL(__bitmap_weight);
344
345unsigned int __bitmap_weight_and(const unsigned long *bitmap1,
346 const unsigned long *bitmap2, unsigned int bits)
347{
348 return BITMAP_WEIGHT(bitmap1[idx] & bitmap2[idx], bits);
349}
350EXPORT_SYMBOL(__bitmap_weight_and);
351
352unsigned int __bitmap_weight_andnot(const unsigned long *bitmap1,
353 const unsigned long *bitmap2, unsigned int bits)
354{
355 return BITMAP_WEIGHT(bitmap1[idx] & ~bitmap2[idx], bits);
356}
357EXPORT_SYMBOL(__bitmap_weight_andnot);
358
359unsigned int __bitmap_weighted_or(unsigned long *dst, const unsigned long *bitmap1,
360 const unsigned long *bitmap2, unsigned int bits)
361{
362 return BITMAP_WEIGHT(({dst[idx] = bitmap1[idx] | bitmap2[idx]; dst[idx]; }), bits);
363}
364EXPORT_SYMBOL(__bitmap_weighted_or);
365
366unsigned int __bitmap_weighted_xor(unsigned long *dst, const unsigned long *bitmap1,
367 const unsigned long *bitmap2, unsigned int bits)
368{
369 return BITMAP_WEIGHT(({dst[idx] = bitmap1[idx] ^ bitmap2[idx]; dst[idx]; }), bits);
370}
371EXPORT_SYMBOL(__bitmap_weighted_xor);
372
373void __bitmap_set(unsigned long *map, unsigned int start, int len)
374{
375 unsigned long *p = map + BIT_WORD(start);
376 const unsigned int size = start + len;
377 int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
378 unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
379
380 while (len - bits_to_set >= 0) {
381 *p |= mask_to_set;
382 len -= bits_to_set;
383 bits_to_set = BITS_PER_LONG;
384 mask_to_set = ~0UL;
385 p++;
386 }
387 if (len) {
388 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
389 *p |= mask_to_set;
390 }
391}
392EXPORT_SYMBOL(__bitmap_set);
393
394void __bitmap_clear(unsigned long *map, unsigned int start, int len)
395{
396 unsigned long *p = map + BIT_WORD(start);
397 const unsigned int size = start + len;
398 int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
399 unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
400
401 while (len - bits_to_clear >= 0) {
402 *p &= ~mask_to_clear;
403 len -= bits_to_clear;
404 bits_to_clear = BITS_PER_LONG;
405 mask_to_clear = ~0UL;
406 p++;
407 }
408 if (len) {
409 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
410 *p &= ~mask_to_clear;
411 }
412}
413EXPORT_SYMBOL(__bitmap_clear);
414
415/**
416 * bitmap_find_next_zero_area_off - find a contiguous aligned zero area
417 * @map: The address to base the search on
418 * @size: The bitmap size in bits
419 * @start: The bitnumber to start searching at
420 * @nr: The number of zeroed bits we're looking for
421 * @align_mask: Alignment mask for zero area
422 * @align_offset: Alignment offset for zero area.
423 *
424 * The @align_mask should be one less than a power of 2; the effect is that
425 * the bit offset of all zero areas this function finds plus @align_offset
426 * is multiple of that power of 2.
427 */
428unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
429 unsigned long size,
430 unsigned long start,
431 unsigned int nr,
432 unsigned long align_mask,
433 unsigned long align_offset)
434{
435 unsigned long index, end, i;
436again:
437 index = find_next_zero_bit(map, size, start);
438
439 /* Align allocation */
440 index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset;
441
442 end = index + nr;
443 if (end > size)
444 return end;
445 i = find_next_bit(map, end, index);
446 if (i < end) {
447 start = i + 1;
448 goto again;
449 }
450 return index;
451}
452EXPORT_SYMBOL(bitmap_find_next_zero_area_off);
453
454/**
455 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
456 * @buf: pointer to a bitmap
457 * @pos: a bit position in @buf (0 <= @pos < @nbits)
458 * @nbits: number of valid bit positions in @buf
459 *
460 * Map the bit at position @pos in @buf (of length @nbits) to the
461 * ordinal of which set bit it is. If it is not set or if @pos
462 * is not a valid bit position, map to -1.
463 *
464 * If for example, just bits 4 through 7 are set in @buf, then @pos
465 * values 4 through 7 will get mapped to 0 through 3, respectively,
466 * and other @pos values will get mapped to -1. When @pos value 7
467 * gets mapped to (returns) @ord value 3 in this example, that means
468 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
469 *
470 * The bit positions 0 through @bits are valid positions in @buf.
471 */
472static int bitmap_pos_to_ord(const unsigned long *buf, unsigned int pos, unsigned int nbits)
473{
474 if (pos >= nbits || !test_bit(pos, buf))
475 return -1;
476
477 return bitmap_weight(buf, pos);
478}
479
480/**
481 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
482 * @dst: remapped result
483 * @src: subset to be remapped
484 * @old: defines domain of map
485 * @new: defines range of map
486 * @nbits: number of bits in each of these bitmaps
487 *
488 * Let @old and @new define a mapping of bit positions, such that
489 * whatever position is held by the n-th set bit in @old is mapped
490 * to the n-th set bit in @new. In the more general case, allowing
491 * for the possibility that the weight 'w' of @new is less than the
492 * weight of @old, map the position of the n-th set bit in @old to
493 * the position of the m-th set bit in @new, where m == n % w.
494 *
495 * If either of the @old and @new bitmaps are empty, or if @src and
496 * @dst point to the same location, then this routine copies @src
497 * to @dst.
498 *
499 * The positions of unset bits in @old are mapped to themselves
500 * (the identity map).
501 *
502 * Apply the above specified mapping to @src, placing the result in
503 * @dst, clearing any bits previously set in @dst.
504 *
505 * For example, lets say that @old has bits 4 through 7 set, and
506 * @new has bits 12 through 15 set. This defines the mapping of bit
507 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
508 * bit positions unchanged. So if say @src comes into this routine
509 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
510 * 13 and 15 set.
511 */
512void bitmap_remap(unsigned long *dst, const unsigned long *src,
513 const unsigned long *old, const unsigned long *new,
514 unsigned int nbits)
515{
516 unsigned int oldbit, w;
517
518 if (dst == src) /* following doesn't handle inplace remaps */
519 return;
520 bitmap_zero(dst, nbits);
521
522 w = bitmap_weight(new, nbits);
523 for_each_set_bit(oldbit, src, nbits) {
524 int n = bitmap_pos_to_ord(old, oldbit, nbits);
525
526 if (n < 0 || w == 0)
527 set_bit(oldbit, dst); /* identity map */
528 else
529 set_bit(find_nth_bit(new, nbits, n % w), dst);
530 }
531}
532EXPORT_SYMBOL(bitmap_remap);
533
534/**
535 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
536 * @oldbit: bit position to be mapped
537 * @old: defines domain of map
538 * @new: defines range of map
539 * @bits: number of bits in each of these bitmaps
540 *
541 * Let @old and @new define a mapping of bit positions, such that
542 * whatever position is held by the n-th set bit in @old is mapped
543 * to the n-th set bit in @new. In the more general case, allowing
544 * for the possibility that the weight 'w' of @new is less than the
545 * weight of @old, map the position of the n-th set bit in @old to
546 * the position of the m-th set bit in @new, where m == n % w.
547 *
548 * The positions of unset bits in @old are mapped to themselves
549 * (the identity map).
550 *
551 * Apply the above specified mapping to bit position @oldbit, returning
552 * the new bit position.
553 *
554 * For example, lets say that @old has bits 4 through 7 set, and
555 * @new has bits 12 through 15 set. This defines the mapping of bit
556 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
557 * bit positions unchanged. So if say @oldbit is 5, then this routine
558 * returns 13.
559 */
560int bitmap_bitremap(int oldbit, const unsigned long *old,
561 const unsigned long *new, int bits)
562{
563 int w = bitmap_weight(new, bits);
564 int n = bitmap_pos_to_ord(old, oldbit, bits);
565 if (n < 0 || w == 0)
566 return oldbit;
567 else
568 return find_nth_bit(new, bits, n % w);
569}
570EXPORT_SYMBOL(bitmap_bitremap);
571
572#ifdef CONFIG_NUMA
573/**
574 * bitmap_onto - translate one bitmap relative to another
575 * @dst: resulting translated bitmap
576 * @orig: original untranslated bitmap
577 * @relmap: bitmap relative to which translated
578 * @bits: number of bits in each of these bitmaps
579 *
580 * Set the n-th bit of @dst iff there exists some m such that the
581 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
582 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
583 * (If you understood the previous sentence the first time your
584 * read it, you're overqualified for your current job.)
585 *
586 * In other words, @orig is mapped onto (surjectively) @dst,
587 * using the map { <n, m> | the n-th bit of @relmap is the
588 * m-th set bit of @relmap }.
589 *
590 * Any set bits in @orig above bit number W, where W is the
591 * weight of (number of set bits in) @relmap are mapped nowhere.
592 * In particular, if for all bits m set in @orig, m >= W, then
593 * @dst will end up empty. In situations where the possibility
594 * of such an empty result is not desired, one way to avoid it is
595 * to use the bitmap_fold() operator, below, to first fold the
596 * @orig bitmap over itself so that all its set bits x are in the
597 * range 0 <= x < W. The bitmap_fold() operator does this by
598 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
599 *
600 * Example [1] for bitmap_onto():
601 * Let's say @relmap has bits 30-39 set, and @orig has bits
602 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,
603 * @dst will have bits 31, 33, 35, 37 and 39 set.
604 *
605 * When bit 0 is set in @orig, it means turn on the bit in
606 * @dst corresponding to whatever is the first bit (if any)
607 * that is turned on in @relmap. Since bit 0 was off in the
608 * above example, we leave off that bit (bit 30) in @dst.
609 *
610 * When bit 1 is set in @orig (as in the above example), it
611 * means turn on the bit in @dst corresponding to whatever
612 * is the second bit that is turned on in @relmap. The second
613 * bit in @relmap that was turned on in the above example was
614 * bit 31, so we turned on bit 31 in @dst.
615 *
616 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
617 * because they were the 4th, 6th, 8th and 10th set bits
618 * set in @relmap, and the 4th, 6th, 8th and 10th bits of
619 * @orig (i.e. bits 3, 5, 7 and 9) were also set.
620 *
621 * When bit 11 is set in @orig, it means turn on the bit in
622 * @dst corresponding to whatever is the twelfth bit that is
623 * turned on in @relmap. In the above example, there were
624 * only ten bits turned on in @relmap (30..39), so that bit
625 * 11 was set in @orig had no affect on @dst.
626 *
627 * Example [2] for bitmap_fold() + bitmap_onto():
628 * Let's say @relmap has these ten bits set::
629 *
630 * 40 41 42 43 45 48 53 61 74 95
631 *
632 * (for the curious, that's 40 plus the first ten terms of the
633 * Fibonacci sequence.)
634 *
635 * Further lets say we use the following code, invoking
636 * bitmap_fold() then bitmap_onto, as suggested above to
637 * avoid the possibility of an empty @dst result::
638 *
639 * unsigned long *tmp; // a temporary bitmap's bits
640 *
641 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
642 * bitmap_onto(dst, tmp, relmap, bits);
643 *
644 * Then this table shows what various values of @dst would be, for
645 * various @orig's. I list the zero-based positions of each set bit.
646 * The tmp column shows the intermediate result, as computed by
647 * using bitmap_fold() to fold the @orig bitmap modulo ten
648 * (the weight of @relmap):
649 *
650 * =============== ============== =================
651 * @orig tmp @dst
652 * 0 0 40
653 * 1 1 41
654 * 9 9 95
655 * 10 0 40 [#f1]_
656 * 1 3 5 7 1 3 5 7 41 43 48 61
657 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45
658 * 0 9 18 27 0 9 8 7 40 61 74 95
659 * 0 10 20 30 0 40
660 * 0 11 22 33 0 1 2 3 40 41 42 43
661 * 0 12 24 36 0 2 4 6 40 42 45 53
662 * 78 102 211 1 2 8 41 42 74 [#f1]_
663 * =============== ============== =================
664 *
665 * .. [#f1]
666 *
667 * For these marked lines, if we hadn't first done bitmap_fold()
668 * into tmp, then the @dst result would have been empty.
669 *
670 * If either of @orig or @relmap is empty (no set bits), then @dst
671 * will be returned empty.
672 *
673 * If (as explained above) the only set bits in @orig are in positions
674 * m where m >= W, (where W is the weight of @relmap) then @dst will
675 * once again be returned empty.
676 *
677 * All bits in @dst not set by the above rule are cleared.
678 */
679void bitmap_onto(unsigned long *dst, const unsigned long *orig,
680 const unsigned long *relmap, unsigned int bits)
681{
682 unsigned int n, m; /* same meaning as in above comment */
683
684 if (dst == orig) /* following doesn't handle inplace mappings */
685 return;
686 bitmap_zero(dst, bits);
687
688 /*
689 * The following code is a more efficient, but less
690 * obvious, equivalent to the loop:
691 * for (m = 0; m < bitmap_weight(relmap, bits); m++) {
692 * n = find_nth_bit(orig, bits, m);
693 * if (test_bit(m, orig))
694 * set_bit(n, dst);
695 * }
696 */
697
698 m = 0;
699 for_each_set_bit(n, relmap, bits) {
700 /* m == bitmap_pos_to_ord(relmap, n, bits) */
701 if (test_bit(m, orig))
702 set_bit(n, dst);
703 m++;
704 }
705}
706
707/**
708 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
709 * @dst: resulting smaller bitmap
710 * @orig: original larger bitmap
711 * @sz: specified size
712 * @nbits: number of bits in each of these bitmaps
713 *
714 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
715 * Clear all other bits in @dst. See further the comment and
716 * Example [2] for bitmap_onto() for why and how to use this.
717 */
718void bitmap_fold(unsigned long *dst, const unsigned long *orig,
719 unsigned int sz, unsigned int nbits)
720{
721 unsigned int oldbit;
722
723 if (dst == orig) /* following doesn't handle inplace mappings */
724 return;
725 bitmap_zero(dst, nbits);
726
727 for_each_set_bit(oldbit, orig, nbits)
728 set_bit(oldbit % sz, dst);
729}
730#endif /* CONFIG_NUMA */
731
732unsigned long *bitmap_alloc(unsigned int nbits, gfp_t flags)
733{
734 return kmalloc_array(BITS_TO_LONGS(nbits), sizeof(unsigned long),
735 flags);
736}
737EXPORT_SYMBOL(bitmap_alloc);
738
739unsigned long *bitmap_zalloc(unsigned int nbits, gfp_t flags)
740{
741 return bitmap_alloc(nbits, flags | __GFP_ZERO);
742}
743EXPORT_SYMBOL(bitmap_zalloc);
744
745unsigned long *bitmap_alloc_node(unsigned int nbits, gfp_t flags, int node)
746{
747 return kmalloc_array_node(BITS_TO_LONGS(nbits), sizeof(unsigned long),
748 flags, node);
749}
750EXPORT_SYMBOL(bitmap_alloc_node);
751
752unsigned long *bitmap_zalloc_node(unsigned int nbits, gfp_t flags, int node)
753{
754 return bitmap_alloc_node(nbits, flags | __GFP_ZERO, node);
755}
756EXPORT_SYMBOL(bitmap_zalloc_node);
757
758void bitmap_free(const unsigned long *bitmap)
759{
760 kfree(bitmap);
761}
762EXPORT_SYMBOL(bitmap_free);
763
764static void devm_bitmap_free(void *data)
765{
766 unsigned long *bitmap = data;
767
768 bitmap_free(bitmap);
769}
770
771unsigned long *devm_bitmap_alloc(struct device *dev,
772 unsigned int nbits, gfp_t flags)
773{
774 unsigned long *bitmap;
775 int ret;
776
777 bitmap = bitmap_alloc(nbits, flags);
778 if (!bitmap)
779 return NULL;
780
781 ret = devm_add_action_or_reset(dev, devm_bitmap_free, bitmap);
782 if (ret)
783 return NULL;
784
785 return bitmap;
786}
787EXPORT_SYMBOL_GPL(devm_bitmap_alloc);
788
789unsigned long *devm_bitmap_zalloc(struct device *dev,
790 unsigned int nbits, gfp_t flags)
791{
792 return devm_bitmap_alloc(dev, nbits, flags | __GFP_ZERO);
793}
794EXPORT_SYMBOL_GPL(devm_bitmap_zalloc);
795
796#if BITS_PER_LONG == 64
797/**
798 * bitmap_from_arr32 - copy the contents of u32 array of bits to bitmap
799 * @bitmap: array of unsigned longs, the destination bitmap
800 * @buf: array of u32 (in host byte order), the source bitmap
801 * @nbits: number of bits in @bitmap
802 */
803void bitmap_from_arr32(unsigned long *bitmap, const u32 *buf, unsigned int nbits)
804{
805 unsigned int i, halfwords;
806
807 halfwords = DIV_ROUND_UP(nbits, 32);
808 for (i = 0; i < halfwords; i++) {
809 bitmap[i/2] = (unsigned long) buf[i];
810 if (++i < halfwords)
811 bitmap[i/2] |= ((unsigned long) buf[i]) << 32;
812 }
813
814 /* Clear tail bits in last word beyond nbits. */
815 if (nbits % BITS_PER_LONG)
816 bitmap[(halfwords - 1) / 2] &= BITMAP_LAST_WORD_MASK(nbits);
817}
818EXPORT_SYMBOL(bitmap_from_arr32);
819
820/**
821 * bitmap_to_arr32 - copy the contents of bitmap to a u32 array of bits
822 * @buf: array of u32 (in host byte order), the dest bitmap
823 * @bitmap: array of unsigned longs, the source bitmap
824 * @nbits: number of bits in @bitmap
825 */
826void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap, unsigned int nbits)
827{
828 unsigned int i, halfwords;
829
830 halfwords = DIV_ROUND_UP(nbits, 32);
831 for (i = 0; i < halfwords; i++) {
832 buf[i] = (u32) (bitmap[i/2] & UINT_MAX);
833 if (++i < halfwords)
834 buf[i] = (u32) (bitmap[i/2] >> 32);
835 }
836
837 /* Clear tail bits in last element of array beyond nbits. */
838 if (nbits % BITS_PER_LONG)
839 buf[halfwords - 1] &= (u32) (UINT_MAX >> ((-nbits) & 31));
840}
841EXPORT_SYMBOL(bitmap_to_arr32);
842#endif
843
844#if BITS_PER_LONG == 32
845/**
846 * bitmap_from_arr64 - copy the contents of u64 array of bits to bitmap
847 * @bitmap: array of unsigned longs, the destination bitmap
848 * @buf: array of u64 (in host byte order), the source bitmap
849 * @nbits: number of bits in @bitmap
850 */
851void bitmap_from_arr64(unsigned long *bitmap, const u64 *buf, unsigned int nbits)
852{
853 int n;
854
855 for (n = nbits; n > 0; n -= 64) {
856 u64 val = *buf++;
857
858 *bitmap++ = val;
859 if (n > 32)
860 *bitmap++ = val >> 32;
861 }
862
863 /*
864 * Clear tail bits in the last word beyond nbits.
865 *
866 * Negative index is OK because here we point to the word next
867 * to the last word of the bitmap, except for nbits == 0, which
868 * is tested implicitly.
869 */
870 if (nbits % BITS_PER_LONG)
871 bitmap[-1] &= BITMAP_LAST_WORD_MASK(nbits);
872}
873EXPORT_SYMBOL(bitmap_from_arr64);
874
875/**
876 * bitmap_to_arr64 - copy the contents of bitmap to a u64 array of bits
877 * @buf: array of u64 (in host byte order), the dest bitmap
878 * @bitmap: array of unsigned longs, the source bitmap
879 * @nbits: number of bits in @bitmap
880 */
881void bitmap_to_arr64(u64 *buf, const unsigned long *bitmap, unsigned int nbits)
882{
883 const unsigned long *end = bitmap + BITS_TO_LONGS(nbits);
884
885 while (bitmap < end) {
886 *buf = *bitmap++;
887 if (bitmap < end)
888 *buf |= (u64)(*bitmap++) << 32;
889 buf++;
890 }
891
892 /* Clear tail bits in the last element of array beyond nbits. */
893 if (nbits % 64)
894 buf[-1] &= GENMASK_ULL((nbits - 1) % 64, 0);
895}
896EXPORT_SYMBOL(bitmap_to_arr64);
897#endif