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