FILE
bitmap.c
File preview with syntax highlighting.
linux-6.19.14/lib/bitmap.c
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} 72 73void __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} 79EXPORT_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 */ 92void __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} 122EXPORT_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 137void __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} 160EXPORT_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 */ 199void 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} 227EXPORT_SYMBOL(bitmap_cut); 228 229bool __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} 243EXPORT_SYMBOL(__bitmap_and); 244 245void __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} 254EXPORT_SYMBOL(__bitmap_or); 255 256void __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} 265EXPORT_SYMBOL(__bitmap_xor); 266 267bool __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} 281EXPORT_SYMBOL(__bitmap_andnot); 282 283void __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} 293EXPORT_SYMBOL(__bitmap_replace); 294 295bool __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} 308EXPORT_SYMBOL(__bitmap_intersects); 309 310bool __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} 323EXPORT_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 338unsigned int __bitmap_weight(const unsigned long *bitmap, unsigned int bits) 339{ 340 return BITMAP_WEIGHT(bitmap[idx], bits); 341} 342EXPORT_SYMBOL(__bitmap_weight); 343 344unsigned 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} 349EXPORT_SYMBOL(__bitmap_weight_and); 350 351unsigned 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} 356EXPORT_SYMBOL(__bitmap_weight_andnot); 357 358unsigned int __bitmap_weighted_or(unsigned long *dst, const unsigned long *bitmap1, 359 const unsigned long *bitmap2, unsigned int bits) 360{ 361 return BITMAP_WEIGHT(({dst[idx] = bitmap1[idx] | bitmap2[idx]; dst[idx]; }), bits); 362} 363 364void __bitmap_set(unsigned long *map, unsigned int start, int len) 365{ 366 unsigned long *p = map + BIT_WORD(start); 367 const unsigned int size = start + len; 368 int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG); 369 unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start); 370 371 while (len - bits_to_set >= 0) { 372 *p |= mask_to_set; 373 len -= bits_to_set; 374 bits_to_set = BITS_PER_LONG; 375 mask_to_set = ~0UL; 376 p++; 377 } 378 if (len) { 379 mask_to_set &= BITMAP_LAST_WORD_MASK(size); 380 *p |= mask_to_set; 381 } 382} 383EXPORT_SYMBOL(__bitmap_set); 384 385void __bitmap_clear(unsigned long *map, unsigned int start, int len) 386{ 387 unsigned long *p = map + BIT_WORD(start); 388 const unsigned int size = start + len; 389 int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG); 390 unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start); 391 392 while (len - bits_to_clear >= 0) { 393 *p &= ~mask_to_clear; 394 len -= bits_to_clear; 395 bits_to_clear = BITS_PER_LONG; 396 mask_to_clear = ~0UL; 397 p++; 398 } 399 if (len) { 400 mask_to_clear &= BITMAP_LAST_WORD_MASK(size); 401 *p &= ~mask_to_clear; 402 } 403} 404EXPORT_SYMBOL(__bitmap_clear); 405 406/** 407 * bitmap_find_next_zero_area_off - find a contiguous aligned zero area 408 * @map: The address to base the search on 409 * @size: The bitmap size in bits 410 * @start: The bitnumber to start searching at 411 * @nr: The number of zeroed bits we're looking for 412 * @align_mask: Alignment mask for zero area 413 * @align_offset: Alignment offset for zero area. 414 * 415 * The @align_mask should be one less than a power of 2; the effect is that 416 * the bit offset of all zero areas this function finds plus @align_offset 417 * is multiple of that power of 2. 418 */ 419unsigned long bitmap_find_next_zero_area_off(unsigned long *map, 420 unsigned long size, 421 unsigned long start, 422 unsigned int nr, 423 unsigned long align_mask, 424 unsigned long align_offset) 425{ 426 unsigned long index, end, i; 427again: 428 index = find_next_zero_bit(map, size, start); 429 430 /* Align allocation */ 431 index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset; 432 433 end = index + nr; 434 if (end > size) 435 return end; 436 i = find_next_bit(map, end, index); 437 if (i < end) { 438 start = i + 1; 439 goto again; 440 } 441 return index; 442} 443EXPORT_SYMBOL(bitmap_find_next_zero_area_off); 444 445/** 446 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap 447 * @buf: pointer to a bitmap 448 * @pos: a bit position in @buf (0 <= @pos < @nbits) 449 * @nbits: number of valid bit positions in @buf 450 * 451 * Map the bit at position @pos in @buf (of length @nbits) to the 452 * ordinal of which set bit it is. If it is not set or if @pos 453 * is not a valid bit position, map to -1. 454 * 455 * If for example, just bits 4 through 7 are set in @buf, then @pos 456 * values 4 through 7 will get mapped to 0 through 3, respectively, 457 * and other @pos values will get mapped to -1. When @pos value 7 458 * gets mapped to (returns) @ord value 3 in this example, that means 459 * that bit 7 is the 3rd (starting with 0th) set bit in @buf. 460 * 461 * The bit positions 0 through @bits are valid positions in @buf. 462 */ 463static int bitmap_pos_to_ord(const unsigned long *buf, unsigned int pos, unsigned int nbits) 464{ 465 if (pos >= nbits || !test_bit(pos, buf)) 466 return -1; 467 468 return bitmap_weight(buf, pos); 469} 470 471/** 472 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap 473 * @dst: remapped result 474 * @src: subset to be remapped 475 * @old: defines domain of map 476 * @new: defines range of map 477 * @nbits: number of bits in each of these bitmaps 478 * 479 * Let @old and @new define a mapping of bit positions, such that 480 * whatever position is held by the n-th set bit in @old is mapped 481 * to the n-th set bit in @new. In the more general case, allowing 482 * for the possibility that the weight 'w' of @new is less than the 483 * weight of @old, map the position of the n-th set bit in @old to 484 * the position of the m-th set bit in @new, where m == n % w. 485 * 486 * If either of the @old and @new bitmaps are empty, or if @src and 487 * @dst point to the same location, then this routine copies @src 488 * to @dst. 489 * 490 * The positions of unset bits in @old are mapped to themselves 491 * (the identity map). 492 * 493 * Apply the above specified mapping to @src, placing the result in 494 * @dst, clearing any bits previously set in @dst. 495 * 496 * For example, lets say that @old has bits 4 through 7 set, and 497 * @new has bits 12 through 15 set. This defines the mapping of bit 498 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other 499 * bit positions unchanged. So if say @src comes into this routine 500 * with bits 1, 5 and 7 set, then @dst should leave with bits 1, 501 * 13 and 15 set. 502 */ 503void bitmap_remap(unsigned long *dst, const unsigned long *src, 504 const unsigned long *old, const unsigned long *new, 505 unsigned int nbits) 506{ 507 unsigned int oldbit, w; 508 509 if (dst == src) /* following doesn't handle inplace remaps */ 510 return; 511 bitmap_zero(dst, nbits); 512 513 w = bitmap_weight(new, nbits); 514 for_each_set_bit(oldbit, src, nbits) { 515 int n = bitmap_pos_to_ord(old, oldbit, nbits); 516 517 if (n < 0 || w == 0) 518 set_bit(oldbit, dst); /* identity map */ 519 else 520 set_bit(find_nth_bit(new, nbits, n % w), dst); 521 } 522} 523EXPORT_SYMBOL(bitmap_remap); 524 525/** 526 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit 527 * @oldbit: bit position to be mapped 528 * @old: defines domain of map 529 * @new: defines range of map 530 * @bits: number of bits in each of these bitmaps 531 * 532 * Let @old and @new define a mapping of bit positions, such that 533 * whatever position is held by the n-th set bit in @old is mapped 534 * to the n-th set bit in @new. In the more general case, allowing 535 * for the possibility that the weight 'w' of @new is less than the 536 * weight of @old, map the position of the n-th set bit in @old to 537 * the position of the m-th set bit in @new, where m == n % w. 538 * 539 * The positions of unset bits in @old are mapped to themselves 540 * (the identity map). 541 * 542 * Apply the above specified mapping to bit position @oldbit, returning 543 * the new bit position. 544 * 545 * For example, lets say that @old has bits 4 through 7 set, and 546 * @new has bits 12 through 15 set. This defines the mapping of bit 547 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other 548 * bit positions unchanged. So if say @oldbit is 5, then this routine 549 * returns 13. 550 */ 551int bitmap_bitremap(int oldbit, const unsigned long *old, 552 const unsigned long *new, int bits) 553{ 554 int w = bitmap_weight(new, bits); 555 int n = bitmap_pos_to_ord(old, oldbit, bits); 556 if (n < 0 || w == 0) 557 return oldbit; 558 else 559 return find_nth_bit(new, bits, n % w); 560} 561EXPORT_SYMBOL(bitmap_bitremap); 562 563#ifdef CONFIG_NUMA 564/** 565 * bitmap_onto - translate one bitmap relative to another 566 * @dst: resulting translated bitmap 567 * @orig: original untranslated bitmap 568 * @relmap: bitmap relative to which translated 569 * @bits: number of bits in each of these bitmaps 570 * 571 * Set the n-th bit of @dst iff there exists some m such that the 572 * n-th bit of @relmap is set, the m-th bit of @orig is set, and 573 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap. 574 * (If you understood the previous sentence the first time your 575 * read it, you're overqualified for your current job.) 576 * 577 * In other words, @orig is mapped onto (surjectively) @dst, 578 * using the map { <n, m> | the n-th bit of @relmap is the 579 * m-th set bit of @relmap }. 580 * 581 * Any set bits in @orig above bit number W, where W is the 582 * weight of (number of set bits in) @relmap are mapped nowhere. 583 * In particular, if for all bits m set in @orig, m >= W, then 584 * @dst will end up empty. In situations where the possibility 585 * of such an empty result is not desired, one way to avoid it is 586 * to use the bitmap_fold() operator, below, to first fold the 587 * @orig bitmap over itself so that all its set bits x are in the 588 * range 0 <= x < W. The bitmap_fold() operator does this by 589 * setting the bit (m % W) in @dst, for each bit (m) set in @orig. 590 * 591 * Example [1] for bitmap_onto(): 592 * Let's say @relmap has bits 30-39 set, and @orig has bits 593 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine, 594 * @dst will have bits 31, 33, 35, 37 and 39 set. 595 * 596 * When bit 0 is set in @orig, it means turn on the bit in 597 * @dst corresponding to whatever is the first bit (if any) 598 * that is turned on in @relmap. Since bit 0 was off in the 599 * above example, we leave off that bit (bit 30) in @dst. 600 * 601 * When bit 1 is set in @orig (as in the above example), it 602 * means turn on the bit in @dst corresponding to whatever 603 * is the second bit that is turned on in @relmap. The second 604 * bit in @relmap that was turned on in the above example was 605 * bit 31, so we turned on bit 31 in @dst. 606 * 607 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst, 608 * because they were the 4th, 6th, 8th and 10th set bits 609 * set in @relmap, and the 4th, 6th, 8th and 10th bits of 610 * @orig (i.e. bits 3, 5, 7 and 9) were also set. 611 * 612 * When bit 11 is set in @orig, it means turn on the bit in 613 * @dst corresponding to whatever is the twelfth bit that is 614 * turned on in @relmap. In the above example, there were 615 * only ten bits turned on in @relmap (30..39), so that bit 616 * 11 was set in @orig had no affect on @dst. 617 * 618 * Example [2] for bitmap_fold() + bitmap_onto(): 619 * Let's say @relmap has these ten bits set:: 620 * 621 * 40 41 42 43 45 48 53 61 74 95 622 * 623 * (for the curious, that's 40 plus the first ten terms of the 624 * Fibonacci sequence.) 625 * 626 * Further lets say we use the following code, invoking 627 * bitmap_fold() then bitmap_onto, as suggested above to 628 * avoid the possibility of an empty @dst result:: 629 * 630 * unsigned long *tmp; // a temporary bitmap's bits 631 * 632 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits); 633 * bitmap_onto(dst, tmp, relmap, bits); 634 * 635 * Then this table shows what various values of @dst would be, for 636 * various @orig's. I list the zero-based positions of each set bit. 637 * The tmp column shows the intermediate result, as computed by 638 * using bitmap_fold() to fold the @orig bitmap modulo ten 639 * (the weight of @relmap): 640 * 641 * =============== ============== ================= 642 * @orig tmp @dst 643 * 0 0 40 644 * 1 1 41 645 * 9 9 95 646 * 10 0 40 [#f1]_ 647 * 1 3 5 7 1 3 5 7 41 43 48 61 648 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45 649 * 0 9 18 27 0 9 8 7 40 61 74 95 650 * 0 10 20 30 0 40 651 * 0 11 22 33 0 1 2 3 40 41 42 43 652 * 0 12 24 36 0 2 4 6 40 42 45 53 653 * 78 102 211 1 2 8 41 42 74 [#f1]_ 654 * =============== ============== ================= 655 * 656 * .. [#f1] 657 * 658 * For these marked lines, if we hadn't first done bitmap_fold() 659 * into tmp, then the @dst result would have been empty. 660 * 661 * If either of @orig or @relmap is empty (no set bits), then @dst 662 * will be returned empty. 663 * 664 * If (as explained above) the only set bits in @orig are in positions 665 * m where m >= W, (where W is the weight of @relmap) then @dst will 666 * once again be returned empty. 667 * 668 * All bits in @dst not set by the above rule are cleared. 669 */ 670void bitmap_onto(unsigned long *dst, const unsigned long *orig, 671 const unsigned long *relmap, unsigned int bits) 672{ 673 unsigned int n, m; /* same meaning as in above comment */ 674 675 if (dst == orig) /* following doesn't handle inplace mappings */ 676 return; 677 bitmap_zero(dst, bits); 678 679 /* 680 * The following code is a more efficient, but less 681 * obvious, equivalent to the loop: 682 * for (m = 0; m < bitmap_weight(relmap, bits); m++) { 683 * n = find_nth_bit(orig, bits, m); 684 * if (test_bit(m, orig)) 685 * set_bit(n, dst); 686 * } 687 */ 688 689 m = 0; 690 for_each_set_bit(n, relmap, bits) { 691 /* m == bitmap_pos_to_ord(relmap, n, bits) */ 692 if (test_bit(m, orig)) 693 set_bit(n, dst); 694 m++; 695 } 696} 697 698/** 699 * bitmap_fold - fold larger bitmap into smaller, modulo specified size 700 * @dst: resulting smaller bitmap 701 * @orig: original larger bitmap 702 * @sz: specified size 703 * @nbits: number of bits in each of these bitmaps 704 * 705 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst. 706 * Clear all other bits in @dst. See further the comment and 707 * Example [2] for bitmap_onto() for why and how to use this. 708 */ 709void bitmap_fold(unsigned long *dst, const unsigned long *orig, 710 unsigned int sz, unsigned int nbits) 711{ 712 unsigned int oldbit; 713 714 if (dst == orig) /* following doesn't handle inplace mappings */ 715 return; 716 bitmap_zero(dst, nbits); 717 718 for_each_set_bit(oldbit, orig, nbits) 719 set_bit(oldbit % sz, dst); 720} 721#endif /* CONFIG_NUMA */ 722 723unsigned long *bitmap_alloc(unsigned int nbits, gfp_t flags) 724{ 725 return kmalloc_array(BITS_TO_LONGS(nbits), sizeof(unsigned long), 726 flags); 727} 728EXPORT_SYMBOL(bitmap_alloc); 729 730unsigned long *bitmap_zalloc(unsigned int nbits, gfp_t flags) 731{ 732 return bitmap_alloc(nbits, flags | __GFP_ZERO); 733} 734EXPORT_SYMBOL(bitmap_zalloc); 735 736unsigned long *bitmap_alloc_node(unsigned int nbits, gfp_t flags, int node) 737{ 738 return kmalloc_array_node(BITS_TO_LONGS(nbits), sizeof(unsigned long), 739 flags, node); 740} 741EXPORT_SYMBOL(bitmap_alloc_node); 742 743unsigned long *bitmap_zalloc_node(unsigned int nbits, gfp_t flags, int node) 744{ 745 return bitmap_alloc_node(nbits, flags | __GFP_ZERO, node); 746} 747EXPORT_SYMBOL(bitmap_zalloc_node); 748 749void bitmap_free(const unsigned long *bitmap) 750{ 751 kfree(bitmap); 752} 753EXPORT_SYMBOL(bitmap_free); 754 755static void devm_bitmap_free(void *data) 756{ 757 unsigned long *bitmap = data; 758 759 bitmap_free(bitmap); 760} 761 762unsigned long *devm_bitmap_alloc(struct device *dev, 763 unsigned int nbits, gfp_t flags) 764{ 765 unsigned long *bitmap; 766 int ret; 767 768 bitmap = bitmap_alloc(nbits, flags); 769 if (!bitmap) 770 return NULL; 771 772 ret = devm_add_action_or_reset(dev, devm_bitmap_free, bitmap); 773 if (ret) 774 return NULL; 775 776 return bitmap; 777} 778EXPORT_SYMBOL_GPL(devm_bitmap_alloc); 779 780unsigned long *devm_bitmap_zalloc(struct device *dev, 781 unsigned int nbits, gfp_t flags) 782{ 783 return devm_bitmap_alloc(dev, nbits, flags | __GFP_ZERO); 784} 785EXPORT_SYMBOL_GPL(devm_bitmap_zalloc); 786 787#if BITS_PER_LONG == 64 788/** 789 * bitmap_from_arr32 - copy the contents of u32 array of bits to bitmap 790 * @bitmap: array of unsigned longs, the destination bitmap 791 * @buf: array of u32 (in host byte order), the source bitmap 792 * @nbits: number of bits in @bitmap 793 */ 794void bitmap_from_arr32(unsigned long *bitmap, const u32 *buf, unsigned int nbits) 795{ 796 unsigned int i, halfwords; 797 798 halfwords = DIV_ROUND_UP(nbits, 32); 799 for (i = 0; i < halfwords; i++) { 800 bitmap[i/2] = (unsigned long) buf[i]; 801 if (++i < halfwords) 802 bitmap[i/2] |= ((unsigned long) buf[i]) << 32; 803 } 804 805 /* Clear tail bits in last word beyond nbits. */ 806 if (nbits % BITS_PER_LONG) 807 bitmap[(halfwords - 1) / 2] &= BITMAP_LAST_WORD_MASK(nbits); 808} 809EXPORT_SYMBOL(bitmap_from_arr32); 810 811/** 812 * bitmap_to_arr32 - copy the contents of bitmap to a u32 array of bits 813 * @buf: array of u32 (in host byte order), the dest bitmap 814 * @bitmap: array of unsigned longs, the source bitmap 815 * @nbits: number of bits in @bitmap 816 */ 817void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap, unsigned int nbits) 818{ 819 unsigned int i, halfwords; 820 821 halfwords = DIV_ROUND_UP(nbits, 32); 822 for (i = 0; i < halfwords; i++) { 823 buf[i] = (u32) (bitmap[i/2] & UINT_MAX); 824 if (++i < halfwords) 825 buf[i] = (u32) (bitmap[i/2] >> 32); 826 } 827 828 /* Clear tail bits in last element of array beyond nbits. */ 829 if (nbits % BITS_PER_LONG) 830 buf[halfwords - 1] &= (u32) (UINT_MAX >> ((-nbits) & 31)); 831} 832EXPORT_SYMBOL(bitmap_to_arr32); 833#endif 834 835#if BITS_PER_LONG == 32 836/** 837 * bitmap_from_arr64 - copy the contents of u64 array of bits to bitmap 838 * @bitmap: array of unsigned longs, the destination bitmap 839 * @buf: array of u64 (in host byte order), the source bitmap 840 * @nbits: number of bits in @bitmap 841 */ 842void bitmap_from_arr64(unsigned long *bitmap, const u64 *buf, unsigned int nbits) 843{ 844 int n; 845 846 for (n = nbits; n > 0; n -= 64) { 847 u64 val = *buf++; 848 849 *bitmap++ = val; 850 if (n > 32) 851 *bitmap++ = val >> 32; 852 } 853 854 /* 855 * Clear tail bits in the last word beyond nbits. 856 * 857 * Negative index is OK because here we point to the word next 858 * to the last word of the bitmap, except for nbits == 0, which 859 * is tested implicitly. 860 */ 861 if (nbits % BITS_PER_LONG) 862 bitmap[-1] &= BITMAP_LAST_WORD_MASK(nbits); 863} 864EXPORT_SYMBOL(bitmap_from_arr64); 865 866/** 867 * bitmap_to_arr64 - copy the contents of bitmap to a u64 array of bits 868 * @buf: array of u64 (in host byte order), the dest bitmap 869 * @bitmap: array of unsigned longs, the source bitmap 870 * @nbits: number of bits in @bitmap 871 */ 872void bitmap_to_arr64(u64 *buf, const unsigned long *bitmap, unsigned int nbits) 873{ 874 const unsigned long *end = bitmap + BITS_TO_LONGS(nbits); 875 876 while (bitmap < end) { 877 *buf = *bitmap++; 878 if (bitmap < end) 879 *buf |= (u64)(*bitmap++) << 32; 880 buf++; 881 } 882 883 /* Clear tail bits in the last element of array beyond nbits. */ 884 if (nbits % 64) 885 buf[-1] &= GENMASK_ULL((nbits - 1) % 64, 0); 886} 887EXPORT_SYMBOL(bitmap_to_arr64); 888#endif
~/
Read-only file preview.