1 /* 2 * lib/bitmap.c 3 * Helper functions for bitmap.h. 4 * 5 * This source code is licensed under the GNU General Public License, 6 * Version 2. See the file COPYING for more details. 7 */ 8 #include <linux/module.h> 9 #include <linux/ctype.h> 10 #include <linux/errno.h> 11 #include <linux/bitmap.h> 12 #include <linux/bitops.h> 13 #include <asm/uaccess.h> 14 15 /* 16 * bitmaps provide an array of bits, implemented using an an 17 * array of unsigned longs. The number of valid bits in a 18 * given bitmap does _not_ need to be an exact multiple of 19 * BITS_PER_LONG. 20 * 21 * The possible unused bits in the last, partially used word 22 * of a bitmap are 'don't care'. The implementation makes 23 * no particular effort to keep them zero. It ensures that 24 * their value will not affect the results of any operation. 25 * The bitmap operations that return Boolean (bitmap_empty, 26 * for example) or scalar (bitmap_weight, for example) results 27 * carefully filter out these unused bits from impacting their 28 * results. 29 * 30 * These operations actually hold to a slightly stronger rule: 31 * if you don't input any bitmaps to these ops that have some 32 * unused bits set, then they won't output any set unused bits 33 * in output bitmaps. 34 * 35 * The byte ordering of bitmaps is more natural on little 36 * endian architectures. See the big-endian headers 37 * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h 38 * for the best explanations of this ordering. 39 */ 40 41 int __bitmap_empty(const unsigned long *bitmap, int bits) 42 { 43 int k, lim = bits/BITS_PER_LONG; 44 for (k = 0; k < lim; ++k) 45 if (bitmap[k]) 46 return 0; 47 48 if (bits % BITS_PER_LONG) 49 if (bitmap[k] & BITMAP_LAST_WORD_MASK(bits)) 50 return 0; 51 52 return 1; 53 } 54 EXPORT_SYMBOL(__bitmap_empty); 55 56 int __bitmap_full(const unsigned long *bitmap, int bits) 57 { 58 int k, lim = bits/BITS_PER_LONG; 59 for (k = 0; k < lim; ++k) 60 if (~bitmap[k]) 61 return 0; 62 63 if (bits % BITS_PER_LONG) 64 if (~bitmap[k] & BITMAP_LAST_WORD_MASK(bits)) 65 return 0; 66 67 return 1; 68 } 69 EXPORT_SYMBOL(__bitmap_full); 70 71 int __bitmap_equal(const unsigned long *bitmap1, 72 const unsigned long *bitmap2, int bits) 73 { 74 int k, lim = bits/BITS_PER_LONG; 75 for (k = 0; k < lim; ++k) 76 if (bitmap1[k] != bitmap2[k]) 77 return 0; 78 79 if (bits % BITS_PER_LONG) 80 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) 81 return 0; 82 83 return 1; 84 } 85 EXPORT_SYMBOL(__bitmap_equal); 86 87 void __bitmap_complement(unsigned long *dst, const unsigned long *src, int bits) 88 { 89 int k, lim = bits/BITS_PER_LONG; 90 for (k = 0; k < lim; ++k) 91 dst[k] = ~src[k]; 92 93 if (bits % BITS_PER_LONG) 94 dst[k] = ~src[k] & BITMAP_LAST_WORD_MASK(bits); 95 } 96 EXPORT_SYMBOL(__bitmap_complement); 97 98 /** 99 * __bitmap_shift_right - logical right shift of the bits in a bitmap 100 * @dst : destination bitmap 101 * @src : source bitmap 102 * @shift : shift by this many bits 103 * @bits : bitmap size, in bits 104 * 105 * Shifting right (dividing) means moving bits in the MS -> LS bit 106 * direction. Zeros are fed into the vacated MS positions and the 107 * LS bits shifted off the bottom are lost. 108 */ 109 void __bitmap_shift_right(unsigned long *dst, 110 const unsigned long *src, int shift, int bits) 111 { 112 int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG; 113 int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG; 114 unsigned long mask = (1UL << left) - 1; 115 for (k = 0; off + k < lim; ++k) { 116 unsigned long upper, lower; 117 118 /* 119 * If shift is not word aligned, take lower rem bits of 120 * word above and make them the top rem bits of result. 121 */ 122 if (!rem || off + k + 1 >= lim) 123 upper = 0; 124 else { 125 upper = src[off + k + 1]; 126 if (off + k + 1 == lim - 1 && left) 127 upper &= mask; 128 } 129 lower = src[off + k]; 130 if (left && off + k == lim - 1) 131 lower &= mask; 132 dst[k] = upper << (BITS_PER_LONG - rem) | lower >> rem; 133 if (left && k == lim - 1) 134 dst[k] &= mask; 135 } 136 if (off) 137 memset(&dst[lim - off], 0, off*sizeof(unsigned long)); 138 } 139 EXPORT_SYMBOL(__bitmap_shift_right); 140 141 142 /** 143 * __bitmap_shift_left - logical left shift of the bits in a bitmap 144 * @dst : destination bitmap 145 * @src : source bitmap 146 * @shift : shift by this many bits 147 * @bits : bitmap size, in bits 148 * 149 * Shifting left (multiplying) means moving bits in the LS -> MS 150 * direction. Zeros are fed into the vacated LS bit positions 151 * and those MS bits shifted off the top are lost. 152 */ 153 154 void __bitmap_shift_left(unsigned long *dst, 155 const unsigned long *src, int shift, int bits) 156 { 157 int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG; 158 int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG; 159 for (k = lim - off - 1; k >= 0; --k) { 160 unsigned long upper, lower; 161 162 /* 163 * If shift is not word aligned, take upper rem bits of 164 * word below and make them the bottom rem bits of result. 165 */ 166 if (rem && k > 0) 167 lower = src[k - 1]; 168 else 169 lower = 0; 170 upper = src[k]; 171 if (left && k == lim - 1) 172 upper &= (1UL << left) - 1; 173 dst[k + off] = lower >> (BITS_PER_LONG - rem) | upper << rem; 174 if (left && k + off == lim - 1) 175 dst[k + off] &= (1UL << left) - 1; 176 } 177 if (off) 178 memset(dst, 0, off*sizeof(unsigned long)); 179 } 180 EXPORT_SYMBOL(__bitmap_shift_left); 181 182 int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1, 183 const unsigned long *bitmap2, int bits) 184 { 185 int k; 186 int nr = BITS_TO_LONGS(bits); 187 unsigned long result = 0; 188 189 for (k = 0; k < nr; k++) 190 result |= (dst[k] = bitmap1[k] & bitmap2[k]); 191 return result != 0; 192 } 193 EXPORT_SYMBOL(__bitmap_and); 194 195 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1, 196 const unsigned long *bitmap2, int bits) 197 { 198 int k; 199 int nr = BITS_TO_LONGS(bits); 200 201 for (k = 0; k < nr; k++) 202 dst[k] = bitmap1[k] | bitmap2[k]; 203 } 204 EXPORT_SYMBOL(__bitmap_or); 205 206 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1, 207 const unsigned long *bitmap2, int bits) 208 { 209 int k; 210 int nr = BITS_TO_LONGS(bits); 211 212 for (k = 0; k < nr; k++) 213 dst[k] = bitmap1[k] ^ bitmap2[k]; 214 } 215 EXPORT_SYMBOL(__bitmap_xor); 216 217 int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1, 218 const unsigned long *bitmap2, int bits) 219 { 220 int k; 221 int nr = BITS_TO_LONGS(bits); 222 unsigned long result = 0; 223 224 for (k = 0; k < nr; k++) 225 result |= (dst[k] = bitmap1[k] & ~bitmap2[k]); 226 return result != 0; 227 } 228 EXPORT_SYMBOL(__bitmap_andnot); 229 230 int __bitmap_intersects(const unsigned long *bitmap1, 231 const unsigned long *bitmap2, int bits) 232 { 233 int k, lim = bits/BITS_PER_LONG; 234 for (k = 0; k < lim; ++k) 235 if (bitmap1[k] & bitmap2[k]) 236 return 1; 237 238 if (bits % BITS_PER_LONG) 239 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) 240 return 1; 241 return 0; 242 } 243 EXPORT_SYMBOL(__bitmap_intersects); 244 245 int __bitmap_subset(const unsigned long *bitmap1, 246 const unsigned long *bitmap2, int bits) 247 { 248 int k, lim = bits/BITS_PER_LONG; 249 for (k = 0; k < lim; ++k) 250 if (bitmap1[k] & ~bitmap2[k]) 251 return 0; 252 253 if (bits % BITS_PER_LONG) 254 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) 255 return 0; 256 return 1; 257 } 258 EXPORT_SYMBOL(__bitmap_subset); 259 260 int __bitmap_weight(const unsigned long *bitmap, int bits) 261 { 262 int k, w = 0, lim = bits/BITS_PER_LONG; 263 264 for (k = 0; k < lim; k++) 265 w += hweight_long(bitmap[k]); 266 267 if (bits % BITS_PER_LONG) 268 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits)); 269 270 return w; 271 } 272 EXPORT_SYMBOL(__bitmap_weight); 273 274 #define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) % BITS_PER_LONG)) 275 276 void bitmap_set(unsigned long *map, int start, int nr) 277 { 278 unsigned long *p = map + BIT_WORD(start); 279 const int size = start + nr; 280 int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG); 281 unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start); 282 283 while (nr - bits_to_set >= 0) { 284 *p |= mask_to_set; 285 nr -= bits_to_set; 286 bits_to_set = BITS_PER_LONG; 287 mask_to_set = ~0UL; 288 p++; 289 } 290 if (nr) { 291 mask_to_set &= BITMAP_LAST_WORD_MASK(size); 292 *p |= mask_to_set; 293 } 294 } 295 EXPORT_SYMBOL(bitmap_set); 296 297 void bitmap_clear(unsigned long *map, int start, int nr) 298 { 299 unsigned long *p = map + BIT_WORD(start); 300 const int size = start + nr; 301 int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG); 302 unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start); 303 304 while (nr - bits_to_clear >= 0) { 305 *p &= ~mask_to_clear; 306 nr -= bits_to_clear; 307 bits_to_clear = BITS_PER_LONG; 308 mask_to_clear = ~0UL; 309 p++; 310 } 311 if (nr) { 312 mask_to_clear &= BITMAP_LAST_WORD_MASK(size); 313 *p &= ~mask_to_clear; 314 } 315 } 316 EXPORT_SYMBOL(bitmap_clear); 317 318 /* 319 * bitmap_find_next_zero_area - find a contiguous aligned zero area 320 * @map: The address to base the search on 321 * @size: The bitmap size in bits 322 * @start: The bitnumber to start searching at 323 * @nr: The number of zeroed bits we're looking for 324 * @align_mask: Alignment mask for zero area 325 * 326 * The @align_mask should be one less than a power of 2; the effect is that 327 * the bit offset of all zero areas this function finds is multiples of that 328 * power of 2. A @align_mask of 0 means no alignment is required. 329 */ 330 unsigned long bitmap_find_next_zero_area(unsigned long *map, 331 unsigned long size, 332 unsigned long start, 333 unsigned int nr, 334 unsigned long align_mask) 335 { 336 unsigned long index, end, i; 337 again: 338 index = find_next_zero_bit(map, size, start); 339 340 /* Align allocation */ 341 index = __ALIGN_MASK(index, align_mask); 342 343 end = index + nr; 344 if (end > size) 345 return end; 346 i = find_next_bit(map, end, index); 347 if (i < end) { 348 start = i + 1; 349 goto again; 350 } 351 return index; 352 } 353 EXPORT_SYMBOL(bitmap_find_next_zero_area); 354 355 /* 356 * Bitmap printing & parsing functions: first version by Bill Irwin, 357 * second version by Paul Jackson, third by Joe Korty. 358 */ 359 360 #define CHUNKSZ 32 361 #define nbits_to_hold_value(val) fls(val) 362 #define unhex(c) (isdigit(c) ? (c - '0') : (toupper(c) - 'A' + 10)) 363 #define BASEDEC 10 /* fancier cpuset lists input in decimal */ 364 365 /** 366 * bitmap_scnprintf - convert bitmap to an ASCII hex string. 367 * @buf: byte buffer into which string is placed 368 * @buflen: reserved size of @buf, in bytes 369 * @maskp: pointer to bitmap to convert 370 * @nmaskbits: size of bitmap, in bits 371 * 372 * Exactly @nmaskbits bits are displayed. Hex digits are grouped into 373 * comma-separated sets of eight digits per set. 374 */ 375 int bitmap_scnprintf(char *buf, unsigned int buflen, 376 const unsigned long *maskp, int nmaskbits) 377 { 378 int i, word, bit, len = 0; 379 unsigned long val; 380 const char *sep = ""; 381 int chunksz; 382 u32 chunkmask; 383 384 chunksz = nmaskbits & (CHUNKSZ - 1); 385 if (chunksz == 0) 386 chunksz = CHUNKSZ; 387 388 i = ALIGN(nmaskbits, CHUNKSZ) - CHUNKSZ; 389 for (; i >= 0; i -= CHUNKSZ) { 390 chunkmask = ((1ULL << chunksz) - 1); 391 word = i / BITS_PER_LONG; 392 bit = i % BITS_PER_LONG; 393 val = (maskp[word] >> bit) & chunkmask; 394 len += scnprintf(buf+len, buflen-len, "%s%0*lx", sep, 395 (chunksz+3)/4, val); 396 chunksz = CHUNKSZ; 397 sep = ","; 398 } 399 return len; 400 } 401 EXPORT_SYMBOL(bitmap_scnprintf); 402 403 /** 404 * __bitmap_parse - convert an ASCII hex string into a bitmap. 405 * @buf: pointer to buffer containing string. 406 * @buflen: buffer size in bytes. If string is smaller than this 407 * then it must be terminated with a \0. 408 * @is_user: location of buffer, 0 indicates kernel space 409 * @maskp: pointer to bitmap array that will contain result. 410 * @nmaskbits: size of bitmap, in bits. 411 * 412 * Commas group hex digits into chunks. Each chunk defines exactly 32 413 * bits of the resultant bitmask. No chunk may specify a value larger 414 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value 415 * then leading 0-bits are prepended. %-EINVAL is returned for illegal 416 * characters and for grouping errors such as "1,,5", ",44", "," and "". 417 * Leading and trailing whitespace accepted, but not embedded whitespace. 418 */ 419 int __bitmap_parse(const char *buf, unsigned int buflen, 420 int is_user, unsigned long *maskp, 421 int nmaskbits) 422 { 423 int c, old_c, totaldigits, ndigits, nchunks, nbits; 424 u32 chunk; 425 const char __user *ubuf = buf; 426 427 bitmap_zero(maskp, nmaskbits); 428 429 nchunks = nbits = totaldigits = c = 0; 430 do { 431 chunk = ndigits = 0; 432 433 /* Get the next chunk of the bitmap */ 434 while (buflen) { 435 old_c = c; 436 if (is_user) { 437 if (__get_user(c, ubuf++)) 438 return -EFAULT; 439 } 440 else 441 c = *buf++; 442 buflen--; 443 if (isspace(c)) 444 continue; 445 446 /* 447 * If the last character was a space and the current 448 * character isn't '\0', we've got embedded whitespace. 449 * This is a no-no, so throw an error. 450 */ 451 if (totaldigits && c && isspace(old_c)) 452 return -EINVAL; 453 454 /* A '\0' or a ',' signal the end of the chunk */ 455 if (c == '\0' || c == ',') 456 break; 457 458 if (!isxdigit(c)) 459 return -EINVAL; 460 461 /* 462 * Make sure there are at least 4 free bits in 'chunk'. 463 * If not, this hexdigit will overflow 'chunk', so 464 * throw an error. 465 */ 466 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1)) 467 return -EOVERFLOW; 468 469 chunk = (chunk << 4) | unhex(c); 470 ndigits++; totaldigits++; 471 } 472 if (ndigits == 0) 473 return -EINVAL; 474 if (nchunks == 0 && chunk == 0) 475 continue; 476 477 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits); 478 *maskp |= chunk; 479 nchunks++; 480 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ; 481 if (nbits > nmaskbits) 482 return -EOVERFLOW; 483 } while (buflen && c == ','); 484 485 return 0; 486 } 487 EXPORT_SYMBOL(__bitmap_parse); 488 489 /** 490 * bitmap_parse_user() 491 * 492 * @ubuf: pointer to user buffer containing string. 493 * @ulen: buffer size in bytes. If string is smaller than this 494 * then it must be terminated with a \0. 495 * @maskp: pointer to bitmap array that will contain result. 496 * @nmaskbits: size of bitmap, in bits. 497 * 498 * Wrapper for __bitmap_parse(), providing it with user buffer. 499 * 500 * We cannot have this as an inline function in bitmap.h because it needs 501 * linux/uaccess.h to get the access_ok() declaration and this causes 502 * cyclic dependencies. 503 */ 504 int bitmap_parse_user(const char __user *ubuf, 505 unsigned int ulen, unsigned long *maskp, 506 int nmaskbits) 507 { 508 if (!access_ok(VERIFY_READ, ubuf, ulen)) 509 return -EFAULT; 510 return __bitmap_parse((const char *)ubuf, ulen, 1, maskp, nmaskbits); 511 } 512 EXPORT_SYMBOL(bitmap_parse_user); 513 514 /* 515 * bscnl_emit(buf, buflen, rbot, rtop, bp) 516 * 517 * Helper routine for bitmap_scnlistprintf(). Write decimal number 518 * or range to buf, suppressing output past buf+buflen, with optional 519 * comma-prefix. Return len of what would be written to buf, if it 520 * all fit. 521 */ 522 static inline int bscnl_emit(char *buf, int buflen, int rbot, int rtop, int len) 523 { 524 if (len > 0) 525 len += scnprintf(buf + len, buflen - len, ","); 526 if (rbot == rtop) 527 len += scnprintf(buf + len, buflen - len, "%d", rbot); 528 else 529 len += scnprintf(buf + len, buflen - len, "%d-%d", rbot, rtop); 530 return len; 531 } 532 533 /** 534 * bitmap_scnlistprintf - convert bitmap to list format ASCII string 535 * @buf: byte buffer into which string is placed 536 * @buflen: reserved size of @buf, in bytes 537 * @maskp: pointer to bitmap to convert 538 * @nmaskbits: size of bitmap, in bits 539 * 540 * Output format is a comma-separated list of decimal numbers and 541 * ranges. Consecutively set bits are shown as two hyphen-separated 542 * decimal numbers, the smallest and largest bit numbers set in 543 * the range. Output format is compatible with the format 544 * accepted as input by bitmap_parselist(). 545 * 546 * The return value is the number of characters which would be 547 * generated for the given input, excluding the trailing '\0', as 548 * per ISO C99. 549 */ 550 int bitmap_scnlistprintf(char *buf, unsigned int buflen, 551 const unsigned long *maskp, int nmaskbits) 552 { 553 int len = 0; 554 /* current bit is 'cur', most recently seen range is [rbot, rtop] */ 555 int cur, rbot, rtop; 556 557 if (buflen == 0) 558 return 0; 559 buf[0] = 0; 560 561 rbot = cur = find_first_bit(maskp, nmaskbits); 562 while (cur < nmaskbits) { 563 rtop = cur; 564 cur = find_next_bit(maskp, nmaskbits, cur+1); 565 if (cur >= nmaskbits || cur > rtop + 1) { 566 len = bscnl_emit(buf, buflen, rbot, rtop, len); 567 rbot = cur; 568 } 569 } 570 return len; 571 } 572 EXPORT_SYMBOL(bitmap_scnlistprintf); 573 574 /** 575 * bitmap_parselist - convert list format ASCII string to bitmap 576 * @bp: read nul-terminated user string from this buffer 577 * @maskp: write resulting mask here 578 * @nmaskbits: number of bits in mask to be written 579 * 580 * Input format is a comma-separated list of decimal numbers and 581 * ranges. Consecutively set bits are shown as two hyphen-separated 582 * decimal numbers, the smallest and largest bit numbers set in 583 * the range. 584 * 585 * Returns 0 on success, -errno on invalid input strings. 586 * Error values: 587 * %-EINVAL: second number in range smaller than first 588 * %-EINVAL: invalid character in string 589 * %-ERANGE: bit number specified too large for mask 590 */ 591 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits) 592 { 593 unsigned a, b; 594 595 bitmap_zero(maskp, nmaskbits); 596 do { 597 if (!isdigit(*bp)) 598 return -EINVAL; 599 b = a = simple_strtoul(bp, (char **)&bp, BASEDEC); 600 if (*bp == '-') { 601 bp++; 602 if (!isdigit(*bp)) 603 return -EINVAL; 604 b = simple_strtoul(bp, (char **)&bp, BASEDEC); 605 } 606 if (!(a <= b)) 607 return -EINVAL; 608 if (b >= nmaskbits) 609 return -ERANGE; 610 while (a <= b) { 611 set_bit(a, maskp); 612 a++; 613 } 614 if (*bp == ',') 615 bp++; 616 } while (*bp != '\0' && *bp != '\n'); 617 return 0; 618 } 619 EXPORT_SYMBOL(bitmap_parselist); 620 621 /** 622 * bitmap_pos_to_ord(buf, pos, bits) 623 * @buf: pointer to a bitmap 624 * @pos: a bit position in @buf (0 <= @pos < @bits) 625 * @bits: number of valid bit positions in @buf 626 * 627 * Map the bit at position @pos in @buf (of length @bits) to the 628 * ordinal of which set bit it is. If it is not set or if @pos 629 * is not a valid bit position, map to -1. 630 * 631 * If for example, just bits 4 through 7 are set in @buf, then @pos 632 * values 4 through 7 will get mapped to 0 through 3, respectively, 633 * and other @pos values will get mapped to 0. When @pos value 7 634 * gets mapped to (returns) @ord value 3 in this example, that means 635 * that bit 7 is the 3rd (starting with 0th) set bit in @buf. 636 * 637 * The bit positions 0 through @bits are valid positions in @buf. 638 */ 639 static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits) 640 { 641 int i, ord; 642 643 if (pos < 0 || pos >= bits || !test_bit(pos, buf)) 644 return -1; 645 646 i = find_first_bit(buf, bits); 647 ord = 0; 648 while (i < pos) { 649 i = find_next_bit(buf, bits, i + 1); 650 ord++; 651 } 652 BUG_ON(i != pos); 653 654 return ord; 655 } 656 657 /** 658 * bitmap_ord_to_pos(buf, ord, bits) 659 * @buf: pointer to bitmap 660 * @ord: ordinal bit position (n-th set bit, n >= 0) 661 * @bits: number of valid bit positions in @buf 662 * 663 * Map the ordinal offset of bit @ord in @buf to its position in @buf. 664 * Value of @ord should be in range 0 <= @ord < weight(buf), else 665 * results are undefined. 666 * 667 * If for example, just bits 4 through 7 are set in @buf, then @ord 668 * values 0 through 3 will get mapped to 4 through 7, respectively, 669 * and all other @ord values return undefined values. When @ord value 3 670 * gets mapped to (returns) @pos value 7 in this example, that means 671 * that the 3rd set bit (starting with 0th) is at position 7 in @buf. 672 * 673 * The bit positions 0 through @bits are valid positions in @buf. 674 */ 675 static int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits) 676 { 677 int pos = 0; 678 679 if (ord >= 0 && ord < bits) { 680 int i; 681 682 for (i = find_first_bit(buf, bits); 683 i < bits && ord > 0; 684 i = find_next_bit(buf, bits, i + 1)) 685 ord--; 686 if (i < bits && ord == 0) 687 pos = i; 688 } 689 690 return pos; 691 } 692 693 /** 694 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap 695 * @dst: remapped result 696 * @src: subset to be remapped 697 * @old: defines domain of map 698 * @new: defines range of map 699 * @bits: number of bits in each of these bitmaps 700 * 701 * Let @old and @new define a mapping of bit positions, such that 702 * whatever position is held by the n-th set bit in @old is mapped 703 * to the n-th set bit in @new. In the more general case, allowing 704 * for the possibility that the weight 'w' of @new is less than the 705 * weight of @old, map the position of the n-th set bit in @old to 706 * the position of the m-th set bit in @new, where m == n % w. 707 * 708 * If either of the @old and @new bitmaps are empty, or if @src and 709 * @dst point to the same location, then this routine copies @src 710 * to @dst. 711 * 712 * The positions of unset bits in @old are mapped to themselves 713 * (the identify map). 714 * 715 * Apply the above specified mapping to @src, placing the result in 716 * @dst, clearing any bits previously set in @dst. 717 * 718 * For example, lets say that @old has bits 4 through 7 set, and 719 * @new has bits 12 through 15 set. This defines the mapping of bit 720 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other 721 * bit positions unchanged. So if say @src comes into this routine 722 * with bits 1, 5 and 7 set, then @dst should leave with bits 1, 723 * 13 and 15 set. 724 */ 725 void bitmap_remap(unsigned long *dst, const unsigned long *src, 726 const unsigned long *old, const unsigned long *new, 727 int bits) 728 { 729 int oldbit, w; 730 731 if (dst == src) /* following doesn't handle inplace remaps */ 732 return; 733 bitmap_zero(dst, bits); 734 735 w = bitmap_weight(new, bits); 736 for (oldbit = find_first_bit(src, bits); 737 oldbit < bits; 738 oldbit = find_next_bit(src, bits, oldbit + 1)) { 739 int n = bitmap_pos_to_ord(old, oldbit, bits); 740 if (n < 0 || w == 0) 741 set_bit(oldbit, dst); /* identity map */ 742 else 743 set_bit(bitmap_ord_to_pos(new, n % w, bits), dst); 744 } 745 } 746 EXPORT_SYMBOL(bitmap_remap); 747 748 /** 749 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit 750 * @oldbit: bit position to be mapped 751 * @old: defines domain of map 752 * @new: defines range of map 753 * @bits: number of bits in each of these bitmaps 754 * 755 * Let @old and @new define a mapping of bit positions, such that 756 * whatever position is held by the n-th set bit in @old is mapped 757 * to the n-th set bit in @new. In the more general case, allowing 758 * for the possibility that the weight 'w' of @new is less than the 759 * weight of @old, map the position of the n-th set bit in @old to 760 * the position of the m-th set bit in @new, where m == n % w. 761 * 762 * The positions of unset bits in @old are mapped to themselves 763 * (the identify map). 764 * 765 * Apply the above specified mapping to bit position @oldbit, returning 766 * the new bit position. 767 * 768 * For example, lets say that @old has bits 4 through 7 set, and 769 * @new has bits 12 through 15 set. This defines the mapping of bit 770 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other 771 * bit positions unchanged. So if say @oldbit is 5, then this routine 772 * returns 13. 773 */ 774 int bitmap_bitremap(int oldbit, const unsigned long *old, 775 const unsigned long *new, int bits) 776 { 777 int w = bitmap_weight(new, bits); 778 int n = bitmap_pos_to_ord(old, oldbit, bits); 779 if (n < 0 || w == 0) 780 return oldbit; 781 else 782 return bitmap_ord_to_pos(new, n % w, bits); 783 } 784 EXPORT_SYMBOL(bitmap_bitremap); 785 786 /** 787 * bitmap_onto - translate one bitmap relative to another 788 * @dst: resulting translated bitmap 789 * @orig: original untranslated bitmap 790 * @relmap: bitmap relative to which translated 791 * @bits: number of bits in each of these bitmaps 792 * 793 * Set the n-th bit of @dst iff there exists some m such that the 794 * n-th bit of @relmap is set, the m-th bit of @orig is set, and 795 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap. 796 * (If you understood the previous sentence the first time your 797 * read it, you're overqualified for your current job.) 798 * 799 * In other words, @orig is mapped onto (surjectively) @dst, 800 * using the the map { <n, m> | the n-th bit of @relmap is the 801 * m-th set bit of @relmap }. 802 * 803 * Any set bits in @orig above bit number W, where W is the 804 * weight of (number of set bits in) @relmap are mapped nowhere. 805 * In particular, if for all bits m set in @orig, m >= W, then 806 * @dst will end up empty. In situations where the possibility 807 * of such an empty result is not desired, one way to avoid it is 808 * to use the bitmap_fold() operator, below, to first fold the 809 * @orig bitmap over itself so that all its set bits x are in the 810 * range 0 <= x < W. The bitmap_fold() operator does this by 811 * setting the bit (m % W) in @dst, for each bit (m) set in @orig. 812 * 813 * Example [1] for bitmap_onto(): 814 * Let's say @relmap has bits 30-39 set, and @orig has bits 815 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine, 816 * @dst will have bits 31, 33, 35, 37 and 39 set. 817 * 818 * When bit 0 is set in @orig, it means turn on the bit in 819 * @dst corresponding to whatever is the first bit (if any) 820 * that is turned on in @relmap. Since bit 0 was off in the 821 * above example, we leave off that bit (bit 30) in @dst. 822 * 823 * When bit 1 is set in @orig (as in the above example), it 824 * means turn on the bit in @dst corresponding to whatever 825 * is the second bit that is turned on in @relmap. The second 826 * bit in @relmap that was turned on in the above example was 827 * bit 31, so we turned on bit 31 in @dst. 828 * 829 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst, 830 * because they were the 4th, 6th, 8th and 10th set bits 831 * set in @relmap, and the 4th, 6th, 8th and 10th bits of 832 * @orig (i.e. bits 3, 5, 7 and 9) were also set. 833 * 834 * When bit 11 is set in @orig, it means turn on the bit in 835 * @dst corresponding to whatever is the twelth bit that is 836 * turned on in @relmap. In the above example, there were 837 * only ten bits turned on in @relmap (30..39), so that bit 838 * 11 was set in @orig had no affect on @dst. 839 * 840 * Example [2] for bitmap_fold() + bitmap_onto(): 841 * Let's say @relmap has these ten bits set: 842 * 40 41 42 43 45 48 53 61 74 95 843 * (for the curious, that's 40 plus the first ten terms of the 844 * Fibonacci sequence.) 845 * 846 * Further lets say we use the following code, invoking 847 * bitmap_fold() then bitmap_onto, as suggested above to 848 * avoid the possitility of an empty @dst result: 849 * 850 * unsigned long *tmp; // a temporary bitmap's bits 851 * 852 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits); 853 * bitmap_onto(dst, tmp, relmap, bits); 854 * 855 * Then this table shows what various values of @dst would be, for 856 * various @orig's. I list the zero-based positions of each set bit. 857 * The tmp column shows the intermediate result, as computed by 858 * using bitmap_fold() to fold the @orig bitmap modulo ten 859 * (the weight of @relmap). 860 * 861 * @orig tmp @dst 862 * 0 0 40 863 * 1 1 41 864 * 9 9 95 865 * 10 0 40 (*) 866 * 1 3 5 7 1 3 5 7 41 43 48 61 867 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45 868 * 0 9 18 27 0 9 8 7 40 61 74 95 869 * 0 10 20 30 0 40 870 * 0 11 22 33 0 1 2 3 40 41 42 43 871 * 0 12 24 36 0 2 4 6 40 42 45 53 872 * 78 102 211 1 2 8 41 42 74 (*) 873 * 874 * (*) For these marked lines, if we hadn't first done bitmap_fold() 875 * into tmp, then the @dst result would have been empty. 876 * 877 * If either of @orig or @relmap is empty (no set bits), then @dst 878 * will be returned empty. 879 * 880 * If (as explained above) the only set bits in @orig are in positions 881 * m where m >= W, (where W is the weight of @relmap) then @dst will 882 * once again be returned empty. 883 * 884 * All bits in @dst not set by the above rule are cleared. 885 */ 886 void bitmap_onto(unsigned long *dst, const unsigned long *orig, 887 const unsigned long *relmap, int bits) 888 { 889 int n, m; /* same meaning as in above comment */ 890 891 if (dst == orig) /* following doesn't handle inplace mappings */ 892 return; 893 bitmap_zero(dst, bits); 894 895 /* 896 * The following code is a more efficient, but less 897 * obvious, equivalent to the loop: 898 * for (m = 0; m < bitmap_weight(relmap, bits); m++) { 899 * n = bitmap_ord_to_pos(orig, m, bits); 900 * if (test_bit(m, orig)) 901 * set_bit(n, dst); 902 * } 903 */ 904 905 m = 0; 906 for (n = find_first_bit(relmap, bits); 907 n < bits; 908 n = find_next_bit(relmap, bits, n + 1)) { 909 /* m == bitmap_pos_to_ord(relmap, n, bits) */ 910 if (test_bit(m, orig)) 911 set_bit(n, dst); 912 m++; 913 } 914 } 915 EXPORT_SYMBOL(bitmap_onto); 916 917 /** 918 * bitmap_fold - fold larger bitmap into smaller, modulo specified size 919 * @dst: resulting smaller bitmap 920 * @orig: original larger bitmap 921 * @sz: specified size 922 * @bits: number of bits in each of these bitmaps 923 * 924 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst. 925 * Clear all other bits in @dst. See further the comment and 926 * Example [2] for bitmap_onto() for why and how to use this. 927 */ 928 void bitmap_fold(unsigned long *dst, const unsigned long *orig, 929 int sz, int bits) 930 { 931 int oldbit; 932 933 if (dst == orig) /* following doesn't handle inplace mappings */ 934 return; 935 bitmap_zero(dst, bits); 936 937 for (oldbit = find_first_bit(orig, bits); 938 oldbit < bits; 939 oldbit = find_next_bit(orig, bits, oldbit + 1)) 940 set_bit(oldbit % sz, dst); 941 } 942 EXPORT_SYMBOL(bitmap_fold); 943 944 /* 945 * Common code for bitmap_*_region() routines. 946 * bitmap: array of unsigned longs corresponding to the bitmap 947 * pos: the beginning of the region 948 * order: region size (log base 2 of number of bits) 949 * reg_op: operation(s) to perform on that region of bitmap 950 * 951 * Can set, verify and/or release a region of bits in a bitmap, 952 * depending on which combination of REG_OP_* flag bits is set. 953 * 954 * A region of a bitmap is a sequence of bits in the bitmap, of 955 * some size '1 << order' (a power of two), aligned to that same 956 * '1 << order' power of two. 957 * 958 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits). 959 * Returns 0 in all other cases and reg_ops. 960 */ 961 962 enum { 963 REG_OP_ISFREE, /* true if region is all zero bits */ 964 REG_OP_ALLOC, /* set all bits in region */ 965 REG_OP_RELEASE, /* clear all bits in region */ 966 }; 967 968 static int __reg_op(unsigned long *bitmap, int pos, int order, int reg_op) 969 { 970 int nbits_reg; /* number of bits in region */ 971 int index; /* index first long of region in bitmap */ 972 int offset; /* bit offset region in bitmap[index] */ 973 int nlongs_reg; /* num longs spanned by region in bitmap */ 974 int nbitsinlong; /* num bits of region in each spanned long */ 975 unsigned long mask; /* bitmask for one long of region */ 976 int i; /* scans bitmap by longs */ 977 int ret = 0; /* return value */ 978 979 /* 980 * Either nlongs_reg == 1 (for small orders that fit in one long) 981 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.) 982 */ 983 nbits_reg = 1 << order; 984 index = pos / BITS_PER_LONG; 985 offset = pos - (index * BITS_PER_LONG); 986 nlongs_reg = BITS_TO_LONGS(nbits_reg); 987 nbitsinlong = min(nbits_reg, BITS_PER_LONG); 988 989 /* 990 * Can't do "mask = (1UL << nbitsinlong) - 1", as that 991 * overflows if nbitsinlong == BITS_PER_LONG. 992 */ 993 mask = (1UL << (nbitsinlong - 1)); 994 mask += mask - 1; 995 mask <<= offset; 996 997 switch (reg_op) { 998 case REG_OP_ISFREE: 999 for (i = 0; i < nlongs_reg; i++) { 1000 if (bitmap[index + i] & mask) 1001 goto done; 1002 } 1003 ret = 1; /* all bits in region free (zero) */ 1004 break; 1005 1006 case REG_OP_ALLOC: 1007 for (i = 0; i < nlongs_reg; i++) 1008 bitmap[index + i] |= mask; 1009 break; 1010 1011 case REG_OP_RELEASE: 1012 for (i = 0; i < nlongs_reg; i++) 1013 bitmap[index + i] &= ~mask; 1014 break; 1015 } 1016 done: 1017 return ret; 1018 } 1019 1020 /** 1021 * bitmap_find_free_region - find a contiguous aligned mem region 1022 * @bitmap: array of unsigned longs corresponding to the bitmap 1023 * @bits: number of bits in the bitmap 1024 * @order: region size (log base 2 of number of bits) to find 1025 * 1026 * Find a region of free (zero) bits in a @bitmap of @bits bits and 1027 * allocate them (set them to one). Only consider regions of length 1028 * a power (@order) of two, aligned to that power of two, which 1029 * makes the search algorithm much faster. 1030 * 1031 * Return the bit offset in bitmap of the allocated region, 1032 * or -errno on failure. 1033 */ 1034 int bitmap_find_free_region(unsigned long *bitmap, int bits, int order) 1035 { 1036 int pos, end; /* scans bitmap by regions of size order */ 1037 1038 for (pos = 0 ; (end = pos + (1 << order)) <= bits; pos = end) { 1039 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE)) 1040 continue; 1041 __reg_op(bitmap, pos, order, REG_OP_ALLOC); 1042 return pos; 1043 } 1044 return -ENOMEM; 1045 } 1046 EXPORT_SYMBOL(bitmap_find_free_region); 1047 1048 /** 1049 * bitmap_release_region - release allocated bitmap region 1050 * @bitmap: array of unsigned longs corresponding to the bitmap 1051 * @pos: beginning of bit region to release 1052 * @order: region size (log base 2 of number of bits) to release 1053 * 1054 * This is the complement to __bitmap_find_free_region() and releases 1055 * the found region (by clearing it in the bitmap). 1056 * 1057 * No return value. 1058 */ 1059 void bitmap_release_region(unsigned long *bitmap, int pos, int order) 1060 { 1061 __reg_op(bitmap, pos, order, REG_OP_RELEASE); 1062 } 1063 EXPORT_SYMBOL(bitmap_release_region); 1064 1065 /** 1066 * bitmap_allocate_region - allocate bitmap region 1067 * @bitmap: array of unsigned longs corresponding to the bitmap 1068 * @pos: beginning of bit region to allocate 1069 * @order: region size (log base 2 of number of bits) to allocate 1070 * 1071 * Allocate (set bits in) a specified region of a bitmap. 1072 * 1073 * Return 0 on success, or %-EBUSY if specified region wasn't 1074 * free (not all bits were zero). 1075 */ 1076 int bitmap_allocate_region(unsigned long *bitmap, int pos, int order) 1077 { 1078 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE)) 1079 return -EBUSY; 1080 __reg_op(bitmap, pos, order, REG_OP_ALLOC); 1081 return 0; 1082 } 1083 EXPORT_SYMBOL(bitmap_allocate_region); 1084 1085 /** 1086 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order. 1087 * @dst: destination buffer 1088 * @src: bitmap to copy 1089 * @nbits: number of bits in the bitmap 1090 * 1091 * Require nbits % BITS_PER_LONG == 0. 1092 */ 1093 void bitmap_copy_le(void *dst, const unsigned long *src, int nbits) 1094 { 1095 unsigned long *d = dst; 1096 int i; 1097 1098 for (i = 0; i < nbits/BITS_PER_LONG; i++) { 1099 if (BITS_PER_LONG == 64) 1100 d[i] = cpu_to_le64(src[i]); 1101 else 1102 d[i] = cpu_to_le32(src[i]); 1103 } 1104 } 1105 EXPORT_SYMBOL(bitmap_copy_le); 1106