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 BASEDEC 10 /* fancier cpuset lists input in decimal */ 363 364 /** 365 * bitmap_scnprintf - convert bitmap to an ASCII hex string. 366 * @buf: byte buffer into which string is placed 367 * @buflen: reserved size of @buf, in bytes 368 * @maskp: pointer to bitmap to convert 369 * @nmaskbits: size of bitmap, in bits 370 * 371 * Exactly @nmaskbits bits are displayed. Hex digits are grouped into 372 * comma-separated sets of eight digits per set. 373 */ 374 int bitmap_scnprintf(char *buf, unsigned int buflen, 375 const unsigned long *maskp, int nmaskbits) 376 { 377 int i, word, bit, len = 0; 378 unsigned long val; 379 const char *sep = ""; 380 int chunksz; 381 u32 chunkmask; 382 383 chunksz = nmaskbits & (CHUNKSZ - 1); 384 if (chunksz == 0) 385 chunksz = CHUNKSZ; 386 387 i = ALIGN(nmaskbits, CHUNKSZ) - CHUNKSZ; 388 for (; i >= 0; i -= CHUNKSZ) { 389 chunkmask = ((1ULL << chunksz) - 1); 390 word = i / BITS_PER_LONG; 391 bit = i % BITS_PER_LONG; 392 val = (maskp[word] >> bit) & chunkmask; 393 len += scnprintf(buf+len, buflen-len, "%s%0*lx", sep, 394 (chunksz+3)/4, val); 395 chunksz = CHUNKSZ; 396 sep = ","; 397 } 398 return len; 399 } 400 EXPORT_SYMBOL(bitmap_scnprintf); 401 402 /** 403 * __bitmap_parse - convert an ASCII hex string into a bitmap. 404 * @buf: pointer to buffer containing string. 405 * @buflen: buffer size in bytes. If string is smaller than this 406 * then it must be terminated with a \0. 407 * @is_user: location of buffer, 0 indicates kernel space 408 * @maskp: pointer to bitmap array that will contain result. 409 * @nmaskbits: size of bitmap, in bits. 410 * 411 * Commas group hex digits into chunks. Each chunk defines exactly 32 412 * bits of the resultant bitmask. No chunk may specify a value larger 413 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value 414 * then leading 0-bits are prepended. %-EINVAL is returned for illegal 415 * characters and for grouping errors such as "1,,5", ",44", "," and "". 416 * Leading and trailing whitespace accepted, but not embedded whitespace. 417 */ 418 int __bitmap_parse(const char *buf, unsigned int buflen, 419 int is_user, unsigned long *maskp, 420 int nmaskbits) 421 { 422 int c, old_c, totaldigits, ndigits, nchunks, nbits; 423 u32 chunk; 424 const char __user *ubuf = buf; 425 426 bitmap_zero(maskp, nmaskbits); 427 428 nchunks = nbits = totaldigits = c = 0; 429 do { 430 chunk = ndigits = 0; 431 432 /* Get the next chunk of the bitmap */ 433 while (buflen) { 434 old_c = c; 435 if (is_user) { 436 if (__get_user(c, ubuf++)) 437 return -EFAULT; 438 } 439 else 440 c = *buf++; 441 buflen--; 442 if (isspace(c)) 443 continue; 444 445 /* 446 * If the last character was a space and the current 447 * character isn't '\0', we've got embedded whitespace. 448 * This is a no-no, so throw an error. 449 */ 450 if (totaldigits && c && isspace(old_c)) 451 return -EINVAL; 452 453 /* A '\0' or a ',' signal the end of the chunk */ 454 if (c == '\0' || c == ',') 455 break; 456 457 if (!isxdigit(c)) 458 return -EINVAL; 459 460 /* 461 * Make sure there are at least 4 free bits in 'chunk'. 462 * If not, this hexdigit will overflow 'chunk', so 463 * throw an error. 464 */ 465 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1)) 466 return -EOVERFLOW; 467 468 chunk = (chunk << 4) | hex_to_bin(c); 469 ndigits++; totaldigits++; 470 } 471 if (ndigits == 0) 472 return -EINVAL; 473 if (nchunks == 0 && chunk == 0) 474 continue; 475 476 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits); 477 *maskp |= chunk; 478 nchunks++; 479 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ; 480 if (nbits > nmaskbits) 481 return -EOVERFLOW; 482 } while (buflen && c == ','); 483 484 return 0; 485 } 486 EXPORT_SYMBOL(__bitmap_parse); 487 488 /** 489 * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap 490 * 491 * @ubuf: pointer to user buffer containing string. 492 * @ulen: buffer size in bytes. If string is smaller than this 493 * then it must be terminated with a \0. 494 * @maskp: pointer to bitmap array that will contain result. 495 * @nmaskbits: size of bitmap, in bits. 496 * 497 * Wrapper for __bitmap_parse(), providing it with user buffer. 498 * 499 * We cannot have this as an inline function in bitmap.h because it needs 500 * linux/uaccess.h to get the access_ok() declaration and this causes 501 * cyclic dependencies. 502 */ 503 int bitmap_parse_user(const char __user *ubuf, 504 unsigned int ulen, unsigned long *maskp, 505 int nmaskbits) 506 { 507 if (!access_ok(VERIFY_READ, ubuf, ulen)) 508 return -EFAULT; 509 return __bitmap_parse((const char *)ubuf, ulen, 1, maskp, nmaskbits); 510 } 511 EXPORT_SYMBOL(bitmap_parse_user); 512 513 /* 514 * bscnl_emit(buf, buflen, rbot, rtop, bp) 515 * 516 * Helper routine for bitmap_scnlistprintf(). Write decimal number 517 * or range to buf, suppressing output past buf+buflen, with optional 518 * comma-prefix. Return len of what would be written to buf, if it 519 * all fit. 520 */ 521 static inline int bscnl_emit(char *buf, int buflen, int rbot, int rtop, int len) 522 { 523 if (len > 0) 524 len += scnprintf(buf + len, buflen - len, ","); 525 if (rbot == rtop) 526 len += scnprintf(buf + len, buflen - len, "%d", rbot); 527 else 528 len += scnprintf(buf + len, buflen - len, "%d-%d", rbot, rtop); 529 return len; 530 } 531 532 /** 533 * bitmap_scnlistprintf - convert bitmap to list format ASCII string 534 * @buf: byte buffer into which string is placed 535 * @buflen: reserved size of @buf, in bytes 536 * @maskp: pointer to bitmap to convert 537 * @nmaskbits: size of bitmap, in bits 538 * 539 * Output format is a comma-separated list of decimal numbers and 540 * ranges. Consecutively set bits are shown as two hyphen-separated 541 * decimal numbers, the smallest and largest bit numbers set in 542 * the range. Output format is compatible with the format 543 * accepted as input by bitmap_parselist(). 544 * 545 * The return value is the number of characters which would be 546 * generated for the given input, excluding the trailing '\0', as 547 * per ISO C99. 548 */ 549 int bitmap_scnlistprintf(char *buf, unsigned int buflen, 550 const unsigned long *maskp, int nmaskbits) 551 { 552 int len = 0; 553 /* current bit is 'cur', most recently seen range is [rbot, rtop] */ 554 int cur, rbot, rtop; 555 556 if (buflen == 0) 557 return 0; 558 buf[0] = 0; 559 560 rbot = cur = find_first_bit(maskp, nmaskbits); 561 while (cur < nmaskbits) { 562 rtop = cur; 563 cur = find_next_bit(maskp, nmaskbits, cur+1); 564 if (cur >= nmaskbits || cur > rtop + 1) { 565 len = bscnl_emit(buf, buflen, rbot, rtop, len); 566 rbot = cur; 567 } 568 } 569 return len; 570 } 571 EXPORT_SYMBOL(bitmap_scnlistprintf); 572 573 /** 574 * bitmap_parselist - convert list format ASCII string to bitmap 575 * @bp: read nul-terminated user string from this buffer 576 * @maskp: write resulting mask here 577 * @nmaskbits: number of bits in mask to be written 578 * 579 * Input format is a comma-separated list of decimal numbers and 580 * ranges. Consecutively set bits are shown as two hyphen-separated 581 * decimal numbers, the smallest and largest bit numbers set in 582 * the range. 583 * 584 * Returns 0 on success, -errno on invalid input strings. 585 * Error values: 586 * %-EINVAL: second number in range smaller than first 587 * %-EINVAL: invalid character in string 588 * %-ERANGE: bit number specified too large for mask 589 */ 590 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits) 591 { 592 unsigned a, b; 593 594 bitmap_zero(maskp, nmaskbits); 595 do { 596 if (!isdigit(*bp)) 597 return -EINVAL; 598 b = a = simple_strtoul(bp, (char **)&bp, BASEDEC); 599 if (*bp == '-') { 600 bp++; 601 if (!isdigit(*bp)) 602 return -EINVAL; 603 b = simple_strtoul(bp, (char **)&bp, BASEDEC); 604 } 605 if (!(a <= b)) 606 return -EINVAL; 607 if (b >= nmaskbits) 608 return -ERANGE; 609 while (a <= b) { 610 set_bit(a, maskp); 611 a++; 612 } 613 if (*bp == ',') 614 bp++; 615 } while (*bp != '\0' && *bp != '\n'); 616 return 0; 617 } 618 EXPORT_SYMBOL(bitmap_parselist); 619 620 /** 621 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap 622 * @buf: pointer to a bitmap 623 * @pos: a bit position in @buf (0 <= @pos < @bits) 624 * @bits: number of valid bit positions in @buf 625 * 626 * Map the bit at position @pos in @buf (of length @bits) to the 627 * ordinal of which set bit it is. If it is not set or if @pos 628 * is not a valid bit position, map to -1. 629 * 630 * If for example, just bits 4 through 7 are set in @buf, then @pos 631 * values 4 through 7 will get mapped to 0 through 3, respectively, 632 * and other @pos values will get mapped to 0. When @pos value 7 633 * gets mapped to (returns) @ord value 3 in this example, that means 634 * that bit 7 is the 3rd (starting with 0th) set bit in @buf. 635 * 636 * The bit positions 0 through @bits are valid positions in @buf. 637 */ 638 static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits) 639 { 640 int i, ord; 641 642 if (pos < 0 || pos >= bits || !test_bit(pos, buf)) 643 return -1; 644 645 i = find_first_bit(buf, bits); 646 ord = 0; 647 while (i < pos) { 648 i = find_next_bit(buf, bits, i + 1); 649 ord++; 650 } 651 BUG_ON(i != pos); 652 653 return ord; 654 } 655 656 /** 657 * bitmap_ord_to_pos - find position of n-th set bit in bitmap 658 * @buf: pointer to bitmap 659 * @ord: ordinal bit position (n-th set bit, n >= 0) 660 * @bits: number of valid bit positions in @buf 661 * 662 * Map the ordinal offset of bit @ord in @buf to its position in @buf. 663 * Value of @ord should be in range 0 <= @ord < weight(buf), else 664 * results are undefined. 665 * 666 * If for example, just bits 4 through 7 are set in @buf, then @ord 667 * values 0 through 3 will get mapped to 4 through 7, respectively, 668 * and all other @ord values return undefined values. When @ord value 3 669 * gets mapped to (returns) @pos value 7 in this example, that means 670 * that the 3rd set bit (starting with 0th) is at position 7 in @buf. 671 * 672 * The bit positions 0 through @bits are valid positions in @buf. 673 */ 674 static int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits) 675 { 676 int pos = 0; 677 678 if (ord >= 0 && ord < bits) { 679 int i; 680 681 for (i = find_first_bit(buf, bits); 682 i < bits && ord > 0; 683 i = find_next_bit(buf, bits, i + 1)) 684 ord--; 685 if (i < bits && ord == 0) 686 pos = i; 687 } 688 689 return pos; 690 } 691 692 /** 693 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap 694 * @dst: remapped result 695 * @src: subset to be remapped 696 * @old: defines domain of map 697 * @new: defines range of map 698 * @bits: number of bits in each of these bitmaps 699 * 700 * Let @old and @new define a mapping of bit positions, such that 701 * whatever position is held by the n-th set bit in @old is mapped 702 * to the n-th set bit in @new. In the more general case, allowing 703 * for the possibility that the weight 'w' of @new is less than the 704 * weight of @old, map the position of the n-th set bit in @old to 705 * the position of the m-th set bit in @new, where m == n % w. 706 * 707 * If either of the @old and @new bitmaps are empty, or if @src and 708 * @dst point to the same location, then this routine copies @src 709 * to @dst. 710 * 711 * The positions of unset bits in @old are mapped to themselves 712 * (the identify map). 713 * 714 * Apply the above specified mapping to @src, placing the result in 715 * @dst, clearing any bits previously set in @dst. 716 * 717 * For example, lets say that @old has bits 4 through 7 set, and 718 * @new has bits 12 through 15 set. This defines the mapping of bit 719 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other 720 * bit positions unchanged. So if say @src comes into this routine 721 * with bits 1, 5 and 7 set, then @dst should leave with bits 1, 722 * 13 and 15 set. 723 */ 724 void bitmap_remap(unsigned long *dst, const unsigned long *src, 725 const unsigned long *old, const unsigned long *new, 726 int bits) 727 { 728 int oldbit, w; 729 730 if (dst == src) /* following doesn't handle inplace remaps */ 731 return; 732 bitmap_zero(dst, bits); 733 734 w = bitmap_weight(new, bits); 735 for_each_set_bit(oldbit, src, bits) { 736 int n = bitmap_pos_to_ord(old, oldbit, bits); 737 738 if (n < 0 || w == 0) 739 set_bit(oldbit, dst); /* identity map */ 740 else 741 set_bit(bitmap_ord_to_pos(new, n % w, bits), dst); 742 } 743 } 744 EXPORT_SYMBOL(bitmap_remap); 745 746 /** 747 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit 748 * @oldbit: bit position to be mapped 749 * @old: defines domain of map 750 * @new: defines range of map 751 * @bits: number of bits in each of these bitmaps 752 * 753 * Let @old and @new define a mapping of bit positions, such that 754 * whatever position is held by the n-th set bit in @old is mapped 755 * to the n-th set bit in @new. In the more general case, allowing 756 * for the possibility that the weight 'w' of @new is less than the 757 * weight of @old, map the position of the n-th set bit in @old to 758 * the position of the m-th set bit in @new, where m == n % w. 759 * 760 * The positions of unset bits in @old are mapped to themselves 761 * (the identify map). 762 * 763 * Apply the above specified mapping to bit position @oldbit, returning 764 * the new bit position. 765 * 766 * For example, lets say that @old has bits 4 through 7 set, and 767 * @new has bits 12 through 15 set. This defines the mapping of bit 768 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other 769 * bit positions unchanged. So if say @oldbit is 5, then this routine 770 * returns 13. 771 */ 772 int bitmap_bitremap(int oldbit, const unsigned long *old, 773 const unsigned long *new, int bits) 774 { 775 int w = bitmap_weight(new, bits); 776 int n = bitmap_pos_to_ord(old, oldbit, bits); 777 if (n < 0 || w == 0) 778 return oldbit; 779 else 780 return bitmap_ord_to_pos(new, n % w, bits); 781 } 782 EXPORT_SYMBOL(bitmap_bitremap); 783 784 /** 785 * bitmap_onto - translate one bitmap relative to another 786 * @dst: resulting translated bitmap 787 * @orig: original untranslated bitmap 788 * @relmap: bitmap relative to which translated 789 * @bits: number of bits in each of these bitmaps 790 * 791 * Set the n-th bit of @dst iff there exists some m such that the 792 * n-th bit of @relmap is set, the m-th bit of @orig is set, and 793 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap. 794 * (If you understood the previous sentence the first time your 795 * read it, you're overqualified for your current job.) 796 * 797 * In other words, @orig is mapped onto (surjectively) @dst, 798 * using the the map { <n, m> | the n-th bit of @relmap is the 799 * m-th set bit of @relmap }. 800 * 801 * Any set bits in @orig above bit number W, where W is the 802 * weight of (number of set bits in) @relmap are mapped nowhere. 803 * In particular, if for all bits m set in @orig, m >= W, then 804 * @dst will end up empty. In situations where the possibility 805 * of such an empty result is not desired, one way to avoid it is 806 * to use the bitmap_fold() operator, below, to first fold the 807 * @orig bitmap over itself so that all its set bits x are in the 808 * range 0 <= x < W. The bitmap_fold() operator does this by 809 * setting the bit (m % W) in @dst, for each bit (m) set in @orig. 810 * 811 * Example [1] for bitmap_onto(): 812 * Let's say @relmap has bits 30-39 set, and @orig has bits 813 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine, 814 * @dst will have bits 31, 33, 35, 37 and 39 set. 815 * 816 * When bit 0 is set in @orig, it means turn on the bit in 817 * @dst corresponding to whatever is the first bit (if any) 818 * that is turned on in @relmap. Since bit 0 was off in the 819 * above example, we leave off that bit (bit 30) in @dst. 820 * 821 * When bit 1 is set in @orig (as in the above example), it 822 * means turn on the bit in @dst corresponding to whatever 823 * is the second bit that is turned on in @relmap. The second 824 * bit in @relmap that was turned on in the above example was 825 * bit 31, so we turned on bit 31 in @dst. 826 * 827 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst, 828 * because they were the 4th, 6th, 8th and 10th set bits 829 * set in @relmap, and the 4th, 6th, 8th and 10th bits of 830 * @orig (i.e. bits 3, 5, 7 and 9) were also set. 831 * 832 * When bit 11 is set in @orig, it means turn on the bit in 833 * @dst corresponding to whatever is the twelfth bit that is 834 * turned on in @relmap. In the above example, there were 835 * only ten bits turned on in @relmap (30..39), so that bit 836 * 11 was set in @orig had no affect on @dst. 837 * 838 * Example [2] for bitmap_fold() + bitmap_onto(): 839 * Let's say @relmap has these ten bits set: 840 * 40 41 42 43 45 48 53 61 74 95 841 * (for the curious, that's 40 plus the first ten terms of the 842 * Fibonacci sequence.) 843 * 844 * Further lets say we use the following code, invoking 845 * bitmap_fold() then bitmap_onto, as suggested above to 846 * avoid the possitility of an empty @dst result: 847 * 848 * unsigned long *tmp; // a temporary bitmap's bits 849 * 850 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits); 851 * bitmap_onto(dst, tmp, relmap, bits); 852 * 853 * Then this table shows what various values of @dst would be, for 854 * various @orig's. I list the zero-based positions of each set bit. 855 * The tmp column shows the intermediate result, as computed by 856 * using bitmap_fold() to fold the @orig bitmap modulo ten 857 * (the weight of @relmap). 858 * 859 * @orig tmp @dst 860 * 0 0 40 861 * 1 1 41 862 * 9 9 95 863 * 10 0 40 (*) 864 * 1 3 5 7 1 3 5 7 41 43 48 61 865 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45 866 * 0 9 18 27 0 9 8 7 40 61 74 95 867 * 0 10 20 30 0 40 868 * 0 11 22 33 0 1 2 3 40 41 42 43 869 * 0 12 24 36 0 2 4 6 40 42 45 53 870 * 78 102 211 1 2 8 41 42 74 (*) 871 * 872 * (*) For these marked lines, if we hadn't first done bitmap_fold() 873 * into tmp, then the @dst result would have been empty. 874 * 875 * If either of @orig or @relmap is empty (no set bits), then @dst 876 * will be returned empty. 877 * 878 * If (as explained above) the only set bits in @orig are in positions 879 * m where m >= W, (where W is the weight of @relmap) then @dst will 880 * once again be returned empty. 881 * 882 * All bits in @dst not set by the above rule are cleared. 883 */ 884 void bitmap_onto(unsigned long *dst, const unsigned long *orig, 885 const unsigned long *relmap, int bits) 886 { 887 int n, m; /* same meaning as in above comment */ 888 889 if (dst == orig) /* following doesn't handle inplace mappings */ 890 return; 891 bitmap_zero(dst, bits); 892 893 /* 894 * The following code is a more efficient, but less 895 * obvious, equivalent to the loop: 896 * for (m = 0; m < bitmap_weight(relmap, bits); m++) { 897 * n = bitmap_ord_to_pos(orig, m, bits); 898 * if (test_bit(m, orig)) 899 * set_bit(n, dst); 900 * } 901 */ 902 903 m = 0; 904 for_each_set_bit(n, relmap, bits) { 905 /* m == bitmap_pos_to_ord(relmap, n, bits) */ 906 if (test_bit(m, orig)) 907 set_bit(n, dst); 908 m++; 909 } 910 } 911 EXPORT_SYMBOL(bitmap_onto); 912 913 /** 914 * bitmap_fold - fold larger bitmap into smaller, modulo specified size 915 * @dst: resulting smaller bitmap 916 * @orig: original larger bitmap 917 * @sz: specified size 918 * @bits: number of bits in each of these bitmaps 919 * 920 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst. 921 * Clear all other bits in @dst. See further the comment and 922 * Example [2] for bitmap_onto() for why and how to use this. 923 */ 924 void bitmap_fold(unsigned long *dst, const unsigned long *orig, 925 int sz, int bits) 926 { 927 int oldbit; 928 929 if (dst == orig) /* following doesn't handle inplace mappings */ 930 return; 931 bitmap_zero(dst, bits); 932 933 for_each_set_bit(oldbit, orig, bits) 934 set_bit(oldbit % sz, dst); 935 } 936 EXPORT_SYMBOL(bitmap_fold); 937 938 /* 939 * Common code for bitmap_*_region() routines. 940 * bitmap: array of unsigned longs corresponding to the bitmap 941 * pos: the beginning of the region 942 * order: region size (log base 2 of number of bits) 943 * reg_op: operation(s) to perform on that region of bitmap 944 * 945 * Can set, verify and/or release a region of bits in a bitmap, 946 * depending on which combination of REG_OP_* flag bits is set. 947 * 948 * A region of a bitmap is a sequence of bits in the bitmap, of 949 * some size '1 << order' (a power of two), aligned to that same 950 * '1 << order' power of two. 951 * 952 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits). 953 * Returns 0 in all other cases and reg_ops. 954 */ 955 956 enum { 957 REG_OP_ISFREE, /* true if region is all zero bits */ 958 REG_OP_ALLOC, /* set all bits in region */ 959 REG_OP_RELEASE, /* clear all bits in region */ 960 }; 961 962 static int __reg_op(unsigned long *bitmap, int pos, int order, int reg_op) 963 { 964 int nbits_reg; /* number of bits in region */ 965 int index; /* index first long of region in bitmap */ 966 int offset; /* bit offset region in bitmap[index] */ 967 int nlongs_reg; /* num longs spanned by region in bitmap */ 968 int nbitsinlong; /* num bits of region in each spanned long */ 969 unsigned long mask; /* bitmask for one long of region */ 970 int i; /* scans bitmap by longs */ 971 int ret = 0; /* return value */ 972 973 /* 974 * Either nlongs_reg == 1 (for small orders that fit in one long) 975 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.) 976 */ 977 nbits_reg = 1 << order; 978 index = pos / BITS_PER_LONG; 979 offset = pos - (index * BITS_PER_LONG); 980 nlongs_reg = BITS_TO_LONGS(nbits_reg); 981 nbitsinlong = min(nbits_reg, BITS_PER_LONG); 982 983 /* 984 * Can't do "mask = (1UL << nbitsinlong) - 1", as that 985 * overflows if nbitsinlong == BITS_PER_LONG. 986 */ 987 mask = (1UL << (nbitsinlong - 1)); 988 mask += mask - 1; 989 mask <<= offset; 990 991 switch (reg_op) { 992 case REG_OP_ISFREE: 993 for (i = 0; i < nlongs_reg; i++) { 994 if (bitmap[index + i] & mask) 995 goto done; 996 } 997 ret = 1; /* all bits in region free (zero) */ 998 break; 999 1000 case REG_OP_ALLOC: 1001 for (i = 0; i < nlongs_reg; i++) 1002 bitmap[index + i] |= mask; 1003 break; 1004 1005 case REG_OP_RELEASE: 1006 for (i = 0; i < nlongs_reg; i++) 1007 bitmap[index + i] &= ~mask; 1008 break; 1009 } 1010 done: 1011 return ret; 1012 } 1013 1014 /** 1015 * bitmap_find_free_region - find a contiguous aligned mem region 1016 * @bitmap: array of unsigned longs corresponding to the bitmap 1017 * @bits: number of bits in the bitmap 1018 * @order: region size (log base 2 of number of bits) to find 1019 * 1020 * Find a region of free (zero) bits in a @bitmap of @bits bits and 1021 * allocate them (set them to one). Only consider regions of length 1022 * a power (@order) of two, aligned to that power of two, which 1023 * makes the search algorithm much faster. 1024 * 1025 * Return the bit offset in bitmap of the allocated region, 1026 * or -errno on failure. 1027 */ 1028 int bitmap_find_free_region(unsigned long *bitmap, int bits, int order) 1029 { 1030 int pos, end; /* scans bitmap by regions of size order */ 1031 1032 for (pos = 0 ; (end = pos + (1 << order)) <= bits; pos = end) { 1033 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE)) 1034 continue; 1035 __reg_op(bitmap, pos, order, REG_OP_ALLOC); 1036 return pos; 1037 } 1038 return -ENOMEM; 1039 } 1040 EXPORT_SYMBOL(bitmap_find_free_region); 1041 1042 /** 1043 * bitmap_release_region - release allocated bitmap region 1044 * @bitmap: array of unsigned longs corresponding to the bitmap 1045 * @pos: beginning of bit region to release 1046 * @order: region size (log base 2 of number of bits) to release 1047 * 1048 * This is the complement to __bitmap_find_free_region() and releases 1049 * the found region (by clearing it in the bitmap). 1050 * 1051 * No return value. 1052 */ 1053 void bitmap_release_region(unsigned long *bitmap, int pos, int order) 1054 { 1055 __reg_op(bitmap, pos, order, REG_OP_RELEASE); 1056 } 1057 EXPORT_SYMBOL(bitmap_release_region); 1058 1059 /** 1060 * bitmap_allocate_region - allocate bitmap region 1061 * @bitmap: array of unsigned longs corresponding to the bitmap 1062 * @pos: beginning of bit region to allocate 1063 * @order: region size (log base 2 of number of bits) to allocate 1064 * 1065 * Allocate (set bits in) a specified region of a bitmap. 1066 * 1067 * Return 0 on success, or %-EBUSY if specified region wasn't 1068 * free (not all bits were zero). 1069 */ 1070 int bitmap_allocate_region(unsigned long *bitmap, int pos, int order) 1071 { 1072 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE)) 1073 return -EBUSY; 1074 __reg_op(bitmap, pos, order, REG_OP_ALLOC); 1075 return 0; 1076 } 1077 EXPORT_SYMBOL(bitmap_allocate_region); 1078 1079 /** 1080 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order. 1081 * @dst: destination buffer 1082 * @src: bitmap to copy 1083 * @nbits: number of bits in the bitmap 1084 * 1085 * Require nbits % BITS_PER_LONG == 0. 1086 */ 1087 void bitmap_copy_le(void *dst, const unsigned long *src, int nbits) 1088 { 1089 unsigned long *d = dst; 1090 int i; 1091 1092 for (i = 0; i < nbits/BITS_PER_LONG; i++) { 1093 if (BITS_PER_LONG == 64) 1094 d[i] = cpu_to_le64(src[i]); 1095 else 1096 d[i] = cpu_to_le32(src[i]); 1097 } 1098 } 1099 EXPORT_SYMBOL(bitmap_copy_le); 1100