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 void __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); 187 188 for (k = 0; k < nr; k++) 189 dst[k] = bitmap1[k] & bitmap2[k]; 190 } 191 EXPORT_SYMBOL(__bitmap_and); 192 193 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1, 194 const unsigned long *bitmap2, int bits) 195 { 196 int k; 197 int nr = BITS_TO_LONGS(bits); 198 199 for (k = 0; k < nr; k++) 200 dst[k] = bitmap1[k] | bitmap2[k]; 201 } 202 EXPORT_SYMBOL(__bitmap_or); 203 204 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1, 205 const unsigned long *bitmap2, int bits) 206 { 207 int k; 208 int nr = BITS_TO_LONGS(bits); 209 210 for (k = 0; k < nr; k++) 211 dst[k] = bitmap1[k] ^ bitmap2[k]; 212 } 213 EXPORT_SYMBOL(__bitmap_xor); 214 215 void __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1, 216 const unsigned long *bitmap2, int bits) 217 { 218 int k; 219 int nr = BITS_TO_LONGS(bits); 220 221 for (k = 0; k < nr; k++) 222 dst[k] = bitmap1[k] & ~bitmap2[k]; 223 } 224 EXPORT_SYMBOL(__bitmap_andnot); 225 226 int __bitmap_intersects(const unsigned long *bitmap1, 227 const unsigned long *bitmap2, int bits) 228 { 229 int k, lim = bits/BITS_PER_LONG; 230 for (k = 0; k < lim; ++k) 231 if (bitmap1[k] & bitmap2[k]) 232 return 1; 233 234 if (bits % BITS_PER_LONG) 235 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) 236 return 1; 237 return 0; 238 } 239 EXPORT_SYMBOL(__bitmap_intersects); 240 241 int __bitmap_subset(const unsigned long *bitmap1, 242 const unsigned long *bitmap2, int bits) 243 { 244 int k, lim = bits/BITS_PER_LONG; 245 for (k = 0; k < lim; ++k) 246 if (bitmap1[k] & ~bitmap2[k]) 247 return 0; 248 249 if (bits % BITS_PER_LONG) 250 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) 251 return 0; 252 return 1; 253 } 254 EXPORT_SYMBOL(__bitmap_subset); 255 256 int __bitmap_weight(const unsigned long *bitmap, int bits) 257 { 258 int k, w = 0, lim = bits/BITS_PER_LONG; 259 260 for (k = 0; k < lim; k++) 261 w += hweight_long(bitmap[k]); 262 263 if (bits % BITS_PER_LONG) 264 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits)); 265 266 return w; 267 } 268 EXPORT_SYMBOL(__bitmap_weight); 269 270 /* 271 * Bitmap printing & parsing functions: first version by Bill Irwin, 272 * second version by Paul Jackson, third by Joe Korty. 273 */ 274 275 #define CHUNKSZ 32 276 #define nbits_to_hold_value(val) fls(val) 277 #define unhex(c) (isdigit(c) ? (c - '0') : (toupper(c) - 'A' + 10)) 278 #define BASEDEC 10 /* fancier cpuset lists input in decimal */ 279 280 /** 281 * bitmap_scnprintf - convert bitmap to an ASCII hex string. 282 * @buf: byte buffer into which string is placed 283 * @buflen: reserved size of @buf, in bytes 284 * @maskp: pointer to bitmap to convert 285 * @nmaskbits: size of bitmap, in bits 286 * 287 * Exactly @nmaskbits bits are displayed. Hex digits are grouped into 288 * comma-separated sets of eight digits per set. 289 */ 290 int bitmap_scnprintf(char *buf, unsigned int buflen, 291 const unsigned long *maskp, int nmaskbits) 292 { 293 int i, word, bit, len = 0; 294 unsigned long val; 295 const char *sep = ""; 296 int chunksz; 297 u32 chunkmask; 298 299 chunksz = nmaskbits & (CHUNKSZ - 1); 300 if (chunksz == 0) 301 chunksz = CHUNKSZ; 302 303 i = ALIGN(nmaskbits, CHUNKSZ) - CHUNKSZ; 304 for (; i >= 0; i -= CHUNKSZ) { 305 chunkmask = ((1ULL << chunksz) - 1); 306 word = i / BITS_PER_LONG; 307 bit = i % BITS_PER_LONG; 308 val = (maskp[word] >> bit) & chunkmask; 309 len += scnprintf(buf+len, buflen-len, "%s%0*lx", sep, 310 (chunksz+3)/4, val); 311 chunksz = CHUNKSZ; 312 sep = ","; 313 } 314 return len; 315 } 316 EXPORT_SYMBOL(bitmap_scnprintf); 317 318 /** 319 * bitmap_scnprintf_len - return buffer length needed to convert 320 * bitmap to an ASCII hex string 321 * @nr_bits: number of bits to be converted 322 */ 323 int bitmap_scnprintf_len(unsigned int nr_bits) 324 { 325 unsigned int nr_nibbles = ALIGN(nr_bits, 4) / 4; 326 return nr_nibbles + ALIGN(nr_nibbles, CHUNKSZ / 4) / (CHUNKSZ / 4) - 1; 327 } 328 329 /** 330 * __bitmap_parse - convert an ASCII hex string into a bitmap. 331 * @buf: pointer to buffer containing string. 332 * @buflen: buffer size in bytes. If string is smaller than this 333 * then it must be terminated with a \0. 334 * @is_user: location of buffer, 0 indicates kernel space 335 * @maskp: pointer to bitmap array that will contain result. 336 * @nmaskbits: size of bitmap, in bits. 337 * 338 * Commas group hex digits into chunks. Each chunk defines exactly 32 339 * bits of the resultant bitmask. No chunk may specify a value larger 340 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value 341 * then leading 0-bits are prepended. %-EINVAL is returned for illegal 342 * characters and for grouping errors such as "1,,5", ",44", "," and "". 343 * Leading and trailing whitespace accepted, but not embedded whitespace. 344 */ 345 int __bitmap_parse(const char *buf, unsigned int buflen, 346 int is_user, unsigned long *maskp, 347 int nmaskbits) 348 { 349 int c, old_c, totaldigits, ndigits, nchunks, nbits; 350 u32 chunk; 351 const char __user *ubuf = buf; 352 353 bitmap_zero(maskp, nmaskbits); 354 355 nchunks = nbits = totaldigits = c = 0; 356 do { 357 chunk = ndigits = 0; 358 359 /* Get the next chunk of the bitmap */ 360 while (buflen) { 361 old_c = c; 362 if (is_user) { 363 if (__get_user(c, ubuf++)) 364 return -EFAULT; 365 } 366 else 367 c = *buf++; 368 buflen--; 369 if (isspace(c)) 370 continue; 371 372 /* 373 * If the last character was a space and the current 374 * character isn't '\0', we've got embedded whitespace. 375 * This is a no-no, so throw an error. 376 */ 377 if (totaldigits && c && isspace(old_c)) 378 return -EINVAL; 379 380 /* A '\0' or a ',' signal the end of the chunk */ 381 if (c == '\0' || c == ',') 382 break; 383 384 if (!isxdigit(c)) 385 return -EINVAL; 386 387 /* 388 * Make sure there are at least 4 free bits in 'chunk'. 389 * If not, this hexdigit will overflow 'chunk', so 390 * throw an error. 391 */ 392 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1)) 393 return -EOVERFLOW; 394 395 chunk = (chunk << 4) | unhex(c); 396 ndigits++; totaldigits++; 397 } 398 if (ndigits == 0) 399 return -EINVAL; 400 if (nchunks == 0 && chunk == 0) 401 continue; 402 403 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits); 404 *maskp |= chunk; 405 nchunks++; 406 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ; 407 if (nbits > nmaskbits) 408 return -EOVERFLOW; 409 } while (buflen && c == ','); 410 411 return 0; 412 } 413 EXPORT_SYMBOL(__bitmap_parse); 414 415 /** 416 * bitmap_parse_user() 417 * 418 * @ubuf: pointer to user buffer containing string. 419 * @ulen: buffer size in bytes. If string is smaller than this 420 * then it must be terminated with a \0. 421 * @maskp: pointer to bitmap array that will contain result. 422 * @nmaskbits: size of bitmap, in bits. 423 * 424 * Wrapper for __bitmap_parse(), providing it with user buffer. 425 * 426 * We cannot have this as an inline function in bitmap.h because it needs 427 * linux/uaccess.h to get the access_ok() declaration and this causes 428 * cyclic dependencies. 429 */ 430 int bitmap_parse_user(const char __user *ubuf, 431 unsigned int ulen, unsigned long *maskp, 432 int nmaskbits) 433 { 434 if (!access_ok(VERIFY_READ, ubuf, ulen)) 435 return -EFAULT; 436 return __bitmap_parse((const char *)ubuf, ulen, 1, maskp, nmaskbits); 437 } 438 EXPORT_SYMBOL(bitmap_parse_user); 439 440 /* 441 * bscnl_emit(buf, buflen, rbot, rtop, bp) 442 * 443 * Helper routine for bitmap_scnlistprintf(). Write decimal number 444 * or range to buf, suppressing output past buf+buflen, with optional 445 * comma-prefix. Return len of what would be written to buf, if it 446 * all fit. 447 */ 448 static inline int bscnl_emit(char *buf, int buflen, int rbot, int rtop, int len) 449 { 450 if (len > 0) 451 len += scnprintf(buf + len, buflen - len, ","); 452 if (rbot == rtop) 453 len += scnprintf(buf + len, buflen - len, "%d", rbot); 454 else 455 len += scnprintf(buf + len, buflen - len, "%d-%d", rbot, rtop); 456 return len; 457 } 458 459 /** 460 * bitmap_scnlistprintf - convert bitmap to list format ASCII string 461 * @buf: byte buffer into which string is placed 462 * @buflen: reserved size of @buf, in bytes 463 * @maskp: pointer to bitmap to convert 464 * @nmaskbits: size of bitmap, in bits 465 * 466 * Output format is a comma-separated list of decimal numbers and 467 * ranges. Consecutively set bits are shown as two hyphen-separated 468 * decimal numbers, the smallest and largest bit numbers set in 469 * the range. Output format is compatible with the format 470 * accepted as input by bitmap_parselist(). 471 * 472 * The return value is the number of characters which would be 473 * generated for the given input, excluding the trailing '\0', as 474 * per ISO C99. 475 */ 476 int bitmap_scnlistprintf(char *buf, unsigned int buflen, 477 const unsigned long *maskp, int nmaskbits) 478 { 479 int len = 0; 480 /* current bit is 'cur', most recently seen range is [rbot, rtop] */ 481 int cur, rbot, rtop; 482 483 if (buflen == 0) 484 return 0; 485 buf[0] = 0; 486 487 rbot = cur = find_first_bit(maskp, nmaskbits); 488 while (cur < nmaskbits) { 489 rtop = cur; 490 cur = find_next_bit(maskp, nmaskbits, cur+1); 491 if (cur >= nmaskbits || cur > rtop + 1) { 492 len = bscnl_emit(buf, buflen, rbot, rtop, len); 493 rbot = cur; 494 } 495 } 496 return len; 497 } 498 EXPORT_SYMBOL(bitmap_scnlistprintf); 499 500 /** 501 * bitmap_parselist - convert list format ASCII string to bitmap 502 * @bp: read nul-terminated user string from this buffer 503 * @maskp: write resulting mask here 504 * @nmaskbits: number of bits in mask to be written 505 * 506 * Input format is a comma-separated list of decimal numbers and 507 * ranges. Consecutively set bits are shown as two hyphen-separated 508 * decimal numbers, the smallest and largest bit numbers set in 509 * the range. 510 * 511 * Returns 0 on success, -errno on invalid input strings. 512 * Error values: 513 * %-EINVAL: second number in range smaller than first 514 * %-EINVAL: invalid character in string 515 * %-ERANGE: bit number specified too large for mask 516 */ 517 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits) 518 { 519 unsigned a, b; 520 521 bitmap_zero(maskp, nmaskbits); 522 do { 523 if (!isdigit(*bp)) 524 return -EINVAL; 525 b = a = simple_strtoul(bp, (char **)&bp, BASEDEC); 526 if (*bp == '-') { 527 bp++; 528 if (!isdigit(*bp)) 529 return -EINVAL; 530 b = simple_strtoul(bp, (char **)&bp, BASEDEC); 531 } 532 if (!(a <= b)) 533 return -EINVAL; 534 if (b >= nmaskbits) 535 return -ERANGE; 536 while (a <= b) { 537 set_bit(a, maskp); 538 a++; 539 } 540 if (*bp == ',') 541 bp++; 542 } while (*bp != '\0' && *bp != '\n'); 543 return 0; 544 } 545 EXPORT_SYMBOL(bitmap_parselist); 546 547 /** 548 * bitmap_pos_to_ord(buf, pos, bits) 549 * @buf: pointer to a bitmap 550 * @pos: a bit position in @buf (0 <= @pos < @bits) 551 * @bits: number of valid bit positions in @buf 552 * 553 * Map the bit at position @pos in @buf (of length @bits) to the 554 * ordinal of which set bit it is. If it is not set or if @pos 555 * is not a valid bit position, map to -1. 556 * 557 * If for example, just bits 4 through 7 are set in @buf, then @pos 558 * values 4 through 7 will get mapped to 0 through 3, respectively, 559 * and other @pos values will get mapped to 0. When @pos value 7 560 * gets mapped to (returns) @ord value 3 in this example, that means 561 * that bit 7 is the 3rd (starting with 0th) set bit in @buf. 562 * 563 * The bit positions 0 through @bits are valid positions in @buf. 564 */ 565 static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits) 566 { 567 int i, ord; 568 569 if (pos < 0 || pos >= bits || !test_bit(pos, buf)) 570 return -1; 571 572 i = find_first_bit(buf, bits); 573 ord = 0; 574 while (i < pos) { 575 i = find_next_bit(buf, bits, i + 1); 576 ord++; 577 } 578 BUG_ON(i != pos); 579 580 return ord; 581 } 582 583 /** 584 * bitmap_ord_to_pos(buf, ord, bits) 585 * @buf: pointer to bitmap 586 * @ord: ordinal bit position (n-th set bit, n >= 0) 587 * @bits: number of valid bit positions in @buf 588 * 589 * Map the ordinal offset of bit @ord in @buf to its position in @buf. 590 * Value of @ord should be in range 0 <= @ord < weight(buf), else 591 * results are undefined. 592 * 593 * If for example, just bits 4 through 7 are set in @buf, then @ord 594 * values 0 through 3 will get mapped to 4 through 7, respectively, 595 * and all other @ord values return undefined values. When @ord value 3 596 * gets mapped to (returns) @pos value 7 in this example, that means 597 * that the 3rd set bit (starting with 0th) is at position 7 in @buf. 598 * 599 * The bit positions 0 through @bits are valid positions in @buf. 600 */ 601 static int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits) 602 { 603 int pos = 0; 604 605 if (ord >= 0 && ord < bits) { 606 int i; 607 608 for (i = find_first_bit(buf, bits); 609 i < bits && ord > 0; 610 i = find_next_bit(buf, bits, i + 1)) 611 ord--; 612 if (i < bits && ord == 0) 613 pos = i; 614 } 615 616 return pos; 617 } 618 619 /** 620 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap 621 * @dst: remapped result 622 * @src: subset to be remapped 623 * @old: defines domain of map 624 * @new: defines range of map 625 * @bits: number of bits in each of these bitmaps 626 * 627 * Let @old and @new define a mapping of bit positions, such that 628 * whatever position is held by the n-th set bit in @old is mapped 629 * to the n-th set bit in @new. In the more general case, allowing 630 * for the possibility that the weight 'w' of @new is less than the 631 * weight of @old, map the position of the n-th set bit in @old to 632 * the position of the m-th set bit in @new, where m == n % w. 633 * 634 * If either of the @old and @new bitmaps are empty, or if @src and 635 * @dst point to the same location, then this routine copies @src 636 * to @dst. 637 * 638 * The positions of unset bits in @old are mapped to themselves 639 * (the identify map). 640 * 641 * Apply the above specified mapping to @src, placing the result in 642 * @dst, clearing any bits previously set in @dst. 643 * 644 * For example, lets say that @old has bits 4 through 7 set, and 645 * @new has bits 12 through 15 set. This defines the mapping of bit 646 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other 647 * bit positions unchanged. So if say @src comes into this routine 648 * with bits 1, 5 and 7 set, then @dst should leave with bits 1, 649 * 13 and 15 set. 650 */ 651 void bitmap_remap(unsigned long *dst, const unsigned long *src, 652 const unsigned long *old, const unsigned long *new, 653 int bits) 654 { 655 int oldbit, w; 656 657 if (dst == src) /* following doesn't handle inplace remaps */ 658 return; 659 bitmap_zero(dst, bits); 660 661 w = bitmap_weight(new, bits); 662 for (oldbit = find_first_bit(src, bits); 663 oldbit < bits; 664 oldbit = find_next_bit(src, bits, oldbit + 1)) { 665 int n = bitmap_pos_to_ord(old, oldbit, bits); 666 if (n < 0 || w == 0) 667 set_bit(oldbit, dst); /* identity map */ 668 else 669 set_bit(bitmap_ord_to_pos(new, n % w, bits), dst); 670 } 671 } 672 EXPORT_SYMBOL(bitmap_remap); 673 674 /** 675 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit 676 * @oldbit: bit position to be mapped 677 * @old: defines domain of map 678 * @new: defines range of map 679 * @bits: number of bits in each of these bitmaps 680 * 681 * Let @old and @new define a mapping of bit positions, such that 682 * whatever position is held by the n-th set bit in @old is mapped 683 * to the n-th set bit in @new. In the more general case, allowing 684 * for the possibility that the weight 'w' of @new is less than the 685 * weight of @old, map the position of the n-th set bit in @old to 686 * the position of the m-th set bit in @new, where m == n % w. 687 * 688 * The positions of unset bits in @old are mapped to themselves 689 * (the identify map). 690 * 691 * Apply the above specified mapping to bit position @oldbit, returning 692 * the new bit position. 693 * 694 * For example, lets say that @old has bits 4 through 7 set, and 695 * @new has bits 12 through 15 set. This defines the mapping of bit 696 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other 697 * bit positions unchanged. So if say @oldbit is 5, then this routine 698 * returns 13. 699 */ 700 int bitmap_bitremap(int oldbit, const unsigned long *old, 701 const unsigned long *new, int bits) 702 { 703 int w = bitmap_weight(new, bits); 704 int n = bitmap_pos_to_ord(old, oldbit, bits); 705 if (n < 0 || w == 0) 706 return oldbit; 707 else 708 return bitmap_ord_to_pos(new, n % w, bits); 709 } 710 EXPORT_SYMBOL(bitmap_bitremap); 711 712 /** 713 * bitmap_onto - translate one bitmap relative to another 714 * @dst: resulting translated bitmap 715 * @orig: original untranslated bitmap 716 * @relmap: bitmap relative to which translated 717 * @bits: number of bits in each of these bitmaps 718 * 719 * Set the n-th bit of @dst iff there exists some m such that the 720 * n-th bit of @relmap is set, the m-th bit of @orig is set, and 721 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap. 722 * (If you understood the previous sentence the first time your 723 * read it, you're overqualified for your current job.) 724 * 725 * In other words, @orig is mapped onto (surjectively) @dst, 726 * using the the map { <n, m> | the n-th bit of @relmap is the 727 * m-th set bit of @relmap }. 728 * 729 * Any set bits in @orig above bit number W, where W is the 730 * weight of (number of set bits in) @relmap are mapped nowhere. 731 * In particular, if for all bits m set in @orig, m >= W, then 732 * @dst will end up empty. In situations where the possibility 733 * of such an empty result is not desired, one way to avoid it is 734 * to use the bitmap_fold() operator, below, to first fold the 735 * @orig bitmap over itself so that all its set bits x are in the 736 * range 0 <= x < W. The bitmap_fold() operator does this by 737 * setting the bit (m % W) in @dst, for each bit (m) set in @orig. 738 * 739 * Example [1] for bitmap_onto(): 740 * Let's say @relmap has bits 30-39 set, and @orig has bits 741 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine, 742 * @dst will have bits 31, 33, 35, 37 and 39 set. 743 * 744 * When bit 0 is set in @orig, it means turn on the bit in 745 * @dst corresponding to whatever is the first bit (if any) 746 * that is turned on in @relmap. Since bit 0 was off in the 747 * above example, we leave off that bit (bit 30) in @dst. 748 * 749 * When bit 1 is set in @orig (as in the above example), it 750 * means turn on the bit in @dst corresponding to whatever 751 * is the second bit that is turned on in @relmap. The second 752 * bit in @relmap that was turned on in the above example was 753 * bit 31, so we turned on bit 31 in @dst. 754 * 755 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst, 756 * because they were the 4th, 6th, 8th and 10th set bits 757 * set in @relmap, and the 4th, 6th, 8th and 10th bits of 758 * @orig (i.e. bits 3, 5, 7 and 9) were also set. 759 * 760 * When bit 11 is set in @orig, it means turn on the bit in 761 * @dst corresponding to whatever is the twelth bit that is 762 * turned on in @relmap. In the above example, there were 763 * only ten bits turned on in @relmap (30..39), so that bit 764 * 11 was set in @orig had no affect on @dst. 765 * 766 * Example [2] for bitmap_fold() + bitmap_onto(): 767 * Let's say @relmap has these ten bits set: 768 * 40 41 42 43 45 48 53 61 74 95 769 * (for the curious, that's 40 plus the first ten terms of the 770 * Fibonacci sequence.) 771 * 772 * Further lets say we use the following code, invoking 773 * bitmap_fold() then bitmap_onto, as suggested above to 774 * avoid the possitility of an empty @dst result: 775 * 776 * unsigned long *tmp; // a temporary bitmap's bits 777 * 778 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits); 779 * bitmap_onto(dst, tmp, relmap, bits); 780 * 781 * Then this table shows what various values of @dst would be, for 782 * various @orig's. I list the zero-based positions of each set bit. 783 * The tmp column shows the intermediate result, as computed by 784 * using bitmap_fold() to fold the @orig bitmap modulo ten 785 * (the weight of @relmap). 786 * 787 * @orig tmp @dst 788 * 0 0 40 789 * 1 1 41 790 * 9 9 95 791 * 10 0 40 (*) 792 * 1 3 5 7 1 3 5 7 41 43 48 61 793 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45 794 * 0 9 18 27 0 9 8 7 40 61 74 95 795 * 0 10 20 30 0 40 796 * 0 11 22 33 0 1 2 3 40 41 42 43 797 * 0 12 24 36 0 2 4 6 40 42 45 53 798 * 78 102 211 1 2 8 41 42 74 (*) 799 * 800 * (*) For these marked lines, if we hadn't first done bitmap_fold() 801 * into tmp, then the @dst result would have been empty. 802 * 803 * If either of @orig or @relmap is empty (no set bits), then @dst 804 * will be returned empty. 805 * 806 * If (as explained above) the only set bits in @orig are in positions 807 * m where m >= W, (where W is the weight of @relmap) then @dst will 808 * once again be returned empty. 809 * 810 * All bits in @dst not set by the above rule are cleared. 811 */ 812 void bitmap_onto(unsigned long *dst, const unsigned long *orig, 813 const unsigned long *relmap, int bits) 814 { 815 int n, m; /* same meaning as in above comment */ 816 817 if (dst == orig) /* following doesn't handle inplace mappings */ 818 return; 819 bitmap_zero(dst, bits); 820 821 /* 822 * The following code is a more efficient, but less 823 * obvious, equivalent to the loop: 824 * for (m = 0; m < bitmap_weight(relmap, bits); m++) { 825 * n = bitmap_ord_to_pos(orig, m, bits); 826 * if (test_bit(m, orig)) 827 * set_bit(n, dst); 828 * } 829 */ 830 831 m = 0; 832 for (n = find_first_bit(relmap, bits); 833 n < bits; 834 n = find_next_bit(relmap, bits, n + 1)) { 835 /* m == bitmap_pos_to_ord(relmap, n, bits) */ 836 if (test_bit(m, orig)) 837 set_bit(n, dst); 838 m++; 839 } 840 } 841 EXPORT_SYMBOL(bitmap_onto); 842 843 /** 844 * bitmap_fold - fold larger bitmap into smaller, modulo specified size 845 * @dst: resulting smaller bitmap 846 * @orig: original larger bitmap 847 * @sz: specified size 848 * @bits: number of bits in each of these bitmaps 849 * 850 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst. 851 * Clear all other bits in @dst. See further the comment and 852 * Example [2] for bitmap_onto() for why and how to use this. 853 */ 854 void bitmap_fold(unsigned long *dst, const unsigned long *orig, 855 int sz, int bits) 856 { 857 int oldbit; 858 859 if (dst == orig) /* following doesn't handle inplace mappings */ 860 return; 861 bitmap_zero(dst, bits); 862 863 for (oldbit = find_first_bit(orig, bits); 864 oldbit < bits; 865 oldbit = find_next_bit(orig, bits, oldbit + 1)) 866 set_bit(oldbit % sz, dst); 867 } 868 EXPORT_SYMBOL(bitmap_fold); 869 870 /* 871 * Common code for bitmap_*_region() routines. 872 * bitmap: array of unsigned longs corresponding to the bitmap 873 * pos: the beginning of the region 874 * order: region size (log base 2 of number of bits) 875 * reg_op: operation(s) to perform on that region of bitmap 876 * 877 * Can set, verify and/or release a region of bits in a bitmap, 878 * depending on which combination of REG_OP_* flag bits is set. 879 * 880 * A region of a bitmap is a sequence of bits in the bitmap, of 881 * some size '1 << order' (a power of two), aligned to that same 882 * '1 << order' power of two. 883 * 884 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits). 885 * Returns 0 in all other cases and reg_ops. 886 */ 887 888 enum { 889 REG_OP_ISFREE, /* true if region is all zero bits */ 890 REG_OP_ALLOC, /* set all bits in region */ 891 REG_OP_RELEASE, /* clear all bits in region */ 892 }; 893 894 static int __reg_op(unsigned long *bitmap, int pos, int order, int reg_op) 895 { 896 int nbits_reg; /* number of bits in region */ 897 int index; /* index first long of region in bitmap */ 898 int offset; /* bit offset region in bitmap[index] */ 899 int nlongs_reg; /* num longs spanned by region in bitmap */ 900 int nbitsinlong; /* num bits of region in each spanned long */ 901 unsigned long mask; /* bitmask for one long of region */ 902 int i; /* scans bitmap by longs */ 903 int ret = 0; /* return value */ 904 905 /* 906 * Either nlongs_reg == 1 (for small orders that fit in one long) 907 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.) 908 */ 909 nbits_reg = 1 << order; 910 index = pos / BITS_PER_LONG; 911 offset = pos - (index * BITS_PER_LONG); 912 nlongs_reg = BITS_TO_LONGS(nbits_reg); 913 nbitsinlong = min(nbits_reg, BITS_PER_LONG); 914 915 /* 916 * Can't do "mask = (1UL << nbitsinlong) - 1", as that 917 * overflows if nbitsinlong == BITS_PER_LONG. 918 */ 919 mask = (1UL << (nbitsinlong - 1)); 920 mask += mask - 1; 921 mask <<= offset; 922 923 switch (reg_op) { 924 case REG_OP_ISFREE: 925 for (i = 0; i < nlongs_reg; i++) { 926 if (bitmap[index + i] & mask) 927 goto done; 928 } 929 ret = 1; /* all bits in region free (zero) */ 930 break; 931 932 case REG_OP_ALLOC: 933 for (i = 0; i < nlongs_reg; i++) 934 bitmap[index + i] |= mask; 935 break; 936 937 case REG_OP_RELEASE: 938 for (i = 0; i < nlongs_reg; i++) 939 bitmap[index + i] &= ~mask; 940 break; 941 } 942 done: 943 return ret; 944 } 945 946 /** 947 * bitmap_find_free_region - find a contiguous aligned mem region 948 * @bitmap: array of unsigned longs corresponding to the bitmap 949 * @bits: number of bits in the bitmap 950 * @order: region size (log base 2 of number of bits) to find 951 * 952 * Find a region of free (zero) bits in a @bitmap of @bits bits and 953 * allocate them (set them to one). Only consider regions of length 954 * a power (@order) of two, aligned to that power of two, which 955 * makes the search algorithm much faster. 956 * 957 * Return the bit offset in bitmap of the allocated region, 958 * or -errno on failure. 959 */ 960 int bitmap_find_free_region(unsigned long *bitmap, int bits, int order) 961 { 962 int pos; /* scans bitmap by regions of size order */ 963 964 for (pos = 0; pos < bits; pos += (1 << order)) 965 if (__reg_op(bitmap, pos, order, REG_OP_ISFREE)) 966 break; 967 if (pos == bits) 968 return -ENOMEM; 969 __reg_op(bitmap, pos, order, REG_OP_ALLOC); 970 return pos; 971 } 972 EXPORT_SYMBOL(bitmap_find_free_region); 973 974 /** 975 * bitmap_release_region - release allocated bitmap region 976 * @bitmap: array of unsigned longs corresponding to the bitmap 977 * @pos: beginning of bit region to release 978 * @order: region size (log base 2 of number of bits) to release 979 * 980 * This is the complement to __bitmap_find_free_region() and releases 981 * the found region (by clearing it in the bitmap). 982 * 983 * No return value. 984 */ 985 void bitmap_release_region(unsigned long *bitmap, int pos, int order) 986 { 987 __reg_op(bitmap, pos, order, REG_OP_RELEASE); 988 } 989 EXPORT_SYMBOL(bitmap_release_region); 990 991 /** 992 * bitmap_allocate_region - allocate bitmap region 993 * @bitmap: array of unsigned longs corresponding to the bitmap 994 * @pos: beginning of bit region to allocate 995 * @order: region size (log base 2 of number of bits) to allocate 996 * 997 * Allocate (set bits in) a specified region of a bitmap. 998 * 999 * Return 0 on success, or %-EBUSY if specified region wasn't 1000 * free (not all bits were zero). 1001 */ 1002 int bitmap_allocate_region(unsigned long *bitmap, int pos, int order) 1003 { 1004 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE)) 1005 return -EBUSY; 1006 __reg_op(bitmap, pos, order, REG_OP_ALLOC); 1007 return 0; 1008 } 1009 EXPORT_SYMBOL(bitmap_allocate_region); 1010