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_parse - convert an ASCII hex string into a bitmap. 320 * @buf: pointer to buffer containing string. 321 * @buflen: buffer size in bytes. If string is smaller than this 322 * then it must be terminated with a \0. 323 * @is_user: location of buffer, 0 indicates kernel space 324 * @maskp: pointer to bitmap array that will contain result. 325 * @nmaskbits: size of bitmap, in bits. 326 * 327 * Commas group hex digits into chunks. Each chunk defines exactly 32 328 * bits of the resultant bitmask. No chunk may specify a value larger 329 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value 330 * then leading 0-bits are prepended. %-EINVAL is returned for illegal 331 * characters and for grouping errors such as "1,,5", ",44", "," and "". 332 * Leading and trailing whitespace accepted, but not embedded whitespace. 333 */ 334 int __bitmap_parse(const char *buf, unsigned int buflen, 335 int is_user, unsigned long *maskp, 336 int nmaskbits) 337 { 338 int c, old_c, totaldigits, ndigits, nchunks, nbits; 339 u32 chunk; 340 const char __user *ubuf = buf; 341 342 bitmap_zero(maskp, nmaskbits); 343 344 nchunks = nbits = totaldigits = c = 0; 345 do { 346 chunk = ndigits = 0; 347 348 /* Get the next chunk of the bitmap */ 349 while (buflen) { 350 old_c = c; 351 if (is_user) { 352 if (__get_user(c, ubuf++)) 353 return -EFAULT; 354 } 355 else 356 c = *buf++; 357 buflen--; 358 if (isspace(c)) 359 continue; 360 361 /* 362 * If the last character was a space and the current 363 * character isn't '\0', we've got embedded whitespace. 364 * This is a no-no, so throw an error. 365 */ 366 if (totaldigits && c && isspace(old_c)) 367 return -EINVAL; 368 369 /* A '\0' or a ',' signal the end of the chunk */ 370 if (c == '\0' || c == ',') 371 break; 372 373 if (!isxdigit(c)) 374 return -EINVAL; 375 376 /* 377 * Make sure there are at least 4 free bits in 'chunk'. 378 * If not, this hexdigit will overflow 'chunk', so 379 * throw an error. 380 */ 381 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1)) 382 return -EOVERFLOW; 383 384 chunk = (chunk << 4) | unhex(c); 385 ndigits++; totaldigits++; 386 } 387 if (ndigits == 0) 388 return -EINVAL; 389 if (nchunks == 0 && chunk == 0) 390 continue; 391 392 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits); 393 *maskp |= chunk; 394 nchunks++; 395 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ; 396 if (nbits > nmaskbits) 397 return -EOVERFLOW; 398 } while (buflen && c == ','); 399 400 return 0; 401 } 402 EXPORT_SYMBOL(__bitmap_parse); 403 404 /** 405 * bitmap_parse_user() 406 * 407 * @ubuf: pointer to user buffer containing string. 408 * @ulen: buffer size in bytes. If string is smaller than this 409 * then it must be terminated with a \0. 410 * @maskp: pointer to bitmap array that will contain result. 411 * @nmaskbits: size of bitmap, in bits. 412 * 413 * Wrapper for __bitmap_parse(), providing it with user buffer. 414 * 415 * We cannot have this as an inline function in bitmap.h because it needs 416 * linux/uaccess.h to get the access_ok() declaration and this causes 417 * cyclic dependencies. 418 */ 419 int bitmap_parse_user(const char __user *ubuf, 420 unsigned int ulen, unsigned long *maskp, 421 int nmaskbits) 422 { 423 if (!access_ok(VERIFY_READ, ubuf, ulen)) 424 return -EFAULT; 425 return __bitmap_parse((const char *)ubuf, ulen, 1, maskp, nmaskbits); 426 } 427 EXPORT_SYMBOL(bitmap_parse_user); 428 429 /* 430 * bscnl_emit(buf, buflen, rbot, rtop, bp) 431 * 432 * Helper routine for bitmap_scnlistprintf(). Write decimal number 433 * or range to buf, suppressing output past buf+buflen, with optional 434 * comma-prefix. Return len of what would be written to buf, if it 435 * all fit. 436 */ 437 static inline int bscnl_emit(char *buf, int buflen, int rbot, int rtop, int len) 438 { 439 if (len > 0) 440 len += scnprintf(buf + len, buflen - len, ","); 441 if (rbot == rtop) 442 len += scnprintf(buf + len, buflen - len, "%d", rbot); 443 else 444 len += scnprintf(buf + len, buflen - len, "%d-%d", rbot, rtop); 445 return len; 446 } 447 448 /** 449 * bitmap_scnlistprintf - convert bitmap to list format ASCII string 450 * @buf: byte buffer into which string is placed 451 * @buflen: reserved size of @buf, in bytes 452 * @maskp: pointer to bitmap to convert 453 * @nmaskbits: size of bitmap, in bits 454 * 455 * Output format is a comma-separated list of decimal numbers and 456 * ranges. Consecutively set bits are shown as two hyphen-separated 457 * decimal numbers, the smallest and largest bit numbers set in 458 * the range. Output format is compatible with the format 459 * accepted as input by bitmap_parselist(). 460 * 461 * The return value is the number of characters which would be 462 * generated for the given input, excluding the trailing '\0', as 463 * per ISO C99. 464 */ 465 int bitmap_scnlistprintf(char *buf, unsigned int buflen, 466 const unsigned long *maskp, int nmaskbits) 467 { 468 int len = 0; 469 /* current bit is 'cur', most recently seen range is [rbot, rtop] */ 470 int cur, rbot, rtop; 471 472 if (buflen == 0) 473 return 0; 474 buf[0] = 0; 475 476 rbot = cur = find_first_bit(maskp, nmaskbits); 477 while (cur < nmaskbits) { 478 rtop = cur; 479 cur = find_next_bit(maskp, nmaskbits, cur+1); 480 if (cur >= nmaskbits || cur > rtop + 1) { 481 len = bscnl_emit(buf, buflen, rbot, rtop, len); 482 rbot = cur; 483 } 484 } 485 return len; 486 } 487 EXPORT_SYMBOL(bitmap_scnlistprintf); 488 489 /** 490 * bitmap_parselist - convert list format ASCII string to bitmap 491 * @bp: read nul-terminated user string from this buffer 492 * @maskp: write resulting mask here 493 * @nmaskbits: number of bits in mask to be written 494 * 495 * Input format is a comma-separated list of decimal numbers and 496 * ranges. Consecutively set bits are shown as two hyphen-separated 497 * decimal numbers, the smallest and largest bit numbers set in 498 * the range. 499 * 500 * Returns 0 on success, -errno on invalid input strings. 501 * Error values: 502 * %-EINVAL: second number in range smaller than first 503 * %-EINVAL: invalid character in string 504 * %-ERANGE: bit number specified too large for mask 505 */ 506 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits) 507 { 508 unsigned a, b; 509 510 bitmap_zero(maskp, nmaskbits); 511 do { 512 if (!isdigit(*bp)) 513 return -EINVAL; 514 b = a = simple_strtoul(bp, (char **)&bp, BASEDEC); 515 if (*bp == '-') { 516 bp++; 517 if (!isdigit(*bp)) 518 return -EINVAL; 519 b = simple_strtoul(bp, (char **)&bp, BASEDEC); 520 } 521 if (!(a <= b)) 522 return -EINVAL; 523 if (b >= nmaskbits) 524 return -ERANGE; 525 while (a <= b) { 526 set_bit(a, maskp); 527 a++; 528 } 529 if (*bp == ',') 530 bp++; 531 } while (*bp != '\0' && *bp != '\n'); 532 return 0; 533 } 534 EXPORT_SYMBOL(bitmap_parselist); 535 536 /** 537 * bitmap_pos_to_ord(buf, pos, bits) 538 * @buf: pointer to a bitmap 539 * @pos: a bit position in @buf (0 <= @pos < @bits) 540 * @bits: number of valid bit positions in @buf 541 * 542 * Map the bit at position @pos in @buf (of length @bits) to the 543 * ordinal of which set bit it is. If it is not set or if @pos 544 * is not a valid bit position, map to -1. 545 * 546 * If for example, just bits 4 through 7 are set in @buf, then @pos 547 * values 4 through 7 will get mapped to 0 through 3, respectively, 548 * and other @pos values will get mapped to 0. When @pos value 7 549 * gets mapped to (returns) @ord value 3 in this example, that means 550 * that bit 7 is the 3rd (starting with 0th) set bit in @buf. 551 * 552 * The bit positions 0 through @bits are valid positions in @buf. 553 */ 554 static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits) 555 { 556 int i, ord; 557 558 if (pos < 0 || pos >= bits || !test_bit(pos, buf)) 559 return -1; 560 561 i = find_first_bit(buf, bits); 562 ord = 0; 563 while (i < pos) { 564 i = find_next_bit(buf, bits, i + 1); 565 ord++; 566 } 567 BUG_ON(i != pos); 568 569 return ord; 570 } 571 572 /** 573 * bitmap_ord_to_pos(buf, ord, bits) 574 * @buf: pointer to bitmap 575 * @ord: ordinal bit position (n-th set bit, n >= 0) 576 * @bits: number of valid bit positions in @buf 577 * 578 * Map the ordinal offset of bit @ord in @buf to its position in @buf. 579 * Value of @ord should be in range 0 <= @ord < weight(buf), else 580 * results are undefined. 581 * 582 * If for example, just bits 4 through 7 are set in @buf, then @ord 583 * values 0 through 3 will get mapped to 4 through 7, respectively, 584 * and all other @ord values return undefined values. When @ord value 3 585 * gets mapped to (returns) @pos value 7 in this example, that means 586 * that the 3rd set bit (starting with 0th) is at position 7 in @buf. 587 * 588 * The bit positions 0 through @bits are valid positions in @buf. 589 */ 590 static int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits) 591 { 592 int pos = 0; 593 594 if (ord >= 0 && ord < bits) { 595 int i; 596 597 for (i = find_first_bit(buf, bits); 598 i < bits && ord > 0; 599 i = find_next_bit(buf, bits, i + 1)) 600 ord--; 601 if (i < bits && ord == 0) 602 pos = i; 603 } 604 605 return pos; 606 } 607 608 /** 609 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap 610 * @dst: remapped result 611 * @src: subset to be remapped 612 * @old: defines domain of map 613 * @new: defines range of map 614 * @bits: number of bits in each of these bitmaps 615 * 616 * Let @old and @new define a mapping of bit positions, such that 617 * whatever position is held by the n-th set bit in @old is mapped 618 * to the n-th set bit in @new. In the more general case, allowing 619 * for the possibility that the weight 'w' of @new is less than the 620 * weight of @old, map the position of the n-th set bit in @old to 621 * the position of the m-th set bit in @new, where m == n % w. 622 * 623 * If either of the @old and @new bitmaps are empty, or if @src and 624 * @dst point to the same location, then this routine copies @src 625 * to @dst. 626 * 627 * The positions of unset bits in @old are mapped to themselves 628 * (the identify map). 629 * 630 * Apply the above specified mapping to @src, placing the result in 631 * @dst, clearing any bits previously set in @dst. 632 * 633 * For example, lets say that @old has bits 4 through 7 set, and 634 * @new has bits 12 through 15 set. This defines the mapping of bit 635 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other 636 * bit positions unchanged. So if say @src comes into this routine 637 * with bits 1, 5 and 7 set, then @dst should leave with bits 1, 638 * 13 and 15 set. 639 */ 640 void bitmap_remap(unsigned long *dst, const unsigned long *src, 641 const unsigned long *old, const unsigned long *new, 642 int bits) 643 { 644 int oldbit, w; 645 646 if (dst == src) /* following doesn't handle inplace remaps */ 647 return; 648 bitmap_zero(dst, bits); 649 650 w = bitmap_weight(new, bits); 651 for (oldbit = find_first_bit(src, bits); 652 oldbit < bits; 653 oldbit = find_next_bit(src, bits, oldbit + 1)) { 654 int n = bitmap_pos_to_ord(old, oldbit, bits); 655 if (n < 0 || w == 0) 656 set_bit(oldbit, dst); /* identity map */ 657 else 658 set_bit(bitmap_ord_to_pos(new, n % w, bits), dst); 659 } 660 } 661 EXPORT_SYMBOL(bitmap_remap); 662 663 /** 664 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit 665 * @oldbit: bit position to be mapped 666 * @old: defines domain of map 667 * @new: defines range of map 668 * @bits: number of bits in each of these bitmaps 669 * 670 * Let @old and @new define a mapping of bit positions, such that 671 * whatever position is held by the n-th set bit in @old is mapped 672 * to the n-th set bit in @new. In the more general case, allowing 673 * for the possibility that the weight 'w' of @new is less than the 674 * weight of @old, map the position of the n-th set bit in @old to 675 * the position of the m-th set bit in @new, where m == n % w. 676 * 677 * The positions of unset bits in @old are mapped to themselves 678 * (the identify map). 679 * 680 * Apply the above specified mapping to bit position @oldbit, returning 681 * the new bit position. 682 * 683 * For example, lets say that @old has bits 4 through 7 set, and 684 * @new has bits 12 through 15 set. This defines the mapping of bit 685 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other 686 * bit positions unchanged. So if say @oldbit is 5, then this routine 687 * returns 13. 688 */ 689 int bitmap_bitremap(int oldbit, const unsigned long *old, 690 const unsigned long *new, int bits) 691 { 692 int w = bitmap_weight(new, bits); 693 int n = bitmap_pos_to_ord(old, oldbit, bits); 694 if (n < 0 || w == 0) 695 return oldbit; 696 else 697 return bitmap_ord_to_pos(new, n % w, bits); 698 } 699 EXPORT_SYMBOL(bitmap_bitremap); 700 701 /** 702 * bitmap_onto - translate one bitmap relative to another 703 * @dst: resulting translated bitmap 704 * @orig: original untranslated bitmap 705 * @relmap: bitmap relative to which translated 706 * @bits: number of bits in each of these bitmaps 707 * 708 * Set the n-th bit of @dst iff there exists some m such that the 709 * n-th bit of @relmap is set, the m-th bit of @orig is set, and 710 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap. 711 * (If you understood the previous sentence the first time your 712 * read it, you're overqualified for your current job.) 713 * 714 * In other words, @orig is mapped onto (surjectively) @dst, 715 * using the the map { <n, m> | the n-th bit of @relmap is the 716 * m-th set bit of @relmap }. 717 * 718 * Any set bits in @orig above bit number W, where W is the 719 * weight of (number of set bits in) @relmap are mapped nowhere. 720 * In particular, if for all bits m set in @orig, m >= W, then 721 * @dst will end up empty. In situations where the possibility 722 * of such an empty result is not desired, one way to avoid it is 723 * to use the bitmap_fold() operator, below, to first fold the 724 * @orig bitmap over itself so that all its set bits x are in the 725 * range 0 <= x < W. The bitmap_fold() operator does this by 726 * setting the bit (m % W) in @dst, for each bit (m) set in @orig. 727 * 728 * Example [1] for bitmap_onto(): 729 * Let's say @relmap has bits 30-39 set, and @orig has bits 730 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine, 731 * @dst will have bits 31, 33, 35, 37 and 39 set. 732 * 733 * When bit 0 is set in @orig, it means turn on the bit in 734 * @dst corresponding to whatever is the first bit (if any) 735 * that is turned on in @relmap. Since bit 0 was off in the 736 * above example, we leave off that bit (bit 30) in @dst. 737 * 738 * When bit 1 is set in @orig (as in the above example), it 739 * means turn on the bit in @dst corresponding to whatever 740 * is the second bit that is turned on in @relmap. The second 741 * bit in @relmap that was turned on in the above example was 742 * bit 31, so we turned on bit 31 in @dst. 743 * 744 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst, 745 * because they were the 4th, 6th, 8th and 10th set bits 746 * set in @relmap, and the 4th, 6th, 8th and 10th bits of 747 * @orig (i.e. bits 3, 5, 7 and 9) were also set. 748 * 749 * When bit 11 is set in @orig, it means turn on the bit in 750 * @dst corresponding to whatever is the twelth bit that is 751 * turned on in @relmap. In the above example, there were 752 * only ten bits turned on in @relmap (30..39), so that bit 753 * 11 was set in @orig had no affect on @dst. 754 * 755 * Example [2] for bitmap_fold() + bitmap_onto(): 756 * Let's say @relmap has these ten bits set: 757 * 40 41 42 43 45 48 53 61 74 95 758 * (for the curious, that's 40 plus the first ten terms of the 759 * Fibonacci sequence.) 760 * 761 * Further lets say we use the following code, invoking 762 * bitmap_fold() then bitmap_onto, as suggested above to 763 * avoid the possitility of an empty @dst result: 764 * 765 * unsigned long *tmp; // a temporary bitmap's bits 766 * 767 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits); 768 * bitmap_onto(dst, tmp, relmap, bits); 769 * 770 * Then this table shows what various values of @dst would be, for 771 * various @orig's. I list the zero-based positions of each set bit. 772 * The tmp column shows the intermediate result, as computed by 773 * using bitmap_fold() to fold the @orig bitmap modulo ten 774 * (the weight of @relmap). 775 * 776 * @orig tmp @dst 777 * 0 0 40 778 * 1 1 41 779 * 9 9 95 780 * 10 0 40 (*) 781 * 1 3 5 7 1 3 5 7 41 43 48 61 782 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45 783 * 0 9 18 27 0 9 8 7 40 61 74 95 784 * 0 10 20 30 0 40 785 * 0 11 22 33 0 1 2 3 40 41 42 43 786 * 0 12 24 36 0 2 4 6 40 42 45 53 787 * 78 102 211 1 2 8 41 42 74 (*) 788 * 789 * (*) For these marked lines, if we hadn't first done bitmap_fold() 790 * into tmp, then the @dst result would have been empty. 791 * 792 * If either of @orig or @relmap is empty (no set bits), then @dst 793 * will be returned empty. 794 * 795 * If (as explained above) the only set bits in @orig are in positions 796 * m where m >= W, (where W is the weight of @relmap) then @dst will 797 * once again be returned empty. 798 * 799 * All bits in @dst not set by the above rule are cleared. 800 */ 801 void bitmap_onto(unsigned long *dst, const unsigned long *orig, 802 const unsigned long *relmap, int bits) 803 { 804 int n, m; /* same meaning as in above comment */ 805 806 if (dst == orig) /* following doesn't handle inplace mappings */ 807 return; 808 bitmap_zero(dst, bits); 809 810 /* 811 * The following code is a more efficient, but less 812 * obvious, equivalent to the loop: 813 * for (m = 0; m < bitmap_weight(relmap, bits); m++) { 814 * n = bitmap_ord_to_pos(orig, m, bits); 815 * if (test_bit(m, orig)) 816 * set_bit(n, dst); 817 * } 818 */ 819 820 m = 0; 821 for (n = find_first_bit(relmap, bits); 822 n < bits; 823 n = find_next_bit(relmap, bits, n + 1)) { 824 /* m == bitmap_pos_to_ord(relmap, n, bits) */ 825 if (test_bit(m, orig)) 826 set_bit(n, dst); 827 m++; 828 } 829 } 830 EXPORT_SYMBOL(bitmap_onto); 831 832 /** 833 * bitmap_fold - fold larger bitmap into smaller, modulo specified size 834 * @dst: resulting smaller bitmap 835 * @orig: original larger bitmap 836 * @sz: specified size 837 * @bits: number of bits in each of these bitmaps 838 * 839 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst. 840 * Clear all other bits in @dst. See further the comment and 841 * Example [2] for bitmap_onto() for why and how to use this. 842 */ 843 void bitmap_fold(unsigned long *dst, const unsigned long *orig, 844 int sz, int bits) 845 { 846 int oldbit; 847 848 if (dst == orig) /* following doesn't handle inplace mappings */ 849 return; 850 bitmap_zero(dst, bits); 851 852 for (oldbit = find_first_bit(orig, bits); 853 oldbit < bits; 854 oldbit = find_next_bit(orig, bits, oldbit + 1)) 855 set_bit(oldbit % sz, dst); 856 } 857 EXPORT_SYMBOL(bitmap_fold); 858 859 /* 860 * Common code for bitmap_*_region() routines. 861 * bitmap: array of unsigned longs corresponding to the bitmap 862 * pos: the beginning of the region 863 * order: region size (log base 2 of number of bits) 864 * reg_op: operation(s) to perform on that region of bitmap 865 * 866 * Can set, verify and/or release a region of bits in a bitmap, 867 * depending on which combination of REG_OP_* flag bits is set. 868 * 869 * A region of a bitmap is a sequence of bits in the bitmap, of 870 * some size '1 << order' (a power of two), aligned to that same 871 * '1 << order' power of two. 872 * 873 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits). 874 * Returns 0 in all other cases and reg_ops. 875 */ 876 877 enum { 878 REG_OP_ISFREE, /* true if region is all zero bits */ 879 REG_OP_ALLOC, /* set all bits in region */ 880 REG_OP_RELEASE, /* clear all bits in region */ 881 }; 882 883 static int __reg_op(unsigned long *bitmap, int pos, int order, int reg_op) 884 { 885 int nbits_reg; /* number of bits in region */ 886 int index; /* index first long of region in bitmap */ 887 int offset; /* bit offset region in bitmap[index] */ 888 int nlongs_reg; /* num longs spanned by region in bitmap */ 889 int nbitsinlong; /* num bits of region in each spanned long */ 890 unsigned long mask; /* bitmask for one long of region */ 891 int i; /* scans bitmap by longs */ 892 int ret = 0; /* return value */ 893 894 /* 895 * Either nlongs_reg == 1 (for small orders that fit in one long) 896 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.) 897 */ 898 nbits_reg = 1 << order; 899 index = pos / BITS_PER_LONG; 900 offset = pos - (index * BITS_PER_LONG); 901 nlongs_reg = BITS_TO_LONGS(nbits_reg); 902 nbitsinlong = min(nbits_reg, BITS_PER_LONG); 903 904 /* 905 * Can't do "mask = (1UL << nbitsinlong) - 1", as that 906 * overflows if nbitsinlong == BITS_PER_LONG. 907 */ 908 mask = (1UL << (nbitsinlong - 1)); 909 mask += mask - 1; 910 mask <<= offset; 911 912 switch (reg_op) { 913 case REG_OP_ISFREE: 914 for (i = 0; i < nlongs_reg; i++) { 915 if (bitmap[index + i] & mask) 916 goto done; 917 } 918 ret = 1; /* all bits in region free (zero) */ 919 break; 920 921 case REG_OP_ALLOC: 922 for (i = 0; i < nlongs_reg; i++) 923 bitmap[index + i] |= mask; 924 break; 925 926 case REG_OP_RELEASE: 927 for (i = 0; i < nlongs_reg; i++) 928 bitmap[index + i] &= ~mask; 929 break; 930 } 931 done: 932 return ret; 933 } 934 935 /** 936 * bitmap_find_free_region - find a contiguous aligned mem region 937 * @bitmap: array of unsigned longs corresponding to the bitmap 938 * @bits: number of bits in the bitmap 939 * @order: region size (log base 2 of number of bits) to find 940 * 941 * Find a region of free (zero) bits in a @bitmap of @bits bits and 942 * allocate them (set them to one). Only consider regions of length 943 * a power (@order) of two, aligned to that power of two, which 944 * makes the search algorithm much faster. 945 * 946 * Return the bit offset in bitmap of the allocated region, 947 * or -errno on failure. 948 */ 949 int bitmap_find_free_region(unsigned long *bitmap, int bits, int order) 950 { 951 int pos; /* scans bitmap by regions of size order */ 952 953 for (pos = 0; pos < bits; pos += (1 << order)) 954 if (__reg_op(bitmap, pos, order, REG_OP_ISFREE)) 955 break; 956 if (pos == bits) 957 return -ENOMEM; 958 __reg_op(bitmap, pos, order, REG_OP_ALLOC); 959 return pos; 960 } 961 EXPORT_SYMBOL(bitmap_find_free_region); 962 963 /** 964 * bitmap_release_region - release allocated bitmap region 965 * @bitmap: array of unsigned longs corresponding to the bitmap 966 * @pos: beginning of bit region to release 967 * @order: region size (log base 2 of number of bits) to release 968 * 969 * This is the complement to __bitmap_find_free_region() and releases 970 * the found region (by clearing it in the bitmap). 971 * 972 * No return value. 973 */ 974 void bitmap_release_region(unsigned long *bitmap, int pos, int order) 975 { 976 __reg_op(bitmap, pos, order, REG_OP_RELEASE); 977 } 978 EXPORT_SYMBOL(bitmap_release_region); 979 980 /** 981 * bitmap_allocate_region - allocate bitmap region 982 * @bitmap: array of unsigned longs corresponding to the bitmap 983 * @pos: beginning of bit region to allocate 984 * @order: region size (log base 2 of number of bits) to allocate 985 * 986 * Allocate (set bits in) a specified region of a bitmap. 987 * 988 * Return 0 on success, or %-EBUSY if specified region wasn't 989 * free (not all bits were zero). 990 */ 991 int bitmap_allocate_region(unsigned long *bitmap, int pos, int order) 992 { 993 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE)) 994 return -EBUSY; 995 __reg_op(bitmap, pos, order, REG_OP_ALLOC); 996 return 0; 997 } 998 EXPORT_SYMBOL(bitmap_allocate_region); 999 1000 /** 1001 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order. 1002 * @dst: destination buffer 1003 * @src: bitmap to copy 1004 * @nbits: number of bits in the bitmap 1005 * 1006 * Require nbits % BITS_PER_LONG == 0. 1007 */ 1008 void bitmap_copy_le(void *dst, const unsigned long *src, int nbits) 1009 { 1010 unsigned long *d = dst; 1011 int i; 1012 1013 for (i = 0; i < nbits/BITS_PER_LONG; i++) { 1014 if (BITS_PER_LONG == 64) 1015 d[i] = cpu_to_le64(src[i]); 1016 else 1017 d[i] = cpu_to_le32(src[i]); 1018 } 1019 } 1020 EXPORT_SYMBOL(bitmap_copy_le); 1021