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