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 * @nbits - 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 * @nbits - 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 * @ubuf: pointer to buffer in user space containing string. 321 * @ubuflen: buffer size in bytes. If string is smaller than this 322 * then it must be terminated with a \0. 323 * @maskp: pointer to bitmap array that will contain result. 324 * @nmaskbits: size of bitmap, in bits. 325 * 326 * Commas group hex digits into chunks. Each chunk defines exactly 32 327 * bits of the resultant bitmask. No chunk may specify a value larger 328 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value 329 * then leading 0-bits are prepended. %-EINVAL is returned for illegal 330 * characters and for grouping errors such as "1,,5", ",44", "," and "". 331 * Leading and trailing whitespace accepted, but not embedded whitespace. 332 */ 333 int bitmap_parse(const char __user *ubuf, unsigned int ubuflen, 334 unsigned long *maskp, int nmaskbits) 335 { 336 int c, old_c, totaldigits, ndigits, nchunks, nbits; 337 u32 chunk; 338 339 bitmap_zero(maskp, nmaskbits); 340 341 nchunks = nbits = totaldigits = c = 0; 342 do { 343 chunk = ndigits = 0; 344 345 /* Get the next chunk of the bitmap */ 346 while (ubuflen) { 347 old_c = c; 348 if (get_user(c, ubuf++)) 349 return -EFAULT; 350 ubuflen--; 351 if (isspace(c)) 352 continue; 353 354 /* 355 * If the last character was a space and the current 356 * character isn't '\0', we've got embedded whitespace. 357 * This is a no-no, so throw an error. 358 */ 359 if (totaldigits && c && isspace(old_c)) 360 return -EINVAL; 361 362 /* A '\0' or a ',' signal the end of the chunk */ 363 if (c == '\0' || c == ',') 364 break; 365 366 if (!isxdigit(c)) 367 return -EINVAL; 368 369 /* 370 * Make sure there are at least 4 free bits in 'chunk'. 371 * If not, this hexdigit will overflow 'chunk', so 372 * throw an error. 373 */ 374 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1)) 375 return -EOVERFLOW; 376 377 chunk = (chunk << 4) | unhex(c); 378 ndigits++; totaldigits++; 379 } 380 if (ndigits == 0) 381 return -EINVAL; 382 if (nchunks == 0 && chunk == 0) 383 continue; 384 385 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits); 386 *maskp |= chunk; 387 nchunks++; 388 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ; 389 if (nbits > nmaskbits) 390 return -EOVERFLOW; 391 } while (ubuflen && c == ','); 392 393 return 0; 394 } 395 EXPORT_SYMBOL(bitmap_parse); 396 397 /* 398 * bscnl_emit(buf, buflen, rbot, rtop, bp) 399 * 400 * Helper routine for bitmap_scnlistprintf(). Write decimal number 401 * or range to buf, suppressing output past buf+buflen, with optional 402 * comma-prefix. Return len of what would be written to buf, if it 403 * all fit. 404 */ 405 static inline int bscnl_emit(char *buf, int buflen, int rbot, int rtop, int len) 406 { 407 if (len > 0) 408 len += scnprintf(buf + len, buflen - len, ","); 409 if (rbot == rtop) 410 len += scnprintf(buf + len, buflen - len, "%d", rbot); 411 else 412 len += scnprintf(buf + len, buflen - len, "%d-%d", rbot, rtop); 413 return len; 414 } 415 416 /** 417 * bitmap_scnlistprintf - convert bitmap to list format ASCII string 418 * @buf: byte buffer into which string is placed 419 * @buflen: reserved size of @buf, in bytes 420 * @maskp: pointer to bitmap to convert 421 * @nmaskbits: size of bitmap, in bits 422 * 423 * Output format is a comma-separated list of decimal numbers and 424 * ranges. Consecutively set bits are shown as two hyphen-separated 425 * decimal numbers, the smallest and largest bit numbers set in 426 * the range. Output format is compatible with the format 427 * accepted as input by bitmap_parselist(). 428 * 429 * The return value is the number of characters which would be 430 * generated for the given input, excluding the trailing '\0', as 431 * per ISO C99. 432 */ 433 int bitmap_scnlistprintf(char *buf, unsigned int buflen, 434 const unsigned long *maskp, int nmaskbits) 435 { 436 int len = 0; 437 /* current bit is 'cur', most recently seen range is [rbot, rtop] */ 438 int cur, rbot, rtop; 439 440 rbot = cur = find_first_bit(maskp, nmaskbits); 441 while (cur < nmaskbits) { 442 rtop = cur; 443 cur = find_next_bit(maskp, nmaskbits, cur+1); 444 if (cur >= nmaskbits || cur > rtop + 1) { 445 len = bscnl_emit(buf, buflen, rbot, rtop, len); 446 rbot = cur; 447 } 448 } 449 return len; 450 } 451 EXPORT_SYMBOL(bitmap_scnlistprintf); 452 453 /** 454 * bitmap_parselist - convert list format ASCII string to bitmap 455 * @bp: read nul-terminated user string from this buffer 456 * @maskp: write resulting mask here 457 * @nmaskbits: number of bits in mask to be written 458 * 459 * Input format is a comma-separated list of decimal numbers and 460 * ranges. Consecutively set bits are shown as two hyphen-separated 461 * decimal numbers, the smallest and largest bit numbers set in 462 * the range. 463 * 464 * Returns 0 on success, -errno on invalid input strings. 465 * Error values: 466 * %-EINVAL: second number in range smaller than first 467 * %-EINVAL: invalid character in string 468 * %-ERANGE: bit number specified too large for mask 469 */ 470 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits) 471 { 472 unsigned a, b; 473 474 bitmap_zero(maskp, nmaskbits); 475 do { 476 if (!isdigit(*bp)) 477 return -EINVAL; 478 b = a = simple_strtoul(bp, (char **)&bp, BASEDEC); 479 if (*bp == '-') { 480 bp++; 481 if (!isdigit(*bp)) 482 return -EINVAL; 483 b = simple_strtoul(bp, (char **)&bp, BASEDEC); 484 } 485 if (!(a <= b)) 486 return -EINVAL; 487 if (b >= nmaskbits) 488 return -ERANGE; 489 while (a <= b) { 490 set_bit(a, maskp); 491 a++; 492 } 493 if (*bp == ',') 494 bp++; 495 } while (*bp != '\0' && *bp != '\n'); 496 return 0; 497 } 498 EXPORT_SYMBOL(bitmap_parselist); 499 500 /* 501 * bitmap_pos_to_ord(buf, pos, bits) 502 * @buf: pointer to a bitmap 503 * @pos: a bit position in @buf (0 <= @pos < @bits) 504 * @bits: number of valid bit positions in @buf 505 * 506 * Map the bit at position @pos in @buf (of length @bits) to the 507 * ordinal of which set bit it is. If it is not set or if @pos 508 * is not a valid bit position, map to -1. 509 * 510 * If for example, just bits 4 through 7 are set in @buf, then @pos 511 * values 4 through 7 will get mapped to 0 through 3, respectively, 512 * and other @pos values will get mapped to 0. When @pos value 7 513 * gets mapped to (returns) @ord value 3 in this example, that means 514 * that bit 7 is the 3rd (starting with 0th) set bit in @buf. 515 * 516 * The bit positions 0 through @bits are valid positions in @buf. 517 */ 518 static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits) 519 { 520 int i, ord; 521 522 if (pos < 0 || pos >= bits || !test_bit(pos, buf)) 523 return -1; 524 525 i = find_first_bit(buf, bits); 526 ord = 0; 527 while (i < pos) { 528 i = find_next_bit(buf, bits, i + 1); 529 ord++; 530 } 531 BUG_ON(i != pos); 532 533 return ord; 534 } 535 536 /** 537 * bitmap_ord_to_pos(buf, ord, bits) 538 * @buf: pointer to bitmap 539 * @ord: ordinal bit position (n-th set bit, n >= 0) 540 * @bits: number of valid bit positions in @buf 541 * 542 * Map the ordinal offset of bit @ord in @buf to its position in @buf. 543 * Value of @ord should be in range 0 <= @ord < weight(buf), else 544 * results are undefined. 545 * 546 * If for example, just bits 4 through 7 are set in @buf, then @ord 547 * values 0 through 3 will get mapped to 4 through 7, respectively, 548 * and all other @ord values return undefined values. When @ord value 3 549 * gets mapped to (returns) @pos value 7 in this example, that means 550 * that the 3rd set bit (starting with 0th) is at position 7 in @buf. 551 * 552 * The bit positions 0 through @bits are valid positions in @buf. 553 */ 554 static int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits) 555 { 556 int pos = 0; 557 558 if (ord >= 0 && ord < bits) { 559 int i; 560 561 for (i = find_first_bit(buf, bits); 562 i < bits && ord > 0; 563 i = find_next_bit(buf, bits, i + 1)) 564 ord--; 565 if (i < bits && ord == 0) 566 pos = i; 567 } 568 569 return pos; 570 } 571 572 /** 573 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap 574 * @dst: remapped result 575 * @src: subset to be remapped 576 * @old: defines domain of map 577 * @new: defines range of map 578 * @bits: number of bits in each of these bitmaps 579 * 580 * Let @old and @new define a mapping of bit positions, such that 581 * whatever position is held by the n-th set bit in @old is mapped 582 * to the n-th set bit in @new. In the more general case, allowing 583 * for the possibility that the weight 'w' of @new is less than the 584 * weight of @old, map the position of the n-th set bit in @old to 585 * the position of the m-th set bit in @new, where m == n % w. 586 * 587 * If either of the @old and @new bitmaps are empty, or if @src and 588 * @dst point to the same location, then this routine copies @src 589 * to @dst. 590 * 591 * The positions of unset bits in @old are mapped to themselves 592 * (the identify map). 593 * 594 * Apply the above specified mapping to @src, placing the result in 595 * @dst, clearing any bits previously set in @dst. 596 * 597 * For example, lets say that @old has bits 4 through 7 set, and 598 * @new has bits 12 through 15 set. This defines the mapping of bit 599 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other 600 * bit positions unchanged. So if say @src comes into this routine 601 * with bits 1, 5 and 7 set, then @dst should leave with bits 1, 602 * 13 and 15 set. 603 */ 604 void bitmap_remap(unsigned long *dst, const unsigned long *src, 605 const unsigned long *old, const unsigned long *new, 606 int bits) 607 { 608 int oldbit, w; 609 610 if (dst == src) /* following doesn't handle inplace remaps */ 611 return; 612 bitmap_zero(dst, bits); 613 614 w = bitmap_weight(new, bits); 615 for (oldbit = find_first_bit(src, bits); 616 oldbit < bits; 617 oldbit = find_next_bit(src, bits, oldbit + 1)) { 618 int n = bitmap_pos_to_ord(old, oldbit, bits); 619 if (n < 0 || w == 0) 620 set_bit(oldbit, dst); /* identity map */ 621 else 622 set_bit(bitmap_ord_to_pos(new, n % w, bits), dst); 623 } 624 } 625 EXPORT_SYMBOL(bitmap_remap); 626 627 /** 628 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit 629 * @oldbit: bit position to be mapped 630 * @old: defines domain of map 631 * @new: defines range of map 632 * @bits: number of bits in each of these bitmaps 633 * 634 * Let @old and @new define a mapping of bit positions, such that 635 * whatever position is held by the n-th set bit in @old is mapped 636 * to the n-th set bit in @new. In the more general case, allowing 637 * for the possibility that the weight 'w' of @new is less than the 638 * weight of @old, map the position of the n-th set bit in @old to 639 * the position of the m-th set bit in @new, where m == n % w. 640 * 641 * The positions of unset bits in @old are mapped to themselves 642 * (the identify map). 643 * 644 * Apply the above specified mapping to bit position @oldbit, returning 645 * the new bit position. 646 * 647 * For example, lets say that @old has bits 4 through 7 set, and 648 * @new has bits 12 through 15 set. This defines the mapping of bit 649 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other 650 * bit positions unchanged. So if say @oldbit is 5, then this routine 651 * returns 13. 652 */ 653 int bitmap_bitremap(int oldbit, const unsigned long *old, 654 const unsigned long *new, int bits) 655 { 656 int w = bitmap_weight(new, bits); 657 int n = bitmap_pos_to_ord(old, oldbit, bits); 658 if (n < 0 || w == 0) 659 return oldbit; 660 else 661 return bitmap_ord_to_pos(new, n % w, bits); 662 } 663 EXPORT_SYMBOL(bitmap_bitremap); 664 665 /* 666 * Common code for bitmap_*_region() routines. 667 * bitmap: array of unsigned longs corresponding to the bitmap 668 * pos: the beginning of the region 669 * order: region size (log base 2 of number of bits) 670 * reg_op: operation(s) to perform on that region of bitmap 671 * 672 * Can set, verify and/or release a region of bits in a bitmap, 673 * depending on which combination of REG_OP_* flag bits is set. 674 * 675 * A region of a bitmap is a sequence of bits in the bitmap, of 676 * some size '1 << order' (a power of two), aligned to that same 677 * '1 << order' power of two. 678 * 679 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits). 680 * Returns 0 in all other cases and reg_ops. 681 */ 682 683 enum { 684 REG_OP_ISFREE, /* true if region is all zero bits */ 685 REG_OP_ALLOC, /* set all bits in region */ 686 REG_OP_RELEASE, /* clear all bits in region */ 687 }; 688 689 static int __reg_op(unsigned long *bitmap, int pos, int order, int reg_op) 690 { 691 int nbits_reg; /* number of bits in region */ 692 int index; /* index first long of region in bitmap */ 693 int offset; /* bit offset region in bitmap[index] */ 694 int nlongs_reg; /* num longs spanned by region in bitmap */ 695 int nbitsinlong; /* num bits of region in each spanned long */ 696 unsigned long mask; /* bitmask for one long of region */ 697 int i; /* scans bitmap by longs */ 698 int ret = 0; /* return value */ 699 700 /* 701 * Either nlongs_reg == 1 (for small orders that fit in one long) 702 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.) 703 */ 704 nbits_reg = 1 << order; 705 index = pos / BITS_PER_LONG; 706 offset = pos - (index * BITS_PER_LONG); 707 nlongs_reg = BITS_TO_LONGS(nbits_reg); 708 nbitsinlong = min(nbits_reg, BITS_PER_LONG); 709 710 /* 711 * Can't do "mask = (1UL << nbitsinlong) - 1", as that 712 * overflows if nbitsinlong == BITS_PER_LONG. 713 */ 714 mask = (1UL << (nbitsinlong - 1)); 715 mask += mask - 1; 716 mask <<= offset; 717 718 switch (reg_op) { 719 case REG_OP_ISFREE: 720 for (i = 0; i < nlongs_reg; i++) { 721 if (bitmap[index + i] & mask) 722 goto done; 723 } 724 ret = 1; /* all bits in region free (zero) */ 725 break; 726 727 case REG_OP_ALLOC: 728 for (i = 0; i < nlongs_reg; i++) 729 bitmap[index + i] |= mask; 730 break; 731 732 case REG_OP_RELEASE: 733 for (i = 0; i < nlongs_reg; i++) 734 bitmap[index + i] &= ~mask; 735 break; 736 } 737 done: 738 return ret; 739 } 740 741 /** 742 * bitmap_find_free_region - find a contiguous aligned mem region 743 * @bitmap: array of unsigned longs corresponding to the bitmap 744 * @bits: number of bits in the bitmap 745 * @order: region size (log base 2 of number of bits) to find 746 * 747 * Find a region of free (zero) bits in a @bitmap of @bits bits and 748 * allocate them (set them to one). Only consider regions of length 749 * a power (@order) of two, aligned to that power of two, which 750 * makes the search algorithm much faster. 751 * 752 * Return the bit offset in bitmap of the allocated region, 753 * or -errno on failure. 754 */ 755 int bitmap_find_free_region(unsigned long *bitmap, int bits, int order) 756 { 757 int pos; /* scans bitmap by regions of size order */ 758 759 for (pos = 0; pos < bits; pos += (1 << order)) 760 if (__reg_op(bitmap, pos, order, REG_OP_ISFREE)) 761 break; 762 if (pos == bits) 763 return -ENOMEM; 764 __reg_op(bitmap, pos, order, REG_OP_ALLOC); 765 return pos; 766 } 767 EXPORT_SYMBOL(bitmap_find_free_region); 768 769 /** 770 * bitmap_release_region - release allocated bitmap region 771 * @bitmap: array of unsigned longs corresponding to the bitmap 772 * @pos: beginning of bit region to release 773 * @order: region size (log base 2 of number of bits) to release 774 * 775 * This is the complement to __bitmap_find_free_region and releases 776 * the found region (by clearing it in the bitmap). 777 * 778 * No return value. 779 */ 780 void bitmap_release_region(unsigned long *bitmap, int pos, int order) 781 { 782 __reg_op(bitmap, pos, order, REG_OP_RELEASE); 783 } 784 EXPORT_SYMBOL(bitmap_release_region); 785 786 /** 787 * bitmap_allocate_region - allocate bitmap region 788 * @bitmap: array of unsigned longs corresponding to the bitmap 789 * @pos: beginning of bit region to allocate 790 * @order: region size (log base 2 of number of bits) to allocate 791 * 792 * Allocate (set bits in) a specified region of a bitmap. 793 * 794 * Return 0 on success, or %-EBUSY if specified region wasn't 795 * free (not all bits were zero). 796 */ 797 int bitmap_allocate_region(unsigned long *bitmap, int pos, int order) 798 { 799 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE)) 800 return -EBUSY; 801 __reg_op(bitmap, pos, order, REG_OP_ALLOC); 802 return 0; 803 } 804 EXPORT_SYMBOL(bitmap_allocate_region); 805