linux/include/linux/bitmap.h
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   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef __LINUX_BITMAP_H
   3#define __LINUX_BITMAP_H
   4
   5#ifndef __ASSEMBLY__
   6
   7#include <linux/align.h>
   8#include <linux/bitops.h>
   9#include <linux/limits.h>
  10#include <linux/string.h>
  11#include <linux/types.h>
  12
  13struct device;
  14
  15/*
  16 * bitmaps provide bit arrays that consume one or more unsigned
  17 * longs.  The bitmap interface and available operations are listed
  18 * here, in bitmap.h
  19 *
  20 * Function implementations generic to all architectures are in
  21 * lib/bitmap.c.  Functions implementations that are architecture
  22 * specific are in various include/asm-<arch>/bitops.h headers
  23 * and other arch/<arch> specific files.
  24 *
  25 * See lib/bitmap.c for more details.
  26 */
  27
  28/**
  29 * DOC: bitmap overview
  30 *
  31 * The available bitmap operations and their rough meaning in the
  32 * case that the bitmap is a single unsigned long are thus:
  33 *
  34 * The generated code is more efficient when nbits is known at
  35 * compile-time and at most BITS_PER_LONG.
  36 *
  37 * ::
  38 *
  39 *  bitmap_zero(dst, nbits)                     *dst = 0UL
  40 *  bitmap_fill(dst, nbits)                     *dst = ~0UL
  41 *  bitmap_copy(dst, src, nbits)                *dst = *src
  42 *  bitmap_and(dst, src1, src2, nbits)          *dst = *src1 & *src2
  43 *  bitmap_or(dst, src1, src2, nbits)           *dst = *src1 | *src2
  44 *  bitmap_xor(dst, src1, src2, nbits)          *dst = *src1 ^ *src2
  45 *  bitmap_andnot(dst, src1, src2, nbits)       *dst = *src1 & ~(*src2)
  46 *  bitmap_complement(dst, src, nbits)          *dst = ~(*src)
  47 *  bitmap_equal(src1, src2, nbits)             Are *src1 and *src2 equal?
  48 *  bitmap_intersects(src1, src2, nbits)        Do *src1 and *src2 overlap?
  49 *  bitmap_subset(src1, src2, nbits)            Is *src1 a subset of *src2?
  50 *  bitmap_empty(src, nbits)                    Are all bits zero in *src?
  51 *  bitmap_full(src, nbits)                     Are all bits set in *src?
  52 *  bitmap_weight(src, nbits)                   Hamming Weight: number set bits
  53 *  bitmap_set(dst, pos, nbits)                 Set specified bit area
  54 *  bitmap_clear(dst, pos, nbits)               Clear specified bit area
  55 *  bitmap_find_next_zero_area(buf, len, pos, n, mask)  Find bit free area
  56 *  bitmap_find_next_zero_area_off(buf, len, pos, n, mask, mask_off)  as above
  57 *  bitmap_next_clear_region(map, &start, &end, nbits)  Find next clear region
  58 *  bitmap_next_set_region(map, &start, &end, nbits)  Find next set region
  59 *  bitmap_for_each_clear_region(map, rs, re, start, end)
  60 *                                              Iterate over all clear regions
  61 *  bitmap_for_each_set_region(map, rs, re, start, end)
  62 *                                              Iterate over all set regions
  63 *  bitmap_shift_right(dst, src, n, nbits)      *dst = *src >> n
  64 *  bitmap_shift_left(dst, src, n, nbits)       *dst = *src << n
  65 *  bitmap_cut(dst, src, first, n, nbits)       Cut n bits from first, copy rest
  66 *  bitmap_replace(dst, old, new, mask, nbits)  *dst = (*old & ~(*mask)) | (*new & *mask)
  67 *  bitmap_remap(dst, src, old, new, nbits)     *dst = map(old, new)(src)
  68 *  bitmap_bitremap(oldbit, old, new, nbits)    newbit = map(old, new)(oldbit)
  69 *  bitmap_onto(dst, orig, relmap, nbits)       *dst = orig relative to relmap
  70 *  bitmap_fold(dst, orig, sz, nbits)           dst bits = orig bits mod sz
  71 *  bitmap_parse(buf, buflen, dst, nbits)       Parse bitmap dst from kernel buf
  72 *  bitmap_parse_user(ubuf, ulen, dst, nbits)   Parse bitmap dst from user buf
  73 *  bitmap_parselist(buf, dst, nbits)           Parse bitmap dst from kernel buf
  74 *  bitmap_parselist_user(buf, dst, nbits)      Parse bitmap dst from user buf
  75 *  bitmap_find_free_region(bitmap, bits, order)  Find and allocate bit region
  76 *  bitmap_release_region(bitmap, pos, order)   Free specified bit region
  77 *  bitmap_allocate_region(bitmap, pos, order)  Allocate specified bit region
  78 *  bitmap_from_arr32(dst, buf, nbits)          Copy nbits from u32[] buf to dst
  79 *  bitmap_to_arr32(buf, src, nbits)            Copy nbits from buf to u32[] dst
  80 *  bitmap_get_value8(map, start)               Get 8bit value from map at start
  81 *  bitmap_set_value8(map, value, start)        Set 8bit value to map at start
  82 *
  83 * Note, bitmap_zero() and bitmap_fill() operate over the region of
  84 * unsigned longs, that is, bits behind bitmap till the unsigned long
  85 * boundary will be zeroed or filled as well. Consider to use
  86 * bitmap_clear() or bitmap_set() to make explicit zeroing or filling
  87 * respectively.
  88 */
  89
  90/**
  91 * DOC: bitmap bitops
  92 *
  93 * Also the following operations in asm/bitops.h apply to bitmaps.::
  94 *
  95 *  set_bit(bit, addr)                  *addr |= bit
  96 *  clear_bit(bit, addr)                *addr &= ~bit
  97 *  change_bit(bit, addr)               *addr ^= bit
  98 *  test_bit(bit, addr)                 Is bit set in *addr?
  99 *  test_and_set_bit(bit, addr)         Set bit and return old value
 100 *  test_and_clear_bit(bit, addr)       Clear bit and return old value
 101 *  test_and_change_bit(bit, addr)      Change bit and return old value
 102 *  find_first_zero_bit(addr, nbits)    Position first zero bit in *addr
 103 *  find_first_bit(addr, nbits)         Position first set bit in *addr
 104 *  find_next_zero_bit(addr, nbits, bit)
 105 *                                      Position next zero bit in *addr >= bit
 106 *  find_next_bit(addr, nbits, bit)     Position next set bit in *addr >= bit
 107 *  find_next_and_bit(addr1, addr2, nbits, bit)
 108 *                                      Same as find_next_bit, but in
 109 *                                      (*addr1 & *addr2)
 110 *
 111 */
 112
 113/**
 114 * DOC: declare bitmap
 115 * The DECLARE_BITMAP(name,bits) macro, in linux/types.h, can be used
 116 * to declare an array named 'name' of just enough unsigned longs to
 117 * contain all bit positions from 0 to 'bits' - 1.
 118 */
 119
 120/*
 121 * Allocation and deallocation of bitmap.
 122 * Provided in lib/bitmap.c to avoid circular dependency.
 123 */
 124unsigned long *bitmap_alloc(unsigned int nbits, gfp_t flags);
 125unsigned long *bitmap_zalloc(unsigned int nbits, gfp_t flags);
 126void bitmap_free(const unsigned long *bitmap);
 127
 128/* Managed variants of the above. */
 129unsigned long *devm_bitmap_alloc(struct device *dev,
 130                                 unsigned int nbits, gfp_t flags);
 131unsigned long *devm_bitmap_zalloc(struct device *dev,
 132                                  unsigned int nbits, gfp_t flags);
 133
 134/*
 135 * lib/bitmap.c provides these functions:
 136 */
 137
 138int __bitmap_equal(const unsigned long *bitmap1,
 139                   const unsigned long *bitmap2, unsigned int nbits);
 140bool __pure __bitmap_or_equal(const unsigned long *src1,
 141                              const unsigned long *src2,
 142                              const unsigned long *src3,
 143                              unsigned int nbits);
 144void __bitmap_complement(unsigned long *dst, const unsigned long *src,
 145                         unsigned int nbits);
 146void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
 147                          unsigned int shift, unsigned int nbits);
 148void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
 149                         unsigned int shift, unsigned int nbits);
 150void bitmap_cut(unsigned long *dst, const unsigned long *src,
 151                unsigned int first, unsigned int cut, unsigned int nbits);
 152int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
 153                 const unsigned long *bitmap2, unsigned int nbits);
 154void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
 155                 const unsigned long *bitmap2, unsigned int nbits);
 156void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
 157                  const unsigned long *bitmap2, unsigned int nbits);
 158int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
 159                    const unsigned long *bitmap2, unsigned int nbits);
 160void __bitmap_replace(unsigned long *dst,
 161                      const unsigned long *old, const unsigned long *new,
 162                      const unsigned long *mask, unsigned int nbits);
 163int __bitmap_intersects(const unsigned long *bitmap1,
 164                        const unsigned long *bitmap2, unsigned int nbits);
 165int __bitmap_subset(const unsigned long *bitmap1,
 166                    const unsigned long *bitmap2, unsigned int nbits);
 167int __bitmap_weight(const unsigned long *bitmap, unsigned int nbits);
 168void __bitmap_set(unsigned long *map, unsigned int start, int len);
 169void __bitmap_clear(unsigned long *map, unsigned int start, int len);
 170
 171unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
 172                                             unsigned long size,
 173                                             unsigned long start,
 174                                             unsigned int nr,
 175                                             unsigned long align_mask,
 176                                             unsigned long align_offset);
 177
 178/**
 179 * bitmap_find_next_zero_area - find a contiguous aligned zero area
 180 * @map: The address to base the search on
 181 * @size: The bitmap size in bits
 182 * @start: The bitnumber to start searching at
 183 * @nr: The number of zeroed bits we're looking for
 184 * @align_mask: Alignment mask for zero area
 185 *
 186 * The @align_mask should be one less than a power of 2; the effect is that
 187 * the bit offset of all zero areas this function finds is multiples of that
 188 * power of 2. A @align_mask of 0 means no alignment is required.
 189 */
 190static inline unsigned long
 191bitmap_find_next_zero_area(unsigned long *map,
 192                           unsigned long size,
 193                           unsigned long start,
 194                           unsigned int nr,
 195                           unsigned long align_mask)
 196{
 197        return bitmap_find_next_zero_area_off(map, size, start, nr,
 198                                              align_mask, 0);
 199}
 200
 201int bitmap_parse(const char *buf, unsigned int buflen,
 202                        unsigned long *dst, int nbits);
 203int bitmap_parse_user(const char __user *ubuf, unsigned int ulen,
 204                        unsigned long *dst, int nbits);
 205int bitmap_parselist(const char *buf, unsigned long *maskp,
 206                        int nmaskbits);
 207int bitmap_parselist_user(const char __user *ubuf, unsigned int ulen,
 208                        unsigned long *dst, int nbits);
 209void bitmap_remap(unsigned long *dst, const unsigned long *src,
 210                const unsigned long *old, const unsigned long *new, unsigned int nbits);
 211int bitmap_bitremap(int oldbit,
 212                const unsigned long *old, const unsigned long *new, int bits);
 213void bitmap_onto(unsigned long *dst, const unsigned long *orig,
 214                const unsigned long *relmap, unsigned int bits);
 215void bitmap_fold(unsigned long *dst, const unsigned long *orig,
 216                unsigned int sz, unsigned int nbits);
 217int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order);
 218void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order);
 219int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order);
 220
 221#ifdef __BIG_ENDIAN
 222void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits);
 223#else
 224#define bitmap_copy_le bitmap_copy
 225#endif
 226unsigned int bitmap_ord_to_pos(const unsigned long *bitmap, unsigned int ord, unsigned int nbits);
 227int bitmap_print_to_pagebuf(bool list, char *buf,
 228                                   const unsigned long *maskp, int nmaskbits);
 229
 230#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1)))
 231#define BITMAP_LAST_WORD_MASK(nbits) (~0UL >> (-(nbits) & (BITS_PER_LONG - 1)))
 232
 233static inline void bitmap_zero(unsigned long *dst, unsigned int nbits)
 234{
 235        unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
 236        memset(dst, 0, len);
 237}
 238
 239static inline void bitmap_fill(unsigned long *dst, unsigned int nbits)
 240{
 241        unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
 242        memset(dst, 0xff, len);
 243}
 244
 245static inline void bitmap_copy(unsigned long *dst, const unsigned long *src,
 246                        unsigned int nbits)
 247{
 248        unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
 249        memcpy(dst, src, len);
 250}
 251
 252/*
 253 * Copy bitmap and clear tail bits in last word.
 254 */
 255static inline void bitmap_copy_clear_tail(unsigned long *dst,
 256                const unsigned long *src, unsigned int nbits)
 257{
 258        bitmap_copy(dst, src, nbits);
 259        if (nbits % BITS_PER_LONG)
 260                dst[nbits / BITS_PER_LONG] &= BITMAP_LAST_WORD_MASK(nbits);
 261}
 262
 263/*
 264 * On 32-bit systems bitmaps are represented as u32 arrays internally, and
 265 * therefore conversion is not needed when copying data from/to arrays of u32.
 266 */
 267#if BITS_PER_LONG == 64
 268void bitmap_from_arr32(unsigned long *bitmap, const u32 *buf,
 269                                                        unsigned int nbits);
 270void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap,
 271                                                        unsigned int nbits);
 272#else
 273#define bitmap_from_arr32(bitmap, buf, nbits)                   \
 274        bitmap_copy_clear_tail((unsigned long *) (bitmap),      \
 275                        (const unsigned long *) (buf), (nbits))
 276#define bitmap_to_arr32(buf, bitmap, nbits)                     \
 277        bitmap_copy_clear_tail((unsigned long *) (buf),         \
 278                        (const unsigned long *) (bitmap), (nbits))
 279#endif
 280
 281static inline int bitmap_and(unsigned long *dst, const unsigned long *src1,
 282                        const unsigned long *src2, unsigned int nbits)
 283{
 284        if (small_const_nbits(nbits))
 285                return (*dst = *src1 & *src2 & BITMAP_LAST_WORD_MASK(nbits)) != 0;
 286        return __bitmap_and(dst, src1, src2, nbits);
 287}
 288
 289static inline void bitmap_or(unsigned long *dst, const unsigned long *src1,
 290                        const unsigned long *src2, unsigned int nbits)
 291{
 292        if (small_const_nbits(nbits))
 293                *dst = *src1 | *src2;
 294        else
 295                __bitmap_or(dst, src1, src2, nbits);
 296}
 297
 298static inline void bitmap_xor(unsigned long *dst, const unsigned long *src1,
 299                        const unsigned long *src2, unsigned int nbits)
 300{
 301        if (small_const_nbits(nbits))
 302                *dst = *src1 ^ *src2;
 303        else
 304                __bitmap_xor(dst, src1, src2, nbits);
 305}
 306
 307static inline int bitmap_andnot(unsigned long *dst, const unsigned long *src1,
 308                        const unsigned long *src2, unsigned int nbits)
 309{
 310        if (small_const_nbits(nbits))
 311                return (*dst = *src1 & ~(*src2) & BITMAP_LAST_WORD_MASK(nbits)) != 0;
 312        return __bitmap_andnot(dst, src1, src2, nbits);
 313}
 314
 315static inline void bitmap_complement(unsigned long *dst, const unsigned long *src,
 316                        unsigned int nbits)
 317{
 318        if (small_const_nbits(nbits))
 319                *dst = ~(*src);
 320        else
 321                __bitmap_complement(dst, src, nbits);
 322}
 323
 324#ifdef __LITTLE_ENDIAN
 325#define BITMAP_MEM_ALIGNMENT 8
 326#else
 327#define BITMAP_MEM_ALIGNMENT (8 * sizeof(unsigned long))
 328#endif
 329#define BITMAP_MEM_MASK (BITMAP_MEM_ALIGNMENT - 1)
 330
 331static inline int bitmap_equal(const unsigned long *src1,
 332                        const unsigned long *src2, unsigned int nbits)
 333{
 334        if (small_const_nbits(nbits))
 335                return !((*src1 ^ *src2) & BITMAP_LAST_WORD_MASK(nbits));
 336        if (__builtin_constant_p(nbits & BITMAP_MEM_MASK) &&
 337            IS_ALIGNED(nbits, BITMAP_MEM_ALIGNMENT))
 338                return !memcmp(src1, src2, nbits / 8);
 339        return __bitmap_equal(src1, src2, nbits);
 340}
 341
 342/**
 343 * bitmap_or_equal - Check whether the or of two bitmaps is equal to a third
 344 * @src1:       Pointer to bitmap 1
 345 * @src2:       Pointer to bitmap 2 will be or'ed with bitmap 1
 346 * @src3:       Pointer to bitmap 3. Compare to the result of *@src1 | *@src2
 347 * @nbits:      number of bits in each of these bitmaps
 348 *
 349 * Returns: True if (*@src1 | *@src2) == *@src3, false otherwise
 350 */
 351static inline bool bitmap_or_equal(const unsigned long *src1,
 352                                   const unsigned long *src2,
 353                                   const unsigned long *src3,
 354                                   unsigned int nbits)
 355{
 356        if (!small_const_nbits(nbits))
 357                return __bitmap_or_equal(src1, src2, src3, nbits);
 358
 359        return !(((*src1 | *src2) ^ *src3) & BITMAP_LAST_WORD_MASK(nbits));
 360}
 361
 362static inline int bitmap_intersects(const unsigned long *src1,
 363                        const unsigned long *src2, unsigned int nbits)
 364{
 365        if (small_const_nbits(nbits))
 366                return ((*src1 & *src2) & BITMAP_LAST_WORD_MASK(nbits)) != 0;
 367        else
 368                return __bitmap_intersects(src1, src2, nbits);
 369}
 370
 371static inline int bitmap_subset(const unsigned long *src1,
 372                        const unsigned long *src2, unsigned int nbits)
 373{
 374        if (small_const_nbits(nbits))
 375                return ! ((*src1 & ~(*src2)) & BITMAP_LAST_WORD_MASK(nbits));
 376        else
 377                return __bitmap_subset(src1, src2, nbits);
 378}
 379
 380static inline bool bitmap_empty(const unsigned long *src, unsigned nbits)
 381{
 382        if (small_const_nbits(nbits))
 383                return ! (*src & BITMAP_LAST_WORD_MASK(nbits));
 384
 385        return find_first_bit(src, nbits) == nbits;
 386}
 387
 388static inline bool bitmap_full(const unsigned long *src, unsigned int nbits)
 389{
 390        if (small_const_nbits(nbits))
 391                return ! (~(*src) & BITMAP_LAST_WORD_MASK(nbits));
 392
 393        return find_first_zero_bit(src, nbits) == nbits;
 394}
 395
 396static __always_inline int bitmap_weight(const unsigned long *src, unsigned int nbits)
 397{
 398        if (small_const_nbits(nbits))
 399                return hweight_long(*src & BITMAP_LAST_WORD_MASK(nbits));
 400        return __bitmap_weight(src, nbits);
 401}
 402
 403static __always_inline void bitmap_set(unsigned long *map, unsigned int start,
 404                unsigned int nbits)
 405{
 406        if (__builtin_constant_p(nbits) && nbits == 1)
 407                __set_bit(start, map);
 408        else if (__builtin_constant_p(start & BITMAP_MEM_MASK) &&
 409                 IS_ALIGNED(start, BITMAP_MEM_ALIGNMENT) &&
 410                 __builtin_constant_p(nbits & BITMAP_MEM_MASK) &&
 411                 IS_ALIGNED(nbits, BITMAP_MEM_ALIGNMENT))
 412                memset((char *)map + start / 8, 0xff, nbits / 8);
 413        else
 414                __bitmap_set(map, start, nbits);
 415}
 416
 417static __always_inline void bitmap_clear(unsigned long *map, unsigned int start,
 418                unsigned int nbits)
 419{
 420        if (__builtin_constant_p(nbits) && nbits == 1)
 421                __clear_bit(start, map);
 422        else if (__builtin_constant_p(start & BITMAP_MEM_MASK) &&
 423                 IS_ALIGNED(start, BITMAP_MEM_ALIGNMENT) &&
 424                 __builtin_constant_p(nbits & BITMAP_MEM_MASK) &&
 425                 IS_ALIGNED(nbits, BITMAP_MEM_ALIGNMENT))
 426                memset((char *)map + start / 8, 0, nbits / 8);
 427        else
 428                __bitmap_clear(map, start, nbits);
 429}
 430
 431static inline void bitmap_shift_right(unsigned long *dst, const unsigned long *src,
 432                                unsigned int shift, unsigned int nbits)
 433{
 434        if (small_const_nbits(nbits))
 435                *dst = (*src & BITMAP_LAST_WORD_MASK(nbits)) >> shift;
 436        else
 437                __bitmap_shift_right(dst, src, shift, nbits);
 438}
 439
 440static inline void bitmap_shift_left(unsigned long *dst, const unsigned long *src,
 441                                unsigned int shift, unsigned int nbits)
 442{
 443        if (small_const_nbits(nbits))
 444                *dst = (*src << shift) & BITMAP_LAST_WORD_MASK(nbits);
 445        else
 446                __bitmap_shift_left(dst, src, shift, nbits);
 447}
 448
 449static inline void bitmap_replace(unsigned long *dst,
 450                                  const unsigned long *old,
 451                                  const unsigned long *new,
 452                                  const unsigned long *mask,
 453                                  unsigned int nbits)
 454{
 455        if (small_const_nbits(nbits))
 456                *dst = (*old & ~(*mask)) | (*new & *mask);
 457        else
 458                __bitmap_replace(dst, old, new, mask, nbits);
 459}
 460
 461static inline void bitmap_next_clear_region(unsigned long *bitmap,
 462                                            unsigned int *rs, unsigned int *re,
 463                                            unsigned int end)
 464{
 465        *rs = find_next_zero_bit(bitmap, end, *rs);
 466        *re = find_next_bit(bitmap, end, *rs + 1);
 467}
 468
 469static inline void bitmap_next_set_region(unsigned long *bitmap,
 470                                          unsigned int *rs, unsigned int *re,
 471                                          unsigned int end)
 472{
 473        *rs = find_next_bit(bitmap, end, *rs);
 474        *re = find_next_zero_bit(bitmap, end, *rs + 1);
 475}
 476
 477/*
 478 * Bitmap region iterators.  Iterates over the bitmap between [@start, @end).
 479 * @rs and @re should be integer variables and will be set to start and end
 480 * index of the current clear or set region.
 481 */
 482#define bitmap_for_each_clear_region(bitmap, rs, re, start, end)             \
 483        for ((rs) = (start),                                                 \
 484             bitmap_next_clear_region((bitmap), &(rs), &(re), (end));        \
 485             (rs) < (re);                                                    \
 486             (rs) = (re) + 1,                                                \
 487             bitmap_next_clear_region((bitmap), &(rs), &(re), (end)))
 488
 489#define bitmap_for_each_set_region(bitmap, rs, re, start, end)               \
 490        for ((rs) = (start),                                                 \
 491             bitmap_next_set_region((bitmap), &(rs), &(re), (end));          \
 492             (rs) < (re);                                                    \
 493             (rs) = (re) + 1,                                                \
 494             bitmap_next_set_region((bitmap), &(rs), &(re), (end)))
 495
 496/**
 497 * BITMAP_FROM_U64() - Represent u64 value in the format suitable for bitmap.
 498 * @n: u64 value
 499 *
 500 * Linux bitmaps are internally arrays of unsigned longs, i.e. 32-bit
 501 * integers in 32-bit environment, and 64-bit integers in 64-bit one.
 502 *
 503 * There are four combinations of endianness and length of the word in linux
 504 * ABIs: LE64, BE64, LE32 and BE32.
 505 *
 506 * On 64-bit kernels 64-bit LE and BE numbers are naturally ordered in
 507 * bitmaps and therefore don't require any special handling.
 508 *
 509 * On 32-bit kernels 32-bit LE ABI orders lo word of 64-bit number in memory
 510 * prior to hi, and 32-bit BE orders hi word prior to lo. The bitmap on the
 511 * other hand is represented as an array of 32-bit words and the position of
 512 * bit N may therefore be calculated as: word #(N/32) and bit #(N%32) in that
 513 * word.  For example, bit #42 is located at 10th position of 2nd word.
 514 * It matches 32-bit LE ABI, and we can simply let the compiler store 64-bit
 515 * values in memory as it usually does. But for BE we need to swap hi and lo
 516 * words manually.
 517 *
 518 * With all that, the macro BITMAP_FROM_U64() does explicit reordering of hi and
 519 * lo parts of u64.  For LE32 it does nothing, and for BE environment it swaps
 520 * hi and lo words, as is expected by bitmap.
 521 */
 522#if __BITS_PER_LONG == 64
 523#define BITMAP_FROM_U64(n) (n)
 524#else
 525#define BITMAP_FROM_U64(n) ((unsigned long) ((u64)(n) & ULONG_MAX)), \
 526                                ((unsigned long) ((u64)(n) >> 32))
 527#endif
 528
 529/**
 530 * bitmap_from_u64 - Check and swap words within u64.
 531 *  @mask: source bitmap
 532 *  @dst:  destination bitmap
 533 *
 534 * In 32-bit Big Endian kernel, when using ``(u32 *)(&val)[*]``
 535 * to read u64 mask, we will get the wrong word.
 536 * That is ``(u32 *)(&val)[0]`` gets the upper 32 bits,
 537 * but we expect the lower 32-bits of u64.
 538 */
 539static inline void bitmap_from_u64(unsigned long *dst, u64 mask)
 540{
 541        dst[0] = mask & ULONG_MAX;
 542
 543        if (sizeof(mask) > sizeof(unsigned long))
 544                dst[1] = mask >> 32;
 545}
 546
 547/**
 548 * bitmap_get_value8 - get an 8-bit value within a memory region
 549 * @map: address to the bitmap memory region
 550 * @start: bit offset of the 8-bit value; must be a multiple of 8
 551 *
 552 * Returns the 8-bit value located at the @start bit offset within the @src
 553 * memory region.
 554 */
 555static inline unsigned long bitmap_get_value8(const unsigned long *map,
 556                                              unsigned long start)
 557{
 558        const size_t index = BIT_WORD(start);
 559        const unsigned long offset = start % BITS_PER_LONG;
 560
 561        return (map[index] >> offset) & 0xFF;
 562}
 563
 564/**
 565 * bitmap_set_value8 - set an 8-bit value within a memory region
 566 * @map: address to the bitmap memory region
 567 * @value: the 8-bit value; values wider than 8 bits may clobber bitmap
 568 * @start: bit offset of the 8-bit value; must be a multiple of 8
 569 */
 570static inline void bitmap_set_value8(unsigned long *map, unsigned long value,
 571                                     unsigned long start)
 572{
 573        const size_t index = BIT_WORD(start);
 574        const unsigned long offset = start % BITS_PER_LONG;
 575
 576        map[index] &= ~(0xFFUL << offset);
 577        map[index] |= value << offset;
 578}
 579
 580#endif /* __ASSEMBLY__ */
 581
 582#endif /* __LINUX_BITMAP_H */
 583