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/types.h>
   8#include <linux/bitops.h>
   9#include <linux/string.h>
  10#include <linux/kernel.h>
  11
  12/*
  13 * bitmaps provide bit arrays that consume one or more unsigned
  14 * longs.  The bitmap interface and available operations are listed
  15 * here, in bitmap.h
  16 *
  17 * Function implementations generic to all architectures are in
  18 * lib/bitmap.c.  Functions implementations that are architecture
  19 * specific are in various include/asm-<arch>/bitops.h headers
  20 * and other arch/<arch> specific files.
  21 *
  22 * See lib/bitmap.c for more details.
  23 */
  24
  25/**
  26 * DOC: bitmap overview
  27 *
  28 * The available bitmap operations and their rough meaning in the
  29 * case that the bitmap is a single unsigned long are thus:
  30 *
  31 * The generated code is more efficient when nbits is known at
  32 * compile-time and at most BITS_PER_LONG.
  33 *
  34 * ::
  35 *
  36 *  bitmap_zero(dst, nbits)                     *dst = 0UL
  37 *  bitmap_fill(dst, nbits)                     *dst = ~0UL
  38 *  bitmap_copy(dst, src, nbits)                *dst = *src
  39 *  bitmap_and(dst, src1, src2, nbits)          *dst = *src1 & *src2
  40 *  bitmap_or(dst, src1, src2, nbits)           *dst = *src1 | *src2
  41 *  bitmap_xor(dst, src1, src2, nbits)          *dst = *src1 ^ *src2
  42 *  bitmap_andnot(dst, src1, src2, nbits)       *dst = *src1 & ~(*src2)
  43 *  bitmap_complement(dst, src, nbits)          *dst = ~(*src)
  44 *  bitmap_equal(src1, src2, nbits)             Are *src1 and *src2 equal?
  45 *  bitmap_intersects(src1, src2, nbits)        Do *src1 and *src2 overlap?
  46 *  bitmap_subset(src1, src2, nbits)            Is *src1 a subset of *src2?
  47 *  bitmap_empty(src, nbits)                    Are all bits zero in *src?
  48 *  bitmap_full(src, nbits)                     Are all bits set in *src?
  49 *  bitmap_weight(src, nbits)                   Hamming Weight: number set bits
  50 *  bitmap_set(dst, pos, nbits)                 Set specified bit area
  51 *  bitmap_clear(dst, pos, nbits)               Clear specified bit area
  52 *  bitmap_find_next_zero_area(buf, len, pos, n, mask)  Find bit free area
  53 *  bitmap_find_next_zero_area_off(buf, len, pos, n, mask, mask_off)  as above
  54 *  bitmap_next_clear_region(map, &start, &end, nbits)  Find next clear region
  55 *  bitmap_next_set_region(map, &start, &end, nbits)  Find next set region
  56 *  bitmap_for_each_clear_region(map, rs, re, start, end)
  57 *                                              Iterate over all clear regions
  58 *  bitmap_for_each_set_region(map, rs, re, start, end)
  59 *                                              Iterate over all set regions
  60 *  bitmap_shift_right(dst, src, n, nbits)      *dst = *src >> n
  61 *  bitmap_shift_left(dst, src, n, nbits)       *dst = *src << n
  62 *  bitmap_cut(dst, src, first, n, nbits)       Cut n bits from first, copy rest
  63 *  bitmap_replace(dst, old, new, mask, nbits)  *dst = (*old & ~(*mask)) | (*new & *mask)
  64 *  bitmap_remap(dst, src, old, new, nbits)     *dst = map(old, new)(src)
  65 *  bitmap_bitremap(oldbit, old, new, nbits)    newbit = map(old, new)(oldbit)
  66 *  bitmap_onto(dst, orig, relmap, nbits)       *dst = orig relative to relmap
  67 *  bitmap_fold(dst, orig, sz, nbits)           dst bits = orig bits mod sz
  68 *  bitmap_parse(buf, buflen, dst, nbits)       Parse bitmap dst from kernel buf
  69 *  bitmap_parse_user(ubuf, ulen, dst, nbits)   Parse bitmap dst from user buf
  70 *  bitmap_parselist(buf, dst, nbits)           Parse bitmap dst from kernel buf
  71 *  bitmap_parselist_user(buf, dst, nbits)      Parse bitmap dst from user buf
  72 *  bitmap_find_free_region(bitmap, bits, order)  Find and allocate bit region
  73 *  bitmap_release_region(bitmap, pos, order)   Free specified bit region
  74 *  bitmap_allocate_region(bitmap, pos, order)  Allocate specified bit region
  75 *  bitmap_from_arr32(dst, buf, nbits)          Copy nbits from u32[] buf to dst
  76 *  bitmap_to_arr32(buf, src, nbits)            Copy nbits from buf to u32[] dst
  77 *  bitmap_get_value8(map, start)               Get 8bit value from map at start
  78 *  bitmap_set_value8(map, value, start)        Set 8bit value to map at start
  79 *
  80 * Note, bitmap_zero() and bitmap_fill() operate over the region of
  81 * unsigned longs, that is, bits behind bitmap till the unsigned long
  82 * boundary will be zeroed or filled as well. Consider to use
  83 * bitmap_clear() or bitmap_set() to make explicit zeroing or filling
  84 * respectively.
  85 */
  86
  87/**
  88 * DOC: bitmap bitops
  89 *
  90 * Also the following operations in asm/bitops.h apply to bitmaps.::
  91 *
  92 *  set_bit(bit, addr)                  *addr |= bit
  93 *  clear_bit(bit, addr)                *addr &= ~bit
  94 *  change_bit(bit, addr)               *addr ^= bit
  95 *  test_bit(bit, addr)                 Is bit set in *addr?
  96 *  test_and_set_bit(bit, addr)         Set bit and return old value
  97 *  test_and_clear_bit(bit, addr)       Clear bit and return old value
  98 *  test_and_change_bit(bit, addr)      Change bit and return old value
  99 *  find_first_zero_bit(addr, nbits)    Position first zero bit in *addr
 100 *  find_first_bit(addr, nbits)         Position first set bit in *addr
 101 *  find_next_zero_bit(addr, nbits, bit)
 102 *                                      Position next zero bit in *addr >= bit
 103 *  find_next_bit(addr, nbits, bit)     Position next set bit in *addr >= bit
 104 *  find_next_and_bit(addr1, addr2, nbits, bit)
 105 *                                      Same as find_next_bit, but in
 106 *                                      (*addr1 & *addr2)
 107 *
 108 */
 109
 110/**
 111 * DOC: declare bitmap
 112 * The DECLARE_BITMAP(name,bits) macro, in linux/types.h, can be used
 113 * to declare an array named 'name' of just enough unsigned longs to
 114 * contain all bit positions from 0 to 'bits' - 1.
 115 */
 116
 117/*
 118 * Allocation and deallocation of bitmap.
 119 * Provided in lib/bitmap.c to avoid circular dependency.
 120 */
 121extern unsigned long *bitmap_alloc(unsigned int nbits, gfp_t flags);
 122extern unsigned long *bitmap_zalloc(unsigned int nbits, gfp_t flags);
 123extern void bitmap_free(const unsigned long *bitmap);
 124
 125/*
 126 * lib/bitmap.c provides these functions:
 127 */
 128
 129extern int __bitmap_empty(const unsigned long *bitmap, unsigned int nbits);
 130extern int __bitmap_full(const unsigned long *bitmap, unsigned int nbits);
 131extern int __bitmap_equal(const unsigned long *bitmap1,
 132                          const unsigned long *bitmap2, unsigned int nbits);
 133extern bool __pure __bitmap_or_equal(const unsigned long *src1,
 134                                     const unsigned long *src2,
 135                                     const unsigned long *src3,
 136                                     unsigned int nbits);
 137extern void __bitmap_complement(unsigned long *dst, const unsigned long *src,
 138                        unsigned int nbits);
 139extern void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
 140                                unsigned int shift, unsigned int nbits);
 141extern void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
 142                                unsigned int shift, unsigned int nbits);
 143extern void bitmap_cut(unsigned long *dst, const unsigned long *src,
 144                       unsigned int first, unsigned int cut,
 145                       unsigned int nbits);
 146extern int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
 147                        const unsigned long *bitmap2, unsigned int nbits);
 148extern void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
 149                        const unsigned long *bitmap2, unsigned int nbits);
 150extern void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
 151                        const unsigned long *bitmap2, unsigned int nbits);
 152extern int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
 153                        const unsigned long *bitmap2, unsigned int nbits);
 154extern void __bitmap_replace(unsigned long *dst,
 155                        const unsigned long *old, const unsigned long *new,
 156                        const unsigned long *mask, unsigned int nbits);
 157extern int __bitmap_intersects(const unsigned long *bitmap1,
 158                        const unsigned long *bitmap2, unsigned int nbits);
 159extern int __bitmap_subset(const unsigned long *bitmap1,
 160                        const unsigned long *bitmap2, unsigned int nbits);
 161extern int __bitmap_weight(const unsigned long *bitmap, unsigned int nbits);
 162extern void __bitmap_set(unsigned long *map, unsigned int start, int len);
 163extern void __bitmap_clear(unsigned long *map, unsigned int start, int len);
 164
 165extern unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
 166                                                    unsigned long size,
 167                                                    unsigned long start,
 168                                                    unsigned int nr,
 169                                                    unsigned long align_mask,
 170                                                    unsigned long align_offset);
 171
 172/**
 173 * bitmap_find_next_zero_area - find a contiguous aligned zero area
 174 * @map: The address to base the search on
 175 * @size: The bitmap size in bits
 176 * @start: The bitnumber to start searching at
 177 * @nr: The number of zeroed bits we're looking for
 178 * @align_mask: Alignment mask for zero area
 179 *
 180 * The @align_mask should be one less than a power of 2; the effect is that
 181 * the bit offset of all zero areas this function finds is multiples of that
 182 * power of 2. A @align_mask of 0 means no alignment is required.
 183 */
 184static inline unsigned long
 185bitmap_find_next_zero_area(unsigned long *map,
 186                           unsigned long size,
 187                           unsigned long start,
 188                           unsigned int nr,
 189                           unsigned long align_mask)
 190{
 191        return bitmap_find_next_zero_area_off(map, size, start, nr,
 192                                              align_mask, 0);
 193}
 194
 195extern int bitmap_parse(const char *buf, unsigned int buflen,
 196                        unsigned long *dst, int nbits);
 197extern int bitmap_parse_user(const char __user *ubuf, unsigned int ulen,
 198                        unsigned long *dst, int nbits);
 199extern int bitmap_parselist(const char *buf, unsigned long *maskp,
 200                        int nmaskbits);
 201extern int bitmap_parselist_user(const char __user *ubuf, unsigned int ulen,
 202                        unsigned long *dst, int nbits);
 203extern void bitmap_remap(unsigned long *dst, const unsigned long *src,
 204                const unsigned long *old, const unsigned long *new, unsigned int nbits);
 205extern int bitmap_bitremap(int oldbit,
 206                const unsigned long *old, const unsigned long *new, int bits);
 207extern void bitmap_onto(unsigned long *dst, const unsigned long *orig,
 208                const unsigned long *relmap, unsigned int bits);
 209extern void bitmap_fold(unsigned long *dst, const unsigned long *orig,
 210                unsigned int sz, unsigned int nbits);
 211extern int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order);
 212extern void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order);
 213extern int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order);
 214
 215#ifdef __BIG_ENDIAN
 216extern void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits);
 217#else
 218#define bitmap_copy_le bitmap_copy
 219#endif
 220extern unsigned int bitmap_ord_to_pos(const unsigned long *bitmap, unsigned int ord, unsigned int nbits);
 221extern int bitmap_print_to_pagebuf(bool list, char *buf,
 222                                   const unsigned long *maskp, int nmaskbits);
 223
 224#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1)))
 225#define BITMAP_LAST_WORD_MASK(nbits) (~0UL >> (-(nbits) & (BITS_PER_LONG - 1)))
 226
 227/*
 228 * The static inlines below do not handle constant nbits==0 correctly,
 229 * so make such users (should any ever turn up) call the out-of-line
 230 * versions.
 231 */
 232#define small_const_nbits(nbits) \
 233        (__builtin_constant_p(nbits) && (nbits) <= BITS_PER_LONG && (nbits) > 0)
 234
 235static inline void bitmap_zero(unsigned long *dst, unsigned int nbits)
 236{
 237        unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
 238        memset(dst, 0, len);
 239}
 240
 241static inline void bitmap_fill(unsigned long *dst, unsigned int nbits)
 242{
 243        unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
 244        memset(dst, 0xff, len);
 245}
 246
 247static inline void bitmap_copy(unsigned long *dst, const unsigned long *src,
 248                        unsigned int nbits)
 249{
 250        unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
 251        memcpy(dst, src, len);
 252}
 253
 254/*
 255 * Copy bitmap and clear tail bits in last word.
 256 */
 257static inline void bitmap_copy_clear_tail(unsigned long *dst,
 258                const unsigned long *src, unsigned int nbits)
 259{
 260        bitmap_copy(dst, src, nbits);
 261        if (nbits % BITS_PER_LONG)
 262                dst[nbits / BITS_PER_LONG] &= BITMAP_LAST_WORD_MASK(nbits);
 263}
 264
 265/*
 266 * On 32-bit systems bitmaps are represented as u32 arrays internally, and
 267 * therefore conversion is not needed when copying data from/to arrays of u32.
 268 */
 269#if BITS_PER_LONG == 64
 270extern void bitmap_from_arr32(unsigned long *bitmap, const u32 *buf,
 271                                                        unsigned int nbits);
 272extern void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap,
 273                                                        unsigned int nbits);
 274#else
 275#define bitmap_from_arr32(bitmap, buf, nbits)                   \
 276        bitmap_copy_clear_tail((unsigned long *) (bitmap),      \
 277                        (const unsigned long *) (buf), (nbits))
 278#define bitmap_to_arr32(buf, bitmap, nbits)                     \
 279        bitmap_copy_clear_tail((unsigned long *) (buf),         \
 280                        (const unsigned long *) (bitmap), (nbits))
 281#endif
 282
 283static inline int bitmap_and(unsigned long *dst, const unsigned long *src1,
 284                        const unsigned long *src2, unsigned int nbits)
 285{
 286        if (small_const_nbits(nbits))
 287                return (*dst = *src1 & *src2 & BITMAP_LAST_WORD_MASK(nbits)) != 0;
 288        return __bitmap_and(dst, src1, src2, nbits);
 289}
 290
 291static inline void bitmap_or(unsigned long *dst, const unsigned long *src1,
 292                        const unsigned long *src2, unsigned int nbits)
 293{
 294        if (small_const_nbits(nbits))
 295                *dst = *src1 | *src2;
 296        else
 297                __bitmap_or(dst, src1, src2, nbits);
 298}
 299
 300static inline void bitmap_xor(unsigned long *dst, const unsigned long *src1,
 301                        const unsigned long *src2, unsigned int nbits)
 302{
 303        if (small_const_nbits(nbits))
 304                *dst = *src1 ^ *src2;
 305        else
 306                __bitmap_xor(dst, src1, src2, nbits);
 307}
 308
 309static inline int bitmap_andnot(unsigned long *dst, const unsigned long *src1,
 310                        const unsigned long *src2, unsigned int nbits)
 311{
 312        if (small_const_nbits(nbits))
 313                return (*dst = *src1 & ~(*src2) & BITMAP_LAST_WORD_MASK(nbits)) != 0;
 314        return __bitmap_andnot(dst, src1, src2, nbits);
 315}
 316
 317static inline void bitmap_complement(unsigned long *dst, const unsigned long *src,
 318                        unsigned int nbits)
 319{
 320        if (small_const_nbits(nbits))
 321                *dst = ~(*src);
 322        else
 323                __bitmap_complement(dst, src, nbits);
 324}
 325
 326#ifdef __LITTLE_ENDIAN
 327#define BITMAP_MEM_ALIGNMENT 8
 328#else
 329#define BITMAP_MEM_ALIGNMENT (8 * sizeof(unsigned long))
 330#endif
 331#define BITMAP_MEM_MASK (BITMAP_MEM_ALIGNMENT - 1)
 332
 333static inline int bitmap_equal(const unsigned long *src1,
 334                        const unsigned long *src2, unsigned int nbits)
 335{
 336        if (small_const_nbits(nbits))
 337                return !((*src1 ^ *src2) & BITMAP_LAST_WORD_MASK(nbits));
 338        if (__builtin_constant_p(nbits & BITMAP_MEM_MASK) &&
 339            IS_ALIGNED(nbits, BITMAP_MEM_ALIGNMENT))
 340                return !memcmp(src1, src2, nbits / 8);
 341        return __bitmap_equal(src1, src2, nbits);
 342}
 343
 344/**
 345 * bitmap_or_equal - Check whether the or of two bitmaps is equal to a third
 346 * @src1:       Pointer to bitmap 1
 347 * @src2:       Pointer to bitmap 2 will be or'ed with bitmap 1
 348 * @src3:       Pointer to bitmap 3. Compare to the result of *@src1 | *@src2
 349 * @nbits:      number of bits in each of these bitmaps
 350 *
 351 * Returns: True if (*@src1 | *@src2) == *@src3, false otherwise
 352 */
 353static inline bool bitmap_or_equal(const unsigned long *src1,
 354                                   const unsigned long *src2,
 355                                   const unsigned long *src3,
 356                                   unsigned int nbits)
 357{
 358        if (!small_const_nbits(nbits))
 359                return __bitmap_or_equal(src1, src2, src3, nbits);
 360
 361        return !(((*src1 | *src2) ^ *src3) & BITMAP_LAST_WORD_MASK(nbits));
 362}
 363
 364static inline int bitmap_intersects(const unsigned long *src1,
 365                        const unsigned long *src2, unsigned int nbits)
 366{
 367        if (small_const_nbits(nbits))
 368                return ((*src1 & *src2) & BITMAP_LAST_WORD_MASK(nbits)) != 0;
 369        else
 370                return __bitmap_intersects(src1, src2, nbits);
 371}
 372
 373static inline int bitmap_subset(const unsigned long *src1,
 374                        const unsigned long *src2, unsigned int nbits)
 375{
 376        if (small_const_nbits(nbits))
 377                return ! ((*src1 & ~(*src2)) & BITMAP_LAST_WORD_MASK(nbits));
 378        else
 379                return __bitmap_subset(src1, src2, nbits);
 380}
 381
 382static inline int bitmap_empty(const unsigned long *src, unsigned nbits)
 383{
 384        if (small_const_nbits(nbits))
 385                return ! (*src & BITMAP_LAST_WORD_MASK(nbits));
 386
 387        return find_first_bit(src, nbits) == nbits;
 388}
 389
 390static inline int bitmap_full(const unsigned long *src, unsigned int nbits)
 391{
 392        if (small_const_nbits(nbits))
 393                return ! (~(*src) & BITMAP_LAST_WORD_MASK(nbits));
 394
 395        return find_first_zero_bit(src, nbits) == nbits;
 396}
 397
 398static __always_inline int bitmap_weight(const unsigned long *src, unsigned int nbits)
 399{
 400        if (small_const_nbits(nbits))
 401                return hweight_long(*src & BITMAP_LAST_WORD_MASK(nbits));
 402        return __bitmap_weight(src, nbits);
 403}
 404
 405static __always_inline void bitmap_set(unsigned long *map, unsigned int start,
 406                unsigned int nbits)
 407{
 408        if (__builtin_constant_p(nbits) && nbits == 1)
 409                __set_bit(start, map);
 410        else if (__builtin_constant_p(start & BITMAP_MEM_MASK) &&
 411                 IS_ALIGNED(start, BITMAP_MEM_ALIGNMENT) &&
 412                 __builtin_constant_p(nbits & BITMAP_MEM_MASK) &&
 413                 IS_ALIGNED(nbits, BITMAP_MEM_ALIGNMENT))
 414                memset((char *)map + start / 8, 0xff, nbits / 8);
 415        else
 416                __bitmap_set(map, start, nbits);
 417}
 418
 419static __always_inline void bitmap_clear(unsigned long *map, unsigned int start,
 420                unsigned int nbits)
 421{
 422        if (__builtin_constant_p(nbits) && nbits == 1)
 423                __clear_bit(start, map);
 424        else if (__builtin_constant_p(start & BITMAP_MEM_MASK) &&
 425                 IS_ALIGNED(start, BITMAP_MEM_ALIGNMENT) &&
 426                 __builtin_constant_p(nbits & BITMAP_MEM_MASK) &&
 427                 IS_ALIGNED(nbits, BITMAP_MEM_ALIGNMENT))
 428                memset((char *)map + start / 8, 0, nbits / 8);
 429        else
 430                __bitmap_clear(map, start, nbits);
 431}
 432
 433static inline void bitmap_shift_right(unsigned long *dst, const unsigned long *src,
 434                                unsigned int shift, unsigned int nbits)
 435{
 436        if (small_const_nbits(nbits))
 437                *dst = (*src & BITMAP_LAST_WORD_MASK(nbits)) >> shift;
 438        else
 439                __bitmap_shift_right(dst, src, shift, nbits);
 440}
 441
 442static inline void bitmap_shift_left(unsigned long *dst, const unsigned long *src,
 443                                unsigned int shift, unsigned int nbits)
 444{
 445        if (small_const_nbits(nbits))
 446                *dst = (*src << shift) & BITMAP_LAST_WORD_MASK(nbits);
 447        else
 448                __bitmap_shift_left(dst, src, shift, nbits);
 449}
 450
 451static inline void bitmap_replace(unsigned long *dst,
 452                                  const unsigned long *old,
 453                                  const unsigned long *new,
 454                                  const unsigned long *mask,
 455                                  unsigned int nbits)
 456{
 457        if (small_const_nbits(nbits))
 458                *dst = (*old & ~(*mask)) | (*new & *mask);
 459        else
 460                __bitmap_replace(dst, old, new, mask, nbits);
 461}
 462
 463static inline void bitmap_next_clear_region(unsigned long *bitmap,
 464                                            unsigned int *rs, unsigned int *re,
 465                                            unsigned int end)
 466{
 467        *rs = find_next_zero_bit(bitmap, end, *rs);
 468        *re = find_next_bit(bitmap, end, *rs + 1);
 469}
 470
 471static inline void bitmap_next_set_region(unsigned long *bitmap,
 472                                          unsigned int *rs, unsigned int *re,
 473                                          unsigned int end)
 474{
 475        *rs = find_next_bit(bitmap, end, *rs);
 476        *re = find_next_zero_bit(bitmap, end, *rs + 1);
 477}
 478
 479/*
 480 * Bitmap region iterators.  Iterates over the bitmap between [@start, @end).
 481 * @rs and @re should be integer variables and will be set to start and end
 482 * index of the current clear or set region.
 483 */
 484#define bitmap_for_each_clear_region(bitmap, rs, re, start, end)             \
 485        for ((rs) = (start),                                                 \
 486             bitmap_next_clear_region((bitmap), &(rs), &(re), (end));        \
 487             (rs) < (re);                                                    \
 488             (rs) = (re) + 1,                                                \
 489             bitmap_next_clear_region((bitmap), &(rs), &(re), (end)))
 490
 491#define bitmap_for_each_set_region(bitmap, rs, re, start, end)               \
 492        for ((rs) = (start),                                                 \
 493             bitmap_next_set_region((bitmap), &(rs), &(re), (end));          \
 494             (rs) < (re);                                                    \
 495             (rs) = (re) + 1,                                                \
 496             bitmap_next_set_region((bitmap), &(rs), &(re), (end)))
 497
 498/**
 499 * BITMAP_FROM_U64() - Represent u64 value in the format suitable for bitmap.
 500 * @n: u64 value
 501 *
 502 * Linux bitmaps are internally arrays of unsigned longs, i.e. 32-bit
 503 * integers in 32-bit environment, and 64-bit integers in 64-bit one.
 504 *
 505 * There are four combinations of endianness and length of the word in linux
 506 * ABIs: LE64, BE64, LE32 and BE32.
 507 *
 508 * On 64-bit kernels 64-bit LE and BE numbers are naturally ordered in
 509 * bitmaps and therefore don't require any special handling.
 510 *
 511 * On 32-bit kernels 32-bit LE ABI orders lo word of 64-bit number in memory
 512 * prior to hi, and 32-bit BE orders hi word prior to lo. The bitmap on the
 513 * other hand is represented as an array of 32-bit words and the position of
 514 * bit N may therefore be calculated as: word #(N/32) and bit #(N%32) in that
 515 * word.  For example, bit #42 is located at 10th position of 2nd word.
 516 * It matches 32-bit LE ABI, and we can simply let the compiler store 64-bit
 517 * values in memory as it usually does. But for BE we need to swap hi and lo
 518 * words manually.
 519 *
 520 * With all that, the macro BITMAP_FROM_U64() does explicit reordering of hi and
 521 * lo parts of u64.  For LE32 it does nothing, and for BE environment it swaps
 522 * hi and lo words, as is expected by bitmap.
 523 */
 524#if __BITS_PER_LONG == 64
 525#define BITMAP_FROM_U64(n) (n)
 526#else
 527#define BITMAP_FROM_U64(n) ((unsigned long) ((u64)(n) & ULONG_MAX)), \
 528                                ((unsigned long) ((u64)(n) >> 32))
 529#endif
 530
 531/**
 532 * bitmap_from_u64 - Check and swap words within u64.
 533 *  @mask: source bitmap
 534 *  @dst:  destination bitmap
 535 *
 536 * In 32-bit Big Endian kernel, when using ``(u32 *)(&val)[*]``
 537 * to read u64 mask, we will get the wrong word.
 538 * That is ``(u32 *)(&val)[0]`` gets the upper 32 bits,
 539 * but we expect the lower 32-bits of u64.
 540 */
 541static inline void bitmap_from_u64(unsigned long *dst, u64 mask)
 542{
 543        dst[0] = mask & ULONG_MAX;
 544
 545        if (sizeof(mask) > sizeof(unsigned long))
 546                dst[1] = mask >> 32;
 547}
 548
 549/**
 550 * bitmap_get_value8 - get an 8-bit value within a memory region
 551 * @map: address to the bitmap memory region
 552 * @start: bit offset of the 8-bit value; must be a multiple of 8
 553 *
 554 * Returns the 8-bit value located at the @start bit offset within the @src
 555 * memory region.
 556 */
 557static inline unsigned long bitmap_get_value8(const unsigned long *map,
 558                                              unsigned long start)
 559{
 560        const size_t index = BIT_WORD(start);
 561        const unsigned long offset = start % BITS_PER_LONG;
 562
 563        return (map[index] >> offset) & 0xFF;
 564}
 565
 566/**
 567 * bitmap_set_value8 - set an 8-bit value within a memory region
 568 * @map: address to the bitmap memory region
 569 * @value: the 8-bit value; values wider than 8 bits may clobber bitmap
 570 * @start: bit offset of the 8-bit value; must be a multiple of 8
 571 */
 572static inline void bitmap_set_value8(unsigned long *map, unsigned long value,
 573                                     unsigned long start)
 574{
 575        const size_t index = BIT_WORD(start);
 576        const unsigned long offset = start % BITS_PER_LONG;
 577
 578        map[index] &= ~(0xFFUL << offset);
 579        map[index] |= value << offset;
 580}
 581
 582#endif /* __ASSEMBLY__ */
 583
 584#endif /* __LINUX_BITMAP_H */
 585