xref: /linux/include/linux/bitmap.h (revision 9a6b55ac)
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)  as above
54  *  bitmap_shift_right(dst, src, n, nbits)      *dst = *src >> n
55  *  bitmap_shift_left(dst, src, n, nbits)       *dst = *src << n
56  *  bitmap_replace(dst, old, new, mask, nbits)  *dst = (*old & ~(*mask)) | (*new & *mask)
57  *  bitmap_remap(dst, src, old, new, nbits)     *dst = map(old, new)(src)
58  *  bitmap_bitremap(oldbit, old, new, nbits)    newbit = map(old, new)(oldbit)
59  *  bitmap_onto(dst, orig, relmap, nbits)       *dst = orig relative to relmap
60  *  bitmap_fold(dst, orig, sz, nbits)           dst bits = orig bits mod sz
61  *  bitmap_parse(buf, buflen, dst, nbits)       Parse bitmap dst from kernel buf
62  *  bitmap_parse_user(ubuf, ulen, dst, nbits)   Parse bitmap dst from user buf
63  *  bitmap_parselist(buf, dst, nbits)           Parse bitmap dst from kernel buf
64  *  bitmap_parselist_user(buf, dst, nbits)      Parse bitmap dst from user buf
65  *  bitmap_find_free_region(bitmap, bits, order)  Find and allocate bit region
66  *  bitmap_release_region(bitmap, pos, order)   Free specified bit region
67  *  bitmap_allocate_region(bitmap, pos, order)  Allocate specified bit region
68  *  bitmap_from_arr32(dst, buf, nbits)          Copy nbits from u32[] buf to dst
69  *  bitmap_to_arr32(buf, src, nbits)            Copy nbits from buf to u32[] dst
70  *  bitmap_get_value8(map, start)               Get 8bit value from map at start
71  *  bitmap_set_value8(map, value, start)        Set 8bit value to map at start
72  *
73  * Note, bitmap_zero() and bitmap_fill() operate over the region of
74  * unsigned longs, that is, bits behind bitmap till the unsigned long
75  * boundary will be zeroed or filled as well. Consider to use
76  * bitmap_clear() or bitmap_set() to make explicit zeroing or filling
77  * respectively.
78  */
79 
80 /**
81  * DOC: bitmap bitops
82  *
83  * Also the following operations in asm/bitops.h apply to bitmaps.::
84  *
85  *  set_bit(bit, addr)                  *addr |= bit
86  *  clear_bit(bit, addr)                *addr &= ~bit
87  *  change_bit(bit, addr)               *addr ^= bit
88  *  test_bit(bit, addr)                 Is bit set in *addr?
89  *  test_and_set_bit(bit, addr)         Set bit and return old value
90  *  test_and_clear_bit(bit, addr)       Clear bit and return old value
91  *  test_and_change_bit(bit, addr)      Change bit and return old value
92  *  find_first_zero_bit(addr, nbits)    Position first zero bit in *addr
93  *  find_first_bit(addr, nbits)         Position first set bit in *addr
94  *  find_next_zero_bit(addr, nbits, bit)
95  *                                      Position next zero bit in *addr >= bit
96  *  find_next_bit(addr, nbits, bit)     Position next set bit in *addr >= bit
97  *  find_next_and_bit(addr1, addr2, nbits, bit)
98  *                                      Same as find_next_bit, but in
99  *                                      (*addr1 & *addr2)
100  *
101  */
102 
103 /**
104  * DOC: declare bitmap
105  * The DECLARE_BITMAP(name,bits) macro, in linux/types.h, can be used
106  * to declare an array named 'name' of just enough unsigned longs to
107  * contain all bit positions from 0 to 'bits' - 1.
108  */
109 
110 /*
111  * Allocation and deallocation of bitmap.
112  * Provided in lib/bitmap.c to avoid circular dependency.
113  */
114 extern unsigned long *bitmap_alloc(unsigned int nbits, gfp_t flags);
115 extern unsigned long *bitmap_zalloc(unsigned int nbits, gfp_t flags);
116 extern void bitmap_free(const unsigned long *bitmap);
117 
118 /*
119  * lib/bitmap.c provides these functions:
120  */
121 
122 extern int __bitmap_empty(const unsigned long *bitmap, unsigned int nbits);
123 extern int __bitmap_full(const unsigned long *bitmap, unsigned int nbits);
124 extern int __bitmap_equal(const unsigned long *bitmap1,
125 			  const unsigned long *bitmap2, unsigned int nbits);
126 extern bool __pure __bitmap_or_equal(const unsigned long *src1,
127 				     const unsigned long *src2,
128 				     const unsigned long *src3,
129 				     unsigned int nbits);
130 extern void __bitmap_complement(unsigned long *dst, const unsigned long *src,
131 			unsigned int nbits);
132 extern void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
133 				unsigned int shift, unsigned int nbits);
134 extern void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
135 				unsigned int shift, unsigned int nbits);
136 extern int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
137 			const unsigned long *bitmap2, unsigned int nbits);
138 extern void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
139 			const unsigned long *bitmap2, unsigned int nbits);
140 extern void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
141 			const unsigned long *bitmap2, unsigned int nbits);
142 extern int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
143 			const unsigned long *bitmap2, unsigned int nbits);
144 extern void __bitmap_replace(unsigned long *dst,
145 			const unsigned long *old, const unsigned long *new,
146 			const unsigned long *mask, unsigned int nbits);
147 extern int __bitmap_intersects(const unsigned long *bitmap1,
148 			const unsigned long *bitmap2, unsigned int nbits);
149 extern int __bitmap_subset(const unsigned long *bitmap1,
150 			const unsigned long *bitmap2, unsigned int nbits);
151 extern int __bitmap_weight(const unsigned long *bitmap, unsigned int nbits);
152 extern void __bitmap_set(unsigned long *map, unsigned int start, int len);
153 extern void __bitmap_clear(unsigned long *map, unsigned int start, int len);
154 
155 extern unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
156 						    unsigned long size,
157 						    unsigned long start,
158 						    unsigned int nr,
159 						    unsigned long align_mask,
160 						    unsigned long align_offset);
161 
162 /**
163  * bitmap_find_next_zero_area - find a contiguous aligned zero area
164  * @map: The address to base the search on
165  * @size: The bitmap size in bits
166  * @start: The bitnumber to start searching at
167  * @nr: The number of zeroed bits we're looking for
168  * @align_mask: Alignment mask for zero area
169  *
170  * The @align_mask should be one less than a power of 2; the effect is that
171  * the bit offset of all zero areas this function finds is multiples of that
172  * power of 2. A @align_mask of 0 means no alignment is required.
173  */
174 static inline unsigned long
175 bitmap_find_next_zero_area(unsigned long *map,
176 			   unsigned long size,
177 			   unsigned long start,
178 			   unsigned int nr,
179 			   unsigned long align_mask)
180 {
181 	return bitmap_find_next_zero_area_off(map, size, start, nr,
182 					      align_mask, 0);
183 }
184 
185 extern int __bitmap_parse(const char *buf, unsigned int buflen, int is_user,
186 			unsigned long *dst, int nbits);
187 extern int bitmap_parse_user(const char __user *ubuf, unsigned int ulen,
188 			unsigned long *dst, int nbits);
189 extern int bitmap_parselist(const char *buf, unsigned long *maskp,
190 			int nmaskbits);
191 extern int bitmap_parselist_user(const char __user *ubuf, unsigned int ulen,
192 			unsigned long *dst, int nbits);
193 extern void bitmap_remap(unsigned long *dst, const unsigned long *src,
194 		const unsigned long *old, const unsigned long *new, unsigned int nbits);
195 extern int bitmap_bitremap(int oldbit,
196 		const unsigned long *old, const unsigned long *new, int bits);
197 extern void bitmap_onto(unsigned long *dst, const unsigned long *orig,
198 		const unsigned long *relmap, unsigned int bits);
199 extern void bitmap_fold(unsigned long *dst, const unsigned long *orig,
200 		unsigned int sz, unsigned int nbits);
201 extern int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order);
202 extern void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order);
203 extern int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order);
204 
205 #ifdef __BIG_ENDIAN
206 extern void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits);
207 #else
208 #define bitmap_copy_le bitmap_copy
209 #endif
210 extern unsigned int bitmap_ord_to_pos(const unsigned long *bitmap, unsigned int ord, unsigned int nbits);
211 extern int bitmap_print_to_pagebuf(bool list, char *buf,
212 				   const unsigned long *maskp, int nmaskbits);
213 
214 #define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1)))
215 #define BITMAP_LAST_WORD_MASK(nbits) (~0UL >> (-(nbits) & (BITS_PER_LONG - 1)))
216 
217 /*
218  * The static inlines below do not handle constant nbits==0 correctly,
219  * so make such users (should any ever turn up) call the out-of-line
220  * versions.
221  */
222 #define small_const_nbits(nbits) \
223 	(__builtin_constant_p(nbits) && (nbits) <= BITS_PER_LONG && (nbits) > 0)
224 
225 static inline void bitmap_zero(unsigned long *dst, unsigned int nbits)
226 {
227 	unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
228 	memset(dst, 0, len);
229 }
230 
231 static inline void bitmap_fill(unsigned long *dst, unsigned int nbits)
232 {
233 	unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
234 	memset(dst, 0xff, len);
235 }
236 
237 static inline void bitmap_copy(unsigned long *dst, const unsigned long *src,
238 			unsigned int nbits)
239 {
240 	unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
241 	memcpy(dst, src, len);
242 }
243 
244 /*
245  * Copy bitmap and clear tail bits in last word.
246  */
247 static inline void bitmap_copy_clear_tail(unsigned long *dst,
248 		const unsigned long *src, unsigned int nbits)
249 {
250 	bitmap_copy(dst, src, nbits);
251 	if (nbits % BITS_PER_LONG)
252 		dst[nbits / BITS_PER_LONG] &= BITMAP_LAST_WORD_MASK(nbits);
253 }
254 
255 /*
256  * On 32-bit systems bitmaps are represented as u32 arrays internally, and
257  * therefore conversion is not needed when copying data from/to arrays of u32.
258  */
259 #if BITS_PER_LONG == 64
260 extern void bitmap_from_arr32(unsigned long *bitmap, const u32 *buf,
261 							unsigned int nbits);
262 extern void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap,
263 							unsigned int nbits);
264 #else
265 #define bitmap_from_arr32(bitmap, buf, nbits)			\
266 	bitmap_copy_clear_tail((unsigned long *) (bitmap),	\
267 			(const unsigned long *) (buf), (nbits))
268 #define bitmap_to_arr32(buf, bitmap, nbits)			\
269 	bitmap_copy_clear_tail((unsigned long *) (buf),		\
270 			(const unsigned long *) (bitmap), (nbits))
271 #endif
272 
273 static inline int bitmap_and(unsigned long *dst, const unsigned long *src1,
274 			const unsigned long *src2, unsigned int nbits)
275 {
276 	if (small_const_nbits(nbits))
277 		return (*dst = *src1 & *src2 & BITMAP_LAST_WORD_MASK(nbits)) != 0;
278 	return __bitmap_and(dst, src1, src2, nbits);
279 }
280 
281 static inline void bitmap_or(unsigned long *dst, const unsigned long *src1,
282 			const unsigned long *src2, unsigned int nbits)
283 {
284 	if (small_const_nbits(nbits))
285 		*dst = *src1 | *src2;
286 	else
287 		__bitmap_or(dst, src1, src2, nbits);
288 }
289 
290 static inline void bitmap_xor(unsigned long *dst, const unsigned long *src1,
291 			const unsigned long *src2, unsigned int nbits)
292 {
293 	if (small_const_nbits(nbits))
294 		*dst = *src1 ^ *src2;
295 	else
296 		__bitmap_xor(dst, src1, src2, nbits);
297 }
298 
299 static inline int bitmap_andnot(unsigned long *dst, const unsigned long *src1,
300 			const unsigned long *src2, unsigned int nbits)
301 {
302 	if (small_const_nbits(nbits))
303 		return (*dst = *src1 & ~(*src2) & BITMAP_LAST_WORD_MASK(nbits)) != 0;
304 	return __bitmap_andnot(dst, src1, src2, nbits);
305 }
306 
307 static inline void bitmap_complement(unsigned long *dst, const unsigned long *src,
308 			unsigned int nbits)
309 {
310 	if (small_const_nbits(nbits))
311 		*dst = ~(*src);
312 	else
313 		__bitmap_complement(dst, src, nbits);
314 }
315 
316 #ifdef __LITTLE_ENDIAN
317 #define BITMAP_MEM_ALIGNMENT 8
318 #else
319 #define BITMAP_MEM_ALIGNMENT (8 * sizeof(unsigned long))
320 #endif
321 #define BITMAP_MEM_MASK (BITMAP_MEM_ALIGNMENT - 1)
322 
323 static inline int bitmap_equal(const unsigned long *src1,
324 			const unsigned long *src2, unsigned int nbits)
325 {
326 	if (small_const_nbits(nbits))
327 		return !((*src1 ^ *src2) & BITMAP_LAST_WORD_MASK(nbits));
328 	if (__builtin_constant_p(nbits & BITMAP_MEM_MASK) &&
329 	    IS_ALIGNED(nbits, BITMAP_MEM_ALIGNMENT))
330 		return !memcmp(src1, src2, nbits / 8);
331 	return __bitmap_equal(src1, src2, nbits);
332 }
333 
334 /**
335  * bitmap_or_equal - Check whether the or of two bitmaps is equal to a third
336  * @src1:	Pointer to bitmap 1
337  * @src2:	Pointer to bitmap 2 will be or'ed with bitmap 1
338  * @src3:	Pointer to bitmap 3. Compare to the result of *@src1 | *@src2
339  * @nbits:	number of bits in each of these bitmaps
340  *
341  * Returns: True if (*@src1 | *@src2) == *@src3, false otherwise
342  */
343 static inline bool bitmap_or_equal(const unsigned long *src1,
344 				   const unsigned long *src2,
345 				   const unsigned long *src3,
346 				   unsigned int nbits)
347 {
348 	if (!small_const_nbits(nbits))
349 		return __bitmap_or_equal(src1, src2, src3, nbits);
350 
351 	return !(((*src1 | *src2) ^ *src3) & BITMAP_LAST_WORD_MASK(nbits));
352 }
353 
354 static inline int bitmap_intersects(const unsigned long *src1,
355 			const unsigned long *src2, unsigned int nbits)
356 {
357 	if (small_const_nbits(nbits))
358 		return ((*src1 & *src2) & BITMAP_LAST_WORD_MASK(nbits)) != 0;
359 	else
360 		return __bitmap_intersects(src1, src2, nbits);
361 }
362 
363 static inline int bitmap_subset(const unsigned long *src1,
364 			const unsigned long *src2, unsigned int nbits)
365 {
366 	if (small_const_nbits(nbits))
367 		return ! ((*src1 & ~(*src2)) & BITMAP_LAST_WORD_MASK(nbits));
368 	else
369 		return __bitmap_subset(src1, src2, nbits);
370 }
371 
372 static inline int bitmap_empty(const unsigned long *src, unsigned nbits)
373 {
374 	if (small_const_nbits(nbits))
375 		return ! (*src & BITMAP_LAST_WORD_MASK(nbits));
376 
377 	return find_first_bit(src, nbits) == nbits;
378 }
379 
380 static inline int bitmap_full(const unsigned long *src, unsigned int nbits)
381 {
382 	if (small_const_nbits(nbits))
383 		return ! (~(*src) & BITMAP_LAST_WORD_MASK(nbits));
384 
385 	return find_first_zero_bit(src, nbits) == nbits;
386 }
387 
388 static __always_inline int bitmap_weight(const unsigned long *src, unsigned int nbits)
389 {
390 	if (small_const_nbits(nbits))
391 		return hweight_long(*src & BITMAP_LAST_WORD_MASK(nbits));
392 	return __bitmap_weight(src, nbits);
393 }
394 
395 static __always_inline void bitmap_set(unsigned long *map, unsigned int start,
396 		unsigned int nbits)
397 {
398 	if (__builtin_constant_p(nbits) && nbits == 1)
399 		__set_bit(start, map);
400 	else if (__builtin_constant_p(start & BITMAP_MEM_MASK) &&
401 		 IS_ALIGNED(start, BITMAP_MEM_ALIGNMENT) &&
402 		 __builtin_constant_p(nbits & BITMAP_MEM_MASK) &&
403 		 IS_ALIGNED(nbits, BITMAP_MEM_ALIGNMENT))
404 		memset((char *)map + start / 8, 0xff, nbits / 8);
405 	else
406 		__bitmap_set(map, start, nbits);
407 }
408 
409 static __always_inline void bitmap_clear(unsigned long *map, unsigned int start,
410 		unsigned int nbits)
411 {
412 	if (__builtin_constant_p(nbits) && nbits == 1)
413 		__clear_bit(start, map);
414 	else if (__builtin_constant_p(start & BITMAP_MEM_MASK) &&
415 		 IS_ALIGNED(start, BITMAP_MEM_ALIGNMENT) &&
416 		 __builtin_constant_p(nbits & BITMAP_MEM_MASK) &&
417 		 IS_ALIGNED(nbits, BITMAP_MEM_ALIGNMENT))
418 		memset((char *)map + start / 8, 0, nbits / 8);
419 	else
420 		__bitmap_clear(map, start, nbits);
421 }
422 
423 static inline void bitmap_shift_right(unsigned long *dst, const unsigned long *src,
424 				unsigned int shift, unsigned int nbits)
425 {
426 	if (small_const_nbits(nbits))
427 		*dst = (*src & BITMAP_LAST_WORD_MASK(nbits)) >> shift;
428 	else
429 		__bitmap_shift_right(dst, src, shift, nbits);
430 }
431 
432 static inline void bitmap_shift_left(unsigned long *dst, const unsigned long *src,
433 				unsigned int shift, unsigned int nbits)
434 {
435 	if (small_const_nbits(nbits))
436 		*dst = (*src << shift) & BITMAP_LAST_WORD_MASK(nbits);
437 	else
438 		__bitmap_shift_left(dst, src, shift, nbits);
439 }
440 
441 static inline void bitmap_replace(unsigned long *dst,
442 				  const unsigned long *old,
443 				  const unsigned long *new,
444 				  const unsigned long *mask,
445 				  unsigned int nbits)
446 {
447 	if (small_const_nbits(nbits))
448 		*dst = (*old & ~(*mask)) | (*new & *mask);
449 	else
450 		__bitmap_replace(dst, old, new, mask, nbits);
451 }
452 
453 static inline int bitmap_parse(const char *buf, unsigned int buflen,
454 			unsigned long *maskp, int nmaskbits)
455 {
456 	return __bitmap_parse(buf, buflen, 0, maskp, nmaskbits);
457 }
458 
459 /**
460  * BITMAP_FROM_U64() - Represent u64 value in the format suitable for bitmap.
461  * @n: u64 value
462  *
463  * Linux bitmaps are internally arrays of unsigned longs, i.e. 32-bit
464  * integers in 32-bit environment, and 64-bit integers in 64-bit one.
465  *
466  * There are four combinations of endianness and length of the word in linux
467  * ABIs: LE64, BE64, LE32 and BE32.
468  *
469  * On 64-bit kernels 64-bit LE and BE numbers are naturally ordered in
470  * bitmaps and therefore don't require any special handling.
471  *
472  * On 32-bit kernels 32-bit LE ABI orders lo word of 64-bit number in memory
473  * prior to hi, and 32-bit BE orders hi word prior to lo. The bitmap on the
474  * other hand is represented as an array of 32-bit words and the position of
475  * bit N may therefore be calculated as: word #(N/32) and bit #(N%32) in that
476  * word.  For example, bit #42 is located at 10th position of 2nd word.
477  * It matches 32-bit LE ABI, and we can simply let the compiler store 64-bit
478  * values in memory as it usually does. But for BE we need to swap hi and lo
479  * words manually.
480  *
481  * With all that, the macro BITMAP_FROM_U64() does explicit reordering of hi and
482  * lo parts of u64.  For LE32 it does nothing, and for BE environment it swaps
483  * hi and lo words, as is expected by bitmap.
484  */
485 #if __BITS_PER_LONG == 64
486 #define BITMAP_FROM_U64(n) (n)
487 #else
488 #define BITMAP_FROM_U64(n) ((unsigned long) ((u64)(n) & ULONG_MAX)), \
489 				((unsigned long) ((u64)(n) >> 32))
490 #endif
491 
492 /**
493  * bitmap_from_u64 - Check and swap words within u64.
494  *  @mask: source bitmap
495  *  @dst:  destination bitmap
496  *
497  * In 32-bit Big Endian kernel, when using ``(u32 *)(&val)[*]``
498  * to read u64 mask, we will get the wrong word.
499  * That is ``(u32 *)(&val)[0]`` gets the upper 32 bits,
500  * but we expect the lower 32-bits of u64.
501  */
502 static inline void bitmap_from_u64(unsigned long *dst, u64 mask)
503 {
504 	dst[0] = mask & ULONG_MAX;
505 
506 	if (sizeof(mask) > sizeof(unsigned long))
507 		dst[1] = mask >> 32;
508 }
509 
510 /**
511  * bitmap_get_value8 - get an 8-bit value within a memory region
512  * @map: address to the bitmap memory region
513  * @start: bit offset of the 8-bit value; must be a multiple of 8
514  *
515  * Returns the 8-bit value located at the @start bit offset within the @src
516  * memory region.
517  */
518 static inline unsigned long bitmap_get_value8(const unsigned long *map,
519 					      unsigned long start)
520 {
521 	const size_t index = BIT_WORD(start);
522 	const unsigned long offset = start % BITS_PER_LONG;
523 
524 	return (map[index] >> offset) & 0xFF;
525 }
526 
527 /**
528  * bitmap_set_value8 - set an 8-bit value within a memory region
529  * @map: address to the bitmap memory region
530  * @value: the 8-bit value; values wider than 8 bits may clobber bitmap
531  * @start: bit offset of the 8-bit value; must be a multiple of 8
532  */
533 static inline void bitmap_set_value8(unsigned long *map, unsigned long value,
534 				     unsigned long start)
535 {
536 	const size_t index = BIT_WORD(start);
537 	const unsigned long offset = start % BITS_PER_LONG;
538 
539 	map[index] &= ~(0xFFUL << offset);
540 	map[index] |= value << offset;
541 }
542 
543 #endif /* __ASSEMBLY__ */
544 
545 #endif /* __LINUX_BITMAP_H */
546