3 * Helper functions for bitmap.h.
5 * This source code is licensed under the GNU General Public License,
6 * Version 2. See the file COPYING for more details.
8 #include <linux/export.h>
9 #include <linux/thread_info.h>
10 #include <linux/ctype.h>
11 #include <linux/errno.h>
12 #include <linux/bitmap.h>
13 #include <linux/bitops.h>
14 #include <linux/bug.h>
15 #include <linux/slab.h>
18 #include <asm/uaccess.h>
21 * bitmaps provide an array of bits, implemented using an an
22 * array of unsigned longs. The number of valid bits in a
23 * given bitmap does _not_ need to be an exact multiple of
26 * The possible unused bits in the last, partially used word
27 * of a bitmap are 'don't care'. The implementation makes
28 * no particular effort to keep them zero. It ensures that
29 * their value will not affect the results of any operation.
30 * The bitmap operations that return Boolean (bitmap_empty,
31 * for example) or scalar (bitmap_weight, for example) results
32 * carefully filter out these unused bits from impacting their
35 * These operations actually hold to a slightly stronger rule:
36 * if you don't input any bitmaps to these ops that have some
37 * unused bits set, then they won't output any set unused bits
40 * The byte ordering of bitmaps is more natural on little
41 * endian architectures. See the big-endian headers
42 * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
43 * for the best explanations of this ordering.
46 int __bitmap_equal(const unsigned long *bitmap1,
47 const unsigned long *bitmap2, unsigned int bits)
49 unsigned int k, lim = bits/BITS_PER_LONG;
50 for (k = 0; k < lim; ++k)
51 if (bitmap1[k] != bitmap2[k])
54 if (bits % BITS_PER_LONG)
55 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
60 EXPORT_SYMBOL(__bitmap_equal);
62 void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits)
64 unsigned int k, lim = bits/BITS_PER_LONG;
65 for (k = 0; k < lim; ++k)
68 if (bits % BITS_PER_LONG)
71 EXPORT_SYMBOL(__bitmap_complement);
74 * __bitmap_shift_right - logical right shift of the bits in a bitmap
75 * @dst : destination bitmap
76 * @src : source bitmap
77 * @shift : shift by this many bits
78 * @nbits : bitmap size, in bits
80 * Shifting right (dividing) means moving bits in the MS -> LS bit
81 * direction. Zeros are fed into the vacated MS positions and the
82 * LS bits shifted off the bottom are lost.
84 void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
85 unsigned shift, unsigned nbits)
87 unsigned k, lim = BITS_TO_LONGS(nbits);
88 unsigned off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
89 unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);
90 for (k = 0; off + k < lim; ++k) {
91 unsigned long upper, lower;
94 * If shift is not word aligned, take lower rem bits of
95 * word above and make them the top rem bits of result.
97 if (!rem || off + k + 1 >= lim)
100 upper = src[off + k + 1];
101 if (off + k + 1 == lim - 1)
103 upper <<= (BITS_PER_LONG - rem);
105 lower = src[off + k];
106 if (off + k == lim - 1)
109 dst[k] = lower | upper;
112 memset(&dst[lim - off], 0, off*sizeof(unsigned long));
114 EXPORT_SYMBOL(__bitmap_shift_right);
118 * __bitmap_shift_left - logical left shift of the bits in a bitmap
119 * @dst : destination bitmap
120 * @src : source bitmap
121 * @shift : shift by this many bits
122 * @nbits : bitmap size, in bits
124 * Shifting left (multiplying) means moving bits in the LS -> MS
125 * direction. Zeros are fed into the vacated LS bit positions
126 * and those MS bits shifted off the top are lost.
129 void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
130 unsigned int shift, unsigned int nbits)
133 unsigned int lim = BITS_TO_LONGS(nbits);
134 unsigned int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
135 for (k = lim - off - 1; k >= 0; --k) {
136 unsigned long upper, lower;
139 * If shift is not word aligned, take upper rem bits of
140 * word below and make them the bottom rem bits of result.
143 lower = src[k - 1] >> (BITS_PER_LONG - rem);
146 upper = src[k] << rem;
147 dst[k + off] = lower | upper;
150 memset(dst, 0, off*sizeof(unsigned long));
152 EXPORT_SYMBOL(__bitmap_shift_left);
154 int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
155 const unsigned long *bitmap2, unsigned int bits)
158 unsigned int lim = bits/BITS_PER_LONG;
159 unsigned long result = 0;
161 for (k = 0; k < lim; k++)
162 result |= (dst[k] = bitmap1[k] & bitmap2[k]);
163 if (bits % BITS_PER_LONG)
164 result |= (dst[k] = bitmap1[k] & bitmap2[k] &
165 BITMAP_LAST_WORD_MASK(bits));
168 EXPORT_SYMBOL(__bitmap_and);
170 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
171 const unsigned long *bitmap2, unsigned int bits)
174 unsigned int nr = BITS_TO_LONGS(bits);
176 for (k = 0; k < nr; k++)
177 dst[k] = bitmap1[k] | bitmap2[k];
179 EXPORT_SYMBOL(__bitmap_or);
181 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
182 const unsigned long *bitmap2, unsigned int bits)
185 unsigned int nr = BITS_TO_LONGS(bits);
187 for (k = 0; k < nr; k++)
188 dst[k] = bitmap1[k] ^ bitmap2[k];
190 EXPORT_SYMBOL(__bitmap_xor);
192 int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
193 const unsigned long *bitmap2, unsigned int bits)
196 unsigned int lim = bits/BITS_PER_LONG;
197 unsigned long result = 0;
199 for (k = 0; k < lim; k++)
200 result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
201 if (bits % BITS_PER_LONG)
202 result |= (dst[k] = bitmap1[k] & ~bitmap2[k] &
203 BITMAP_LAST_WORD_MASK(bits));
206 EXPORT_SYMBOL(__bitmap_andnot);
208 int __bitmap_intersects(const unsigned long *bitmap1,
209 const unsigned long *bitmap2, unsigned int bits)
211 unsigned int k, lim = bits/BITS_PER_LONG;
212 for (k = 0; k < lim; ++k)
213 if (bitmap1[k] & bitmap2[k])
216 if (bits % BITS_PER_LONG)
217 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
221 EXPORT_SYMBOL(__bitmap_intersects);
223 int __bitmap_subset(const unsigned long *bitmap1,
224 const unsigned long *bitmap2, unsigned int bits)
226 unsigned int k, lim = bits/BITS_PER_LONG;
227 for (k = 0; k < lim; ++k)
228 if (bitmap1[k] & ~bitmap2[k])
231 if (bits % BITS_PER_LONG)
232 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
236 EXPORT_SYMBOL(__bitmap_subset);
238 int __bitmap_weight(const unsigned long *bitmap, unsigned int bits)
240 unsigned int k, lim = bits/BITS_PER_LONG;
243 for (k = 0; k < lim; k++)
244 w += hweight_long(bitmap[k]);
246 if (bits % BITS_PER_LONG)
247 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
251 EXPORT_SYMBOL(__bitmap_weight);
253 void bitmap_set(unsigned long *map, unsigned int start, int len)
255 unsigned long *p = map + BIT_WORD(start);
256 const unsigned int size = start + len;
257 int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
258 unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
260 while (len - bits_to_set >= 0) {
263 bits_to_set = BITS_PER_LONG;
268 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
272 EXPORT_SYMBOL(bitmap_set);
274 void bitmap_clear(unsigned long *map, unsigned int start, int len)
276 unsigned long *p = map + BIT_WORD(start);
277 const unsigned int size = start + len;
278 int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
279 unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
281 while (len - bits_to_clear >= 0) {
282 *p &= ~mask_to_clear;
283 len -= bits_to_clear;
284 bits_to_clear = BITS_PER_LONG;
285 mask_to_clear = ~0UL;
289 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
290 *p &= ~mask_to_clear;
293 EXPORT_SYMBOL(bitmap_clear);
296 * bitmap_find_next_zero_area_off - find a contiguous aligned zero area
297 * @map: The address to base the search on
298 * @size: The bitmap size in bits
299 * @start: The bitnumber to start searching at
300 * @nr: The number of zeroed bits we're looking for
301 * @align_mask: Alignment mask for zero area
302 * @align_offset: Alignment offset for zero area.
304 * The @align_mask should be one less than a power of 2; the effect is that
305 * the bit offset of all zero areas this function finds plus @align_offset
306 * is multiple of that power of 2.
308 unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
312 unsigned long align_mask,
313 unsigned long align_offset)
315 unsigned long index, end, i;
317 index = find_next_zero_bit(map, size, start);
319 /* Align allocation */
320 index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset;
325 i = find_next_bit(map, end, index);
332 EXPORT_SYMBOL(bitmap_find_next_zero_area_off);
335 * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,
336 * second version by Paul Jackson, third by Joe Korty.
340 #define nbits_to_hold_value(val) fls(val)
341 #define BASEDEC 10 /* fancier cpuset lists input in decimal */
344 * __bitmap_parse - convert an ASCII hex string into a bitmap.
345 * @buf: pointer to buffer containing string.
346 * @buflen: buffer size in bytes. If string is smaller than this
347 * then it must be terminated with a \0.
348 * @is_user: location of buffer, 0 indicates kernel space
349 * @maskp: pointer to bitmap array that will contain result.
350 * @nmaskbits: size of bitmap, in bits.
352 * Commas group hex digits into chunks. Each chunk defines exactly 32
353 * bits of the resultant bitmask. No chunk may specify a value larger
354 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
355 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
356 * characters and for grouping errors such as "1,,5", ",44", "," and "".
357 * Leading and trailing whitespace accepted, but not embedded whitespace.
359 int __bitmap_parse(const char *buf, unsigned int buflen,
360 int is_user, unsigned long *maskp,
363 int c, old_c, totaldigits, ndigits, nchunks, nbits;
365 const char __user __force *ubuf = (const char __user __force *)buf;
367 bitmap_zero(maskp, nmaskbits);
369 nchunks = nbits = totaldigits = c = 0;
372 ndigits = totaldigits;
374 /* Get the next chunk of the bitmap */
378 if (__get_user(c, ubuf++))
388 * If the last character was a space and the current
389 * character isn't '\0', we've got embedded whitespace.
390 * This is a no-no, so throw an error.
392 if (totaldigits && c && isspace(old_c))
395 /* A '\0' or a ',' signal the end of the chunk */
396 if (c == '\0' || c == ',')
403 * Make sure there are at least 4 free bits in 'chunk'.
404 * If not, this hexdigit will overflow 'chunk', so
407 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
410 chunk = (chunk << 4) | hex_to_bin(c);
413 if (ndigits == totaldigits)
415 if (nchunks == 0 && chunk == 0)
418 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
421 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
422 if (nbits > nmaskbits)
424 } while (buflen && c == ',');
428 EXPORT_SYMBOL(__bitmap_parse);
431 * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
433 * @ubuf: pointer to user buffer containing string.
434 * @ulen: buffer size in bytes. If string is smaller than this
435 * then it must be terminated with a \0.
436 * @maskp: pointer to bitmap array that will contain result.
437 * @nmaskbits: size of bitmap, in bits.
439 * Wrapper for __bitmap_parse(), providing it with user buffer.
441 * We cannot have this as an inline function in bitmap.h because it needs
442 * linux/uaccess.h to get the access_ok() declaration and this causes
443 * cyclic dependencies.
445 int bitmap_parse_user(const char __user *ubuf,
446 unsigned int ulen, unsigned long *maskp,
449 if (!access_ok(VERIFY_READ, ubuf, ulen))
451 return __bitmap_parse((const char __force *)ubuf,
452 ulen, 1, maskp, nmaskbits);
455 EXPORT_SYMBOL(bitmap_parse_user);
458 * bitmap_print_to_pagebuf - convert bitmap to list or hex format ASCII string
459 * @list: indicates whether the bitmap must be list
460 * @buf: page aligned buffer into which string is placed
461 * @maskp: pointer to bitmap to convert
462 * @nmaskbits: size of bitmap, in bits
464 * Output format is a comma-separated list of decimal numbers and
465 * ranges if list is specified or hex digits grouped into comma-separated
466 * sets of 8 digits/set. Returns the number of characters written to buf.
468 * It is assumed that @buf is a pointer into a PAGE_SIZE area and that
469 * sufficient storage remains at @buf to accommodate the
470 * bitmap_print_to_pagebuf() output.
472 int bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp,
475 ptrdiff_t len = PTR_ALIGN(buf + PAGE_SIZE - 1, PAGE_SIZE) - buf;
479 n = list ? scnprintf(buf, len, "%*pbl\n", nmaskbits, maskp) :
480 scnprintf(buf, len, "%*pb\n", nmaskbits, maskp);
483 EXPORT_SYMBOL(bitmap_print_to_pagebuf);
486 * __bitmap_parselist - convert list format ASCII string to bitmap
487 * @buf: read nul-terminated user string from this buffer
488 * @buflen: buffer size in bytes. If string is smaller than this
489 * then it must be terminated with a \0.
490 * @is_user: location of buffer, 0 indicates kernel space
491 * @maskp: write resulting mask here
492 * @nmaskbits: number of bits in mask to be written
494 * Input format is a comma-separated list of decimal numbers and
495 * ranges. Consecutively set bits are shown as two hyphen-separated
496 * decimal numbers, the smallest and largest bit numbers set in
499 * Returns 0 on success, -errno on invalid input strings.
501 * %-EINVAL: second number in range smaller than first
502 * %-EINVAL: invalid character in string
503 * %-ERANGE: bit number specified too large for mask
505 static int __bitmap_parselist(const char *buf, unsigned int buflen,
506 int is_user, unsigned long *maskp,
510 int c, old_c, totaldigits, ndigits;
511 const char __user __force *ubuf = (const char __user __force *)buf;
512 int at_start, in_range;
515 bitmap_zero(maskp, nmaskbits);
520 ndigits = totaldigits;
522 /* Get the next cpu# or a range of cpu#'s */
526 if (__get_user(c, ubuf++))
534 /* A '\0' or a ',' signal the end of a cpu# or range */
535 if (c == '\0' || c == ',')
538 * whitespaces between digits are not allowed,
539 * but it's ok if whitespaces are on head or tail.
540 * when old_c is whilespace,
541 * if totaldigits == ndigits, whitespace is on head.
542 * if whitespace is on tail, it should not run here.
543 * as c was ',' or '\0',
544 * the last code line has broken the current loop.
546 if ((totaldigits != ndigits) && isspace(old_c))
550 if (at_start || in_range)
561 b = b * 10 + (c - '0');
567 if (ndigits == totaldigits)
569 /* if no digit is after '-', it's wrong*/
570 if (at_start && in_range)
580 } while (buflen && c == ',');
584 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
586 char *nl = strchrnul(bp, '\n');
589 return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
591 EXPORT_SYMBOL(bitmap_parselist);
595 * bitmap_parselist_user()
597 * @ubuf: pointer to user buffer containing string.
598 * @ulen: buffer size in bytes. If string is smaller than this
599 * then it must be terminated with a \0.
600 * @maskp: pointer to bitmap array that will contain result.
601 * @nmaskbits: size of bitmap, in bits.
603 * Wrapper for bitmap_parselist(), providing it with user buffer.
605 * We cannot have this as an inline function in bitmap.h because it needs
606 * linux/uaccess.h to get the access_ok() declaration and this causes
607 * cyclic dependencies.
609 int bitmap_parselist_user(const char __user *ubuf,
610 unsigned int ulen, unsigned long *maskp,
613 if (!access_ok(VERIFY_READ, ubuf, ulen))
615 return __bitmap_parselist((const char __force *)ubuf,
616 ulen, 1, maskp, nmaskbits);
618 EXPORT_SYMBOL(bitmap_parselist_user);
622 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
623 * @buf: pointer to a bitmap
624 * @pos: a bit position in @buf (0 <= @pos < @nbits)
625 * @nbits: number of valid bit positions in @buf
627 * Map the bit at position @pos in @buf (of length @nbits) to the
628 * ordinal of which set bit it is. If it is not set or if @pos
629 * is not a valid bit position, map to -1.
631 * If for example, just bits 4 through 7 are set in @buf, then @pos
632 * values 4 through 7 will get mapped to 0 through 3, respectively,
633 * and other @pos values will get mapped to -1. When @pos value 7
634 * gets mapped to (returns) @ord value 3 in this example, that means
635 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
637 * The bit positions 0 through @bits are valid positions in @buf.
639 static int bitmap_pos_to_ord(const unsigned long *buf, unsigned int pos, unsigned int nbits)
641 if (pos >= nbits || !test_bit(pos, buf))
644 return __bitmap_weight(buf, pos);
648 * bitmap_ord_to_pos - find position of n-th set bit in bitmap
649 * @buf: pointer to bitmap
650 * @ord: ordinal bit position (n-th set bit, n >= 0)
651 * @nbits: number of valid bit positions in @buf
653 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
654 * Value of @ord should be in range 0 <= @ord < weight(buf). If @ord
655 * >= weight(buf), returns @nbits.
657 * If for example, just bits 4 through 7 are set in @buf, then @ord
658 * values 0 through 3 will get mapped to 4 through 7, respectively,
659 * and all other @ord values returns @nbits. When @ord value 3
660 * gets mapped to (returns) @pos value 7 in this example, that means
661 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
663 * The bit positions 0 through @nbits-1 are valid positions in @buf.
665 unsigned int bitmap_ord_to_pos(const unsigned long *buf, unsigned int ord, unsigned int nbits)
669 for (pos = find_first_bit(buf, nbits);
671 pos = find_next_bit(buf, nbits, pos + 1))
678 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
679 * @dst: remapped result
680 * @src: subset to be remapped
681 * @old: defines domain of map
682 * @new: defines range of map
683 * @nbits: number of bits in each of these bitmaps
685 * Let @old and @new define a mapping of bit positions, such that
686 * whatever position is held by the n-th set bit in @old is mapped
687 * to the n-th set bit in @new. In the more general case, allowing
688 * for the possibility that the weight 'w' of @new is less than the
689 * weight of @old, map the position of the n-th set bit in @old to
690 * the position of the m-th set bit in @new, where m == n % w.
692 * If either of the @old and @new bitmaps are empty, or if @src and
693 * @dst point to the same location, then this routine copies @src
696 * The positions of unset bits in @old are mapped to themselves
697 * (the identify map).
699 * Apply the above specified mapping to @src, placing the result in
700 * @dst, clearing any bits previously set in @dst.
702 * For example, lets say that @old has bits 4 through 7 set, and
703 * @new has bits 12 through 15 set. This defines the mapping of bit
704 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
705 * bit positions unchanged. So if say @src comes into this routine
706 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
709 void bitmap_remap(unsigned long *dst, const unsigned long *src,
710 const unsigned long *old, const unsigned long *new,
713 unsigned int oldbit, w;
715 if (dst == src) /* following doesn't handle inplace remaps */
717 bitmap_zero(dst, nbits);
719 w = bitmap_weight(new, nbits);
720 for_each_set_bit(oldbit, src, nbits) {
721 int n = bitmap_pos_to_ord(old, oldbit, nbits);
724 set_bit(oldbit, dst); /* identity map */
726 set_bit(bitmap_ord_to_pos(new, n % w, nbits), dst);
729 EXPORT_SYMBOL(bitmap_remap);
732 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
733 * @oldbit: bit position to be mapped
734 * @old: defines domain of map
735 * @new: defines range of map
736 * @bits: number of bits in each of these bitmaps
738 * Let @old and @new define a mapping of bit positions, such that
739 * whatever position is held by the n-th set bit in @old is mapped
740 * to the n-th set bit in @new. In the more general case, allowing
741 * for the possibility that the weight 'w' of @new is less than the
742 * weight of @old, map the position of the n-th set bit in @old to
743 * the position of the m-th set bit in @new, where m == n % w.
745 * The positions of unset bits in @old are mapped to themselves
746 * (the identify map).
748 * Apply the above specified mapping to bit position @oldbit, returning
749 * the new bit position.
751 * For example, lets say that @old has bits 4 through 7 set, and
752 * @new has bits 12 through 15 set. This defines the mapping of bit
753 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
754 * bit positions unchanged. So if say @oldbit is 5, then this routine
757 int bitmap_bitremap(int oldbit, const unsigned long *old,
758 const unsigned long *new, int bits)
760 int w = bitmap_weight(new, bits);
761 int n = bitmap_pos_to_ord(old, oldbit, bits);
765 return bitmap_ord_to_pos(new, n % w, bits);
767 EXPORT_SYMBOL(bitmap_bitremap);
770 * bitmap_onto - translate one bitmap relative to another
771 * @dst: resulting translated bitmap
772 * @orig: original untranslated bitmap
773 * @relmap: bitmap relative to which translated
774 * @bits: number of bits in each of these bitmaps
776 * Set the n-th bit of @dst iff there exists some m such that the
777 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
778 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
779 * (If you understood the previous sentence the first time your
780 * read it, you're overqualified for your current job.)
782 * In other words, @orig is mapped onto (surjectively) @dst,
783 * using the map { <n, m> | the n-th bit of @relmap is the
784 * m-th set bit of @relmap }.
786 * Any set bits in @orig above bit number W, where W is the
787 * weight of (number of set bits in) @relmap are mapped nowhere.
788 * In particular, if for all bits m set in @orig, m >= W, then
789 * @dst will end up empty. In situations where the possibility
790 * of such an empty result is not desired, one way to avoid it is
791 * to use the bitmap_fold() operator, below, to first fold the
792 * @orig bitmap over itself so that all its set bits x are in the
793 * range 0 <= x < W. The bitmap_fold() operator does this by
794 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
796 * Example [1] for bitmap_onto():
797 * Let's say @relmap has bits 30-39 set, and @orig has bits
798 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,
799 * @dst will have bits 31, 33, 35, 37 and 39 set.
801 * When bit 0 is set in @orig, it means turn on the bit in
802 * @dst corresponding to whatever is the first bit (if any)
803 * that is turned on in @relmap. Since bit 0 was off in the
804 * above example, we leave off that bit (bit 30) in @dst.
806 * When bit 1 is set in @orig (as in the above example), it
807 * means turn on the bit in @dst corresponding to whatever
808 * is the second bit that is turned on in @relmap. The second
809 * bit in @relmap that was turned on in the above example was
810 * bit 31, so we turned on bit 31 in @dst.
812 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
813 * because they were the 4th, 6th, 8th and 10th set bits
814 * set in @relmap, and the 4th, 6th, 8th and 10th bits of
815 * @orig (i.e. bits 3, 5, 7 and 9) were also set.
817 * When bit 11 is set in @orig, it means turn on the bit in
818 * @dst corresponding to whatever is the twelfth bit that is
819 * turned on in @relmap. In the above example, there were
820 * only ten bits turned on in @relmap (30..39), so that bit
821 * 11 was set in @orig had no affect on @dst.
823 * Example [2] for bitmap_fold() + bitmap_onto():
824 * Let's say @relmap has these ten bits set:
825 * 40 41 42 43 45 48 53 61 74 95
826 * (for the curious, that's 40 plus the first ten terms of the
827 * Fibonacci sequence.)
829 * Further lets say we use the following code, invoking
830 * bitmap_fold() then bitmap_onto, as suggested above to
831 * avoid the possibility of an empty @dst result:
833 * unsigned long *tmp; // a temporary bitmap's bits
835 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
836 * bitmap_onto(dst, tmp, relmap, bits);
838 * Then this table shows what various values of @dst would be, for
839 * various @orig's. I list the zero-based positions of each set bit.
840 * The tmp column shows the intermediate result, as computed by
841 * using bitmap_fold() to fold the @orig bitmap modulo ten
842 * (the weight of @relmap).
849 * 1 3 5 7 1 3 5 7 41 43 48 61
850 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45
851 * 0 9 18 27 0 9 8 7 40 61 74 95
853 * 0 11 22 33 0 1 2 3 40 41 42 43
854 * 0 12 24 36 0 2 4 6 40 42 45 53
855 * 78 102 211 1 2 8 41 42 74 (*)
857 * (*) For these marked lines, if we hadn't first done bitmap_fold()
858 * into tmp, then the @dst result would have been empty.
860 * If either of @orig or @relmap is empty (no set bits), then @dst
861 * will be returned empty.
863 * If (as explained above) the only set bits in @orig are in positions
864 * m where m >= W, (where W is the weight of @relmap) then @dst will
865 * once again be returned empty.
867 * All bits in @dst not set by the above rule are cleared.
869 void bitmap_onto(unsigned long *dst, const unsigned long *orig,
870 const unsigned long *relmap, unsigned int bits)
872 unsigned int n, m; /* same meaning as in above comment */
874 if (dst == orig) /* following doesn't handle inplace mappings */
876 bitmap_zero(dst, bits);
879 * The following code is a more efficient, but less
880 * obvious, equivalent to the loop:
881 * for (m = 0; m < bitmap_weight(relmap, bits); m++) {
882 * n = bitmap_ord_to_pos(orig, m, bits);
883 * if (test_bit(m, orig))
889 for_each_set_bit(n, relmap, bits) {
890 /* m == bitmap_pos_to_ord(relmap, n, bits) */
891 if (test_bit(m, orig))
896 EXPORT_SYMBOL(bitmap_onto);
899 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
900 * @dst: resulting smaller bitmap
901 * @orig: original larger bitmap
902 * @sz: specified size
903 * @nbits: number of bits in each of these bitmaps
905 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
906 * Clear all other bits in @dst. See further the comment and
907 * Example [2] for bitmap_onto() for why and how to use this.
909 void bitmap_fold(unsigned long *dst, const unsigned long *orig,
910 unsigned int sz, unsigned int nbits)
914 if (dst == orig) /* following doesn't handle inplace mappings */
916 bitmap_zero(dst, nbits);
918 for_each_set_bit(oldbit, orig, nbits)
919 set_bit(oldbit % sz, dst);
921 EXPORT_SYMBOL(bitmap_fold);
924 * Common code for bitmap_*_region() routines.
925 * bitmap: array of unsigned longs corresponding to the bitmap
926 * pos: the beginning of the region
927 * order: region size (log base 2 of number of bits)
928 * reg_op: operation(s) to perform on that region of bitmap
930 * Can set, verify and/or release a region of bits in a bitmap,
931 * depending on which combination of REG_OP_* flag bits is set.
933 * A region of a bitmap is a sequence of bits in the bitmap, of
934 * some size '1 << order' (a power of two), aligned to that same
935 * '1 << order' power of two.
937 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
938 * Returns 0 in all other cases and reg_ops.
942 REG_OP_ISFREE, /* true if region is all zero bits */
943 REG_OP_ALLOC, /* set all bits in region */
944 REG_OP_RELEASE, /* clear all bits in region */
947 static int __reg_op(unsigned long *bitmap, unsigned int pos, int order, int reg_op)
949 int nbits_reg; /* number of bits in region */
950 int index; /* index first long of region in bitmap */
951 int offset; /* bit offset region in bitmap[index] */
952 int nlongs_reg; /* num longs spanned by region in bitmap */
953 int nbitsinlong; /* num bits of region in each spanned long */
954 unsigned long mask; /* bitmask for one long of region */
955 int i; /* scans bitmap by longs */
956 int ret = 0; /* return value */
959 * Either nlongs_reg == 1 (for small orders that fit in one long)
960 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
962 nbits_reg = 1 << order;
963 index = pos / BITS_PER_LONG;
964 offset = pos - (index * BITS_PER_LONG);
965 nlongs_reg = BITS_TO_LONGS(nbits_reg);
966 nbitsinlong = min(nbits_reg, BITS_PER_LONG);
969 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
970 * overflows if nbitsinlong == BITS_PER_LONG.
972 mask = (1UL << (nbitsinlong - 1));
978 for (i = 0; i < nlongs_reg; i++) {
979 if (bitmap[index + i] & mask)
982 ret = 1; /* all bits in region free (zero) */
986 for (i = 0; i < nlongs_reg; i++)
987 bitmap[index + i] |= mask;
991 for (i = 0; i < nlongs_reg; i++)
992 bitmap[index + i] &= ~mask;
1000 * bitmap_find_free_region - find a contiguous aligned mem region
1001 * @bitmap: array of unsigned longs corresponding to the bitmap
1002 * @bits: number of bits in the bitmap
1003 * @order: region size (log base 2 of number of bits) to find
1005 * Find a region of free (zero) bits in a @bitmap of @bits bits and
1006 * allocate them (set them to one). Only consider regions of length
1007 * a power (@order) of two, aligned to that power of two, which
1008 * makes the search algorithm much faster.
1010 * Return the bit offset in bitmap of the allocated region,
1011 * or -errno on failure.
1013 int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order)
1015 unsigned int pos, end; /* scans bitmap by regions of size order */
1017 for (pos = 0 ; (end = pos + (1U << order)) <= bits; pos = end) {
1018 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1020 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1025 EXPORT_SYMBOL(bitmap_find_free_region);
1028 * bitmap_release_region - release allocated bitmap region
1029 * @bitmap: array of unsigned longs corresponding to the bitmap
1030 * @pos: beginning of bit region to release
1031 * @order: region size (log base 2 of number of bits) to release
1033 * This is the complement to __bitmap_find_free_region() and releases
1034 * the found region (by clearing it in the bitmap).
1038 void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order)
1040 __reg_op(bitmap, pos, order, REG_OP_RELEASE);
1042 EXPORT_SYMBOL(bitmap_release_region);
1045 * bitmap_allocate_region - allocate bitmap region
1046 * @bitmap: array of unsigned longs corresponding to the bitmap
1047 * @pos: beginning of bit region to allocate
1048 * @order: region size (log base 2 of number of bits) to allocate
1050 * Allocate (set bits in) a specified region of a bitmap.
1052 * Return 0 on success, or %-EBUSY if specified region wasn't
1053 * free (not all bits were zero).
1055 int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order)
1057 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1059 return __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1061 EXPORT_SYMBOL(bitmap_allocate_region);
1064 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1065 * @dst: destination buffer
1066 * @src: bitmap to copy
1067 * @nbits: number of bits in the bitmap
1069 * Require nbits % BITS_PER_LONG == 0.
1072 void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits)
1076 for (i = 0; i < nbits/BITS_PER_LONG; i++) {
1077 if (BITS_PER_LONG == 64)
1078 dst[i] = cpu_to_le64(src[i]);
1080 dst[i] = cpu_to_le32(src[i]);
1083 EXPORT_SYMBOL(bitmap_copy_le);
1086 unsigned long *bitmap_alloc(unsigned int nbits, gfp_t flags)
1088 return kmalloc_array(BITS_TO_LONGS(nbits), sizeof(unsigned long),
1091 EXPORT_SYMBOL(bitmap_alloc);
1093 unsigned long *bitmap_zalloc(unsigned int nbits, gfp_t flags)
1095 return bitmap_alloc(nbits, flags | __GFP_ZERO);
1097 EXPORT_SYMBOL(bitmap_zalloc);
1099 void bitmap_free(const unsigned long *bitmap)
1103 EXPORT_SYMBOL(bitmap_free);