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/kernel.h>
16 #include <linux/slab.h>
17 #include <linux/string.h>
18 #include <linux/uaccess.h>
23 * DOC: bitmap introduction
25 * bitmaps provide an array of bits, implemented using an an
26 * array of unsigned longs. The number of valid bits in a
27 * given bitmap does _not_ need to be an exact multiple of
30 * The possible unused bits in the last, partially used word
31 * of a bitmap are 'don't care'. The implementation makes
32 * no particular effort to keep them zero. It ensures that
33 * their value will not affect the results of any operation.
34 * The bitmap operations that return Boolean (bitmap_empty,
35 * for example) or scalar (bitmap_weight, for example) results
36 * carefully filter out these unused bits from impacting their
39 * The byte ordering of bitmaps is more natural on little
40 * endian architectures. See the big-endian headers
41 * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
42 * for the best explanations of this ordering.
45 int __bitmap_equal(const unsigned long *bitmap1,
46 const unsigned long *bitmap2, unsigned int bits)
48 unsigned int k, lim = bits/BITS_PER_LONG;
49 for (k = 0; k < lim; ++k)
50 if (bitmap1[k] != bitmap2[k])
53 if (bits % BITS_PER_LONG)
54 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
59 EXPORT_SYMBOL(__bitmap_equal);
61 void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits)
63 unsigned int k, lim = BITS_TO_LONGS(bits);
64 for (k = 0; k < lim; ++k)
67 EXPORT_SYMBOL(__bitmap_complement);
70 * __bitmap_shift_right - logical right shift of the bits in a bitmap
71 * @dst : destination bitmap
72 * @src : source bitmap
73 * @shift : shift by this many bits
74 * @nbits : bitmap size, in bits
76 * Shifting right (dividing) means moving bits in the MS -> LS bit
77 * direction. Zeros are fed into the vacated MS positions and the
78 * LS bits shifted off the bottom are lost.
80 void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
81 unsigned shift, unsigned nbits)
83 unsigned k, lim = BITS_TO_LONGS(nbits);
84 unsigned off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
85 unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);
86 for (k = 0; off + k < lim; ++k) {
87 unsigned long upper, lower;
90 * If shift is not word aligned, take lower rem bits of
91 * word above and make them the top rem bits of result.
93 if (!rem || off + k + 1 >= lim)
96 upper = src[off + k + 1];
97 if (off + k + 1 == lim - 1)
99 upper <<= (BITS_PER_LONG - rem);
101 lower = src[off + k];
102 if (off + k == lim - 1)
105 dst[k] = lower | upper;
108 memset(&dst[lim - off], 0, off*sizeof(unsigned long));
110 EXPORT_SYMBOL(__bitmap_shift_right);
114 * __bitmap_shift_left - logical left shift of the bits in a bitmap
115 * @dst : destination bitmap
116 * @src : source bitmap
117 * @shift : shift by this many bits
118 * @nbits : bitmap size, in bits
120 * Shifting left (multiplying) means moving bits in the LS -> MS
121 * direction. Zeros are fed into the vacated LS bit positions
122 * and those MS bits shifted off the top are lost.
125 void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
126 unsigned int shift, unsigned int nbits)
129 unsigned int lim = BITS_TO_LONGS(nbits);
130 unsigned int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
131 for (k = lim - off - 1; k >= 0; --k) {
132 unsigned long upper, lower;
135 * If shift is not word aligned, take upper rem bits of
136 * word below and make them the bottom rem bits of result.
139 lower = src[k - 1] >> (BITS_PER_LONG - rem);
142 upper = src[k] << rem;
143 dst[k + off] = lower | upper;
146 memset(dst, 0, off*sizeof(unsigned long));
148 EXPORT_SYMBOL(__bitmap_shift_left);
150 int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
151 const unsigned long *bitmap2, unsigned int bits)
154 unsigned int lim = bits/BITS_PER_LONG;
155 unsigned long result = 0;
157 for (k = 0; k < lim; k++)
158 result |= (dst[k] = bitmap1[k] & bitmap2[k]);
159 if (bits % BITS_PER_LONG)
160 result |= (dst[k] = bitmap1[k] & bitmap2[k] &
161 BITMAP_LAST_WORD_MASK(bits));
164 EXPORT_SYMBOL(__bitmap_and);
166 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
167 const unsigned long *bitmap2, unsigned int bits)
170 unsigned int nr = BITS_TO_LONGS(bits);
172 for (k = 0; k < nr; k++)
173 dst[k] = bitmap1[k] | bitmap2[k];
175 EXPORT_SYMBOL(__bitmap_or);
177 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
178 const unsigned long *bitmap2, unsigned int bits)
181 unsigned int nr = BITS_TO_LONGS(bits);
183 for (k = 0; k < nr; k++)
184 dst[k] = bitmap1[k] ^ bitmap2[k];
186 EXPORT_SYMBOL(__bitmap_xor);
188 int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
189 const unsigned long *bitmap2, unsigned int bits)
192 unsigned int lim = bits/BITS_PER_LONG;
193 unsigned long result = 0;
195 for (k = 0; k < lim; k++)
196 result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
197 if (bits % BITS_PER_LONG)
198 result |= (dst[k] = bitmap1[k] & ~bitmap2[k] &
199 BITMAP_LAST_WORD_MASK(bits));
202 EXPORT_SYMBOL(__bitmap_andnot);
204 int __bitmap_intersects(const unsigned long *bitmap1,
205 const unsigned long *bitmap2, unsigned int bits)
207 unsigned int k, lim = bits/BITS_PER_LONG;
208 for (k = 0; k < lim; ++k)
209 if (bitmap1[k] & bitmap2[k])
212 if (bits % BITS_PER_LONG)
213 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
217 EXPORT_SYMBOL(__bitmap_intersects);
219 int __bitmap_subset(const unsigned long *bitmap1,
220 const unsigned long *bitmap2, unsigned int bits)
222 unsigned int k, lim = bits/BITS_PER_LONG;
223 for (k = 0; k < lim; ++k)
224 if (bitmap1[k] & ~bitmap2[k])
227 if (bits % BITS_PER_LONG)
228 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
232 EXPORT_SYMBOL(__bitmap_subset);
234 int __bitmap_weight(const unsigned long *bitmap, unsigned int bits)
236 unsigned int k, lim = bits/BITS_PER_LONG;
239 for (k = 0; k < lim; k++)
240 w += hweight_long(bitmap[k]);
242 if (bits % BITS_PER_LONG)
243 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
247 EXPORT_SYMBOL(__bitmap_weight);
249 void __bitmap_set(unsigned long *map, unsigned int start, int len)
251 unsigned long *p = map + BIT_WORD(start);
252 const unsigned int size = start + len;
253 int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
254 unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
256 while (len - bits_to_set >= 0) {
259 bits_to_set = BITS_PER_LONG;
264 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
268 EXPORT_SYMBOL(__bitmap_set);
270 void __bitmap_clear(unsigned long *map, unsigned int start, int len)
272 unsigned long *p = map + BIT_WORD(start);
273 const unsigned int size = start + len;
274 int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
275 unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
277 while (len - bits_to_clear >= 0) {
278 *p &= ~mask_to_clear;
279 len -= bits_to_clear;
280 bits_to_clear = BITS_PER_LONG;
281 mask_to_clear = ~0UL;
285 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
286 *p &= ~mask_to_clear;
289 EXPORT_SYMBOL(__bitmap_clear);
292 * bitmap_find_next_zero_area_off - find a contiguous aligned zero area
293 * @map: The address to base the search on
294 * @size: The bitmap size in bits
295 * @start: The bitnumber to start searching at
296 * @nr: The number of zeroed bits we're looking for
297 * @align_mask: Alignment mask for zero area
298 * @align_offset: Alignment offset for zero area.
300 * The @align_mask should be one less than a power of 2; the effect is that
301 * the bit offset of all zero areas this function finds plus @align_offset
302 * is multiple of that power of 2.
304 unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
308 unsigned long align_mask,
309 unsigned long align_offset)
311 unsigned long index, end, i;
313 index = find_next_zero_bit(map, size, start);
315 /* Align allocation */
316 index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset;
321 i = find_next_bit(map, end, index);
328 EXPORT_SYMBOL(bitmap_find_next_zero_area_off);
331 * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,
332 * second version by Paul Jackson, third by Joe Korty.
336 #define nbits_to_hold_value(val) fls(val)
337 #define BASEDEC 10 /* fancier cpuset lists input in decimal */
340 * __bitmap_parse - convert an ASCII hex string into a bitmap.
341 * @buf: pointer to buffer containing string.
342 * @buflen: buffer size in bytes. If string is smaller than this
343 * then it must be terminated with a \0.
344 * @is_user: location of buffer, 0 indicates kernel space
345 * @maskp: pointer to bitmap array that will contain result.
346 * @nmaskbits: size of bitmap, in bits.
348 * Commas group hex digits into chunks. Each chunk defines exactly 32
349 * bits of the resultant bitmask. No chunk may specify a value larger
350 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
351 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
352 * characters and for grouping errors such as "1,,5", ",44", "," and "".
353 * Leading and trailing whitespace accepted, but not embedded whitespace.
355 int __bitmap_parse(const char *buf, unsigned int buflen,
356 int is_user, unsigned long *maskp,
359 int c, old_c, totaldigits, ndigits, nchunks, nbits;
361 const char __user __force *ubuf = (const char __user __force *)buf;
363 bitmap_zero(maskp, nmaskbits);
365 nchunks = nbits = totaldigits = c = 0;
368 ndigits = totaldigits;
370 /* Get the next chunk of the bitmap */
374 if (__get_user(c, ubuf++))
384 * If the last character was a space and the current
385 * character isn't '\0', we've got embedded whitespace.
386 * This is a no-no, so throw an error.
388 if (totaldigits && c && isspace(old_c))
391 /* A '\0' or a ',' signal the end of the chunk */
392 if (c == '\0' || c == ',')
399 * Make sure there are at least 4 free bits in 'chunk'.
400 * If not, this hexdigit will overflow 'chunk', so
403 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
406 chunk = (chunk << 4) | hex_to_bin(c);
409 if (ndigits == totaldigits)
411 if (nchunks == 0 && chunk == 0)
414 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
417 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
418 if (nbits > nmaskbits)
420 } while (buflen && c == ',');
424 EXPORT_SYMBOL(__bitmap_parse);
427 * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
429 * @ubuf: pointer to user buffer containing string.
430 * @ulen: buffer size in bytes. If string is smaller than this
431 * then it must be terminated with a \0.
432 * @maskp: pointer to bitmap array that will contain result.
433 * @nmaskbits: size of bitmap, in bits.
435 * Wrapper for __bitmap_parse(), providing it with user buffer.
437 * We cannot have this as an inline function in bitmap.h because it needs
438 * linux/uaccess.h to get the access_ok() declaration and this causes
439 * cyclic dependencies.
441 int bitmap_parse_user(const char __user *ubuf,
442 unsigned int ulen, unsigned long *maskp,
445 if (!access_ok(VERIFY_READ, ubuf, ulen))
447 return __bitmap_parse((const char __force *)ubuf,
448 ulen, 1, maskp, nmaskbits);
451 EXPORT_SYMBOL(bitmap_parse_user);
454 * bitmap_print_to_pagebuf - convert bitmap to list or hex format ASCII string
455 * @list: indicates whether the bitmap must be list
456 * @buf: page aligned buffer into which string is placed
457 * @maskp: pointer to bitmap to convert
458 * @nmaskbits: size of bitmap, in bits
460 * Output format is a comma-separated list of decimal numbers and
461 * ranges if list is specified or hex digits grouped into comma-separated
462 * sets of 8 digits/set. Returns the number of characters written to buf.
464 * It is assumed that @buf is a pointer into a PAGE_SIZE area and that
465 * sufficient storage remains at @buf to accommodate the
466 * bitmap_print_to_pagebuf() output.
468 int bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp,
471 ptrdiff_t len = PTR_ALIGN(buf + PAGE_SIZE - 1, PAGE_SIZE) - buf;
475 n = list ? scnprintf(buf, len, "%*pbl\n", nmaskbits, maskp) :
476 scnprintf(buf, len, "%*pb\n", nmaskbits, maskp);
479 EXPORT_SYMBOL(bitmap_print_to_pagebuf);
482 * __bitmap_parselist - convert list format ASCII string to bitmap
483 * @buf: read nul-terminated user string from this buffer
484 * @buflen: buffer size in bytes. If string is smaller than this
485 * then it must be terminated with a \0.
486 * @is_user: location of buffer, 0 indicates kernel space
487 * @maskp: write resulting mask here
488 * @nmaskbits: number of bits in mask to be written
490 * Input format is a comma-separated list of decimal numbers and
491 * ranges. Consecutively set bits are shown as two hyphen-separated
492 * decimal numbers, the smallest and largest bit numbers set in
494 * Optionally each range can be postfixed to denote that only parts of it
495 * should be set. The range will divided to groups of specific size.
496 * From each group will be used only defined amount of bits.
497 * Syntax: range:used_size/group_size
498 * Example: 0-1023:2/256 ==> 0,1,256,257,512,513,768,769
500 * Returns: 0 on success, -errno on invalid input strings. Error values:
502 * - ``-EINVAL``: second number in range smaller than first
503 * - ``-EINVAL``: invalid character in string
504 * - ``-ERANGE``: bit number specified too large for mask
506 static int __bitmap_parselist(const char *buf, unsigned int buflen,
507 int is_user, unsigned long *maskp,
510 unsigned int a, b, old_a, old_b;
511 unsigned int group_size, used_size, off;
512 int c, old_c, totaldigits, ndigits;
513 const char __user __force *ubuf = (const char __user __force *)buf;
514 int at_start, in_range, in_partial_range;
518 group_size = used_size = 0;
519 bitmap_zero(maskp, nmaskbits);
523 in_partial_range = 0;
525 ndigits = totaldigits;
527 /* Get the next cpu# or a range of cpu#'s */
531 if (__get_user(c, ubuf++))
539 /* A '\0' or a ',' signal the end of a cpu# or range */
540 if (c == '\0' || c == ',')
543 * whitespaces between digits are not allowed,
544 * but it's ok if whitespaces are on head or tail.
545 * when old_c is whilespace,
546 * if totaldigits == ndigits, whitespace is on head.
547 * if whitespace is on tail, it should not run here.
548 * as c was ',' or '\0',
549 * the last code line has broken the current loop.
551 if ((totaldigits != ndigits) && isspace(old_c))
567 in_partial_range = 1;
573 if (at_start || in_range)
584 b = b * 10 + (c - '0');
590 if (ndigits == totaldigits)
592 if (in_partial_range) {
598 used_size = group_size = b - a + 1;
600 /* if no digit is after '-', it's wrong*/
601 if (at_start && in_range)
603 if (!(a <= b) || group_size == 0 || !(used_size <= group_size))
608 off = min(b - a + 1, used_size);
609 bitmap_set(maskp, a, off);
612 } while (buflen && c == ',');
616 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
618 char *nl = strchrnul(bp, '\n');
621 return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
623 EXPORT_SYMBOL(bitmap_parselist);
627 * bitmap_parselist_user()
629 * @ubuf: pointer to user buffer containing string.
630 * @ulen: buffer size in bytes. If string is smaller than this
631 * then it must be terminated with a \0.
632 * @maskp: pointer to bitmap array that will contain result.
633 * @nmaskbits: size of bitmap, in bits.
635 * Wrapper for bitmap_parselist(), providing it with user buffer.
637 * We cannot have this as an inline function in bitmap.h because it needs
638 * linux/uaccess.h to get the access_ok() declaration and this causes
639 * cyclic dependencies.
641 int bitmap_parselist_user(const char __user *ubuf,
642 unsigned int ulen, unsigned long *maskp,
645 if (!access_ok(VERIFY_READ, ubuf, ulen))
647 return __bitmap_parselist((const char __force *)ubuf,
648 ulen, 1, maskp, nmaskbits);
650 EXPORT_SYMBOL(bitmap_parselist_user);
654 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
655 * @buf: pointer to a bitmap
656 * @pos: a bit position in @buf (0 <= @pos < @nbits)
657 * @nbits: number of valid bit positions in @buf
659 * Map the bit at position @pos in @buf (of length @nbits) to the
660 * ordinal of which set bit it is. If it is not set or if @pos
661 * is not a valid bit position, map to -1.
663 * If for example, just bits 4 through 7 are set in @buf, then @pos
664 * values 4 through 7 will get mapped to 0 through 3, respectively,
665 * and other @pos values will get mapped to -1. When @pos value 7
666 * gets mapped to (returns) @ord value 3 in this example, that means
667 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
669 * The bit positions 0 through @bits are valid positions in @buf.
671 static int bitmap_pos_to_ord(const unsigned long *buf, unsigned int pos, unsigned int nbits)
673 if (pos >= nbits || !test_bit(pos, buf))
676 return __bitmap_weight(buf, pos);
680 * bitmap_ord_to_pos - find position of n-th set bit in bitmap
681 * @buf: pointer to bitmap
682 * @ord: ordinal bit position (n-th set bit, n >= 0)
683 * @nbits: number of valid bit positions in @buf
685 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
686 * Value of @ord should be in range 0 <= @ord < weight(buf). If @ord
687 * >= weight(buf), returns @nbits.
689 * If for example, just bits 4 through 7 are set in @buf, then @ord
690 * values 0 through 3 will get mapped to 4 through 7, respectively,
691 * and all other @ord values returns @nbits. When @ord value 3
692 * gets mapped to (returns) @pos value 7 in this example, that means
693 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
695 * The bit positions 0 through @nbits-1 are valid positions in @buf.
697 unsigned int bitmap_ord_to_pos(const unsigned long *buf, unsigned int ord, unsigned int nbits)
701 for (pos = find_first_bit(buf, nbits);
703 pos = find_next_bit(buf, nbits, pos + 1))
710 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
711 * @dst: remapped result
712 * @src: subset to be remapped
713 * @old: defines domain of map
714 * @new: defines range of map
715 * @nbits: number of bits in each of these bitmaps
717 * Let @old and @new define a mapping of bit positions, such that
718 * whatever position is held by the n-th set bit in @old is mapped
719 * to the n-th set bit in @new. In the more general case, allowing
720 * for the possibility that the weight 'w' of @new is less than the
721 * weight of @old, map the position of the n-th set bit in @old to
722 * the position of the m-th set bit in @new, where m == n % w.
724 * If either of the @old and @new bitmaps are empty, or if @src and
725 * @dst point to the same location, then this routine copies @src
728 * The positions of unset bits in @old are mapped to themselves
729 * (the identify map).
731 * Apply the above specified mapping to @src, placing the result in
732 * @dst, clearing any bits previously set in @dst.
734 * For example, lets say that @old has bits 4 through 7 set, and
735 * @new has bits 12 through 15 set. This defines the mapping of bit
736 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
737 * bit positions unchanged. So if say @src comes into this routine
738 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
741 void bitmap_remap(unsigned long *dst, const unsigned long *src,
742 const unsigned long *old, const unsigned long *new,
745 unsigned int oldbit, w;
747 if (dst == src) /* following doesn't handle inplace remaps */
749 bitmap_zero(dst, nbits);
751 w = bitmap_weight(new, nbits);
752 for_each_set_bit(oldbit, src, nbits) {
753 int n = bitmap_pos_to_ord(old, oldbit, nbits);
756 set_bit(oldbit, dst); /* identity map */
758 set_bit(bitmap_ord_to_pos(new, n % w, nbits), dst);
761 EXPORT_SYMBOL(bitmap_remap);
764 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
765 * @oldbit: bit position to be mapped
766 * @old: defines domain of map
767 * @new: defines range of map
768 * @bits: number of bits in each of these bitmaps
770 * Let @old and @new define a mapping of bit positions, such that
771 * whatever position is held by the n-th set bit in @old is mapped
772 * to the n-th set bit in @new. In the more general case, allowing
773 * for the possibility that the weight 'w' of @new is less than the
774 * weight of @old, map the position of the n-th set bit in @old to
775 * the position of the m-th set bit in @new, where m == n % w.
777 * The positions of unset bits in @old are mapped to themselves
778 * (the identify map).
780 * Apply the above specified mapping to bit position @oldbit, returning
781 * the new bit position.
783 * For example, lets say that @old has bits 4 through 7 set, and
784 * @new has bits 12 through 15 set. This defines the mapping of bit
785 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
786 * bit positions unchanged. So if say @oldbit is 5, then this routine
789 int bitmap_bitremap(int oldbit, const unsigned long *old,
790 const unsigned long *new, int bits)
792 int w = bitmap_weight(new, bits);
793 int n = bitmap_pos_to_ord(old, oldbit, bits);
797 return bitmap_ord_to_pos(new, n % w, bits);
799 EXPORT_SYMBOL(bitmap_bitremap);
802 * bitmap_onto - translate one bitmap relative to another
803 * @dst: resulting translated bitmap
804 * @orig: original untranslated bitmap
805 * @relmap: bitmap relative to which translated
806 * @bits: number of bits in each of these bitmaps
808 * Set the n-th bit of @dst iff there exists some m such that the
809 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
810 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
811 * (If you understood the previous sentence the first time your
812 * read it, you're overqualified for your current job.)
814 * In other words, @orig is mapped onto (surjectively) @dst,
815 * using the map { <n, m> | the n-th bit of @relmap is the
816 * m-th set bit of @relmap }.
818 * Any set bits in @orig above bit number W, where W is the
819 * weight of (number of set bits in) @relmap are mapped nowhere.
820 * In particular, if for all bits m set in @orig, m >= W, then
821 * @dst will end up empty. In situations where the possibility
822 * of such an empty result is not desired, one way to avoid it is
823 * to use the bitmap_fold() operator, below, to first fold the
824 * @orig bitmap over itself so that all its set bits x are in the
825 * range 0 <= x < W. The bitmap_fold() operator does this by
826 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
828 * Example [1] for bitmap_onto():
829 * Let's say @relmap has bits 30-39 set, and @orig has bits
830 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,
831 * @dst will have bits 31, 33, 35, 37 and 39 set.
833 * When bit 0 is set in @orig, it means turn on the bit in
834 * @dst corresponding to whatever is the first bit (if any)
835 * that is turned on in @relmap. Since bit 0 was off in the
836 * above example, we leave off that bit (bit 30) in @dst.
838 * When bit 1 is set in @orig (as in the above example), it
839 * means turn on the bit in @dst corresponding to whatever
840 * is the second bit that is turned on in @relmap. The second
841 * bit in @relmap that was turned on in the above example was
842 * bit 31, so we turned on bit 31 in @dst.
844 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
845 * because they were the 4th, 6th, 8th and 10th set bits
846 * set in @relmap, and the 4th, 6th, 8th and 10th bits of
847 * @orig (i.e. bits 3, 5, 7 and 9) were also set.
849 * When bit 11 is set in @orig, it means turn on the bit in
850 * @dst corresponding to whatever is the twelfth bit that is
851 * turned on in @relmap. In the above example, there were
852 * only ten bits turned on in @relmap (30..39), so that bit
853 * 11 was set in @orig had no affect on @dst.
855 * Example [2] for bitmap_fold() + bitmap_onto():
856 * Let's say @relmap has these ten bits set::
858 * 40 41 42 43 45 48 53 61 74 95
860 * (for the curious, that's 40 plus the first ten terms of the
861 * Fibonacci sequence.)
863 * Further lets say we use the following code, invoking
864 * bitmap_fold() then bitmap_onto, as suggested above to
865 * avoid the possibility of an empty @dst result::
867 * unsigned long *tmp; // a temporary bitmap's bits
869 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
870 * bitmap_onto(dst, tmp, relmap, bits);
872 * Then this table shows what various values of @dst would be, for
873 * various @orig's. I list the zero-based positions of each set bit.
874 * The tmp column shows the intermediate result, as computed by
875 * using bitmap_fold() to fold the @orig bitmap modulo ten
876 * (the weight of @relmap):
878 * =============== ============== =================
884 * 1 3 5 7 1 3 5 7 41 43 48 61
885 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45
886 * 0 9 18 27 0 9 8 7 40 61 74 95
888 * 0 11 22 33 0 1 2 3 40 41 42 43
889 * 0 12 24 36 0 2 4 6 40 42 45 53
890 * 78 102 211 1 2 8 41 42 74 [#f1]_
891 * =============== ============== =================
895 * For these marked lines, if we hadn't first done bitmap_fold()
896 * into tmp, then the @dst result would have been empty.
898 * If either of @orig or @relmap is empty (no set bits), then @dst
899 * will be returned empty.
901 * If (as explained above) the only set bits in @orig are in positions
902 * m where m >= W, (where W is the weight of @relmap) then @dst will
903 * once again be returned empty.
905 * All bits in @dst not set by the above rule are cleared.
907 void bitmap_onto(unsigned long *dst, const unsigned long *orig,
908 const unsigned long *relmap, unsigned int bits)
910 unsigned int n, m; /* same meaning as in above comment */
912 if (dst == orig) /* following doesn't handle inplace mappings */
914 bitmap_zero(dst, bits);
917 * The following code is a more efficient, but less
918 * obvious, equivalent to the loop:
919 * for (m = 0; m < bitmap_weight(relmap, bits); m++) {
920 * n = bitmap_ord_to_pos(orig, m, bits);
921 * if (test_bit(m, orig))
927 for_each_set_bit(n, relmap, bits) {
928 /* m == bitmap_pos_to_ord(relmap, n, bits) */
929 if (test_bit(m, orig))
934 EXPORT_SYMBOL(bitmap_onto);
937 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
938 * @dst: resulting smaller bitmap
939 * @orig: original larger bitmap
940 * @sz: specified size
941 * @nbits: number of bits in each of these bitmaps
943 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
944 * Clear all other bits in @dst. See further the comment and
945 * Example [2] for bitmap_onto() for why and how to use this.
947 void bitmap_fold(unsigned long *dst, const unsigned long *orig,
948 unsigned int sz, unsigned int nbits)
952 if (dst == orig) /* following doesn't handle inplace mappings */
954 bitmap_zero(dst, nbits);
956 for_each_set_bit(oldbit, orig, nbits)
957 set_bit(oldbit % sz, dst);
959 EXPORT_SYMBOL(bitmap_fold);
962 * Common code for bitmap_*_region() routines.
963 * bitmap: array of unsigned longs corresponding to the bitmap
964 * pos: the beginning of the region
965 * order: region size (log base 2 of number of bits)
966 * reg_op: operation(s) to perform on that region of bitmap
968 * Can set, verify and/or release a region of bits in a bitmap,
969 * depending on which combination of REG_OP_* flag bits is set.
971 * A region of a bitmap is a sequence of bits in the bitmap, of
972 * some size '1 << order' (a power of two), aligned to that same
973 * '1 << order' power of two.
975 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
976 * Returns 0 in all other cases and reg_ops.
980 REG_OP_ISFREE, /* true if region is all zero bits */
981 REG_OP_ALLOC, /* set all bits in region */
982 REG_OP_RELEASE, /* clear all bits in region */
985 static int __reg_op(unsigned long *bitmap, unsigned int pos, int order, int reg_op)
987 int nbits_reg; /* number of bits in region */
988 int index; /* index first long of region in bitmap */
989 int offset; /* bit offset region in bitmap[index] */
990 int nlongs_reg; /* num longs spanned by region in bitmap */
991 int nbitsinlong; /* num bits of region in each spanned long */
992 unsigned long mask; /* bitmask for one long of region */
993 int i; /* scans bitmap by longs */
994 int ret = 0; /* return value */
997 * Either nlongs_reg == 1 (for small orders that fit in one long)
998 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
1000 nbits_reg = 1 << order;
1001 index = pos / BITS_PER_LONG;
1002 offset = pos - (index * BITS_PER_LONG);
1003 nlongs_reg = BITS_TO_LONGS(nbits_reg);
1004 nbitsinlong = min(nbits_reg, BITS_PER_LONG);
1007 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
1008 * overflows if nbitsinlong == BITS_PER_LONG.
1010 mask = (1UL << (nbitsinlong - 1));
1016 for (i = 0; i < nlongs_reg; i++) {
1017 if (bitmap[index + i] & mask)
1020 ret = 1; /* all bits in region free (zero) */
1024 for (i = 0; i < nlongs_reg; i++)
1025 bitmap[index + i] |= mask;
1028 case REG_OP_RELEASE:
1029 for (i = 0; i < nlongs_reg; i++)
1030 bitmap[index + i] &= ~mask;
1038 * bitmap_find_free_region - find a contiguous aligned mem region
1039 * @bitmap: array of unsigned longs corresponding to the bitmap
1040 * @bits: number of bits in the bitmap
1041 * @order: region size (log base 2 of number of bits) to find
1043 * Find a region of free (zero) bits in a @bitmap of @bits bits and
1044 * allocate them (set them to one). Only consider regions of length
1045 * a power (@order) of two, aligned to that power of two, which
1046 * makes the search algorithm much faster.
1048 * Return the bit offset in bitmap of the allocated region,
1049 * or -errno on failure.
1051 int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order)
1053 unsigned int pos, end; /* scans bitmap by regions of size order */
1055 for (pos = 0 ; (end = pos + (1U << order)) <= bits; pos = end) {
1056 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1058 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1063 EXPORT_SYMBOL(bitmap_find_free_region);
1066 * bitmap_release_region - release allocated bitmap region
1067 * @bitmap: array of unsigned longs corresponding to the bitmap
1068 * @pos: beginning of bit region to release
1069 * @order: region size (log base 2 of number of bits) to release
1071 * This is the complement to __bitmap_find_free_region() and releases
1072 * the found region (by clearing it in the bitmap).
1076 void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order)
1078 __reg_op(bitmap, pos, order, REG_OP_RELEASE);
1080 EXPORT_SYMBOL(bitmap_release_region);
1083 * bitmap_allocate_region - allocate bitmap region
1084 * @bitmap: array of unsigned longs corresponding to the bitmap
1085 * @pos: beginning of bit region to allocate
1086 * @order: region size (log base 2 of number of bits) to allocate
1088 * Allocate (set bits in) a specified region of a bitmap.
1090 * Return 0 on success, or %-EBUSY if specified region wasn't
1091 * free (not all bits were zero).
1093 int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order)
1095 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1097 return __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1099 EXPORT_SYMBOL(bitmap_allocate_region);
1102 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1103 * @dst: destination buffer
1104 * @src: bitmap to copy
1105 * @nbits: number of bits in the bitmap
1107 * Require nbits % BITS_PER_LONG == 0.
1110 void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits)
1114 for (i = 0; i < nbits/BITS_PER_LONG; i++) {
1115 if (BITS_PER_LONG == 64)
1116 dst[i] = cpu_to_le64(src[i]);
1118 dst[i] = cpu_to_le32(src[i]);
1121 EXPORT_SYMBOL(bitmap_copy_le);
1124 unsigned long *bitmap_alloc(unsigned int nbits, gfp_t flags)
1126 return kmalloc_array(BITS_TO_LONGS(nbits), sizeof(unsigned long),
1129 EXPORT_SYMBOL(bitmap_alloc);
1131 unsigned long *bitmap_zalloc(unsigned int nbits, gfp_t flags)
1133 return bitmap_alloc(nbits, flags | __GFP_ZERO);
1135 EXPORT_SYMBOL(bitmap_zalloc);
1137 void bitmap_free(const unsigned long *bitmap)
1141 EXPORT_SYMBOL(bitmap_free);
1143 #if BITS_PER_LONG == 64
1145 * bitmap_from_arr32 - copy the contents of u32 array of bits to bitmap
1146 * @bitmap: array of unsigned longs, the destination bitmap
1147 * @buf: array of u32 (in host byte order), the source bitmap
1148 * @nbits: number of bits in @bitmap
1150 void bitmap_from_arr32(unsigned long *bitmap, const u32 *buf, unsigned int nbits)
1152 unsigned int i, halfwords;
1154 halfwords = DIV_ROUND_UP(nbits, 32);
1155 for (i = 0; i < halfwords; i++) {
1156 bitmap[i/2] = (unsigned long) buf[i];
1157 if (++i < halfwords)
1158 bitmap[i/2] |= ((unsigned long) buf[i]) << 32;
1161 /* Clear tail bits in last word beyond nbits. */
1162 if (nbits % BITS_PER_LONG)
1163 bitmap[(halfwords - 1) / 2] &= BITMAP_LAST_WORD_MASK(nbits);
1165 EXPORT_SYMBOL(bitmap_from_arr32);
1168 * bitmap_to_arr32 - copy the contents of bitmap to a u32 array of bits
1169 * @buf: array of u32 (in host byte order), the dest bitmap
1170 * @bitmap: array of unsigned longs, the source bitmap
1171 * @nbits: number of bits in @bitmap
1173 void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap, unsigned int nbits)
1175 unsigned int i, halfwords;
1177 halfwords = DIV_ROUND_UP(nbits, 32);
1178 for (i = 0; i < halfwords; i++) {
1179 buf[i] = (u32) (bitmap[i/2] & UINT_MAX);
1180 if (++i < halfwords)
1181 buf[i] = (u32) (bitmap[i/2] >> 32);
1184 /* Clear tail bits in last element of array beyond nbits. */
1185 if (nbits % BITS_PER_LONG)
1186 buf[halfwords - 1] &= (u32) (UINT_MAX >> ((-nbits) & 31));
1188 EXPORT_SYMBOL(bitmap_to_arr32);