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 * These operations actually hold to a slightly stronger rule:
40 * if you don't input any bitmaps to these ops that have some
41 * unused bits set, then they won't output any set unused bits
44 * The byte ordering of bitmaps is more natural on little
45 * endian architectures. See the big-endian headers
46 * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
47 * for the best explanations of this ordering.
50 int __bitmap_equal(const unsigned long *bitmap1,
51 const unsigned long *bitmap2, unsigned int bits)
53 unsigned int k, lim = bits/BITS_PER_LONG;
54 for (k = 0; k < lim; ++k)
55 if (bitmap1[k] != bitmap2[k])
58 if (bits % BITS_PER_LONG)
59 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
64 EXPORT_SYMBOL(__bitmap_equal);
66 void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits)
68 unsigned int k, lim = bits/BITS_PER_LONG;
69 for (k = 0; k < lim; ++k)
72 if (bits % BITS_PER_LONG)
75 EXPORT_SYMBOL(__bitmap_complement);
78 * __bitmap_shift_right - logical right shift of the bits in a bitmap
79 * @dst : destination bitmap
80 * @src : source bitmap
81 * @shift : shift by this many bits
82 * @nbits : bitmap size, in bits
84 * Shifting right (dividing) means moving bits in the MS -> LS bit
85 * direction. Zeros are fed into the vacated MS positions and the
86 * LS bits shifted off the bottom are lost.
88 void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
89 unsigned shift, unsigned nbits)
91 unsigned k, lim = BITS_TO_LONGS(nbits);
92 unsigned off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
93 unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);
94 for (k = 0; off + k < lim; ++k) {
95 unsigned long upper, lower;
98 * If shift is not word aligned, take lower rem bits of
99 * word above and make them the top rem bits of result.
101 if (!rem || off + k + 1 >= lim)
104 upper = src[off + k + 1];
105 if (off + k + 1 == lim - 1)
107 upper <<= (BITS_PER_LONG - rem);
109 lower = src[off + k];
110 if (off + k == lim - 1)
113 dst[k] = lower | upper;
116 memset(&dst[lim - off], 0, off*sizeof(unsigned long));
118 EXPORT_SYMBOL(__bitmap_shift_right);
122 * __bitmap_shift_left - logical left shift of the bits in a bitmap
123 * @dst : destination bitmap
124 * @src : source bitmap
125 * @shift : shift by this many bits
126 * @nbits : bitmap size, in bits
128 * Shifting left (multiplying) means moving bits in the LS -> MS
129 * direction. Zeros are fed into the vacated LS bit positions
130 * and those MS bits shifted off the top are lost.
133 void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
134 unsigned int shift, unsigned int nbits)
137 unsigned int lim = BITS_TO_LONGS(nbits);
138 unsigned int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
139 for (k = lim - off - 1; k >= 0; --k) {
140 unsigned long upper, lower;
143 * If shift is not word aligned, take upper rem bits of
144 * word below and make them the bottom rem bits of result.
147 lower = src[k - 1] >> (BITS_PER_LONG - rem);
150 upper = src[k] << rem;
151 dst[k + off] = lower | upper;
154 memset(dst, 0, off*sizeof(unsigned long));
156 EXPORT_SYMBOL(__bitmap_shift_left);
158 int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
159 const unsigned long *bitmap2, unsigned int bits)
162 unsigned int lim = bits/BITS_PER_LONG;
163 unsigned long result = 0;
165 for (k = 0; k < lim; k++)
166 result |= (dst[k] = bitmap1[k] & bitmap2[k]);
167 if (bits % BITS_PER_LONG)
168 result |= (dst[k] = bitmap1[k] & bitmap2[k] &
169 BITMAP_LAST_WORD_MASK(bits));
172 EXPORT_SYMBOL(__bitmap_and);
174 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
175 const unsigned long *bitmap2, unsigned int bits)
178 unsigned int nr = BITS_TO_LONGS(bits);
180 for (k = 0; k < nr; k++)
181 dst[k] = bitmap1[k] | bitmap2[k];
183 EXPORT_SYMBOL(__bitmap_or);
185 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
186 const unsigned long *bitmap2, unsigned int bits)
189 unsigned int nr = BITS_TO_LONGS(bits);
191 for (k = 0; k < nr; k++)
192 dst[k] = bitmap1[k] ^ bitmap2[k];
194 EXPORT_SYMBOL(__bitmap_xor);
196 int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
197 const unsigned long *bitmap2, unsigned int bits)
200 unsigned int lim = bits/BITS_PER_LONG;
201 unsigned long result = 0;
203 for (k = 0; k < lim; k++)
204 result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
205 if (bits % BITS_PER_LONG)
206 result |= (dst[k] = bitmap1[k] & ~bitmap2[k] &
207 BITMAP_LAST_WORD_MASK(bits));
210 EXPORT_SYMBOL(__bitmap_andnot);
212 int __bitmap_intersects(const unsigned long *bitmap1,
213 const unsigned long *bitmap2, unsigned int bits)
215 unsigned int k, lim = bits/BITS_PER_LONG;
216 for (k = 0; k < lim; ++k)
217 if (bitmap1[k] & bitmap2[k])
220 if (bits % BITS_PER_LONG)
221 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
225 EXPORT_SYMBOL(__bitmap_intersects);
227 int __bitmap_subset(const unsigned long *bitmap1,
228 const unsigned long *bitmap2, unsigned int bits)
230 unsigned int k, lim = bits/BITS_PER_LONG;
231 for (k = 0; k < lim; ++k)
232 if (bitmap1[k] & ~bitmap2[k])
235 if (bits % BITS_PER_LONG)
236 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
240 EXPORT_SYMBOL(__bitmap_subset);
242 int __bitmap_weight(const unsigned long *bitmap, unsigned int bits)
244 unsigned int k, lim = bits/BITS_PER_LONG;
247 for (k = 0; k < lim; k++)
248 w += hweight_long(bitmap[k]);
250 if (bits % BITS_PER_LONG)
251 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
255 EXPORT_SYMBOL(__bitmap_weight);
257 void __bitmap_set(unsigned long *map, unsigned int start, int len)
259 unsigned long *p = map + BIT_WORD(start);
260 const unsigned int size = start + len;
261 int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
262 unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
264 while (len - bits_to_set >= 0) {
267 bits_to_set = BITS_PER_LONG;
272 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
276 EXPORT_SYMBOL(__bitmap_set);
278 void __bitmap_clear(unsigned long *map, unsigned int start, int len)
280 unsigned long *p = map + BIT_WORD(start);
281 const unsigned int size = start + len;
282 int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
283 unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
285 while (len - bits_to_clear >= 0) {
286 *p &= ~mask_to_clear;
287 len -= bits_to_clear;
288 bits_to_clear = BITS_PER_LONG;
289 mask_to_clear = ~0UL;
293 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
294 *p &= ~mask_to_clear;
297 EXPORT_SYMBOL(__bitmap_clear);
300 * bitmap_find_next_zero_area_off - find a contiguous aligned zero area
301 * @map: The address to base the search on
302 * @size: The bitmap size in bits
303 * @start: The bitnumber to start searching at
304 * @nr: The number of zeroed bits we're looking for
305 * @align_mask: Alignment mask for zero area
306 * @align_offset: Alignment offset for zero area.
308 * The @align_mask should be one less than a power of 2; the effect is that
309 * the bit offset of all zero areas this function finds plus @align_offset
310 * is multiple of that power of 2.
312 unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
316 unsigned long align_mask,
317 unsigned long align_offset)
319 unsigned long index, end, i;
321 index = find_next_zero_bit(map, size, start);
323 /* Align allocation */
324 index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset;
329 i = find_next_bit(map, end, index);
336 EXPORT_SYMBOL(bitmap_find_next_zero_area_off);
339 * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,
340 * second version by Paul Jackson, third by Joe Korty.
344 #define nbits_to_hold_value(val) fls(val)
345 #define BASEDEC 10 /* fancier cpuset lists input in decimal */
348 * __bitmap_parse - convert an ASCII hex string into a bitmap.
349 * @buf: pointer to buffer containing string.
350 * @buflen: buffer size in bytes. If string is smaller than this
351 * then it must be terminated with a \0.
352 * @is_user: location of buffer, 0 indicates kernel space
353 * @maskp: pointer to bitmap array that will contain result.
354 * @nmaskbits: size of bitmap, in bits.
356 * Commas group hex digits into chunks. Each chunk defines exactly 32
357 * bits of the resultant bitmask. No chunk may specify a value larger
358 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
359 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
360 * characters and for grouping errors such as "1,,5", ",44", "," and "".
361 * Leading and trailing whitespace accepted, but not embedded whitespace.
363 int __bitmap_parse(const char *buf, unsigned int buflen,
364 int is_user, unsigned long *maskp,
367 int c, old_c, totaldigits, ndigits, nchunks, nbits;
369 const char __user __force *ubuf = (const char __user __force *)buf;
371 bitmap_zero(maskp, nmaskbits);
373 nchunks = nbits = totaldigits = c = 0;
376 ndigits = totaldigits;
378 /* Get the next chunk of the bitmap */
382 if (__get_user(c, ubuf++))
392 * If the last character was a space and the current
393 * character isn't '\0', we've got embedded whitespace.
394 * This is a no-no, so throw an error.
396 if (totaldigits && c && isspace(old_c))
399 /* A '\0' or a ',' signal the end of the chunk */
400 if (c == '\0' || c == ',')
407 * Make sure there are at least 4 free bits in 'chunk'.
408 * If not, this hexdigit will overflow 'chunk', so
411 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
414 chunk = (chunk << 4) | hex_to_bin(c);
417 if (ndigits == totaldigits)
419 if (nchunks == 0 && chunk == 0)
422 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
425 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
426 if (nbits > nmaskbits)
428 } while (buflen && c == ',');
432 EXPORT_SYMBOL(__bitmap_parse);
435 * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
437 * @ubuf: pointer to user buffer containing string.
438 * @ulen: buffer size in bytes. If string is smaller than this
439 * then it must be terminated with a \0.
440 * @maskp: pointer to bitmap array that will contain result.
441 * @nmaskbits: size of bitmap, in bits.
443 * Wrapper for __bitmap_parse(), providing it with user buffer.
445 * We cannot have this as an inline function in bitmap.h because it needs
446 * linux/uaccess.h to get the access_ok() declaration and this causes
447 * cyclic dependencies.
449 int bitmap_parse_user(const char __user *ubuf,
450 unsigned int ulen, unsigned long *maskp,
453 if (!access_ok(VERIFY_READ, ubuf, ulen))
455 return __bitmap_parse((const char __force *)ubuf,
456 ulen, 1, maskp, nmaskbits);
459 EXPORT_SYMBOL(bitmap_parse_user);
462 * bitmap_print_to_pagebuf - convert bitmap to list or hex format ASCII string
463 * @list: indicates whether the bitmap must be list
464 * @buf: page aligned buffer into which string is placed
465 * @maskp: pointer to bitmap to convert
466 * @nmaskbits: size of bitmap, in bits
468 * Output format is a comma-separated list of decimal numbers and
469 * ranges if list is specified or hex digits grouped into comma-separated
470 * sets of 8 digits/set. Returns the number of characters written to buf.
472 * It is assumed that @buf is a pointer into a PAGE_SIZE area and that
473 * sufficient storage remains at @buf to accommodate the
474 * bitmap_print_to_pagebuf() output.
476 int bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp,
479 ptrdiff_t len = PTR_ALIGN(buf + PAGE_SIZE - 1, PAGE_SIZE) - buf;
483 n = list ? scnprintf(buf, len, "%*pbl\n", nmaskbits, maskp) :
484 scnprintf(buf, len, "%*pb\n", nmaskbits, maskp);
487 EXPORT_SYMBOL(bitmap_print_to_pagebuf);
490 * __bitmap_parselist - convert list format ASCII string to bitmap
491 * @buf: read nul-terminated user string from this buffer
492 * @buflen: buffer size in bytes. If string is smaller than this
493 * then it must be terminated with a \0.
494 * @is_user: location of buffer, 0 indicates kernel space
495 * @maskp: write resulting mask here
496 * @nmaskbits: number of bits in mask to be written
498 * Input format is a comma-separated list of decimal numbers and
499 * ranges. Consecutively set bits are shown as two hyphen-separated
500 * decimal numbers, the smallest and largest bit numbers set in
502 * Optionally each range can be postfixed to denote that only parts of it
503 * should be set. The range will divided to groups of specific size.
504 * From each group will be used only defined amount of bits.
505 * Syntax: range:used_size/group_size
506 * Example: 0-1023:2/256 ==> 0,1,256,257,512,513,768,769
508 * Returns: 0 on success, -errno on invalid input strings. Error values:
510 * - ``-EINVAL``: second number in range smaller than first
511 * - ``-EINVAL``: invalid character in string
512 * - ``-ERANGE``: bit number specified too large for mask
514 static int __bitmap_parselist(const char *buf, unsigned int buflen,
515 int is_user, unsigned long *maskp,
518 unsigned int a, b, old_a, old_b;
519 unsigned int group_size, used_size, off;
520 int c, old_c, totaldigits, ndigits;
521 const char __user __force *ubuf = (const char __user __force *)buf;
522 int at_start, in_range, in_partial_range;
526 group_size = used_size = 0;
527 bitmap_zero(maskp, nmaskbits);
531 in_partial_range = 0;
533 ndigits = totaldigits;
535 /* Get the next cpu# or a range of cpu#'s */
539 if (__get_user(c, ubuf++))
547 /* A '\0' or a ',' signal the end of a cpu# or range */
548 if (c == '\0' || c == ',')
551 * whitespaces between digits are not allowed,
552 * but it's ok if whitespaces are on head or tail.
553 * when old_c is whilespace,
554 * if totaldigits == ndigits, whitespace is on head.
555 * if whitespace is on tail, it should not run here.
556 * as c was ',' or '\0',
557 * the last code line has broken the current loop.
559 if ((totaldigits != ndigits) && isspace(old_c))
575 in_partial_range = 1;
581 if (at_start || in_range)
592 b = b * 10 + (c - '0');
598 if (ndigits == totaldigits)
600 if (in_partial_range) {
606 used_size = group_size = b - a + 1;
608 /* if no digit is after '-', it's wrong*/
609 if (at_start && in_range)
611 if (!(a <= b) || group_size == 0 || !(used_size <= group_size))
616 off = min(b - a + 1, used_size);
617 bitmap_set(maskp, a, off);
620 } while (buflen && c == ',');
624 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
626 char *nl = strchrnul(bp, '\n');
629 return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
631 EXPORT_SYMBOL(bitmap_parselist);
635 * bitmap_parselist_user()
637 * @ubuf: pointer to user buffer containing string.
638 * @ulen: buffer size in bytes. If string is smaller than this
639 * then it must be terminated with a \0.
640 * @maskp: pointer to bitmap array that will contain result.
641 * @nmaskbits: size of bitmap, in bits.
643 * Wrapper for bitmap_parselist(), providing it with user buffer.
645 * We cannot have this as an inline function in bitmap.h because it needs
646 * linux/uaccess.h to get the access_ok() declaration and this causes
647 * cyclic dependencies.
649 int bitmap_parselist_user(const char __user *ubuf,
650 unsigned int ulen, unsigned long *maskp,
653 if (!access_ok(VERIFY_READ, ubuf, ulen))
655 return __bitmap_parselist((const char __force *)ubuf,
656 ulen, 1, maskp, nmaskbits);
658 EXPORT_SYMBOL(bitmap_parselist_user);
662 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
663 * @buf: pointer to a bitmap
664 * @pos: a bit position in @buf (0 <= @pos < @nbits)
665 * @nbits: number of valid bit positions in @buf
667 * Map the bit at position @pos in @buf (of length @nbits) to the
668 * ordinal of which set bit it is. If it is not set or if @pos
669 * is not a valid bit position, map to -1.
671 * If for example, just bits 4 through 7 are set in @buf, then @pos
672 * values 4 through 7 will get mapped to 0 through 3, respectively,
673 * and other @pos values will get mapped to -1. When @pos value 7
674 * gets mapped to (returns) @ord value 3 in this example, that means
675 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
677 * The bit positions 0 through @bits are valid positions in @buf.
679 static int bitmap_pos_to_ord(const unsigned long *buf, unsigned int pos, unsigned int nbits)
681 if (pos >= nbits || !test_bit(pos, buf))
684 return __bitmap_weight(buf, pos);
688 * bitmap_ord_to_pos - find position of n-th set bit in bitmap
689 * @buf: pointer to bitmap
690 * @ord: ordinal bit position (n-th set bit, n >= 0)
691 * @nbits: number of valid bit positions in @buf
693 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
694 * Value of @ord should be in range 0 <= @ord < weight(buf). If @ord
695 * >= weight(buf), returns @nbits.
697 * If for example, just bits 4 through 7 are set in @buf, then @ord
698 * values 0 through 3 will get mapped to 4 through 7, respectively,
699 * and all other @ord values returns @nbits. When @ord value 3
700 * gets mapped to (returns) @pos value 7 in this example, that means
701 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
703 * The bit positions 0 through @nbits-1 are valid positions in @buf.
705 unsigned int bitmap_ord_to_pos(const unsigned long *buf, unsigned int ord, unsigned int nbits)
709 for (pos = find_first_bit(buf, nbits);
711 pos = find_next_bit(buf, nbits, pos + 1))
718 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
719 * @dst: remapped result
720 * @src: subset to be remapped
721 * @old: defines domain of map
722 * @new: defines range of map
723 * @nbits: number of bits in each of these bitmaps
725 * Let @old and @new define a mapping of bit positions, such that
726 * whatever position is held by the n-th set bit in @old is mapped
727 * to the n-th set bit in @new. In the more general case, allowing
728 * for the possibility that the weight 'w' of @new is less than the
729 * weight of @old, map the position of the n-th set bit in @old to
730 * the position of the m-th set bit in @new, where m == n % w.
732 * If either of the @old and @new bitmaps are empty, or if @src and
733 * @dst point to the same location, then this routine copies @src
736 * The positions of unset bits in @old are mapped to themselves
737 * (the identify map).
739 * Apply the above specified mapping to @src, placing the result in
740 * @dst, clearing any bits previously set in @dst.
742 * For example, lets say that @old has bits 4 through 7 set, and
743 * @new has bits 12 through 15 set. This defines the mapping of bit
744 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
745 * bit positions unchanged. So if say @src comes into this routine
746 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
749 void bitmap_remap(unsigned long *dst, const unsigned long *src,
750 const unsigned long *old, const unsigned long *new,
753 unsigned int oldbit, w;
755 if (dst == src) /* following doesn't handle inplace remaps */
757 bitmap_zero(dst, nbits);
759 w = bitmap_weight(new, nbits);
760 for_each_set_bit(oldbit, src, nbits) {
761 int n = bitmap_pos_to_ord(old, oldbit, nbits);
764 set_bit(oldbit, dst); /* identity map */
766 set_bit(bitmap_ord_to_pos(new, n % w, nbits), dst);
769 EXPORT_SYMBOL(bitmap_remap);
772 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
773 * @oldbit: bit position to be mapped
774 * @old: defines domain of map
775 * @new: defines range of map
776 * @bits: number of bits in each of these bitmaps
778 * Let @old and @new define a mapping of bit positions, such that
779 * whatever position is held by the n-th set bit in @old is mapped
780 * to the n-th set bit in @new. In the more general case, allowing
781 * for the possibility that the weight 'w' of @new is less than the
782 * weight of @old, map the position of the n-th set bit in @old to
783 * the position of the m-th set bit in @new, where m == n % w.
785 * The positions of unset bits in @old are mapped to themselves
786 * (the identify map).
788 * Apply the above specified mapping to bit position @oldbit, returning
789 * the new bit position.
791 * For example, lets say that @old has bits 4 through 7 set, and
792 * @new has bits 12 through 15 set. This defines the mapping of bit
793 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
794 * bit positions unchanged. So if say @oldbit is 5, then this routine
797 int bitmap_bitremap(int oldbit, const unsigned long *old,
798 const unsigned long *new, int bits)
800 int w = bitmap_weight(new, bits);
801 int n = bitmap_pos_to_ord(old, oldbit, bits);
805 return bitmap_ord_to_pos(new, n % w, bits);
807 EXPORT_SYMBOL(bitmap_bitremap);
810 * bitmap_onto - translate one bitmap relative to another
811 * @dst: resulting translated bitmap
812 * @orig: original untranslated bitmap
813 * @relmap: bitmap relative to which translated
814 * @bits: number of bits in each of these bitmaps
816 * Set the n-th bit of @dst iff there exists some m such that the
817 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
818 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
819 * (If you understood the previous sentence the first time your
820 * read it, you're overqualified for your current job.)
822 * In other words, @orig is mapped onto (surjectively) @dst,
823 * using the map { <n, m> | the n-th bit of @relmap is the
824 * m-th set bit of @relmap }.
826 * Any set bits in @orig above bit number W, where W is the
827 * weight of (number of set bits in) @relmap are mapped nowhere.
828 * In particular, if for all bits m set in @orig, m >= W, then
829 * @dst will end up empty. In situations where the possibility
830 * of such an empty result is not desired, one way to avoid it is
831 * to use the bitmap_fold() operator, below, to first fold the
832 * @orig bitmap over itself so that all its set bits x are in the
833 * range 0 <= x < W. The bitmap_fold() operator does this by
834 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
836 * Example [1] for bitmap_onto():
837 * Let's say @relmap has bits 30-39 set, and @orig has bits
838 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,
839 * @dst will have bits 31, 33, 35, 37 and 39 set.
841 * When bit 0 is set in @orig, it means turn on the bit in
842 * @dst corresponding to whatever is the first bit (if any)
843 * that is turned on in @relmap. Since bit 0 was off in the
844 * above example, we leave off that bit (bit 30) in @dst.
846 * When bit 1 is set in @orig (as in the above example), it
847 * means turn on the bit in @dst corresponding to whatever
848 * is the second bit that is turned on in @relmap. The second
849 * bit in @relmap that was turned on in the above example was
850 * bit 31, so we turned on bit 31 in @dst.
852 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
853 * because they were the 4th, 6th, 8th and 10th set bits
854 * set in @relmap, and the 4th, 6th, 8th and 10th bits of
855 * @orig (i.e. bits 3, 5, 7 and 9) were also set.
857 * When bit 11 is set in @orig, it means turn on the bit in
858 * @dst corresponding to whatever is the twelfth bit that is
859 * turned on in @relmap. In the above example, there were
860 * only ten bits turned on in @relmap (30..39), so that bit
861 * 11 was set in @orig had no affect on @dst.
863 * Example [2] for bitmap_fold() + bitmap_onto():
864 * Let's say @relmap has these ten bits set::
866 * 40 41 42 43 45 48 53 61 74 95
868 * (for the curious, that's 40 plus the first ten terms of the
869 * Fibonacci sequence.)
871 * Further lets say we use the following code, invoking
872 * bitmap_fold() then bitmap_onto, as suggested above to
873 * avoid the possibility of an empty @dst result::
875 * unsigned long *tmp; // a temporary bitmap's bits
877 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
878 * bitmap_onto(dst, tmp, relmap, bits);
880 * Then this table shows what various values of @dst would be, for
881 * various @orig's. I list the zero-based positions of each set bit.
882 * The tmp column shows the intermediate result, as computed by
883 * using bitmap_fold() to fold the @orig bitmap modulo ten
884 * (the weight of @relmap):
886 * =============== ============== =================
892 * 1 3 5 7 1 3 5 7 41 43 48 61
893 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45
894 * 0 9 18 27 0 9 8 7 40 61 74 95
896 * 0 11 22 33 0 1 2 3 40 41 42 43
897 * 0 12 24 36 0 2 4 6 40 42 45 53
898 * 78 102 211 1 2 8 41 42 74 [#f1]_
899 * =============== ============== =================
903 * For these marked lines, if we hadn't first done bitmap_fold()
904 * into tmp, then the @dst result would have been empty.
906 * If either of @orig or @relmap is empty (no set bits), then @dst
907 * will be returned empty.
909 * If (as explained above) the only set bits in @orig are in positions
910 * m where m >= W, (where W is the weight of @relmap) then @dst will
911 * once again be returned empty.
913 * All bits in @dst not set by the above rule are cleared.
915 void bitmap_onto(unsigned long *dst, const unsigned long *orig,
916 const unsigned long *relmap, unsigned int bits)
918 unsigned int n, m; /* same meaning as in above comment */
920 if (dst == orig) /* following doesn't handle inplace mappings */
922 bitmap_zero(dst, bits);
925 * The following code is a more efficient, but less
926 * obvious, equivalent to the loop:
927 * for (m = 0; m < bitmap_weight(relmap, bits); m++) {
928 * n = bitmap_ord_to_pos(orig, m, bits);
929 * if (test_bit(m, orig))
935 for_each_set_bit(n, relmap, bits) {
936 /* m == bitmap_pos_to_ord(relmap, n, bits) */
937 if (test_bit(m, orig))
942 EXPORT_SYMBOL(bitmap_onto);
945 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
946 * @dst: resulting smaller bitmap
947 * @orig: original larger bitmap
948 * @sz: specified size
949 * @nbits: number of bits in each of these bitmaps
951 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
952 * Clear all other bits in @dst. See further the comment and
953 * Example [2] for bitmap_onto() for why and how to use this.
955 void bitmap_fold(unsigned long *dst, const unsigned long *orig,
956 unsigned int sz, unsigned int nbits)
960 if (dst == orig) /* following doesn't handle inplace mappings */
962 bitmap_zero(dst, nbits);
964 for_each_set_bit(oldbit, orig, nbits)
965 set_bit(oldbit % sz, dst);
967 EXPORT_SYMBOL(bitmap_fold);
970 * Common code for bitmap_*_region() routines.
971 * bitmap: array of unsigned longs corresponding to the bitmap
972 * pos: the beginning of the region
973 * order: region size (log base 2 of number of bits)
974 * reg_op: operation(s) to perform on that region of bitmap
976 * Can set, verify and/or release a region of bits in a bitmap,
977 * depending on which combination of REG_OP_* flag bits is set.
979 * A region of a bitmap is a sequence of bits in the bitmap, of
980 * some size '1 << order' (a power of two), aligned to that same
981 * '1 << order' power of two.
983 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
984 * Returns 0 in all other cases and reg_ops.
988 REG_OP_ISFREE, /* true if region is all zero bits */
989 REG_OP_ALLOC, /* set all bits in region */
990 REG_OP_RELEASE, /* clear all bits in region */
993 static int __reg_op(unsigned long *bitmap, unsigned int pos, int order, int reg_op)
995 int nbits_reg; /* number of bits in region */
996 int index; /* index first long of region in bitmap */
997 int offset; /* bit offset region in bitmap[index] */
998 int nlongs_reg; /* num longs spanned by region in bitmap */
999 int nbitsinlong; /* num bits of region in each spanned long */
1000 unsigned long mask; /* bitmask for one long of region */
1001 int i; /* scans bitmap by longs */
1002 int ret = 0; /* return value */
1005 * Either nlongs_reg == 1 (for small orders that fit in one long)
1006 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
1008 nbits_reg = 1 << order;
1009 index = pos / BITS_PER_LONG;
1010 offset = pos - (index * BITS_PER_LONG);
1011 nlongs_reg = BITS_TO_LONGS(nbits_reg);
1012 nbitsinlong = min(nbits_reg, BITS_PER_LONG);
1015 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
1016 * overflows if nbitsinlong == BITS_PER_LONG.
1018 mask = (1UL << (nbitsinlong - 1));
1024 for (i = 0; i < nlongs_reg; i++) {
1025 if (bitmap[index + i] & mask)
1028 ret = 1; /* all bits in region free (zero) */
1032 for (i = 0; i < nlongs_reg; i++)
1033 bitmap[index + i] |= mask;
1036 case REG_OP_RELEASE:
1037 for (i = 0; i < nlongs_reg; i++)
1038 bitmap[index + i] &= ~mask;
1046 * bitmap_find_free_region - find a contiguous aligned mem region
1047 * @bitmap: array of unsigned longs corresponding to the bitmap
1048 * @bits: number of bits in the bitmap
1049 * @order: region size (log base 2 of number of bits) to find
1051 * Find a region of free (zero) bits in a @bitmap of @bits bits and
1052 * allocate them (set them to one). Only consider regions of length
1053 * a power (@order) of two, aligned to that power of two, which
1054 * makes the search algorithm much faster.
1056 * Return the bit offset in bitmap of the allocated region,
1057 * or -errno on failure.
1059 int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order)
1061 unsigned int pos, end; /* scans bitmap by regions of size order */
1063 for (pos = 0 ; (end = pos + (1U << order)) <= bits; pos = end) {
1064 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1066 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1071 EXPORT_SYMBOL(bitmap_find_free_region);
1074 * bitmap_release_region - release allocated bitmap region
1075 * @bitmap: array of unsigned longs corresponding to the bitmap
1076 * @pos: beginning of bit region to release
1077 * @order: region size (log base 2 of number of bits) to release
1079 * This is the complement to __bitmap_find_free_region() and releases
1080 * the found region (by clearing it in the bitmap).
1084 void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order)
1086 __reg_op(bitmap, pos, order, REG_OP_RELEASE);
1088 EXPORT_SYMBOL(bitmap_release_region);
1091 * bitmap_allocate_region - allocate bitmap region
1092 * @bitmap: array of unsigned longs corresponding to the bitmap
1093 * @pos: beginning of bit region to allocate
1094 * @order: region size (log base 2 of number of bits) to allocate
1096 * Allocate (set bits in) a specified region of a bitmap.
1098 * Return 0 on success, or %-EBUSY if specified region wasn't
1099 * free (not all bits were zero).
1101 int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order)
1103 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1105 return __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1107 EXPORT_SYMBOL(bitmap_allocate_region);
1110 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1111 * @dst: destination buffer
1112 * @src: bitmap to copy
1113 * @nbits: number of bits in the bitmap
1115 * Require nbits % BITS_PER_LONG == 0.
1118 void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits)
1122 for (i = 0; i < nbits/BITS_PER_LONG; i++) {
1123 if (BITS_PER_LONG == 64)
1124 dst[i] = cpu_to_le64(src[i]);
1126 dst[i] = cpu_to_le32(src[i]);
1129 EXPORT_SYMBOL(bitmap_copy_le);
1132 unsigned long *bitmap_alloc(unsigned int nbits, gfp_t flags)
1134 return kmalloc_array(BITS_TO_LONGS(nbits), sizeof(unsigned long),
1137 EXPORT_SYMBOL(bitmap_alloc);
1139 unsigned long *bitmap_zalloc(unsigned int nbits, gfp_t flags)
1141 return bitmap_alloc(nbits, flags | __GFP_ZERO);
1143 EXPORT_SYMBOL(bitmap_zalloc);
1145 void bitmap_free(const unsigned long *bitmap)
1149 EXPORT_SYMBOL(bitmap_free);
1151 #if BITS_PER_LONG == 64
1153 * bitmap_from_arr32 - copy the contents of u32 array of bits to bitmap
1154 * @bitmap: array of unsigned longs, the destination bitmap
1155 * @buf: array of u32 (in host byte order), the source bitmap
1156 * @nbits: number of bits in @bitmap
1158 void bitmap_from_arr32(unsigned long *bitmap, const u32 *buf,
1161 unsigned int i, halfwords;
1166 halfwords = DIV_ROUND_UP(nbits, 32);
1167 for (i = 0; i < halfwords; i++) {
1168 bitmap[i/2] = (unsigned long) buf[i];
1169 if (++i < halfwords)
1170 bitmap[i/2] |= ((unsigned long) buf[i]) << 32;
1173 /* Clear tail bits in last word beyond nbits. */
1174 if (nbits % BITS_PER_LONG)
1175 bitmap[(halfwords - 1) / 2] &= BITMAP_LAST_WORD_MASK(nbits);
1177 EXPORT_SYMBOL(bitmap_from_arr32);
1180 * bitmap_to_arr32 - copy the contents of bitmap to a u32 array of bits
1181 * @buf: array of u32 (in host byte order), the dest bitmap
1182 * @bitmap: array of unsigned longs, the source bitmap
1183 * @nbits: number of bits in @bitmap
1185 void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap, unsigned int nbits)
1187 unsigned int i, halfwords;
1192 halfwords = DIV_ROUND_UP(nbits, 32);
1193 for (i = 0; i < halfwords; i++) {
1194 buf[i] = (u32) (bitmap[i/2] & UINT_MAX);
1195 if (++i < halfwords)
1196 buf[i] = (u32) (bitmap[i/2] >> 32);
1199 /* Clear tail bits in last element of array beyond nbits. */
1200 if (nbits % BITS_PER_LONG)
1201 buf[halfwords - 1] &= (u32) (UINT_MAX >> ((-nbits) & 31));
1203 EXPORT_SYMBOL(bitmap_to_arr32);