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/string.h>
17 #include <linux/uaccess.h>
22 * bitmaps provide an array of bits, implemented using an an
23 * array of unsigned longs. The number of valid bits in a
24 * given bitmap does _not_ need to be an exact multiple of
27 * The possible unused bits in the last, partially used word
28 * of a bitmap are 'don't care'. The implementation makes
29 * no particular effort to keep them zero. It ensures that
30 * their value will not affect the results of any operation.
31 * The bitmap operations that return Boolean (bitmap_empty,
32 * for example) or scalar (bitmap_weight, for example) results
33 * carefully filter out these unused bits from impacting their
36 * These operations actually hold to a slightly stronger rule:
37 * if you don't input any bitmaps to these ops that have some
38 * unused bits set, then they won't output any set unused bits
41 * The byte ordering of bitmaps is more natural on little
42 * endian architectures. See the big-endian headers
43 * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
44 * for the best explanations of this ordering.
47 int __bitmap_equal(const unsigned long *bitmap1,
48 const unsigned long *bitmap2, unsigned int bits)
50 unsigned int k, lim = bits/BITS_PER_LONG;
51 for (k = 0; k < lim; ++k)
52 if (bitmap1[k] != bitmap2[k])
55 if (bits % BITS_PER_LONG)
56 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
61 EXPORT_SYMBOL(__bitmap_equal);
63 void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits)
65 unsigned int k, lim = bits/BITS_PER_LONG;
66 for (k = 0; k < lim; ++k)
69 if (bits % BITS_PER_LONG)
72 EXPORT_SYMBOL(__bitmap_complement);
75 * __bitmap_shift_right - logical right shift of the bits in a bitmap
76 * @dst : destination bitmap
77 * @src : source bitmap
78 * @shift : shift by this many bits
79 * @nbits : bitmap size, in bits
81 * Shifting right (dividing) means moving bits in the MS -> LS bit
82 * direction. Zeros are fed into the vacated MS positions and the
83 * LS bits shifted off the bottom are lost.
85 void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
86 unsigned shift, unsigned nbits)
88 unsigned k, lim = BITS_TO_LONGS(nbits);
89 unsigned off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
90 unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);
91 for (k = 0; off + k < lim; ++k) {
92 unsigned long upper, lower;
95 * If shift is not word aligned, take lower rem bits of
96 * word above and make them the top rem bits of result.
98 if (!rem || off + k + 1 >= lim)
101 upper = src[off + k + 1];
102 if (off + k + 1 == lim - 1)
104 upper <<= (BITS_PER_LONG - rem);
106 lower = src[off + k];
107 if (off + k == lim - 1)
110 dst[k] = lower | upper;
113 memset(&dst[lim - off], 0, off*sizeof(unsigned long));
115 EXPORT_SYMBOL(__bitmap_shift_right);
119 * __bitmap_shift_left - logical left shift of the bits in a bitmap
120 * @dst : destination bitmap
121 * @src : source bitmap
122 * @shift : shift by this many bits
123 * @nbits : bitmap size, in bits
125 * Shifting left (multiplying) means moving bits in the LS -> MS
126 * direction. Zeros are fed into the vacated LS bit positions
127 * and those MS bits shifted off the top are lost.
130 void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
131 unsigned int shift, unsigned int nbits)
134 unsigned int lim = BITS_TO_LONGS(nbits);
135 unsigned int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
136 for (k = lim - off - 1; k >= 0; --k) {
137 unsigned long upper, lower;
140 * If shift is not word aligned, take upper rem bits of
141 * word below and make them the bottom rem bits of result.
144 lower = src[k - 1] >> (BITS_PER_LONG - rem);
147 upper = src[k] << rem;
148 dst[k + off] = lower | upper;
151 memset(dst, 0, off*sizeof(unsigned long));
153 EXPORT_SYMBOL(__bitmap_shift_left);
155 int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
156 const unsigned long *bitmap2, unsigned int bits)
159 unsigned int lim = bits/BITS_PER_LONG;
160 unsigned long result = 0;
162 for (k = 0; k < lim; k++)
163 result |= (dst[k] = bitmap1[k] & bitmap2[k]);
164 if (bits % BITS_PER_LONG)
165 result |= (dst[k] = bitmap1[k] & bitmap2[k] &
166 BITMAP_LAST_WORD_MASK(bits));
169 EXPORT_SYMBOL(__bitmap_and);
171 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
172 const unsigned long *bitmap2, unsigned int bits)
175 unsigned int nr = BITS_TO_LONGS(bits);
177 for (k = 0; k < nr; k++)
178 dst[k] = bitmap1[k] | bitmap2[k];
180 EXPORT_SYMBOL(__bitmap_or);
182 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
183 const unsigned long *bitmap2, unsigned int bits)
186 unsigned int nr = BITS_TO_LONGS(bits);
188 for (k = 0; k < nr; k++)
189 dst[k] = bitmap1[k] ^ bitmap2[k];
191 EXPORT_SYMBOL(__bitmap_xor);
193 int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
194 const unsigned long *bitmap2, unsigned int bits)
197 unsigned int lim = bits/BITS_PER_LONG;
198 unsigned long result = 0;
200 for (k = 0; k < lim; k++)
201 result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
202 if (bits % BITS_PER_LONG)
203 result |= (dst[k] = bitmap1[k] & ~bitmap2[k] &
204 BITMAP_LAST_WORD_MASK(bits));
207 EXPORT_SYMBOL(__bitmap_andnot);
209 int __bitmap_intersects(const unsigned long *bitmap1,
210 const unsigned long *bitmap2, unsigned int bits)
212 unsigned int k, lim = bits/BITS_PER_LONG;
213 for (k = 0; k < lim; ++k)
214 if (bitmap1[k] & bitmap2[k])
217 if (bits % BITS_PER_LONG)
218 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
222 EXPORT_SYMBOL(__bitmap_intersects);
224 int __bitmap_subset(const unsigned long *bitmap1,
225 const unsigned long *bitmap2, unsigned int bits)
227 unsigned int k, lim = bits/BITS_PER_LONG;
228 for (k = 0; k < lim; ++k)
229 if (bitmap1[k] & ~bitmap2[k])
232 if (bits % BITS_PER_LONG)
233 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
237 EXPORT_SYMBOL(__bitmap_subset);
239 int __bitmap_weight(const unsigned long *bitmap, unsigned int bits)
241 unsigned int k, lim = bits/BITS_PER_LONG;
244 for (k = 0; k < lim; k++)
245 w += hweight_long(bitmap[k]);
247 if (bits % BITS_PER_LONG)
248 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
252 EXPORT_SYMBOL(__bitmap_weight);
254 void bitmap_set(unsigned long *map, unsigned int start, int len)
256 unsigned long *p = map + BIT_WORD(start);
257 const unsigned int size = start + len;
258 int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
259 unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
261 while (len - bits_to_set >= 0) {
264 bits_to_set = BITS_PER_LONG;
269 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
273 EXPORT_SYMBOL(bitmap_set);
275 void bitmap_clear(unsigned long *map, unsigned int start, int len)
277 unsigned long *p = map + BIT_WORD(start);
278 const unsigned int size = start + len;
279 int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
280 unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
282 while (len - bits_to_clear >= 0) {
283 *p &= ~mask_to_clear;
284 len -= bits_to_clear;
285 bits_to_clear = BITS_PER_LONG;
286 mask_to_clear = ~0UL;
290 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
291 *p &= ~mask_to_clear;
294 EXPORT_SYMBOL(bitmap_clear);
297 * bitmap_find_next_zero_area_off - find a contiguous aligned zero area
298 * @map: The address to base the search on
299 * @size: The bitmap size in bits
300 * @start: The bitnumber to start searching at
301 * @nr: The number of zeroed bits we're looking for
302 * @align_mask: Alignment mask for zero area
303 * @align_offset: Alignment offset for zero area.
305 * The @align_mask should be one less than a power of 2; the effect is that
306 * the bit offset of all zero areas this function finds plus @align_offset
307 * is multiple of that power of 2.
309 unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
313 unsigned long align_mask,
314 unsigned long align_offset)
316 unsigned long index, end, i;
318 index = find_next_zero_bit(map, size, start);
320 /* Align allocation */
321 index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset;
326 i = find_next_bit(map, end, index);
333 EXPORT_SYMBOL(bitmap_find_next_zero_area_off);
336 * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,
337 * second version by Paul Jackson, third by Joe Korty.
341 #define nbits_to_hold_value(val) fls(val)
342 #define BASEDEC 10 /* fancier cpuset lists input in decimal */
345 * __bitmap_parse - convert an ASCII hex string into a bitmap.
346 * @buf: pointer to buffer containing string.
347 * @buflen: buffer size in bytes. If string is smaller than this
348 * then it must be terminated with a \0.
349 * @is_user: location of buffer, 0 indicates kernel space
350 * @maskp: pointer to bitmap array that will contain result.
351 * @nmaskbits: size of bitmap, in bits.
353 * Commas group hex digits into chunks. Each chunk defines exactly 32
354 * bits of the resultant bitmask. No chunk may specify a value larger
355 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
356 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
357 * characters and for grouping errors such as "1,,5", ",44", "," and "".
358 * Leading and trailing whitespace accepted, but not embedded whitespace.
360 int __bitmap_parse(const char *buf, unsigned int buflen,
361 int is_user, unsigned long *maskp,
364 int c, old_c, totaldigits, ndigits, nchunks, nbits;
366 const char __user __force *ubuf = (const char __user __force *)buf;
368 bitmap_zero(maskp, nmaskbits);
370 nchunks = nbits = totaldigits = c = 0;
373 ndigits = totaldigits;
375 /* Get the next chunk of the bitmap */
379 if (__get_user(c, ubuf++))
389 * If the last character was a space and the current
390 * character isn't '\0', we've got embedded whitespace.
391 * This is a no-no, so throw an error.
393 if (totaldigits && c && isspace(old_c))
396 /* A '\0' or a ',' signal the end of the chunk */
397 if (c == '\0' || c == ',')
404 * Make sure there are at least 4 free bits in 'chunk'.
405 * If not, this hexdigit will overflow 'chunk', so
408 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
411 chunk = (chunk << 4) | hex_to_bin(c);
414 if (ndigits == totaldigits)
416 if (nchunks == 0 && chunk == 0)
419 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
422 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
423 if (nbits > nmaskbits)
425 } while (buflen && c == ',');
429 EXPORT_SYMBOL(__bitmap_parse);
432 * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
434 * @ubuf: pointer to user buffer containing string.
435 * @ulen: buffer size in bytes. If string is smaller than this
436 * then it must be terminated with a \0.
437 * @maskp: pointer to bitmap array that will contain result.
438 * @nmaskbits: size of bitmap, in bits.
440 * Wrapper for __bitmap_parse(), providing it with user buffer.
442 * We cannot have this as an inline function in bitmap.h because it needs
443 * linux/uaccess.h to get the access_ok() declaration and this causes
444 * cyclic dependencies.
446 int bitmap_parse_user(const char __user *ubuf,
447 unsigned int ulen, unsigned long *maskp,
450 if (!access_ok(VERIFY_READ, ubuf, ulen))
452 return __bitmap_parse((const char __force *)ubuf,
453 ulen, 1, maskp, nmaskbits);
456 EXPORT_SYMBOL(bitmap_parse_user);
459 * bitmap_print_to_pagebuf - convert bitmap to list or hex format ASCII string
460 * @list: indicates whether the bitmap must be list
461 * @buf: page aligned buffer into which string is placed
462 * @maskp: pointer to bitmap to convert
463 * @nmaskbits: size of bitmap, in bits
465 * Output format is a comma-separated list of decimal numbers and
466 * ranges if list is specified or hex digits grouped into comma-separated
467 * sets of 8 digits/set. Returns the number of characters written to buf.
469 * It is assumed that @buf is a pointer into a PAGE_SIZE area and that
470 * sufficient storage remains at @buf to accommodate the
471 * bitmap_print_to_pagebuf() output.
473 int bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp,
476 ptrdiff_t len = PTR_ALIGN(buf + PAGE_SIZE - 1, PAGE_SIZE) - buf;
480 n = list ? scnprintf(buf, len, "%*pbl\n", nmaskbits, maskp) :
481 scnprintf(buf, len, "%*pb\n", nmaskbits, maskp);
484 EXPORT_SYMBOL(bitmap_print_to_pagebuf);
487 * __bitmap_parselist - convert list format ASCII string to bitmap
488 * @buf: read nul-terminated user string from this buffer
489 * @buflen: buffer size in bytes. If string is smaller than this
490 * then it must be terminated with a \0.
491 * @is_user: location of buffer, 0 indicates kernel space
492 * @maskp: write resulting mask here
493 * @nmaskbits: number of bits in mask to be written
495 * Input format is a comma-separated list of decimal numbers and
496 * ranges. Consecutively set bits are shown as two hyphen-separated
497 * decimal numbers, the smallest and largest bit numbers set in
499 * Optionally each range can be postfixed to denote that only parts of it
500 * should be set. The range will divided to groups of specific size.
501 * From each group will be used only defined amount of bits.
502 * Syntax: range:used_size/group_size
503 * Example: 0-1023:2/256 ==> 0,1,256,257,512,513,768,769
505 * Returns 0 on success, -errno on invalid input strings.
507 * %-EINVAL: second number in range smaller than first
508 * %-EINVAL: invalid character in string
509 * %-ERANGE: bit number specified too large for mask
511 static int __bitmap_parselist(const char *buf, unsigned int buflen,
512 int is_user, unsigned long *maskp,
515 unsigned int a, b, old_a, old_b;
516 unsigned int group_size, used_size;
517 int c, old_c, totaldigits, ndigits;
518 const char __user __force *ubuf = (const char __user __force *)buf;
519 int at_start, in_range, in_partial_range;
523 group_size = used_size = 0;
524 bitmap_zero(maskp, nmaskbits);
528 in_partial_range = 0;
530 ndigits = totaldigits;
532 /* Get the next cpu# or a range of cpu#'s */
536 if (__get_user(c, ubuf++))
544 /* A '\0' or a ',' signal the end of a cpu# or range */
545 if (c == '\0' || c == ',')
548 * whitespaces between digits are not allowed,
549 * but it's ok if whitespaces are on head or tail.
550 * when old_c is whilespace,
551 * if totaldigits == ndigits, whitespace is on head.
552 * if whitespace is on tail, it should not run here.
553 * as c was ',' or '\0',
554 * the last code line has broken the current loop.
556 if ((totaldigits != ndigits) && isspace(old_c))
572 in_partial_range = 1;
578 if (at_start || in_range)
589 b = b * 10 + (c - '0');
595 if (ndigits == totaldigits)
597 if (in_partial_range) {
603 /* if no digit is after '-', it's wrong*/
604 if (at_start && in_range)
606 if (!(a <= b) || !(used_size <= group_size))
611 if (in_partial_range) {
612 static int pos_in_group = 1;
614 if (pos_in_group <= used_size)
617 if (a == b || ++pos_in_group > group_size)
623 } while (buflen && c == ',');
627 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
629 char *nl = strchrnul(bp, '\n');
632 return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
634 EXPORT_SYMBOL(bitmap_parselist);
638 * bitmap_parselist_user()
640 * @ubuf: pointer to user buffer containing string.
641 * @ulen: buffer size in bytes. If string is smaller than this
642 * then it must be terminated with a \0.
643 * @maskp: pointer to bitmap array that will contain result.
644 * @nmaskbits: size of bitmap, in bits.
646 * Wrapper for bitmap_parselist(), providing it with user buffer.
648 * We cannot have this as an inline function in bitmap.h because it needs
649 * linux/uaccess.h to get the access_ok() declaration and this causes
650 * cyclic dependencies.
652 int bitmap_parselist_user(const char __user *ubuf,
653 unsigned int ulen, unsigned long *maskp,
656 if (!access_ok(VERIFY_READ, ubuf, ulen))
658 return __bitmap_parselist((const char __force *)ubuf,
659 ulen, 1, maskp, nmaskbits);
661 EXPORT_SYMBOL(bitmap_parselist_user);
665 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
666 * @buf: pointer to a bitmap
667 * @pos: a bit position in @buf (0 <= @pos < @nbits)
668 * @nbits: number of valid bit positions in @buf
670 * Map the bit at position @pos in @buf (of length @nbits) to the
671 * ordinal of which set bit it is. If it is not set or if @pos
672 * is not a valid bit position, map to -1.
674 * If for example, just bits 4 through 7 are set in @buf, then @pos
675 * values 4 through 7 will get mapped to 0 through 3, respectively,
676 * and other @pos values will get mapped to -1. When @pos value 7
677 * gets mapped to (returns) @ord value 3 in this example, that means
678 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
680 * The bit positions 0 through @bits are valid positions in @buf.
682 static int bitmap_pos_to_ord(const unsigned long *buf, unsigned int pos, unsigned int nbits)
684 if (pos >= nbits || !test_bit(pos, buf))
687 return __bitmap_weight(buf, pos);
691 * bitmap_ord_to_pos - find position of n-th set bit in bitmap
692 * @buf: pointer to bitmap
693 * @ord: ordinal bit position (n-th set bit, n >= 0)
694 * @nbits: number of valid bit positions in @buf
696 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
697 * Value of @ord should be in range 0 <= @ord < weight(buf). If @ord
698 * >= weight(buf), returns @nbits.
700 * If for example, just bits 4 through 7 are set in @buf, then @ord
701 * values 0 through 3 will get mapped to 4 through 7, respectively,
702 * and all other @ord values returns @nbits. When @ord value 3
703 * gets mapped to (returns) @pos value 7 in this example, that means
704 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
706 * The bit positions 0 through @nbits-1 are valid positions in @buf.
708 unsigned int bitmap_ord_to_pos(const unsigned long *buf, unsigned int ord, unsigned int nbits)
712 for (pos = find_first_bit(buf, nbits);
714 pos = find_next_bit(buf, nbits, pos + 1))
721 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
722 * @dst: remapped result
723 * @src: subset to be remapped
724 * @old: defines domain of map
725 * @new: defines range of map
726 * @nbits: number of bits in each of these bitmaps
728 * Let @old and @new define a mapping of bit positions, such that
729 * whatever position is held by the n-th set bit in @old is mapped
730 * to the n-th set bit in @new. In the more general case, allowing
731 * for the possibility that the weight 'w' of @new is less than the
732 * weight of @old, map the position of the n-th set bit in @old to
733 * the position of the m-th set bit in @new, where m == n % w.
735 * If either of the @old and @new bitmaps are empty, or if @src and
736 * @dst point to the same location, then this routine copies @src
739 * The positions of unset bits in @old are mapped to themselves
740 * (the identify map).
742 * Apply the above specified mapping to @src, placing the result in
743 * @dst, clearing any bits previously set in @dst.
745 * For example, lets say that @old has bits 4 through 7 set, and
746 * @new has bits 12 through 15 set. This defines the mapping of bit
747 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
748 * bit positions unchanged. So if say @src comes into this routine
749 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
752 void bitmap_remap(unsigned long *dst, const unsigned long *src,
753 const unsigned long *old, const unsigned long *new,
756 unsigned int oldbit, w;
758 if (dst == src) /* following doesn't handle inplace remaps */
760 bitmap_zero(dst, nbits);
762 w = bitmap_weight(new, nbits);
763 for_each_set_bit(oldbit, src, nbits) {
764 int n = bitmap_pos_to_ord(old, oldbit, nbits);
767 set_bit(oldbit, dst); /* identity map */
769 set_bit(bitmap_ord_to_pos(new, n % w, nbits), dst);
772 EXPORT_SYMBOL(bitmap_remap);
775 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
776 * @oldbit: bit position to be mapped
777 * @old: defines domain of map
778 * @new: defines range of map
779 * @bits: number of bits in each of these bitmaps
781 * Let @old and @new define a mapping of bit positions, such that
782 * whatever position is held by the n-th set bit in @old is mapped
783 * to the n-th set bit in @new. In the more general case, allowing
784 * for the possibility that the weight 'w' of @new is less than the
785 * weight of @old, map the position of the n-th set bit in @old to
786 * the position of the m-th set bit in @new, where m == n % w.
788 * The positions of unset bits in @old are mapped to themselves
789 * (the identify map).
791 * Apply the above specified mapping to bit position @oldbit, returning
792 * the new bit position.
794 * For example, lets say that @old has bits 4 through 7 set, and
795 * @new has bits 12 through 15 set. This defines the mapping of bit
796 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
797 * bit positions unchanged. So if say @oldbit is 5, then this routine
800 int bitmap_bitremap(int oldbit, const unsigned long *old,
801 const unsigned long *new, int bits)
803 int w = bitmap_weight(new, bits);
804 int n = bitmap_pos_to_ord(old, oldbit, bits);
808 return bitmap_ord_to_pos(new, n % w, bits);
810 EXPORT_SYMBOL(bitmap_bitremap);
813 * bitmap_onto - translate one bitmap relative to another
814 * @dst: resulting translated bitmap
815 * @orig: original untranslated bitmap
816 * @relmap: bitmap relative to which translated
817 * @bits: number of bits in each of these bitmaps
819 * Set the n-th bit of @dst iff there exists some m such that the
820 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
821 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
822 * (If you understood the previous sentence the first time your
823 * read it, you're overqualified for your current job.)
825 * In other words, @orig is mapped onto (surjectively) @dst,
826 * using the map { <n, m> | the n-th bit of @relmap is the
827 * m-th set bit of @relmap }.
829 * Any set bits in @orig above bit number W, where W is the
830 * weight of (number of set bits in) @relmap are mapped nowhere.
831 * In particular, if for all bits m set in @orig, m >= W, then
832 * @dst will end up empty. In situations where the possibility
833 * of such an empty result is not desired, one way to avoid it is
834 * to use the bitmap_fold() operator, below, to first fold the
835 * @orig bitmap over itself so that all its set bits x are in the
836 * range 0 <= x < W. The bitmap_fold() operator does this by
837 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
839 * Example [1] for bitmap_onto():
840 * Let's say @relmap has bits 30-39 set, and @orig has bits
841 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,
842 * @dst will have bits 31, 33, 35, 37 and 39 set.
844 * When bit 0 is set in @orig, it means turn on the bit in
845 * @dst corresponding to whatever is the first bit (if any)
846 * that is turned on in @relmap. Since bit 0 was off in the
847 * above example, we leave off that bit (bit 30) in @dst.
849 * When bit 1 is set in @orig (as in the above example), it
850 * means turn on the bit in @dst corresponding to whatever
851 * is the second bit that is turned on in @relmap. The second
852 * bit in @relmap that was turned on in the above example was
853 * bit 31, so we turned on bit 31 in @dst.
855 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
856 * because they were the 4th, 6th, 8th and 10th set bits
857 * set in @relmap, and the 4th, 6th, 8th and 10th bits of
858 * @orig (i.e. bits 3, 5, 7 and 9) were also set.
860 * When bit 11 is set in @orig, it means turn on the bit in
861 * @dst corresponding to whatever is the twelfth bit that is
862 * turned on in @relmap. In the above example, there were
863 * only ten bits turned on in @relmap (30..39), so that bit
864 * 11 was set in @orig had no affect on @dst.
866 * Example [2] for bitmap_fold() + bitmap_onto():
867 * Let's say @relmap has these ten bits set:
868 * 40 41 42 43 45 48 53 61 74 95
869 * (for the curious, that's 40 plus the first ten terms of the
870 * Fibonacci sequence.)
872 * Further lets say we use the following code, invoking
873 * bitmap_fold() then bitmap_onto, as suggested above to
874 * avoid the possibility of an empty @dst result:
876 * unsigned long *tmp; // a temporary bitmap's bits
878 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
879 * bitmap_onto(dst, tmp, relmap, bits);
881 * Then this table shows what various values of @dst would be, for
882 * various @orig's. I list the zero-based positions of each set bit.
883 * The tmp column shows the intermediate result, as computed by
884 * using bitmap_fold() to fold the @orig bitmap modulo ten
885 * (the weight of @relmap).
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 (*)
900 * (*) For these marked lines, if we hadn't first done bitmap_fold()
901 * into tmp, then the @dst result would have been empty.
903 * If either of @orig or @relmap is empty (no set bits), then @dst
904 * will be returned empty.
906 * If (as explained above) the only set bits in @orig are in positions
907 * m where m >= W, (where W is the weight of @relmap) then @dst will
908 * once again be returned empty.
910 * All bits in @dst not set by the above rule are cleared.
912 void bitmap_onto(unsigned long *dst, const unsigned long *orig,
913 const unsigned long *relmap, unsigned int bits)
915 unsigned int n, m; /* same meaning as in above comment */
917 if (dst == orig) /* following doesn't handle inplace mappings */
919 bitmap_zero(dst, bits);
922 * The following code is a more efficient, but less
923 * obvious, equivalent to the loop:
924 * for (m = 0; m < bitmap_weight(relmap, bits); m++) {
925 * n = bitmap_ord_to_pos(orig, m, bits);
926 * if (test_bit(m, orig))
932 for_each_set_bit(n, relmap, bits) {
933 /* m == bitmap_pos_to_ord(relmap, n, bits) */
934 if (test_bit(m, orig))
939 EXPORT_SYMBOL(bitmap_onto);
942 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
943 * @dst: resulting smaller bitmap
944 * @orig: original larger bitmap
945 * @sz: specified size
946 * @nbits: number of bits in each of these bitmaps
948 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
949 * Clear all other bits in @dst. See further the comment and
950 * Example [2] for bitmap_onto() for why and how to use this.
952 void bitmap_fold(unsigned long *dst, const unsigned long *orig,
953 unsigned int sz, unsigned int nbits)
957 if (dst == orig) /* following doesn't handle inplace mappings */
959 bitmap_zero(dst, nbits);
961 for_each_set_bit(oldbit, orig, nbits)
962 set_bit(oldbit % sz, dst);
964 EXPORT_SYMBOL(bitmap_fold);
967 * Common code for bitmap_*_region() routines.
968 * bitmap: array of unsigned longs corresponding to the bitmap
969 * pos: the beginning of the region
970 * order: region size (log base 2 of number of bits)
971 * reg_op: operation(s) to perform on that region of bitmap
973 * Can set, verify and/or release a region of bits in a bitmap,
974 * depending on which combination of REG_OP_* flag bits is set.
976 * A region of a bitmap is a sequence of bits in the bitmap, of
977 * some size '1 << order' (a power of two), aligned to that same
978 * '1 << order' power of two.
980 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
981 * Returns 0 in all other cases and reg_ops.
985 REG_OP_ISFREE, /* true if region is all zero bits */
986 REG_OP_ALLOC, /* set all bits in region */
987 REG_OP_RELEASE, /* clear all bits in region */
990 static int __reg_op(unsigned long *bitmap, unsigned int pos, int order, int reg_op)
992 int nbits_reg; /* number of bits in region */
993 int index; /* index first long of region in bitmap */
994 int offset; /* bit offset region in bitmap[index] */
995 int nlongs_reg; /* num longs spanned by region in bitmap */
996 int nbitsinlong; /* num bits of region in each spanned long */
997 unsigned long mask; /* bitmask for one long of region */
998 int i; /* scans bitmap by longs */
999 int ret = 0; /* return value */
1002 * Either nlongs_reg == 1 (for small orders that fit in one long)
1003 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
1005 nbits_reg = 1 << order;
1006 index = pos / BITS_PER_LONG;
1007 offset = pos - (index * BITS_PER_LONG);
1008 nlongs_reg = BITS_TO_LONGS(nbits_reg);
1009 nbitsinlong = min(nbits_reg, BITS_PER_LONG);
1012 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
1013 * overflows if nbitsinlong == BITS_PER_LONG.
1015 mask = (1UL << (nbitsinlong - 1));
1021 for (i = 0; i < nlongs_reg; i++) {
1022 if (bitmap[index + i] & mask)
1025 ret = 1; /* all bits in region free (zero) */
1029 for (i = 0; i < nlongs_reg; i++)
1030 bitmap[index + i] |= mask;
1033 case REG_OP_RELEASE:
1034 for (i = 0; i < nlongs_reg; i++)
1035 bitmap[index + i] &= ~mask;
1043 * bitmap_find_free_region - find a contiguous aligned mem region
1044 * @bitmap: array of unsigned longs corresponding to the bitmap
1045 * @bits: number of bits in the bitmap
1046 * @order: region size (log base 2 of number of bits) to find
1048 * Find a region of free (zero) bits in a @bitmap of @bits bits and
1049 * allocate them (set them to one). Only consider regions of length
1050 * a power (@order) of two, aligned to that power of two, which
1051 * makes the search algorithm much faster.
1053 * Return the bit offset in bitmap of the allocated region,
1054 * or -errno on failure.
1056 int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order)
1058 unsigned int pos, end; /* scans bitmap by regions of size order */
1060 for (pos = 0 ; (end = pos + (1U << order)) <= bits; pos = end) {
1061 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1063 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1068 EXPORT_SYMBOL(bitmap_find_free_region);
1071 * bitmap_release_region - release allocated bitmap region
1072 * @bitmap: array of unsigned longs corresponding to the bitmap
1073 * @pos: beginning of bit region to release
1074 * @order: region size (log base 2 of number of bits) to release
1076 * This is the complement to __bitmap_find_free_region() and releases
1077 * the found region (by clearing it in the bitmap).
1081 void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order)
1083 __reg_op(bitmap, pos, order, REG_OP_RELEASE);
1085 EXPORT_SYMBOL(bitmap_release_region);
1088 * bitmap_allocate_region - allocate bitmap region
1089 * @bitmap: array of unsigned longs corresponding to the bitmap
1090 * @pos: beginning of bit region to allocate
1091 * @order: region size (log base 2 of number of bits) to allocate
1093 * Allocate (set bits in) a specified region of a bitmap.
1095 * Return 0 on success, or %-EBUSY if specified region wasn't
1096 * free (not all bits were zero).
1098 int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order)
1100 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1102 return __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1104 EXPORT_SYMBOL(bitmap_allocate_region);
1107 * bitmap_from_u32array - copy the contents of a u32 array of bits to bitmap
1108 * @bitmap: array of unsigned longs, the destination bitmap, non NULL
1109 * @nbits: number of bits in @bitmap
1110 * @buf: array of u32 (in host byte order), the source bitmap, non NULL
1111 * @nwords: number of u32 words in @buf
1113 * copy min(nbits, 32*nwords) bits from @buf to @bitmap, remaining
1114 * bits between nword and nbits in @bitmap (if any) are cleared. In
1115 * last word of @bitmap, the bits beyond nbits (if any) are kept
1118 * Return the number of bits effectively copied.
1121 bitmap_from_u32array(unsigned long *bitmap, unsigned int nbits,
1122 const u32 *buf, unsigned int nwords)
1124 unsigned int dst_idx, src_idx;
1126 for (src_idx = dst_idx = 0; dst_idx < BITS_TO_LONGS(nbits); ++dst_idx) {
1127 unsigned long part = 0;
1129 if (src_idx < nwords)
1130 part = buf[src_idx++];
1132 #if BITS_PER_LONG == 64
1133 if (src_idx < nwords)
1134 part |= ((unsigned long) buf[src_idx++]) << 32;
1137 if (dst_idx < nbits/BITS_PER_LONG)
1138 bitmap[dst_idx] = part;
1140 unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);
1142 bitmap[dst_idx] = (bitmap[dst_idx] & ~mask)
1147 return min_t(unsigned int, nbits, 32*nwords);
1149 EXPORT_SYMBOL(bitmap_from_u32array);
1152 * bitmap_to_u32array - copy the contents of bitmap to a u32 array of bits
1153 * @buf: array of u32 (in host byte order), the dest bitmap, non NULL
1154 * @nwords: number of u32 words in @buf
1155 * @bitmap: array of unsigned longs, the source bitmap, non NULL
1156 * @nbits: number of bits in @bitmap
1158 * copy min(nbits, 32*nwords) bits from @bitmap to @buf. Remaining
1159 * bits after nbits in @buf (if any) are cleared.
1161 * Return the number of bits effectively copied.
1164 bitmap_to_u32array(u32 *buf, unsigned int nwords,
1165 const unsigned long *bitmap, unsigned int nbits)
1167 unsigned int dst_idx = 0, src_idx = 0;
1169 while (dst_idx < nwords) {
1170 unsigned long part = 0;
1172 if (src_idx < BITS_TO_LONGS(nbits)) {
1173 part = bitmap[src_idx];
1174 if (src_idx >= nbits/BITS_PER_LONG)
1175 part &= BITMAP_LAST_WORD_MASK(nbits);
1179 buf[dst_idx++] = part & 0xffffffffUL;
1181 #if BITS_PER_LONG == 64
1182 if (dst_idx < nwords) {
1184 buf[dst_idx++] = part & 0xffffffffUL;
1189 return min_t(unsigned int, nbits, 32*nwords);
1191 EXPORT_SYMBOL(bitmap_to_u32array);
1194 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1195 * @dst: destination buffer
1196 * @src: bitmap to copy
1197 * @nbits: number of bits in the bitmap
1199 * Require nbits % BITS_PER_LONG == 0.
1202 void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits)
1206 for (i = 0; i < nbits/BITS_PER_LONG; i++) {
1207 if (BITS_PER_LONG == 64)
1208 dst[i] = cpu_to_le64(src[i]);
1210 dst[i] = cpu_to_le32(src[i]);
1213 EXPORT_SYMBOL(bitmap_copy_le);