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>
17 #include <asm/uaccess.h>
20 * bitmaps provide an array of bits, implemented using an an
21 * array of unsigned longs. The number of valid bits in a
22 * given bitmap does _not_ need to be an exact multiple of
25 * The possible unused bits in the last, partially used word
26 * of a bitmap are 'don't care'. The implementation makes
27 * no particular effort to keep them zero. It ensures that
28 * their value will not affect the results of any operation.
29 * The bitmap operations that return Boolean (bitmap_empty,
30 * for example) or scalar (bitmap_weight, for example) results
31 * carefully filter out these unused bits from impacting their
34 * These operations actually hold to a slightly stronger rule:
35 * if you don't input any bitmaps to these ops that have some
36 * unused bits set, then they won't output any set unused bits
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_empty(const unsigned long *bitmap, unsigned int bits)
47 unsigned int k, lim = bits/BITS_PER_LONG;
48 for (k = 0; k < lim; ++k)
52 if (bits % BITS_PER_LONG)
53 if (bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
58 EXPORT_SYMBOL(__bitmap_empty);
60 int __bitmap_full(const unsigned long *bitmap, unsigned int bits)
62 unsigned int k, lim = bits/BITS_PER_LONG;
63 for (k = 0; k < lim; ++k)
67 if (bits % BITS_PER_LONG)
68 if (~bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
73 EXPORT_SYMBOL(__bitmap_full);
75 int __bitmap_equal(const unsigned long *bitmap1,
76 const unsigned long *bitmap2, unsigned int bits)
78 unsigned int k, lim = bits/BITS_PER_LONG;
79 for (k = 0; k < lim; ++k)
80 if (bitmap1[k] != bitmap2[k])
83 if (bits % BITS_PER_LONG)
84 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
89 EXPORT_SYMBOL(__bitmap_equal);
91 void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits)
93 unsigned int k, lim = bits/BITS_PER_LONG;
94 for (k = 0; k < lim; ++k)
97 if (bits % BITS_PER_LONG)
100 EXPORT_SYMBOL(__bitmap_complement);
103 * __bitmap_shift_right - logical right shift of the bits in a bitmap
104 * @dst : destination bitmap
105 * @src : source bitmap
106 * @shift : shift by this many bits
107 * @nbits : bitmap size, in bits
109 * Shifting right (dividing) means moving bits in the MS -> LS bit
110 * direction. Zeros are fed into the vacated MS positions and the
111 * LS bits shifted off the bottom are lost.
113 void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
114 unsigned shift, unsigned nbits)
116 unsigned k, lim = BITS_TO_LONGS(nbits);
117 unsigned off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
118 unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);
119 for (k = 0; off + k < lim; ++k) {
120 unsigned long upper, lower;
123 * If shift is not word aligned, take lower rem bits of
124 * word above and make them the top rem bits of result.
126 if (!rem || off + k + 1 >= lim)
129 upper = src[off + k + 1];
130 if (off + k + 1 == lim - 1)
132 upper <<= (BITS_PER_LONG - rem);
134 lower = src[off + k];
135 if (off + k == lim - 1)
138 dst[k] = lower | upper;
141 memset(&dst[lim - off], 0, off*sizeof(unsigned long));
143 EXPORT_SYMBOL(__bitmap_shift_right);
147 * __bitmap_shift_left - logical left shift of the bits in a bitmap
148 * @dst : destination bitmap
149 * @src : source bitmap
150 * @shift : shift by this many bits
151 * @nbits : bitmap size, in bits
153 * Shifting left (multiplying) means moving bits in the LS -> MS
154 * direction. Zeros are fed into the vacated LS bit positions
155 * and those MS bits shifted off the top are lost.
158 void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
159 unsigned int shift, unsigned int nbits)
162 unsigned int lim = BITS_TO_LONGS(nbits);
163 unsigned int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
164 for (k = lim - off - 1; k >= 0; --k) {
165 unsigned long upper, lower;
168 * If shift is not word aligned, take upper rem bits of
169 * word below and make them the bottom rem bits of result.
172 lower = src[k - 1] >> (BITS_PER_LONG - rem);
175 upper = src[k] << rem;
176 dst[k + off] = lower | upper;
179 memset(dst, 0, off*sizeof(unsigned long));
181 EXPORT_SYMBOL(__bitmap_shift_left);
183 int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
184 const unsigned long *bitmap2, unsigned int bits)
187 unsigned int lim = bits/BITS_PER_LONG;
188 unsigned long result = 0;
190 for (k = 0; k < lim; k++)
191 result |= (dst[k] = bitmap1[k] & bitmap2[k]);
192 if (bits % BITS_PER_LONG)
193 result |= (dst[k] = bitmap1[k] & bitmap2[k] &
194 BITMAP_LAST_WORD_MASK(bits));
197 EXPORT_SYMBOL(__bitmap_and);
199 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
200 const unsigned long *bitmap2, unsigned int bits)
203 unsigned int nr = BITS_TO_LONGS(bits);
205 for (k = 0; k < nr; k++)
206 dst[k] = bitmap1[k] | bitmap2[k];
208 EXPORT_SYMBOL(__bitmap_or);
210 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
211 const unsigned long *bitmap2, unsigned int bits)
214 unsigned int nr = BITS_TO_LONGS(bits);
216 for (k = 0; k < nr; k++)
217 dst[k] = bitmap1[k] ^ bitmap2[k];
219 EXPORT_SYMBOL(__bitmap_xor);
221 int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
222 const unsigned long *bitmap2, unsigned int bits)
225 unsigned int lim = bits/BITS_PER_LONG;
226 unsigned long result = 0;
228 for (k = 0; k < lim; k++)
229 result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
230 if (bits % BITS_PER_LONG)
231 result |= (dst[k] = bitmap1[k] & ~bitmap2[k] &
232 BITMAP_LAST_WORD_MASK(bits));
235 EXPORT_SYMBOL(__bitmap_andnot);
237 int __bitmap_intersects(const unsigned long *bitmap1,
238 const unsigned long *bitmap2, unsigned int bits)
240 unsigned int k, lim = bits/BITS_PER_LONG;
241 for (k = 0; k < lim; ++k)
242 if (bitmap1[k] & bitmap2[k])
245 if (bits % BITS_PER_LONG)
246 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
250 EXPORT_SYMBOL(__bitmap_intersects);
252 int __bitmap_subset(const unsigned long *bitmap1,
253 const unsigned long *bitmap2, unsigned int bits)
255 unsigned int k, lim = bits/BITS_PER_LONG;
256 for (k = 0; k < lim; ++k)
257 if (bitmap1[k] & ~bitmap2[k])
260 if (bits % BITS_PER_LONG)
261 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
265 EXPORT_SYMBOL(__bitmap_subset);
267 int __bitmap_weight(const unsigned long *bitmap, unsigned int bits)
269 unsigned int k, lim = bits/BITS_PER_LONG;
272 for (k = 0; k < lim; k++)
273 w += hweight_long(bitmap[k]);
275 if (bits % BITS_PER_LONG)
276 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
280 EXPORT_SYMBOL(__bitmap_weight);
282 void bitmap_set(unsigned long *map, unsigned int start, int len)
284 unsigned long *p = map + BIT_WORD(start);
285 const unsigned int size = start + len;
286 int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
287 unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
289 while (len - bits_to_set >= 0) {
292 bits_to_set = BITS_PER_LONG;
297 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
301 EXPORT_SYMBOL(bitmap_set);
303 void bitmap_clear(unsigned long *map, unsigned int start, int len)
305 unsigned long *p = map + BIT_WORD(start);
306 const unsigned int size = start + len;
307 int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
308 unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
310 while (len - bits_to_clear >= 0) {
311 *p &= ~mask_to_clear;
312 len -= bits_to_clear;
313 bits_to_clear = BITS_PER_LONG;
314 mask_to_clear = ~0UL;
318 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
319 *p &= ~mask_to_clear;
322 EXPORT_SYMBOL(bitmap_clear);
325 * bitmap_find_next_zero_area_off - find a contiguous aligned zero area
326 * @map: The address to base the search on
327 * @size: The bitmap size in bits
328 * @start: The bitnumber to start searching at
329 * @nr: The number of zeroed bits we're looking for
330 * @align_mask: Alignment mask for zero area
331 * @align_offset: Alignment offset for zero area.
333 * The @align_mask should be one less than a power of 2; the effect is that
334 * the bit offset of all zero areas this function finds plus @align_offset
335 * is multiple of that power of 2.
337 unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
341 unsigned long align_mask,
342 unsigned long align_offset)
344 unsigned long index, end, i;
346 index = find_next_zero_bit(map, size, start);
348 /* Align allocation */
349 index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset;
354 i = find_next_bit(map, end, index);
361 EXPORT_SYMBOL(bitmap_find_next_zero_area_off);
364 * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,
365 * second version by Paul Jackson, third by Joe Korty.
369 #define nbits_to_hold_value(val) fls(val)
370 #define BASEDEC 10 /* fancier cpuset lists input in decimal */
373 * bitmap_scnprintf - convert bitmap to an ASCII hex string.
374 * @buf: byte buffer into which string is placed
375 * @buflen: reserved size of @buf, in bytes
376 * @maskp: pointer to bitmap to convert
377 * @nmaskbits: size of bitmap, in bits
379 * Exactly @nmaskbits bits are displayed. Hex digits are grouped into
380 * comma-separated sets of eight digits per set. Returns the number of
381 * characters which were written to *buf, excluding the trailing \0.
383 int bitmap_scnprintf(char *buf, unsigned int buflen,
384 const unsigned long *maskp, int nmaskbits)
386 return scnprintf(buf, buflen, "%*pb", nmaskbits, maskp);
388 EXPORT_SYMBOL(bitmap_scnprintf);
391 * __bitmap_parse - convert an ASCII hex string into a bitmap.
392 * @buf: pointer to buffer containing string.
393 * @buflen: buffer size in bytes. If string is smaller than this
394 * then it must be terminated with a \0.
395 * @is_user: location of buffer, 0 indicates kernel space
396 * @maskp: pointer to bitmap array that will contain result.
397 * @nmaskbits: size of bitmap, in bits.
399 * Commas group hex digits into chunks. Each chunk defines exactly 32
400 * bits of the resultant bitmask. No chunk may specify a value larger
401 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
402 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
403 * characters and for grouping errors such as "1,,5", ",44", "," and "".
404 * Leading and trailing whitespace accepted, but not embedded whitespace.
406 int __bitmap_parse(const char *buf, unsigned int buflen,
407 int is_user, unsigned long *maskp,
410 int c, old_c, totaldigits, ndigits, nchunks, nbits;
412 const char __user __force *ubuf = (const char __user __force *)buf;
414 bitmap_zero(maskp, nmaskbits);
416 nchunks = nbits = totaldigits = c = 0;
420 /* Get the next chunk of the bitmap */
424 if (__get_user(c, ubuf++))
434 * If the last character was a space and the current
435 * character isn't '\0', we've got embedded whitespace.
436 * This is a no-no, so throw an error.
438 if (totaldigits && c && isspace(old_c))
441 /* A '\0' or a ',' signal the end of the chunk */
442 if (c == '\0' || c == ',')
449 * Make sure there are at least 4 free bits in 'chunk'.
450 * If not, this hexdigit will overflow 'chunk', so
453 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
456 chunk = (chunk << 4) | hex_to_bin(c);
457 ndigits++; totaldigits++;
461 if (nchunks == 0 && chunk == 0)
464 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
467 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
468 if (nbits > nmaskbits)
470 } while (buflen && c == ',');
474 EXPORT_SYMBOL(__bitmap_parse);
477 * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
479 * @ubuf: pointer to user buffer containing string.
480 * @ulen: buffer size in bytes. If string is smaller than this
481 * then it must be terminated with a \0.
482 * @maskp: pointer to bitmap array that will contain result.
483 * @nmaskbits: size of bitmap, in bits.
485 * Wrapper for __bitmap_parse(), providing it with user buffer.
487 * We cannot have this as an inline function in bitmap.h because it needs
488 * linux/uaccess.h to get the access_ok() declaration and this causes
489 * cyclic dependencies.
491 int bitmap_parse_user(const char __user *ubuf,
492 unsigned int ulen, unsigned long *maskp,
495 if (!access_ok(VERIFY_READ, ubuf, ulen))
497 return __bitmap_parse((const char __force *)ubuf,
498 ulen, 1, maskp, nmaskbits);
501 EXPORT_SYMBOL(bitmap_parse_user);
504 * bitmap_scnlistprintf - convert bitmap to list format ASCII string
505 * @buf: byte buffer into which string is placed
506 * @buflen: reserved size of @buf, in bytes
507 * @maskp: pointer to bitmap to convert
508 * @nmaskbits: size of bitmap, in bits
510 * Output format is a comma-separated list of decimal numbers and
511 * ranges. Consecutively set bits are shown as two hyphen-separated
512 * decimal numbers, the smallest and largest bit numbers set in
513 * the range. Output format is compatible with the format
514 * accepted as input by bitmap_parselist().
516 * The return value is the number of characters which were written to *buf
517 * excluding the trailing '\0', as per ISO C99's scnprintf.
519 int bitmap_scnlistprintf(char *buf, unsigned int buflen,
520 const unsigned long *maskp, int nmaskbits)
522 return scnprintf(buf, buflen, "%*pbl", nmaskbits, maskp);
524 EXPORT_SYMBOL(bitmap_scnlistprintf);
527 * bitmap_print_to_pagebuf - convert bitmap to list or hex format ASCII string
528 * @list: indicates whether the bitmap must be list
529 * @buf: page aligned buffer into which string is placed
530 * @maskp: pointer to bitmap to convert
531 * @nmaskbits: size of bitmap, in bits
533 * Output format is a comma-separated list of decimal numbers and
534 * ranges if list is specified or hex digits grouped into comma-separated
535 * sets of 8 digits/set. Returns the number of characters written to buf.
537 int bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp,
540 ptrdiff_t len = PTR_ALIGN(buf + PAGE_SIZE - 1, PAGE_SIZE) - buf - 2;
544 n = list ? scnprintf(buf, len, "%*pbl", nmaskbits, maskp) :
545 scnprintf(buf, len, "%*pb", nmaskbits, maskp);
551 EXPORT_SYMBOL(bitmap_print_to_pagebuf);
554 * __bitmap_parselist - convert list format ASCII string to bitmap
555 * @buf: read nul-terminated user string from this buffer
556 * @buflen: buffer size in bytes. If string is smaller than this
557 * then it must be terminated with a \0.
558 * @is_user: location of buffer, 0 indicates kernel space
559 * @maskp: write resulting mask here
560 * @nmaskbits: number of bits in mask to be written
562 * Input format is a comma-separated list of decimal numbers and
563 * ranges. Consecutively set bits are shown as two hyphen-separated
564 * decimal numbers, the smallest and largest bit numbers set in
567 * Returns 0 on success, -errno on invalid input strings.
569 * %-EINVAL: second number in range smaller than first
570 * %-EINVAL: invalid character in string
571 * %-ERANGE: bit number specified too large for mask
573 static int __bitmap_parselist(const char *buf, unsigned int buflen,
574 int is_user, unsigned long *maskp,
578 int c, old_c, totaldigits;
579 const char __user __force *ubuf = (const char __user __force *)buf;
580 int exp_digit, in_range;
583 bitmap_zero(maskp, nmaskbits);
589 /* Get the next cpu# or a range of cpu#'s */
593 if (__get_user(c, ubuf++))
602 * If the last character was a space and the current
603 * character isn't '\0', we've got embedded whitespace.
604 * This is a no-no, so throw an error.
606 if (totaldigits && c && isspace(old_c))
609 /* A '\0' or a ',' signal the end of a cpu# or range */
610 if (c == '\0' || c == ',')
614 if (exp_digit || in_range)
625 b = b * 10 + (c - '0');
639 } while (buflen && c == ',');
643 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
645 char *nl = strchrnul(bp, '\n');
648 return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
650 EXPORT_SYMBOL(bitmap_parselist);
654 * bitmap_parselist_user()
656 * @ubuf: pointer to user buffer containing string.
657 * @ulen: buffer size in bytes. If string is smaller than this
658 * then it must be terminated with a \0.
659 * @maskp: pointer to bitmap array that will contain result.
660 * @nmaskbits: size of bitmap, in bits.
662 * Wrapper for bitmap_parselist(), providing it with user buffer.
664 * We cannot have this as an inline function in bitmap.h because it needs
665 * linux/uaccess.h to get the access_ok() declaration and this causes
666 * cyclic dependencies.
668 int bitmap_parselist_user(const char __user *ubuf,
669 unsigned int ulen, unsigned long *maskp,
672 if (!access_ok(VERIFY_READ, ubuf, ulen))
674 return __bitmap_parselist((const char __force *)ubuf,
675 ulen, 1, maskp, nmaskbits);
677 EXPORT_SYMBOL(bitmap_parselist_user);
681 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
682 * @buf: pointer to a bitmap
683 * @pos: a bit position in @buf (0 <= @pos < @nbits)
684 * @nbits: number of valid bit positions in @buf
686 * Map the bit at position @pos in @buf (of length @nbits) to the
687 * ordinal of which set bit it is. If it is not set or if @pos
688 * is not a valid bit position, map to -1.
690 * If for example, just bits 4 through 7 are set in @buf, then @pos
691 * values 4 through 7 will get mapped to 0 through 3, respectively,
692 * and other @pos values will get mapped to -1. When @pos value 7
693 * gets mapped to (returns) @ord value 3 in this example, that means
694 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
696 * The bit positions 0 through @bits are valid positions in @buf.
698 static int bitmap_pos_to_ord(const unsigned long *buf, unsigned int pos, unsigned int nbits)
700 if (pos >= nbits || !test_bit(pos, buf))
703 return __bitmap_weight(buf, pos);
707 * bitmap_ord_to_pos - find position of n-th set bit in bitmap
708 * @buf: pointer to bitmap
709 * @ord: ordinal bit position (n-th set bit, n >= 0)
710 * @nbits: number of valid bit positions in @buf
712 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
713 * Value of @ord should be in range 0 <= @ord < weight(buf). If @ord
714 * >= weight(buf), returns @nbits.
716 * If for example, just bits 4 through 7 are set in @buf, then @ord
717 * values 0 through 3 will get mapped to 4 through 7, respectively,
718 * and all other @ord values returns @nbits. When @ord value 3
719 * gets mapped to (returns) @pos value 7 in this example, that means
720 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
722 * The bit positions 0 through @nbits-1 are valid positions in @buf.
724 unsigned int bitmap_ord_to_pos(const unsigned long *buf, unsigned int ord, unsigned int nbits)
728 for (pos = find_first_bit(buf, nbits);
730 pos = find_next_bit(buf, nbits, pos + 1))
737 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
738 * @dst: remapped result
739 * @src: subset to be remapped
740 * @old: defines domain of map
741 * @new: defines range of map
742 * @nbits: number of bits in each of these bitmaps
744 * Let @old and @new define a mapping of bit positions, such that
745 * whatever position is held by the n-th set bit in @old is mapped
746 * to the n-th set bit in @new. In the more general case, allowing
747 * for the possibility that the weight 'w' of @new is less than the
748 * weight of @old, map the position of the n-th set bit in @old to
749 * the position of the m-th set bit in @new, where m == n % w.
751 * If either of the @old and @new bitmaps are empty, or if @src and
752 * @dst point to the same location, then this routine copies @src
755 * The positions of unset bits in @old are mapped to themselves
756 * (the identify map).
758 * Apply the above specified mapping to @src, placing the result in
759 * @dst, clearing any bits previously set in @dst.
761 * For example, lets say that @old has bits 4 through 7 set, and
762 * @new has bits 12 through 15 set. This defines the mapping of bit
763 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
764 * bit positions unchanged. So if say @src comes into this routine
765 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
768 void bitmap_remap(unsigned long *dst, const unsigned long *src,
769 const unsigned long *old, const unsigned long *new,
772 unsigned int oldbit, w;
774 if (dst == src) /* following doesn't handle inplace remaps */
776 bitmap_zero(dst, nbits);
778 w = bitmap_weight(new, nbits);
779 for_each_set_bit(oldbit, src, nbits) {
780 int n = bitmap_pos_to_ord(old, oldbit, nbits);
783 set_bit(oldbit, dst); /* identity map */
785 set_bit(bitmap_ord_to_pos(new, n % w, nbits), dst);
788 EXPORT_SYMBOL(bitmap_remap);
791 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
792 * @oldbit: bit position to be mapped
793 * @old: defines domain of map
794 * @new: defines range of map
795 * @bits: number of bits in each of these bitmaps
797 * Let @old and @new define a mapping of bit positions, such that
798 * whatever position is held by the n-th set bit in @old is mapped
799 * to the n-th set bit in @new. In the more general case, allowing
800 * for the possibility that the weight 'w' of @new is less than the
801 * weight of @old, map the position of the n-th set bit in @old to
802 * the position of the m-th set bit in @new, where m == n % w.
804 * The positions of unset bits in @old are mapped to themselves
805 * (the identify map).
807 * Apply the above specified mapping to bit position @oldbit, returning
808 * the new bit position.
810 * For example, lets say that @old has bits 4 through 7 set, and
811 * @new has bits 12 through 15 set. This defines the mapping of bit
812 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
813 * bit positions unchanged. So if say @oldbit is 5, then this routine
816 int bitmap_bitremap(int oldbit, const unsigned long *old,
817 const unsigned long *new, int bits)
819 int w = bitmap_weight(new, bits);
820 int n = bitmap_pos_to_ord(old, oldbit, bits);
824 return bitmap_ord_to_pos(new, n % w, bits);
826 EXPORT_SYMBOL(bitmap_bitremap);
829 * bitmap_onto - translate one bitmap relative to another
830 * @dst: resulting translated bitmap
831 * @orig: original untranslated bitmap
832 * @relmap: bitmap relative to which translated
833 * @bits: number of bits in each of these bitmaps
835 * Set the n-th bit of @dst iff there exists some m such that the
836 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
837 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
838 * (If you understood the previous sentence the first time your
839 * read it, you're overqualified for your current job.)
841 * In other words, @orig is mapped onto (surjectively) @dst,
842 * using the map { <n, m> | the n-th bit of @relmap is the
843 * m-th set bit of @relmap }.
845 * Any set bits in @orig above bit number W, where W is the
846 * weight of (number of set bits in) @relmap are mapped nowhere.
847 * In particular, if for all bits m set in @orig, m >= W, then
848 * @dst will end up empty. In situations where the possibility
849 * of such an empty result is not desired, one way to avoid it is
850 * to use the bitmap_fold() operator, below, to first fold the
851 * @orig bitmap over itself so that all its set bits x are in the
852 * range 0 <= x < W. The bitmap_fold() operator does this by
853 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
855 * Example [1] for bitmap_onto():
856 * Let's say @relmap has bits 30-39 set, and @orig has bits
857 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,
858 * @dst will have bits 31, 33, 35, 37 and 39 set.
860 * When bit 0 is set in @orig, it means turn on the bit in
861 * @dst corresponding to whatever is the first bit (if any)
862 * that is turned on in @relmap. Since bit 0 was off in the
863 * above example, we leave off that bit (bit 30) in @dst.
865 * When bit 1 is set in @orig (as in the above example), it
866 * means turn on the bit in @dst corresponding to whatever
867 * is the second bit that is turned on in @relmap. The second
868 * bit in @relmap that was turned on in the above example was
869 * bit 31, so we turned on bit 31 in @dst.
871 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
872 * because they were the 4th, 6th, 8th and 10th set bits
873 * set in @relmap, and the 4th, 6th, 8th and 10th bits of
874 * @orig (i.e. bits 3, 5, 7 and 9) were also set.
876 * When bit 11 is set in @orig, it means turn on the bit in
877 * @dst corresponding to whatever is the twelfth bit that is
878 * turned on in @relmap. In the above example, there were
879 * only ten bits turned on in @relmap (30..39), so that bit
880 * 11 was set in @orig had no affect on @dst.
882 * Example [2] for bitmap_fold() + bitmap_onto():
883 * Let's say @relmap has these ten bits set:
884 * 40 41 42 43 45 48 53 61 74 95
885 * (for the curious, that's 40 plus the first ten terms of the
886 * Fibonacci sequence.)
888 * Further lets say we use the following code, invoking
889 * bitmap_fold() then bitmap_onto, as suggested above to
890 * avoid the possibility of an empty @dst result:
892 * unsigned long *tmp; // a temporary bitmap's bits
894 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
895 * bitmap_onto(dst, tmp, relmap, bits);
897 * Then this table shows what various values of @dst would be, for
898 * various @orig's. I list the zero-based positions of each set bit.
899 * The tmp column shows the intermediate result, as computed by
900 * using bitmap_fold() to fold the @orig bitmap modulo ten
901 * (the weight of @relmap).
908 * 1 3 5 7 1 3 5 7 41 43 48 61
909 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45
910 * 0 9 18 27 0 9 8 7 40 61 74 95
912 * 0 11 22 33 0 1 2 3 40 41 42 43
913 * 0 12 24 36 0 2 4 6 40 42 45 53
914 * 78 102 211 1 2 8 41 42 74 (*)
916 * (*) For these marked lines, if we hadn't first done bitmap_fold()
917 * into tmp, then the @dst result would have been empty.
919 * If either of @orig or @relmap is empty (no set bits), then @dst
920 * will be returned empty.
922 * If (as explained above) the only set bits in @orig are in positions
923 * m where m >= W, (where W is the weight of @relmap) then @dst will
924 * once again be returned empty.
926 * All bits in @dst not set by the above rule are cleared.
928 void bitmap_onto(unsigned long *dst, const unsigned long *orig,
929 const unsigned long *relmap, unsigned int bits)
931 unsigned int n, m; /* same meaning as in above comment */
933 if (dst == orig) /* following doesn't handle inplace mappings */
935 bitmap_zero(dst, bits);
938 * The following code is a more efficient, but less
939 * obvious, equivalent to the loop:
940 * for (m = 0; m < bitmap_weight(relmap, bits); m++) {
941 * n = bitmap_ord_to_pos(orig, m, bits);
942 * if (test_bit(m, orig))
948 for_each_set_bit(n, relmap, bits) {
949 /* m == bitmap_pos_to_ord(relmap, n, bits) */
950 if (test_bit(m, orig))
955 EXPORT_SYMBOL(bitmap_onto);
958 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
959 * @dst: resulting smaller bitmap
960 * @orig: original larger bitmap
961 * @sz: specified size
962 * @nbits: number of bits in each of these bitmaps
964 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
965 * Clear all other bits in @dst. See further the comment and
966 * Example [2] for bitmap_onto() for why and how to use this.
968 void bitmap_fold(unsigned long *dst, const unsigned long *orig,
969 unsigned int sz, unsigned int nbits)
973 if (dst == orig) /* following doesn't handle inplace mappings */
975 bitmap_zero(dst, nbits);
977 for_each_set_bit(oldbit, orig, nbits)
978 set_bit(oldbit % sz, dst);
980 EXPORT_SYMBOL(bitmap_fold);
983 * Common code for bitmap_*_region() routines.
984 * bitmap: array of unsigned longs corresponding to the bitmap
985 * pos: the beginning of the region
986 * order: region size (log base 2 of number of bits)
987 * reg_op: operation(s) to perform on that region of bitmap
989 * Can set, verify and/or release a region of bits in a bitmap,
990 * depending on which combination of REG_OP_* flag bits is set.
992 * A region of a bitmap is a sequence of bits in the bitmap, of
993 * some size '1 << order' (a power of two), aligned to that same
994 * '1 << order' power of two.
996 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
997 * Returns 0 in all other cases and reg_ops.
1001 REG_OP_ISFREE, /* true if region is all zero bits */
1002 REG_OP_ALLOC, /* set all bits in region */
1003 REG_OP_RELEASE, /* clear all bits in region */
1006 static int __reg_op(unsigned long *bitmap, unsigned int pos, int order, int reg_op)
1008 int nbits_reg; /* number of bits in region */
1009 int index; /* index first long of region in bitmap */
1010 int offset; /* bit offset region in bitmap[index] */
1011 int nlongs_reg; /* num longs spanned by region in bitmap */
1012 int nbitsinlong; /* num bits of region in each spanned long */
1013 unsigned long mask; /* bitmask for one long of region */
1014 int i; /* scans bitmap by longs */
1015 int ret = 0; /* return value */
1018 * Either nlongs_reg == 1 (for small orders that fit in one long)
1019 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
1021 nbits_reg = 1 << order;
1022 index = pos / BITS_PER_LONG;
1023 offset = pos - (index * BITS_PER_LONG);
1024 nlongs_reg = BITS_TO_LONGS(nbits_reg);
1025 nbitsinlong = min(nbits_reg, BITS_PER_LONG);
1028 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
1029 * overflows if nbitsinlong == BITS_PER_LONG.
1031 mask = (1UL << (nbitsinlong - 1));
1037 for (i = 0; i < nlongs_reg; i++) {
1038 if (bitmap[index + i] & mask)
1041 ret = 1; /* all bits in region free (zero) */
1045 for (i = 0; i < nlongs_reg; i++)
1046 bitmap[index + i] |= mask;
1049 case REG_OP_RELEASE:
1050 for (i = 0; i < nlongs_reg; i++)
1051 bitmap[index + i] &= ~mask;
1059 * bitmap_find_free_region - find a contiguous aligned mem region
1060 * @bitmap: array of unsigned longs corresponding to the bitmap
1061 * @bits: number of bits in the bitmap
1062 * @order: region size (log base 2 of number of bits) to find
1064 * Find a region of free (zero) bits in a @bitmap of @bits bits and
1065 * allocate them (set them to one). Only consider regions of length
1066 * a power (@order) of two, aligned to that power of two, which
1067 * makes the search algorithm much faster.
1069 * Return the bit offset in bitmap of the allocated region,
1070 * or -errno on failure.
1072 int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order)
1074 unsigned int pos, end; /* scans bitmap by regions of size order */
1076 for (pos = 0 ; (end = pos + (1U << order)) <= bits; pos = end) {
1077 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1079 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1084 EXPORT_SYMBOL(bitmap_find_free_region);
1087 * bitmap_release_region - release allocated bitmap region
1088 * @bitmap: array of unsigned longs corresponding to the bitmap
1089 * @pos: beginning of bit region to release
1090 * @order: region size (log base 2 of number of bits) to release
1092 * This is the complement to __bitmap_find_free_region() and releases
1093 * the found region (by clearing it in the bitmap).
1097 void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order)
1099 __reg_op(bitmap, pos, order, REG_OP_RELEASE);
1101 EXPORT_SYMBOL(bitmap_release_region);
1104 * bitmap_allocate_region - allocate bitmap region
1105 * @bitmap: array of unsigned longs corresponding to the bitmap
1106 * @pos: beginning of bit region to allocate
1107 * @order: region size (log base 2 of number of bits) to allocate
1109 * Allocate (set bits in) a specified region of a bitmap.
1111 * Return 0 on success, or %-EBUSY if specified region wasn't
1112 * free (not all bits were zero).
1114 int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order)
1116 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1118 return __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1120 EXPORT_SYMBOL(bitmap_allocate_region);
1123 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1124 * @dst: destination buffer
1125 * @src: bitmap to copy
1126 * @nbits: number of bits in the bitmap
1128 * Require nbits % BITS_PER_LONG == 0.
1131 void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits)
1135 for (i = 0; i < nbits/BITS_PER_LONG; i++) {
1136 if (BITS_PER_LONG == 64)
1137 dst[i] = cpu_to_le64(src[i]);
1139 dst[i] = cpu_to_le32(src[i]);
1142 EXPORT_SYMBOL(bitmap_copy_le);