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/module.h>
9 #include <linux/ctype.h>
10 #include <linux/errno.h>
11 #include <linux/bitmap.h>
12 #include <linux/bitops.h>
13 #include <asm/uaccess.h>
16 * bitmaps provide an array of bits, implemented using an an
17 * array of unsigned longs. The number of valid bits in a
18 * given bitmap does _not_ need to be an exact multiple of
21 * The possible unused bits in the last, partially used word
22 * of a bitmap are 'don't care'. The implementation makes
23 * no particular effort to keep them zero. It ensures that
24 * their value will not affect the results of any operation.
25 * The bitmap operations that return Boolean (bitmap_empty,
26 * for example) or scalar (bitmap_weight, for example) results
27 * carefully filter out these unused bits from impacting their
30 * These operations actually hold to a slightly stronger rule:
31 * if you don't input any bitmaps to these ops that have some
32 * unused bits set, then they won't output any set unused bits
35 * The byte ordering of bitmaps is more natural on little
36 * endian architectures. See the big-endian headers
37 * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
38 * for the best explanations of this ordering.
41 int __bitmap_empty(const unsigned long *bitmap, int bits)
43 int k, lim = bits/BITS_PER_LONG;
44 for (k = 0; k < lim; ++k)
48 if (bits % BITS_PER_LONG)
49 if (bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
54 EXPORT_SYMBOL(__bitmap_empty);
56 int __bitmap_full(const unsigned long *bitmap, int bits)
58 int k, lim = bits/BITS_PER_LONG;
59 for (k = 0; k < lim; ++k)
63 if (bits % BITS_PER_LONG)
64 if (~bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
69 EXPORT_SYMBOL(__bitmap_full);
71 int __bitmap_equal(const unsigned long *bitmap1,
72 const unsigned long *bitmap2, int bits)
74 int k, lim = bits/BITS_PER_LONG;
75 for (k = 0; k < lim; ++k)
76 if (bitmap1[k] != bitmap2[k])
79 if (bits % BITS_PER_LONG)
80 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
85 EXPORT_SYMBOL(__bitmap_equal);
87 void __bitmap_complement(unsigned long *dst, const unsigned long *src, int bits)
89 int k, lim = bits/BITS_PER_LONG;
90 for (k = 0; k < lim; ++k)
93 if (bits % BITS_PER_LONG)
94 dst[k] = ~src[k] & BITMAP_LAST_WORD_MASK(bits);
96 EXPORT_SYMBOL(__bitmap_complement);
99 * __bitmap_shift_right - logical right shift of the bits in a bitmap
100 * @dst : destination bitmap
101 * @src : source bitmap
102 * @shift : shift by this many bits
103 * @bits : bitmap size, in bits
105 * Shifting right (dividing) means moving bits in the MS -> LS bit
106 * direction. Zeros are fed into the vacated MS positions and the
107 * LS bits shifted off the bottom are lost.
109 void __bitmap_shift_right(unsigned long *dst,
110 const unsigned long *src, int shift, int bits)
112 int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;
113 int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
114 unsigned long mask = (1UL << left) - 1;
115 for (k = 0; off + k < lim; ++k) {
116 unsigned long upper, lower;
119 * If shift is not word aligned, take lower rem bits of
120 * word above and make them the top rem bits of result.
122 if (!rem || off + k + 1 >= lim)
125 upper = src[off + k + 1];
126 if (off + k + 1 == lim - 1 && left)
129 lower = src[off + k];
130 if (left && off + k == lim - 1)
132 dst[k] = upper << (BITS_PER_LONG - rem) | lower >> rem;
133 if (left && k == lim - 1)
137 memset(&dst[lim - off], 0, off*sizeof(unsigned long));
139 EXPORT_SYMBOL(__bitmap_shift_right);
143 * __bitmap_shift_left - logical left shift of the bits in a bitmap
144 * @dst : destination bitmap
145 * @src : source bitmap
146 * @shift : shift by this many bits
147 * @bits : bitmap size, in bits
149 * Shifting left (multiplying) means moving bits in the LS -> MS
150 * direction. Zeros are fed into the vacated LS bit positions
151 * and those MS bits shifted off the top are lost.
154 void __bitmap_shift_left(unsigned long *dst,
155 const unsigned long *src, int shift, int bits)
157 int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;
158 int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
159 for (k = lim - off - 1; k >= 0; --k) {
160 unsigned long upper, lower;
163 * If shift is not word aligned, take upper rem bits of
164 * word below and make them the bottom rem bits of result.
171 if (left && k == lim - 1)
172 upper &= (1UL << left) - 1;
173 dst[k + off] = lower >> (BITS_PER_LONG - rem) | upper << rem;
174 if (left && k + off == lim - 1)
175 dst[k + off] &= (1UL << left) - 1;
178 memset(dst, 0, off*sizeof(unsigned long));
180 EXPORT_SYMBOL(__bitmap_shift_left);
182 int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
183 const unsigned long *bitmap2, int bits)
186 int nr = BITS_TO_LONGS(bits);
187 unsigned long result = 0;
189 for (k = 0; k < nr; k++)
190 result |= (dst[k] = bitmap1[k] & bitmap2[k]);
193 EXPORT_SYMBOL(__bitmap_and);
195 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
196 const unsigned long *bitmap2, int bits)
199 int nr = BITS_TO_LONGS(bits);
201 for (k = 0; k < nr; k++)
202 dst[k] = bitmap1[k] | bitmap2[k];
204 EXPORT_SYMBOL(__bitmap_or);
206 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
207 const unsigned long *bitmap2, int bits)
210 int nr = BITS_TO_LONGS(bits);
212 for (k = 0; k < nr; k++)
213 dst[k] = bitmap1[k] ^ bitmap2[k];
215 EXPORT_SYMBOL(__bitmap_xor);
217 int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
218 const unsigned long *bitmap2, int bits)
221 int nr = BITS_TO_LONGS(bits);
222 unsigned long result = 0;
224 for (k = 0; k < nr; k++)
225 result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
228 EXPORT_SYMBOL(__bitmap_andnot);
230 int __bitmap_intersects(const unsigned long *bitmap1,
231 const unsigned long *bitmap2, int bits)
233 int k, lim = bits/BITS_PER_LONG;
234 for (k = 0; k < lim; ++k)
235 if (bitmap1[k] & bitmap2[k])
238 if (bits % BITS_PER_LONG)
239 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
243 EXPORT_SYMBOL(__bitmap_intersects);
245 int __bitmap_subset(const unsigned long *bitmap1,
246 const unsigned long *bitmap2, int bits)
248 int k, lim = bits/BITS_PER_LONG;
249 for (k = 0; k < lim; ++k)
250 if (bitmap1[k] & ~bitmap2[k])
253 if (bits % BITS_PER_LONG)
254 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
258 EXPORT_SYMBOL(__bitmap_subset);
260 int __bitmap_weight(const unsigned long *bitmap, int bits)
262 int k, w = 0, lim = bits/BITS_PER_LONG;
264 for (k = 0; k < lim; k++)
265 w += hweight_long(bitmap[k]);
267 if (bits % BITS_PER_LONG)
268 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
272 EXPORT_SYMBOL(__bitmap_weight);
274 #define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) % BITS_PER_LONG))
276 void bitmap_set(unsigned long *map, int start, int nr)
278 unsigned long *p = map + BIT_WORD(start);
279 const int size = start + nr;
280 int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
281 unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
283 while (nr - bits_to_set >= 0) {
286 bits_to_set = BITS_PER_LONG;
291 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
295 EXPORT_SYMBOL(bitmap_set);
297 void bitmap_clear(unsigned long *map, int start, int nr)
299 unsigned long *p = map + BIT_WORD(start);
300 const int size = start + nr;
301 int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
302 unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
304 while (nr - bits_to_clear >= 0) {
305 *p &= ~mask_to_clear;
307 bits_to_clear = BITS_PER_LONG;
308 mask_to_clear = ~0UL;
312 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
313 *p &= ~mask_to_clear;
316 EXPORT_SYMBOL(bitmap_clear);
319 * bitmap_find_next_zero_area - find a contiguous aligned zero area
320 * @map: The address to base the search on
321 * @size: The bitmap size in bits
322 * @start: The bitnumber to start searching at
323 * @nr: The number of zeroed bits we're looking for
324 * @align_mask: Alignment mask for zero area
325 * @align_offset: Alignment offset for zero area.
327 * The @align_mask should be one less than a power of 2; the effect is that
328 * the bit offset of all zero areas this function finds plus @align_offset
329 * is multiple of that power of 2.
331 unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
335 unsigned long align_mask,
336 unsigned long align_offset)
338 unsigned long index, end, i;
340 index = find_next_zero_bit(map, size, start);
342 /* Align allocation */
343 index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset;
348 i = find_next_bit(map, end, index);
355 EXPORT_SYMBOL(bitmap_find_next_zero_area_off);
358 * Bitmap printing & parsing functions: first version by Bill Irwin,
359 * second version by Paul Jackson, third by Joe Korty.
363 #define nbits_to_hold_value(val) fls(val)
364 #define unhex(c) (isdigit(c) ? (c - '0') : (toupper(c) - 'A' + 10))
365 #define BASEDEC 10 /* fancier cpuset lists input in decimal */
368 * bitmap_scnprintf - convert bitmap to an ASCII hex string.
369 * @buf: byte buffer into which string is placed
370 * @buflen: reserved size of @buf, in bytes
371 * @maskp: pointer to bitmap to convert
372 * @nmaskbits: size of bitmap, in bits
374 * Exactly @nmaskbits bits are displayed. Hex digits are grouped into
375 * comma-separated sets of eight digits per set.
377 int bitmap_scnprintf(char *buf, unsigned int buflen,
378 const unsigned long *maskp, int nmaskbits)
380 int i, word, bit, len = 0;
382 const char *sep = "";
386 chunksz = nmaskbits & (CHUNKSZ - 1);
390 i = ALIGN(nmaskbits, CHUNKSZ) - CHUNKSZ;
391 for (; i >= 0; i -= CHUNKSZ) {
392 chunkmask = ((1ULL << chunksz) - 1);
393 word = i / BITS_PER_LONG;
394 bit = i % BITS_PER_LONG;
395 val = (maskp[word] >> bit) & chunkmask;
396 len += scnprintf(buf+len, buflen-len, "%s%0*lx", sep,
403 EXPORT_SYMBOL(bitmap_scnprintf);
406 * __bitmap_parse - convert an ASCII hex string into a bitmap.
407 * @buf: pointer to buffer containing string.
408 * @buflen: buffer size in bytes. If string is smaller than this
409 * then it must be terminated with a \0.
410 * @is_user: location of buffer, 0 indicates kernel space
411 * @maskp: pointer to bitmap array that will contain result.
412 * @nmaskbits: size of bitmap, in bits.
414 * Commas group hex digits into chunks. Each chunk defines exactly 32
415 * bits of the resultant bitmask. No chunk may specify a value larger
416 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
417 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
418 * characters and for grouping errors such as "1,,5", ",44", "," and "".
419 * Leading and trailing whitespace accepted, but not embedded whitespace.
421 int __bitmap_parse(const char *buf, unsigned int buflen,
422 int is_user, unsigned long *maskp,
425 int c, old_c, totaldigits, ndigits, nchunks, nbits;
427 const char __user *ubuf = buf;
429 bitmap_zero(maskp, nmaskbits);
431 nchunks = nbits = totaldigits = c = 0;
435 /* Get the next chunk of the bitmap */
439 if (__get_user(c, ubuf++))
449 * If the last character was a space and the current
450 * character isn't '\0', we've got embedded whitespace.
451 * This is a no-no, so throw an error.
453 if (totaldigits && c && isspace(old_c))
456 /* A '\0' or a ',' signal the end of the chunk */
457 if (c == '\0' || c == ',')
464 * Make sure there are at least 4 free bits in 'chunk'.
465 * If not, this hexdigit will overflow 'chunk', so
468 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
471 chunk = (chunk << 4) | unhex(c);
472 ndigits++; totaldigits++;
476 if (nchunks == 0 && chunk == 0)
479 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
482 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
483 if (nbits > nmaskbits)
485 } while (buflen && c == ',');
489 EXPORT_SYMBOL(__bitmap_parse);
492 * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
494 * @ubuf: pointer to user buffer containing string.
495 * @ulen: buffer size in bytes. If string is smaller than this
496 * then it must be terminated with a \0.
497 * @maskp: pointer to bitmap array that will contain result.
498 * @nmaskbits: size of bitmap, in bits.
500 * Wrapper for __bitmap_parse(), providing it with user buffer.
502 * We cannot have this as an inline function in bitmap.h because it needs
503 * linux/uaccess.h to get the access_ok() declaration and this causes
504 * cyclic dependencies.
506 int bitmap_parse_user(const char __user *ubuf,
507 unsigned int ulen, unsigned long *maskp,
510 if (!access_ok(VERIFY_READ, ubuf, ulen))
512 return __bitmap_parse((const char *)ubuf, ulen, 1, maskp, nmaskbits);
514 EXPORT_SYMBOL(bitmap_parse_user);
517 * bscnl_emit(buf, buflen, rbot, rtop, bp)
519 * Helper routine for bitmap_scnlistprintf(). Write decimal number
520 * or range to buf, suppressing output past buf+buflen, with optional
521 * comma-prefix. Return len of what would be written to buf, if it
524 static inline int bscnl_emit(char *buf, int buflen, int rbot, int rtop, int len)
527 len += scnprintf(buf + len, buflen - len, ",");
529 len += scnprintf(buf + len, buflen - len, "%d", rbot);
531 len += scnprintf(buf + len, buflen - len, "%d-%d", rbot, rtop);
536 * bitmap_scnlistprintf - convert bitmap to list format ASCII string
537 * @buf: byte buffer into which string is placed
538 * @buflen: reserved size of @buf, in bytes
539 * @maskp: pointer to bitmap to convert
540 * @nmaskbits: size of bitmap, in bits
542 * Output format is a comma-separated list of decimal numbers and
543 * ranges. Consecutively set bits are shown as two hyphen-separated
544 * decimal numbers, the smallest and largest bit numbers set in
545 * the range. Output format is compatible with the format
546 * accepted as input by bitmap_parselist().
548 * The return value is the number of characters which would be
549 * generated for the given input, excluding the trailing '\0', as
552 int bitmap_scnlistprintf(char *buf, unsigned int buflen,
553 const unsigned long *maskp, int nmaskbits)
556 /* current bit is 'cur', most recently seen range is [rbot, rtop] */
563 rbot = cur = find_first_bit(maskp, nmaskbits);
564 while (cur < nmaskbits) {
566 cur = find_next_bit(maskp, nmaskbits, cur+1);
567 if (cur >= nmaskbits || cur > rtop + 1) {
568 len = bscnl_emit(buf, buflen, rbot, rtop, len);
574 EXPORT_SYMBOL(bitmap_scnlistprintf);
577 * bitmap_parselist - convert list format ASCII string to bitmap
578 * @bp: read nul-terminated user string from this buffer
579 * @maskp: write resulting mask here
580 * @nmaskbits: number of bits in mask to be written
582 * Input format is a comma-separated list of decimal numbers and
583 * ranges. Consecutively set bits are shown as two hyphen-separated
584 * decimal numbers, the smallest and largest bit numbers set in
587 * Returns 0 on success, -errno on invalid input strings.
589 * %-EINVAL: second number in range smaller than first
590 * %-EINVAL: invalid character in string
591 * %-ERANGE: bit number specified too large for mask
593 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
597 bitmap_zero(maskp, nmaskbits);
601 b = a = simple_strtoul(bp, (char **)&bp, BASEDEC);
606 b = simple_strtoul(bp, (char **)&bp, BASEDEC);
618 } while (*bp != '\0' && *bp != '\n');
621 EXPORT_SYMBOL(bitmap_parselist);
624 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
625 * @buf: pointer to a bitmap
626 * @pos: a bit position in @buf (0 <= @pos < @bits)
627 * @bits: number of valid bit positions in @buf
629 * Map the bit at position @pos in @buf (of length @bits) to the
630 * ordinal of which set bit it is. If it is not set or if @pos
631 * is not a valid bit position, map to -1.
633 * If for example, just bits 4 through 7 are set in @buf, then @pos
634 * values 4 through 7 will get mapped to 0 through 3, respectively,
635 * and other @pos values will get mapped to 0. When @pos value 7
636 * gets mapped to (returns) @ord value 3 in this example, that means
637 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
639 * The bit positions 0 through @bits are valid positions in @buf.
641 static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits)
645 if (pos < 0 || pos >= bits || !test_bit(pos, buf))
648 i = find_first_bit(buf, bits);
651 i = find_next_bit(buf, bits, i + 1);
660 * bitmap_ord_to_pos - find position of n-th set bit in bitmap
661 * @buf: pointer to bitmap
662 * @ord: ordinal bit position (n-th set bit, n >= 0)
663 * @bits: number of valid bit positions in @buf
665 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
666 * Value of @ord should be in range 0 <= @ord < weight(buf), else
667 * results are undefined.
669 * If for example, just bits 4 through 7 are set in @buf, then @ord
670 * values 0 through 3 will get mapped to 4 through 7, respectively,
671 * and all other @ord values return undefined values. When @ord value 3
672 * gets mapped to (returns) @pos value 7 in this example, that means
673 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
675 * The bit positions 0 through @bits are valid positions in @buf.
677 static int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits)
681 if (ord >= 0 && ord < bits) {
684 for (i = find_first_bit(buf, bits);
686 i = find_next_bit(buf, bits, i + 1))
688 if (i < bits && ord == 0)
696 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
697 * @dst: remapped result
698 * @src: subset to be remapped
699 * @old: defines domain of map
700 * @new: defines range of map
701 * @bits: number of bits in each of these bitmaps
703 * Let @old and @new define a mapping of bit positions, such that
704 * whatever position is held by the n-th set bit in @old is mapped
705 * to the n-th set bit in @new. In the more general case, allowing
706 * for the possibility that the weight 'w' of @new is less than the
707 * weight of @old, map the position of the n-th set bit in @old to
708 * the position of the m-th set bit in @new, where m == n % w.
710 * If either of the @old and @new bitmaps are empty, or if @src and
711 * @dst point to the same location, then this routine copies @src
714 * The positions of unset bits in @old are mapped to themselves
715 * (the identify map).
717 * Apply the above specified mapping to @src, placing the result in
718 * @dst, clearing any bits previously set in @dst.
720 * For example, lets say that @old has bits 4 through 7 set, and
721 * @new has bits 12 through 15 set. This defines the mapping of bit
722 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
723 * bit positions unchanged. So if say @src comes into this routine
724 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
727 void bitmap_remap(unsigned long *dst, const unsigned long *src,
728 const unsigned long *old, const unsigned long *new,
733 if (dst == src) /* following doesn't handle inplace remaps */
735 bitmap_zero(dst, bits);
737 w = bitmap_weight(new, bits);
738 for_each_set_bit(oldbit, src, bits) {
739 int n = bitmap_pos_to_ord(old, oldbit, bits);
742 set_bit(oldbit, dst); /* identity map */
744 set_bit(bitmap_ord_to_pos(new, n % w, bits), dst);
747 EXPORT_SYMBOL(bitmap_remap);
750 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
751 * @oldbit: bit position to be mapped
752 * @old: defines domain of map
753 * @new: defines range of map
754 * @bits: number of bits in each of these bitmaps
756 * Let @old and @new define a mapping of bit positions, such that
757 * whatever position is held by the n-th set bit in @old is mapped
758 * to the n-th set bit in @new. In the more general case, allowing
759 * for the possibility that the weight 'w' of @new is less than the
760 * weight of @old, map the position of the n-th set bit in @old to
761 * the position of the m-th set bit in @new, where m == n % w.
763 * The positions of unset bits in @old are mapped to themselves
764 * (the identify map).
766 * Apply the above specified mapping to bit position @oldbit, returning
767 * the new bit position.
769 * For example, lets say that @old has bits 4 through 7 set, and
770 * @new has bits 12 through 15 set. This defines the mapping of bit
771 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
772 * bit positions unchanged. So if say @oldbit is 5, then this routine
775 int bitmap_bitremap(int oldbit, const unsigned long *old,
776 const unsigned long *new, int bits)
778 int w = bitmap_weight(new, bits);
779 int n = bitmap_pos_to_ord(old, oldbit, bits);
783 return bitmap_ord_to_pos(new, n % w, bits);
785 EXPORT_SYMBOL(bitmap_bitremap);
788 * bitmap_onto - translate one bitmap relative to another
789 * @dst: resulting translated bitmap
790 * @orig: original untranslated bitmap
791 * @relmap: bitmap relative to which translated
792 * @bits: number of bits in each of these bitmaps
794 * Set the n-th bit of @dst iff there exists some m such that the
795 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
796 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
797 * (If you understood the previous sentence the first time your
798 * read it, you're overqualified for your current job.)
800 * In other words, @orig is mapped onto (surjectively) @dst,
801 * using the the map { <n, m> | the n-th bit of @relmap is the
802 * m-th set bit of @relmap }.
804 * Any set bits in @orig above bit number W, where W is the
805 * weight of (number of set bits in) @relmap are mapped nowhere.
806 * In particular, if for all bits m set in @orig, m >= W, then
807 * @dst will end up empty. In situations where the possibility
808 * of such an empty result is not desired, one way to avoid it is
809 * to use the bitmap_fold() operator, below, to first fold the
810 * @orig bitmap over itself so that all its set bits x are in the
811 * range 0 <= x < W. The bitmap_fold() operator does this by
812 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
814 * Example [1] for bitmap_onto():
815 * Let's say @relmap has bits 30-39 set, and @orig has bits
816 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,
817 * @dst will have bits 31, 33, 35, 37 and 39 set.
819 * When bit 0 is set in @orig, it means turn on the bit in
820 * @dst corresponding to whatever is the first bit (if any)
821 * that is turned on in @relmap. Since bit 0 was off in the
822 * above example, we leave off that bit (bit 30) in @dst.
824 * When bit 1 is set in @orig (as in the above example), it
825 * means turn on the bit in @dst corresponding to whatever
826 * is the second bit that is turned on in @relmap. The second
827 * bit in @relmap that was turned on in the above example was
828 * bit 31, so we turned on bit 31 in @dst.
830 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
831 * because they were the 4th, 6th, 8th and 10th set bits
832 * set in @relmap, and the 4th, 6th, 8th and 10th bits of
833 * @orig (i.e. bits 3, 5, 7 and 9) were also set.
835 * When bit 11 is set in @orig, it means turn on the bit in
836 * @dst corresponding to whatever is the twelth bit that is
837 * turned on in @relmap. In the above example, there were
838 * only ten bits turned on in @relmap (30..39), so that bit
839 * 11 was set in @orig had no affect on @dst.
841 * Example [2] for bitmap_fold() + bitmap_onto():
842 * Let's say @relmap has these ten bits set:
843 * 40 41 42 43 45 48 53 61 74 95
844 * (for the curious, that's 40 plus the first ten terms of the
845 * Fibonacci sequence.)
847 * Further lets say we use the following code, invoking
848 * bitmap_fold() then bitmap_onto, as suggested above to
849 * avoid the possitility of an empty @dst result:
851 * unsigned long *tmp; // a temporary bitmap's bits
853 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
854 * bitmap_onto(dst, tmp, relmap, bits);
856 * Then this table shows what various values of @dst would be, for
857 * various @orig's. I list the zero-based positions of each set bit.
858 * The tmp column shows the intermediate result, as computed by
859 * using bitmap_fold() to fold the @orig bitmap modulo ten
860 * (the weight of @relmap).
867 * 1 3 5 7 1 3 5 7 41 43 48 61
868 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45
869 * 0 9 18 27 0 9 8 7 40 61 74 95
871 * 0 11 22 33 0 1 2 3 40 41 42 43
872 * 0 12 24 36 0 2 4 6 40 42 45 53
873 * 78 102 211 1 2 8 41 42 74 (*)
875 * (*) For these marked lines, if we hadn't first done bitmap_fold()
876 * into tmp, then the @dst result would have been empty.
878 * If either of @orig or @relmap is empty (no set bits), then @dst
879 * will be returned empty.
881 * If (as explained above) the only set bits in @orig are in positions
882 * m where m >= W, (where W is the weight of @relmap) then @dst will
883 * once again be returned empty.
885 * All bits in @dst not set by the above rule are cleared.
887 void bitmap_onto(unsigned long *dst, const unsigned long *orig,
888 const unsigned long *relmap, int bits)
890 int n, m; /* same meaning as in above comment */
892 if (dst == orig) /* following doesn't handle inplace mappings */
894 bitmap_zero(dst, bits);
897 * The following code is a more efficient, but less
898 * obvious, equivalent to the loop:
899 * for (m = 0; m < bitmap_weight(relmap, bits); m++) {
900 * n = bitmap_ord_to_pos(orig, m, bits);
901 * if (test_bit(m, orig))
907 for_each_set_bit(n, relmap, bits) {
908 /* m == bitmap_pos_to_ord(relmap, n, bits) */
909 if (test_bit(m, orig))
914 EXPORT_SYMBOL(bitmap_onto);
917 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
918 * @dst: resulting smaller bitmap
919 * @orig: original larger bitmap
920 * @sz: specified size
921 * @bits: number of bits in each of these bitmaps
923 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
924 * Clear all other bits in @dst. See further the comment and
925 * Example [2] for bitmap_onto() for why and how to use this.
927 void bitmap_fold(unsigned long *dst, const unsigned long *orig,
932 if (dst == orig) /* following doesn't handle inplace mappings */
934 bitmap_zero(dst, bits);
936 for_each_set_bit(oldbit, orig, bits)
937 set_bit(oldbit % sz, dst);
939 EXPORT_SYMBOL(bitmap_fold);
942 * Common code for bitmap_*_region() routines.
943 * bitmap: array of unsigned longs corresponding to the bitmap
944 * pos: the beginning of the region
945 * order: region size (log base 2 of number of bits)
946 * reg_op: operation(s) to perform on that region of bitmap
948 * Can set, verify and/or release a region of bits in a bitmap,
949 * depending on which combination of REG_OP_* flag bits is set.
951 * A region of a bitmap is a sequence of bits in the bitmap, of
952 * some size '1 << order' (a power of two), aligned to that same
953 * '1 << order' power of two.
955 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
956 * Returns 0 in all other cases and reg_ops.
960 REG_OP_ISFREE, /* true if region is all zero bits */
961 REG_OP_ALLOC, /* set all bits in region */
962 REG_OP_RELEASE, /* clear all bits in region */
965 static int __reg_op(unsigned long *bitmap, int pos, int order, int reg_op)
967 int nbits_reg; /* number of bits in region */
968 int index; /* index first long of region in bitmap */
969 int offset; /* bit offset region in bitmap[index] */
970 int nlongs_reg; /* num longs spanned by region in bitmap */
971 int nbitsinlong; /* num bits of region in each spanned long */
972 unsigned long mask; /* bitmask for one long of region */
973 int i; /* scans bitmap by longs */
974 int ret = 0; /* return value */
977 * Either nlongs_reg == 1 (for small orders that fit in one long)
978 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
980 nbits_reg = 1 << order;
981 index = pos / BITS_PER_LONG;
982 offset = pos - (index * BITS_PER_LONG);
983 nlongs_reg = BITS_TO_LONGS(nbits_reg);
984 nbitsinlong = min(nbits_reg, BITS_PER_LONG);
987 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
988 * overflows if nbitsinlong == BITS_PER_LONG.
990 mask = (1UL << (nbitsinlong - 1));
996 for (i = 0; i < nlongs_reg; i++) {
997 if (bitmap[index + i] & mask)
1000 ret = 1; /* all bits in region free (zero) */
1004 for (i = 0; i < nlongs_reg; i++)
1005 bitmap[index + i] |= mask;
1008 case REG_OP_RELEASE:
1009 for (i = 0; i < nlongs_reg; i++)
1010 bitmap[index + i] &= ~mask;
1018 * bitmap_find_free_region - find a contiguous aligned mem region
1019 * @bitmap: array of unsigned longs corresponding to the bitmap
1020 * @bits: number of bits in the bitmap
1021 * @order: region size (log base 2 of number of bits) to find
1023 * Find a region of free (zero) bits in a @bitmap of @bits bits and
1024 * allocate them (set them to one). Only consider regions of length
1025 * a power (@order) of two, aligned to that power of two, which
1026 * makes the search algorithm much faster.
1028 * Return the bit offset in bitmap of the allocated region,
1029 * or -errno on failure.
1031 int bitmap_find_free_region(unsigned long *bitmap, int bits, int order)
1033 int pos, end; /* scans bitmap by regions of size order */
1035 for (pos = 0 ; (end = pos + (1 << order)) <= bits; pos = end) {
1036 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1038 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1043 EXPORT_SYMBOL(bitmap_find_free_region);
1046 * bitmap_release_region - release allocated bitmap region
1047 * @bitmap: array of unsigned longs corresponding to the bitmap
1048 * @pos: beginning of bit region to release
1049 * @order: region size (log base 2 of number of bits) to release
1051 * This is the complement to __bitmap_find_free_region() and releases
1052 * the found region (by clearing it in the bitmap).
1056 void bitmap_release_region(unsigned long *bitmap, int pos, int order)
1058 __reg_op(bitmap, pos, order, REG_OP_RELEASE);
1060 EXPORT_SYMBOL(bitmap_release_region);
1063 * bitmap_allocate_region - allocate bitmap region
1064 * @bitmap: array of unsigned longs corresponding to the bitmap
1065 * @pos: beginning of bit region to allocate
1066 * @order: region size (log base 2 of number of bits) to allocate
1068 * Allocate (set bits in) a specified region of a bitmap.
1070 * Return 0 on success, or %-EBUSY if specified region wasn't
1071 * free (not all bits were zero).
1073 int bitmap_allocate_region(unsigned long *bitmap, int pos, int order)
1075 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1077 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1080 EXPORT_SYMBOL(bitmap_allocate_region);
1083 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1084 * @dst: destination buffer
1085 * @src: bitmap to copy
1086 * @nbits: number of bits in the bitmap
1088 * Require nbits % BITS_PER_LONG == 0.
1090 void bitmap_copy_le(void *dst, const unsigned long *src, int nbits)
1092 unsigned long *d = dst;
1095 for (i = 0; i < nbits/BITS_PER_LONG; i++) {
1096 if (BITS_PER_LONG == 64)
1097 d[i] = cpu_to_le64(src[i]);
1099 d[i] = cpu_to_le32(src[i]);
1102 EXPORT_SYMBOL(bitmap_copy_le);