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_equal(const unsigned long *bitmap1,
46 const unsigned long *bitmap2, unsigned int bits)
48 unsigned int k, lim = bits/BITS_PER_LONG;
49 for (k = 0; k < lim; ++k)
50 if (bitmap1[k] != bitmap2[k])
53 if (bits % BITS_PER_LONG)
54 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
59 EXPORT_SYMBOL(__bitmap_equal);
61 void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits)
63 unsigned int k, lim = bits/BITS_PER_LONG;
64 for (k = 0; k < lim; ++k)
67 if (bits % BITS_PER_LONG)
70 EXPORT_SYMBOL(__bitmap_complement);
73 * __bitmap_shift_right - logical right shift of the bits in a bitmap
74 * @dst : destination bitmap
75 * @src : source bitmap
76 * @shift : shift by this many bits
77 * @nbits : bitmap size, in bits
79 * Shifting right (dividing) means moving bits in the MS -> LS bit
80 * direction. Zeros are fed into the vacated MS positions and the
81 * LS bits shifted off the bottom are lost.
83 void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
84 unsigned shift, unsigned nbits)
86 unsigned k, lim = BITS_TO_LONGS(nbits);
87 unsigned off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
88 unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);
89 for (k = 0; off + k < lim; ++k) {
90 unsigned long upper, lower;
93 * If shift is not word aligned, take lower rem bits of
94 * word above and make them the top rem bits of result.
96 if (!rem || off + k + 1 >= lim)
99 upper = src[off + k + 1];
100 if (off + k + 1 == lim - 1)
102 upper <<= (BITS_PER_LONG - rem);
104 lower = src[off + k];
105 if (off + k == lim - 1)
108 dst[k] = lower | upper;
111 memset(&dst[lim - off], 0, off*sizeof(unsigned long));
113 EXPORT_SYMBOL(__bitmap_shift_right);
117 * __bitmap_shift_left - logical left shift of the bits in a bitmap
118 * @dst : destination bitmap
119 * @src : source bitmap
120 * @shift : shift by this many bits
121 * @nbits : bitmap size, in bits
123 * Shifting left (multiplying) means moving bits in the LS -> MS
124 * direction. Zeros are fed into the vacated LS bit positions
125 * and those MS bits shifted off the top are lost.
128 void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
129 unsigned int shift, unsigned int nbits)
132 unsigned int lim = BITS_TO_LONGS(nbits);
133 unsigned int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
134 for (k = lim - off - 1; k >= 0; --k) {
135 unsigned long upper, lower;
138 * If shift is not word aligned, take upper rem bits of
139 * word below and make them the bottom rem bits of result.
142 lower = src[k - 1] >> (BITS_PER_LONG - rem);
145 upper = src[k] << rem;
146 dst[k + off] = lower | upper;
149 memset(dst, 0, off*sizeof(unsigned long));
151 EXPORT_SYMBOL(__bitmap_shift_left);
153 int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
154 const unsigned long *bitmap2, unsigned int bits)
157 unsigned int lim = bits/BITS_PER_LONG;
158 unsigned long result = 0;
160 for (k = 0; k < lim; k++)
161 result |= (dst[k] = bitmap1[k] & bitmap2[k]);
162 if (bits % BITS_PER_LONG)
163 result |= (dst[k] = bitmap1[k] & bitmap2[k] &
164 BITMAP_LAST_WORD_MASK(bits));
167 EXPORT_SYMBOL(__bitmap_and);
169 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
170 const unsigned long *bitmap2, unsigned int bits)
173 unsigned int nr = BITS_TO_LONGS(bits);
175 for (k = 0; k < nr; k++)
176 dst[k] = bitmap1[k] | bitmap2[k];
178 EXPORT_SYMBOL(__bitmap_or);
180 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
181 const unsigned long *bitmap2, unsigned int bits)
184 unsigned int nr = BITS_TO_LONGS(bits);
186 for (k = 0; k < nr; k++)
187 dst[k] = bitmap1[k] ^ bitmap2[k];
189 EXPORT_SYMBOL(__bitmap_xor);
191 int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
192 const unsigned long *bitmap2, unsigned int bits)
195 unsigned int lim = bits/BITS_PER_LONG;
196 unsigned long result = 0;
198 for (k = 0; k < lim; k++)
199 result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
200 if (bits % BITS_PER_LONG)
201 result |= (dst[k] = bitmap1[k] & ~bitmap2[k] &
202 BITMAP_LAST_WORD_MASK(bits));
205 EXPORT_SYMBOL(__bitmap_andnot);
207 int __bitmap_intersects(const unsigned long *bitmap1,
208 const unsigned long *bitmap2, unsigned int bits)
210 unsigned int k, lim = bits/BITS_PER_LONG;
211 for (k = 0; k < lim; ++k)
212 if (bitmap1[k] & bitmap2[k])
215 if (bits % BITS_PER_LONG)
216 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
220 EXPORT_SYMBOL(__bitmap_intersects);
222 int __bitmap_subset(const unsigned long *bitmap1,
223 const unsigned long *bitmap2, unsigned int bits)
225 unsigned int k, lim = bits/BITS_PER_LONG;
226 for (k = 0; k < lim; ++k)
227 if (bitmap1[k] & ~bitmap2[k])
230 if (bits % BITS_PER_LONG)
231 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
235 EXPORT_SYMBOL(__bitmap_subset);
237 int __bitmap_weight(const unsigned long *bitmap, unsigned int bits)
239 unsigned int k, lim = bits/BITS_PER_LONG;
242 for (k = 0; k < lim; k++)
243 w += hweight_long(bitmap[k]);
245 if (bits % BITS_PER_LONG)
246 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
250 EXPORT_SYMBOL(__bitmap_weight);
252 void bitmap_set(unsigned long *map, unsigned int start, int len)
254 unsigned long *p = map + BIT_WORD(start);
255 const unsigned int size = start + len;
256 int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
257 unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
259 while (len - bits_to_set >= 0) {
262 bits_to_set = BITS_PER_LONG;
267 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
271 EXPORT_SYMBOL(bitmap_set);
273 void bitmap_clear(unsigned long *map, unsigned int start, int len)
275 unsigned long *p = map + BIT_WORD(start);
276 const unsigned int size = start + len;
277 int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
278 unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
280 while (len - bits_to_clear >= 0) {
281 *p &= ~mask_to_clear;
282 len -= bits_to_clear;
283 bits_to_clear = BITS_PER_LONG;
284 mask_to_clear = ~0UL;
288 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
289 *p &= ~mask_to_clear;
292 EXPORT_SYMBOL(bitmap_clear);
295 * bitmap_find_next_zero_area_off - find a contiguous aligned zero area
296 * @map: The address to base the search on
297 * @size: The bitmap size in bits
298 * @start: The bitnumber to start searching at
299 * @nr: The number of zeroed bits we're looking for
300 * @align_mask: Alignment mask for zero area
301 * @align_offset: Alignment offset for zero area.
303 * The @align_mask should be one less than a power of 2; the effect is that
304 * the bit offset of all zero areas this function finds plus @align_offset
305 * is multiple of that power of 2.
307 unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
311 unsigned long align_mask,
312 unsigned long align_offset)
314 unsigned long index, end, i;
316 index = find_next_zero_bit(map, size, start);
318 /* Align allocation */
319 index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset;
324 i = find_next_bit(map, end, index);
331 EXPORT_SYMBOL(bitmap_find_next_zero_area_off);
334 * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,
335 * second version by Paul Jackson, third by Joe Korty.
339 #define nbits_to_hold_value(val) fls(val)
340 #define BASEDEC 10 /* fancier cpuset lists input in decimal */
343 * __bitmap_parse - convert an ASCII hex string into a bitmap.
344 * @buf: pointer to buffer containing string.
345 * @buflen: buffer size in bytes. If string is smaller than this
346 * then it must be terminated with a \0.
347 * @is_user: location of buffer, 0 indicates kernel space
348 * @maskp: pointer to bitmap array that will contain result.
349 * @nmaskbits: size of bitmap, in bits.
351 * Commas group hex digits into chunks. Each chunk defines exactly 32
352 * bits of the resultant bitmask. No chunk may specify a value larger
353 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
354 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
355 * characters and for grouping errors such as "1,,5", ",44", "," and "".
356 * Leading and trailing whitespace accepted, but not embedded whitespace.
358 int __bitmap_parse(const char *buf, unsigned int buflen,
359 int is_user, unsigned long *maskp,
362 int c, old_c, totaldigits, ndigits, nchunks, nbits;
364 const char __user __force *ubuf = (const char __user __force *)buf;
366 bitmap_zero(maskp, nmaskbits);
368 nchunks = nbits = totaldigits = c = 0;
371 ndigits = totaldigits;
373 /* Get the next chunk of the bitmap */
377 if (__get_user(c, ubuf++))
387 * If the last character was a space and the current
388 * character isn't '\0', we've got embedded whitespace.
389 * This is a no-no, so throw an error.
391 if (totaldigits && c && isspace(old_c))
394 /* A '\0' or a ',' signal the end of the chunk */
395 if (c == '\0' || c == ',')
402 * Make sure there are at least 4 free bits in 'chunk'.
403 * If not, this hexdigit will overflow 'chunk', so
406 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
409 chunk = (chunk << 4) | hex_to_bin(c);
412 if (ndigits == totaldigits)
414 if (nchunks == 0 && chunk == 0)
417 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
420 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
421 if (nbits > nmaskbits)
423 } while (buflen && c == ',');
427 EXPORT_SYMBOL(__bitmap_parse);
430 * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
432 * @ubuf: pointer to user buffer containing string.
433 * @ulen: buffer size in bytes. If string is smaller than this
434 * then it must be terminated with a \0.
435 * @maskp: pointer to bitmap array that will contain result.
436 * @nmaskbits: size of bitmap, in bits.
438 * Wrapper for __bitmap_parse(), providing it with user buffer.
440 * We cannot have this as an inline function in bitmap.h because it needs
441 * linux/uaccess.h to get the access_ok() declaration and this causes
442 * cyclic dependencies.
444 int bitmap_parse_user(const char __user *ubuf,
445 unsigned int ulen, unsigned long *maskp,
448 if (!access_ok(VERIFY_READ, ubuf, ulen))
450 return __bitmap_parse((const char __force *)ubuf,
451 ulen, 1, maskp, nmaskbits);
454 EXPORT_SYMBOL(bitmap_parse_user);
457 * bitmap_print_to_pagebuf - convert bitmap to list or hex format ASCII string
458 * @list: indicates whether the bitmap must be list
459 * @buf: page aligned buffer into which string is placed
460 * @maskp: pointer to bitmap to convert
461 * @nmaskbits: size of bitmap, in bits
463 * Output format is a comma-separated list of decimal numbers and
464 * ranges if list is specified or hex digits grouped into comma-separated
465 * sets of 8 digits/set. Returns the number of characters written to buf.
467 * It is assumed that @buf is a pointer into a PAGE_SIZE area and that
468 * sufficient storage remains at @buf to accommodate the
469 * bitmap_print_to_pagebuf() output.
471 int bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp,
474 ptrdiff_t len = PTR_ALIGN(buf + PAGE_SIZE - 1, PAGE_SIZE) - buf;
478 n = list ? scnprintf(buf, len, "%*pbl\n", nmaskbits, maskp) :
479 scnprintf(buf, len, "%*pb\n", nmaskbits, maskp);
482 EXPORT_SYMBOL(bitmap_print_to_pagebuf);
485 * __bitmap_parselist - convert list format ASCII string to bitmap
486 * @buf: read nul-terminated user string from this buffer
487 * @buflen: buffer size in bytes. If string is smaller than this
488 * then it must be terminated with a \0.
489 * @is_user: location of buffer, 0 indicates kernel space
490 * @maskp: write resulting mask here
491 * @nmaskbits: number of bits in mask to be written
493 * Input format is a comma-separated list of decimal numbers and
494 * ranges. Consecutively set bits are shown as two hyphen-separated
495 * decimal numbers, the smallest and largest bit numbers set in
498 * Returns 0 on success, -errno on invalid input strings.
500 * %-EINVAL: second number in range smaller than first
501 * %-EINVAL: invalid character in string
502 * %-ERANGE: bit number specified too large for mask
504 static int __bitmap_parselist(const char *buf, unsigned int buflen,
505 int is_user, unsigned long *maskp,
509 int c, old_c, totaldigits;
510 const char __user __force *ubuf = (const char __user __force *)buf;
511 int at_start, in_range;
514 bitmap_zero(maskp, nmaskbits);
520 /* Get the next cpu# or a range of cpu#'s */
524 if (__get_user(c, ubuf++))
533 * If the last character was a space and the current
534 * character isn't '\0', we've got embedded whitespace.
535 * This is a no-no, so throw an error.
537 if (totaldigits && c && isspace(old_c))
540 /* A '\0' or a ',' signal the end of a cpu# or range */
541 if (c == '\0' || c == ',')
545 if (at_start || in_range)
555 b = b * 10 + (c - '0');
571 } while (buflen && c == ',');
575 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
577 char *nl = strchrnul(bp, '\n');
580 return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
582 EXPORT_SYMBOL(bitmap_parselist);
586 * bitmap_parselist_user()
588 * @ubuf: pointer to user buffer containing string.
589 * @ulen: buffer size in bytes. If string is smaller than this
590 * then it must be terminated with a \0.
591 * @maskp: pointer to bitmap array that will contain result.
592 * @nmaskbits: size of bitmap, in bits.
594 * Wrapper for bitmap_parselist(), providing it with user buffer.
596 * We cannot have this as an inline function in bitmap.h because it needs
597 * linux/uaccess.h to get the access_ok() declaration and this causes
598 * cyclic dependencies.
600 int bitmap_parselist_user(const char __user *ubuf,
601 unsigned int ulen, unsigned long *maskp,
604 if (!access_ok(VERIFY_READ, ubuf, ulen))
606 return __bitmap_parselist((const char __force *)ubuf,
607 ulen, 1, maskp, nmaskbits);
609 EXPORT_SYMBOL(bitmap_parselist_user);
613 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
614 * @buf: pointer to a bitmap
615 * @pos: a bit position in @buf (0 <= @pos < @nbits)
616 * @nbits: number of valid bit positions in @buf
618 * Map the bit at position @pos in @buf (of length @nbits) to the
619 * ordinal of which set bit it is. If it is not set or if @pos
620 * is not a valid bit position, map to -1.
622 * If for example, just bits 4 through 7 are set in @buf, then @pos
623 * values 4 through 7 will get mapped to 0 through 3, respectively,
624 * and other @pos values will get mapped to -1. When @pos value 7
625 * gets mapped to (returns) @ord value 3 in this example, that means
626 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
628 * The bit positions 0 through @bits are valid positions in @buf.
630 static int bitmap_pos_to_ord(const unsigned long *buf, unsigned int pos, unsigned int nbits)
632 if (pos >= nbits || !test_bit(pos, buf))
635 return __bitmap_weight(buf, pos);
639 * bitmap_ord_to_pos - find position of n-th set bit in bitmap
640 * @buf: pointer to bitmap
641 * @ord: ordinal bit position (n-th set bit, n >= 0)
642 * @nbits: number of valid bit positions in @buf
644 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
645 * Value of @ord should be in range 0 <= @ord < weight(buf). If @ord
646 * >= weight(buf), returns @nbits.
648 * If for example, just bits 4 through 7 are set in @buf, then @ord
649 * values 0 through 3 will get mapped to 4 through 7, respectively,
650 * and all other @ord values returns @nbits. When @ord value 3
651 * gets mapped to (returns) @pos value 7 in this example, that means
652 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
654 * The bit positions 0 through @nbits-1 are valid positions in @buf.
656 unsigned int bitmap_ord_to_pos(const unsigned long *buf, unsigned int ord, unsigned int nbits)
660 for (pos = find_first_bit(buf, nbits);
662 pos = find_next_bit(buf, nbits, pos + 1))
669 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
670 * @dst: remapped result
671 * @src: subset to be remapped
672 * @old: defines domain of map
673 * @new: defines range of map
674 * @nbits: number of bits in each of these bitmaps
676 * Let @old and @new define a mapping of bit positions, such that
677 * whatever position is held by the n-th set bit in @old is mapped
678 * to the n-th set bit in @new. In the more general case, allowing
679 * for the possibility that the weight 'w' of @new is less than the
680 * weight of @old, map the position of the n-th set bit in @old to
681 * the position of the m-th set bit in @new, where m == n % w.
683 * If either of the @old and @new bitmaps are empty, or if @src and
684 * @dst point to the same location, then this routine copies @src
687 * The positions of unset bits in @old are mapped to themselves
688 * (the identify map).
690 * Apply the above specified mapping to @src, placing the result in
691 * @dst, clearing any bits previously set in @dst.
693 * For example, lets say that @old has bits 4 through 7 set, and
694 * @new has bits 12 through 15 set. This defines the mapping of bit
695 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
696 * bit positions unchanged. So if say @src comes into this routine
697 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
700 void bitmap_remap(unsigned long *dst, const unsigned long *src,
701 const unsigned long *old, const unsigned long *new,
704 unsigned int oldbit, w;
706 if (dst == src) /* following doesn't handle inplace remaps */
708 bitmap_zero(dst, nbits);
710 w = bitmap_weight(new, nbits);
711 for_each_set_bit(oldbit, src, nbits) {
712 int n = bitmap_pos_to_ord(old, oldbit, nbits);
715 set_bit(oldbit, dst); /* identity map */
717 set_bit(bitmap_ord_to_pos(new, n % w, nbits), dst);
720 EXPORT_SYMBOL(bitmap_remap);
723 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
724 * @oldbit: bit position to be mapped
725 * @old: defines domain of map
726 * @new: defines range of map
727 * @bits: number of bits in each of these bitmaps
729 * Let @old and @new define a mapping of bit positions, such that
730 * whatever position is held by the n-th set bit in @old is mapped
731 * to the n-th set bit in @new. In the more general case, allowing
732 * for the possibility that the weight 'w' of @new is less than the
733 * weight of @old, map the position of the n-th set bit in @old to
734 * the position of the m-th set bit in @new, where m == n % w.
736 * The positions of unset bits in @old are mapped to themselves
737 * (the identify map).
739 * Apply the above specified mapping to bit position @oldbit, returning
740 * the new bit position.
742 * For example, lets say that @old has bits 4 through 7 set, and
743 * @new has bits 12 through 15 set. This defines the mapping of bit
744 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
745 * bit positions unchanged. So if say @oldbit is 5, then this routine
748 int bitmap_bitremap(int oldbit, const unsigned long *old,
749 const unsigned long *new, int bits)
751 int w = bitmap_weight(new, bits);
752 int n = bitmap_pos_to_ord(old, oldbit, bits);
756 return bitmap_ord_to_pos(new, n % w, bits);
758 EXPORT_SYMBOL(bitmap_bitremap);
761 * bitmap_onto - translate one bitmap relative to another
762 * @dst: resulting translated bitmap
763 * @orig: original untranslated bitmap
764 * @relmap: bitmap relative to which translated
765 * @bits: number of bits in each of these bitmaps
767 * Set the n-th bit of @dst iff there exists some m such that the
768 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
769 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
770 * (If you understood the previous sentence the first time your
771 * read it, you're overqualified for your current job.)
773 * In other words, @orig is mapped onto (surjectively) @dst,
774 * using the map { <n, m> | the n-th bit of @relmap is the
775 * m-th set bit of @relmap }.
777 * Any set bits in @orig above bit number W, where W is the
778 * weight of (number of set bits in) @relmap are mapped nowhere.
779 * In particular, if for all bits m set in @orig, m >= W, then
780 * @dst will end up empty. In situations where the possibility
781 * of such an empty result is not desired, one way to avoid it is
782 * to use the bitmap_fold() operator, below, to first fold the
783 * @orig bitmap over itself so that all its set bits x are in the
784 * range 0 <= x < W. The bitmap_fold() operator does this by
785 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
787 * Example [1] for bitmap_onto():
788 * Let's say @relmap has bits 30-39 set, and @orig has bits
789 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,
790 * @dst will have bits 31, 33, 35, 37 and 39 set.
792 * When bit 0 is set in @orig, it means turn on the bit in
793 * @dst corresponding to whatever is the first bit (if any)
794 * that is turned on in @relmap. Since bit 0 was off in the
795 * above example, we leave off that bit (bit 30) in @dst.
797 * When bit 1 is set in @orig (as in the above example), it
798 * means turn on the bit in @dst corresponding to whatever
799 * is the second bit that is turned on in @relmap. The second
800 * bit in @relmap that was turned on in the above example was
801 * bit 31, so we turned on bit 31 in @dst.
803 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
804 * because they were the 4th, 6th, 8th and 10th set bits
805 * set in @relmap, and the 4th, 6th, 8th and 10th bits of
806 * @orig (i.e. bits 3, 5, 7 and 9) were also set.
808 * When bit 11 is set in @orig, it means turn on the bit in
809 * @dst corresponding to whatever is the twelfth bit that is
810 * turned on in @relmap. In the above example, there were
811 * only ten bits turned on in @relmap (30..39), so that bit
812 * 11 was set in @orig had no affect on @dst.
814 * Example [2] for bitmap_fold() + bitmap_onto():
815 * Let's say @relmap has these ten bits set:
816 * 40 41 42 43 45 48 53 61 74 95
817 * (for the curious, that's 40 plus the first ten terms of the
818 * Fibonacci sequence.)
820 * Further lets say we use the following code, invoking
821 * bitmap_fold() then bitmap_onto, as suggested above to
822 * avoid the possibility of an empty @dst result:
824 * unsigned long *tmp; // a temporary bitmap's bits
826 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
827 * bitmap_onto(dst, tmp, relmap, bits);
829 * Then this table shows what various values of @dst would be, for
830 * various @orig's. I list the zero-based positions of each set bit.
831 * The tmp column shows the intermediate result, as computed by
832 * using bitmap_fold() to fold the @orig bitmap modulo ten
833 * (the weight of @relmap).
840 * 1 3 5 7 1 3 5 7 41 43 48 61
841 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45
842 * 0 9 18 27 0 9 8 7 40 61 74 95
844 * 0 11 22 33 0 1 2 3 40 41 42 43
845 * 0 12 24 36 0 2 4 6 40 42 45 53
846 * 78 102 211 1 2 8 41 42 74 (*)
848 * (*) For these marked lines, if we hadn't first done bitmap_fold()
849 * into tmp, then the @dst result would have been empty.
851 * If either of @orig or @relmap is empty (no set bits), then @dst
852 * will be returned empty.
854 * If (as explained above) the only set bits in @orig are in positions
855 * m where m >= W, (where W is the weight of @relmap) then @dst will
856 * once again be returned empty.
858 * All bits in @dst not set by the above rule are cleared.
860 void bitmap_onto(unsigned long *dst, const unsigned long *orig,
861 const unsigned long *relmap, unsigned int bits)
863 unsigned int n, m; /* same meaning as in above comment */
865 if (dst == orig) /* following doesn't handle inplace mappings */
867 bitmap_zero(dst, bits);
870 * The following code is a more efficient, but less
871 * obvious, equivalent to the loop:
872 * for (m = 0; m < bitmap_weight(relmap, bits); m++) {
873 * n = bitmap_ord_to_pos(orig, m, bits);
874 * if (test_bit(m, orig))
880 for_each_set_bit(n, relmap, bits) {
881 /* m == bitmap_pos_to_ord(relmap, n, bits) */
882 if (test_bit(m, orig))
887 EXPORT_SYMBOL(bitmap_onto);
890 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
891 * @dst: resulting smaller bitmap
892 * @orig: original larger bitmap
893 * @sz: specified size
894 * @nbits: number of bits in each of these bitmaps
896 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
897 * Clear all other bits in @dst. See further the comment and
898 * Example [2] for bitmap_onto() for why and how to use this.
900 void bitmap_fold(unsigned long *dst, const unsigned long *orig,
901 unsigned int sz, unsigned int nbits)
905 if (dst == orig) /* following doesn't handle inplace mappings */
907 bitmap_zero(dst, nbits);
909 for_each_set_bit(oldbit, orig, nbits)
910 set_bit(oldbit % sz, dst);
912 EXPORT_SYMBOL(bitmap_fold);
915 * Common code for bitmap_*_region() routines.
916 * bitmap: array of unsigned longs corresponding to the bitmap
917 * pos: the beginning of the region
918 * order: region size (log base 2 of number of bits)
919 * reg_op: operation(s) to perform on that region of bitmap
921 * Can set, verify and/or release a region of bits in a bitmap,
922 * depending on which combination of REG_OP_* flag bits is set.
924 * A region of a bitmap is a sequence of bits in the bitmap, of
925 * some size '1 << order' (a power of two), aligned to that same
926 * '1 << order' power of two.
928 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
929 * Returns 0 in all other cases and reg_ops.
933 REG_OP_ISFREE, /* true if region is all zero bits */
934 REG_OP_ALLOC, /* set all bits in region */
935 REG_OP_RELEASE, /* clear all bits in region */
938 static int __reg_op(unsigned long *bitmap, unsigned int pos, int order, int reg_op)
940 int nbits_reg; /* number of bits in region */
941 int index; /* index first long of region in bitmap */
942 int offset; /* bit offset region in bitmap[index] */
943 int nlongs_reg; /* num longs spanned by region in bitmap */
944 int nbitsinlong; /* num bits of region in each spanned long */
945 unsigned long mask; /* bitmask for one long of region */
946 int i; /* scans bitmap by longs */
947 int ret = 0; /* return value */
950 * Either nlongs_reg == 1 (for small orders that fit in one long)
951 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
953 nbits_reg = 1 << order;
954 index = pos / BITS_PER_LONG;
955 offset = pos - (index * BITS_PER_LONG);
956 nlongs_reg = BITS_TO_LONGS(nbits_reg);
957 nbitsinlong = min(nbits_reg, BITS_PER_LONG);
960 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
961 * overflows if nbitsinlong == BITS_PER_LONG.
963 mask = (1UL << (nbitsinlong - 1));
969 for (i = 0; i < nlongs_reg; i++) {
970 if (bitmap[index + i] & mask)
973 ret = 1; /* all bits in region free (zero) */
977 for (i = 0; i < nlongs_reg; i++)
978 bitmap[index + i] |= mask;
982 for (i = 0; i < nlongs_reg; i++)
983 bitmap[index + i] &= ~mask;
991 * bitmap_find_free_region - find a contiguous aligned mem region
992 * @bitmap: array of unsigned longs corresponding to the bitmap
993 * @bits: number of bits in the bitmap
994 * @order: region size (log base 2 of number of bits) to find
996 * Find a region of free (zero) bits in a @bitmap of @bits bits and
997 * allocate them (set them to one). Only consider regions of length
998 * a power (@order) of two, aligned to that power of two, which
999 * makes the search algorithm much faster.
1001 * Return the bit offset in bitmap of the allocated region,
1002 * or -errno on failure.
1004 int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order)
1006 unsigned int pos, end; /* scans bitmap by regions of size order */
1008 for (pos = 0 ; (end = pos + (1U << order)) <= bits; pos = end) {
1009 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1011 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1016 EXPORT_SYMBOL(bitmap_find_free_region);
1019 * bitmap_release_region - release allocated bitmap region
1020 * @bitmap: array of unsigned longs corresponding to the bitmap
1021 * @pos: beginning of bit region to release
1022 * @order: region size (log base 2 of number of bits) to release
1024 * This is the complement to __bitmap_find_free_region() and releases
1025 * the found region (by clearing it in the bitmap).
1029 void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order)
1031 __reg_op(bitmap, pos, order, REG_OP_RELEASE);
1033 EXPORT_SYMBOL(bitmap_release_region);
1036 * bitmap_allocate_region - allocate bitmap region
1037 * @bitmap: array of unsigned longs corresponding to the bitmap
1038 * @pos: beginning of bit region to allocate
1039 * @order: region size (log base 2 of number of bits) to allocate
1041 * Allocate (set bits in) a specified region of a bitmap.
1043 * Return 0 on success, or %-EBUSY if specified region wasn't
1044 * free (not all bits were zero).
1046 int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order)
1048 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1050 return __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1052 EXPORT_SYMBOL(bitmap_allocate_region);
1055 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1056 * @dst: destination buffer
1057 * @src: bitmap to copy
1058 * @nbits: number of bits in the bitmap
1060 * Require nbits % BITS_PER_LONG == 0.
1063 void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits)
1067 for (i = 0; i < nbits/BITS_PER_LONG; i++) {
1068 if (BITS_PER_LONG == 64)
1069 dst[i] = cpu_to_le64(src[i]);
1071 dst[i] = cpu_to_le32(src[i]);
1074 EXPORT_SYMBOL(bitmap_copy_le);