3 * Helper functions for bitmap.h.
5 * This source code is licensed under the GNU General Public License,
6 * Version 2. See the file COPYING for more details.
8 #include <linux/export.h>
9 #include <linux/thread_info.h>
10 #include <linux/ctype.h>
11 #include <linux/errno.h>
12 #include <linux/bitmap.h>
13 #include <linux/bitops.h>
14 #include <linux/bug.h>
15 #include <asm/uaccess.h>
18 * bitmaps provide an array of bits, implemented using an an
19 * array of unsigned longs. The number of valid bits in a
20 * given bitmap does _not_ need to be an exact multiple of
23 * The possible unused bits in the last, partially used word
24 * of a bitmap are 'don't care'. The implementation makes
25 * no particular effort to keep them zero. It ensures that
26 * their value will not affect the results of any operation.
27 * The bitmap operations that return Boolean (bitmap_empty,
28 * for example) or scalar (bitmap_weight, for example) results
29 * carefully filter out these unused bits from impacting their
32 * These operations actually hold to a slightly stronger rule:
33 * if you don't input any bitmaps to these ops that have some
34 * unused bits set, then they won't output any set unused bits
37 * The byte ordering of bitmaps is more natural on little
38 * endian architectures. See the big-endian headers
39 * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
40 * for the best explanations of this ordering.
43 int __bitmap_empty(const unsigned long *bitmap, int bits)
45 int k, lim = bits/BITS_PER_LONG;
46 for (k = 0; k < lim; ++k)
50 if (bits % BITS_PER_LONG)
51 if (bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
56 EXPORT_SYMBOL(__bitmap_empty);
58 int __bitmap_full(const unsigned long *bitmap, int bits)
60 int k, lim = bits/BITS_PER_LONG;
61 for (k = 0; k < lim; ++k)
65 if (bits % BITS_PER_LONG)
66 if (~bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
71 EXPORT_SYMBOL(__bitmap_full);
73 int __bitmap_equal(const unsigned long *bitmap1,
74 const unsigned long *bitmap2, int bits)
76 int k, lim = bits/BITS_PER_LONG;
77 for (k = 0; k < lim; ++k)
78 if (bitmap1[k] != bitmap2[k])
81 if (bits % BITS_PER_LONG)
82 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
87 EXPORT_SYMBOL(__bitmap_equal);
89 void __bitmap_complement(unsigned long *dst, const unsigned long *src, int bits)
91 int k, lim = bits/BITS_PER_LONG;
92 for (k = 0; k < lim; ++k)
95 if (bits % BITS_PER_LONG)
96 dst[k] = ~src[k] & BITMAP_LAST_WORD_MASK(bits);
98 EXPORT_SYMBOL(__bitmap_complement);
101 * __bitmap_shift_right - logical right shift of the bits in a bitmap
102 * @dst : destination bitmap
103 * @src : source bitmap
104 * @shift : shift by this many bits
105 * @bits : bitmap size, in bits
107 * Shifting right (dividing) means moving bits in the MS -> LS bit
108 * direction. Zeros are fed into the vacated MS positions and the
109 * LS bits shifted off the bottom are lost.
111 void __bitmap_shift_right(unsigned long *dst,
112 const unsigned long *src, int shift, int bits)
114 int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;
115 int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
116 unsigned long mask = (1UL << left) - 1;
117 for (k = 0; off + k < lim; ++k) {
118 unsigned long upper, lower;
121 * If shift is not word aligned, take lower rem bits of
122 * word above and make them the top rem bits of result.
124 if (!rem || off + k + 1 >= lim)
127 upper = src[off + k + 1];
128 if (off + k + 1 == lim - 1 && left)
131 lower = src[off + k];
132 if (left && off + k == lim - 1)
134 dst[k] = lower >> rem;
136 dst[k] |= upper << (BITS_PER_LONG - rem);
137 if (left && k == lim - 1)
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 * @bits : 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,
159 const unsigned long *src, int shift, int bits)
161 int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;
162 int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
163 for (k = lim - off - 1; k >= 0; --k) {
164 unsigned long upper, lower;
167 * If shift is not word aligned, take upper rem bits of
168 * word below and make them the bottom rem bits of result.
175 if (left && k == lim - 1)
176 upper &= (1UL << left) - 1;
177 dst[k + off] = upper << rem;
179 dst[k + off] |= lower >> (BITS_PER_LONG - rem);
180 if (left && k + off == lim - 1)
181 dst[k + off] &= (1UL << left) - 1;
184 memset(dst, 0, off*sizeof(unsigned long));
186 EXPORT_SYMBOL(__bitmap_shift_left);
188 int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
189 const unsigned long *bitmap2, int bits)
192 int nr = BITS_TO_LONGS(bits);
193 unsigned long result = 0;
195 for (k = 0; k < nr; k++)
196 result |= (dst[k] = bitmap1[k] & bitmap2[k]);
199 EXPORT_SYMBOL(__bitmap_and);
201 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
202 const unsigned long *bitmap2, int bits)
205 int nr = BITS_TO_LONGS(bits);
207 for (k = 0; k < nr; k++)
208 dst[k] = bitmap1[k] | bitmap2[k];
210 EXPORT_SYMBOL(__bitmap_or);
212 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
213 const unsigned long *bitmap2, int bits)
216 int nr = BITS_TO_LONGS(bits);
218 for (k = 0; k < nr; k++)
219 dst[k] = bitmap1[k] ^ bitmap2[k];
221 EXPORT_SYMBOL(__bitmap_xor);
223 int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
224 const unsigned long *bitmap2, int bits)
227 int nr = BITS_TO_LONGS(bits);
228 unsigned long result = 0;
230 for (k = 0; k < nr; k++)
231 result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
234 EXPORT_SYMBOL(__bitmap_andnot);
236 int __bitmap_intersects(const unsigned long *bitmap1,
237 const unsigned long *bitmap2, int bits)
239 int k, lim = bits/BITS_PER_LONG;
240 for (k = 0; k < lim; ++k)
241 if (bitmap1[k] & bitmap2[k])
244 if (bits % BITS_PER_LONG)
245 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
249 EXPORT_SYMBOL(__bitmap_intersects);
251 int __bitmap_subset(const unsigned long *bitmap1,
252 const unsigned long *bitmap2, int bits)
254 int k, lim = bits/BITS_PER_LONG;
255 for (k = 0; k < lim; ++k)
256 if (bitmap1[k] & ~bitmap2[k])
259 if (bits % BITS_PER_LONG)
260 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
264 EXPORT_SYMBOL(__bitmap_subset);
266 int __bitmap_weight(const unsigned long *bitmap, int bits)
268 int k, w = 0, lim = bits/BITS_PER_LONG;
270 for (k = 0; k < lim; k++)
271 w += hweight_long(bitmap[k]);
273 if (bits % BITS_PER_LONG)
274 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
278 EXPORT_SYMBOL(__bitmap_weight);
280 void bitmap_set(unsigned long *map, int start, int nr)
282 unsigned long *p = map + BIT_WORD(start);
283 const int size = start + nr;
284 int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
285 unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
287 while (nr - bits_to_set >= 0) {
290 bits_to_set = BITS_PER_LONG;
295 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
299 EXPORT_SYMBOL(bitmap_set);
301 void bitmap_clear(unsigned long *map, int start, int nr)
303 unsigned long *p = map + BIT_WORD(start);
304 const int size = start + nr;
305 int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
306 unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
308 while (nr - bits_to_clear >= 0) {
309 *p &= ~mask_to_clear;
311 bits_to_clear = BITS_PER_LONG;
312 mask_to_clear = ~0UL;
316 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
317 *p &= ~mask_to_clear;
320 EXPORT_SYMBOL(bitmap_clear);
323 * bitmap_find_next_zero_area - find a contiguous aligned zero area
324 * @map: The address to base the search on
325 * @size: The bitmap size in bits
326 * @start: The bitnumber to start searching at
327 * @nr: The number of zeroed bits we're looking for
328 * @align_mask: Alignment mask for zero area
330 * The @align_mask should be one less than a power of 2; the effect is that
331 * the bit offset of all zero areas this function finds is multiples of that
332 * power of 2. A @align_mask of 0 means no alignment is required.
334 unsigned long bitmap_find_next_zero_area(unsigned long *map,
338 unsigned long align_mask)
340 unsigned long index, end, i;
342 index = find_next_zero_bit(map, size, start);
344 /* Align allocation */
345 index = __ALIGN_MASK(index, align_mask);
350 i = find_next_bit(map, end, index);
357 EXPORT_SYMBOL(bitmap_find_next_zero_area);
360 * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,
361 * second version by Paul Jackson, third by Joe Korty.
365 #define nbits_to_hold_value(val) fls(val)
366 #define BASEDEC 10 /* fancier cpuset lists input in decimal */
369 * bitmap_scnprintf - convert bitmap to an ASCII hex string.
370 * @buf: byte buffer into which string is placed
371 * @buflen: reserved size of @buf, in bytes
372 * @maskp: pointer to bitmap to convert
373 * @nmaskbits: size of bitmap, in bits
375 * Exactly @nmaskbits bits are displayed. Hex digits are grouped into
376 * comma-separated sets of eight digits per set. Returns the number of
377 * characters which were written to *buf, excluding the trailing \0.
379 int bitmap_scnprintf(char *buf, unsigned int buflen,
380 const unsigned long *maskp, int nmaskbits)
382 int i, word, bit, len = 0;
384 const char *sep = "";
388 chunksz = nmaskbits & (CHUNKSZ - 1);
392 i = ALIGN(nmaskbits, CHUNKSZ) - CHUNKSZ;
393 for (; i >= 0; i -= CHUNKSZ) {
394 chunkmask = ((1ULL << chunksz) - 1);
395 word = i / BITS_PER_LONG;
396 bit = i % BITS_PER_LONG;
397 val = (maskp[word] >> bit) & chunkmask;
398 len += scnprintf(buf+len, buflen-len, "%s%0*lx", sep,
405 EXPORT_SYMBOL(bitmap_scnprintf);
408 * __bitmap_parse - convert an ASCII hex string into a bitmap.
409 * @buf: pointer to buffer containing string.
410 * @buflen: buffer size in bytes. If string is smaller than this
411 * then it must be terminated with a \0.
412 * @is_user: location of buffer, 0 indicates kernel space
413 * @maskp: pointer to bitmap array that will contain result.
414 * @nmaskbits: size of bitmap, in bits.
416 * Commas group hex digits into chunks. Each chunk defines exactly 32
417 * bits of the resultant bitmask. No chunk may specify a value larger
418 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
419 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
420 * characters and for grouping errors such as "1,,5", ",44", "," and "".
421 * Leading and trailing whitespace accepted, but not embedded whitespace.
423 int __bitmap_parse(const char *buf, unsigned int buflen,
424 int is_user, unsigned long *maskp,
427 int c, old_c, totaldigits, ndigits, nchunks, nbits;
429 const char __user __force *ubuf = (const char __user __force *)buf;
431 bitmap_zero(maskp, nmaskbits);
433 nchunks = nbits = totaldigits = c = 0;
437 /* Get the next chunk of the bitmap */
441 if (__get_user(c, ubuf++))
451 * If the last character was a space and the current
452 * character isn't '\0', we've got embedded whitespace.
453 * This is a no-no, so throw an error.
455 if (totaldigits && c && isspace(old_c))
458 /* A '\0' or a ',' signal the end of the chunk */
459 if (c == '\0' || c == ',')
466 * Make sure there are at least 4 free bits in 'chunk'.
467 * If not, this hexdigit will overflow 'chunk', so
470 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
473 chunk = (chunk << 4) | hex_to_bin(c);
474 ndigits++; totaldigits++;
478 if (nchunks == 0 && chunk == 0)
481 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
484 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
485 if (nbits > nmaskbits)
487 } while (buflen && c == ',');
491 EXPORT_SYMBOL(__bitmap_parse);
494 * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
496 * @ubuf: pointer to user buffer containing string.
497 * @ulen: buffer size in bytes. If string is smaller than this
498 * then it must be terminated with a \0.
499 * @maskp: pointer to bitmap array that will contain result.
500 * @nmaskbits: size of bitmap, in bits.
502 * Wrapper for __bitmap_parse(), providing it with user buffer.
504 * We cannot have this as an inline function in bitmap.h because it needs
505 * linux/uaccess.h to get the access_ok() declaration and this causes
506 * cyclic dependencies.
508 int bitmap_parse_user(const char __user *ubuf,
509 unsigned int ulen, unsigned long *maskp,
512 if (!access_ok(VERIFY_READ, ubuf, ulen))
514 return __bitmap_parse((const char __force *)ubuf,
515 ulen, 1, maskp, nmaskbits);
518 EXPORT_SYMBOL(bitmap_parse_user);
521 * bscnl_emit(buf, buflen, rbot, rtop, bp)
523 * Helper routine for bitmap_scnlistprintf(). Write decimal number
524 * or range to buf, suppressing output past buf+buflen, with optional
525 * comma-prefix. Return len of what was written to *buf, excluding the
528 static inline int bscnl_emit(char *buf, int buflen, int rbot, int rtop, int len)
531 len += scnprintf(buf + len, buflen - len, ",");
533 len += scnprintf(buf + len, buflen - len, "%d", rbot);
535 len += scnprintf(buf + len, buflen - len, "%d-%d", rbot, rtop);
540 * bitmap_scnlistprintf - convert bitmap to list format ASCII string
541 * @buf: byte buffer into which string is placed
542 * @buflen: reserved size of @buf, in bytes
543 * @maskp: pointer to bitmap to convert
544 * @nmaskbits: size of bitmap, in bits
546 * Output format is a comma-separated list of decimal numbers and
547 * ranges. Consecutively set bits are shown as two hyphen-separated
548 * decimal numbers, the smallest and largest bit numbers set in
549 * the range. Output format is compatible with the format
550 * accepted as input by bitmap_parselist().
552 * The return value is the number of characters which were written to *buf
553 * excluding the trailing '\0', as per ISO C99's scnprintf.
555 int bitmap_scnlistprintf(char *buf, unsigned int buflen,
556 const unsigned long *maskp, int nmaskbits)
559 /* current bit is 'cur', most recently seen range is [rbot, rtop] */
566 rbot = cur = find_first_bit(maskp, nmaskbits);
567 while (cur < nmaskbits) {
569 cur = find_next_bit(maskp, nmaskbits, cur+1);
570 if (cur >= nmaskbits || cur > rtop + 1) {
571 len = bscnl_emit(buf, buflen, rbot, rtop, len);
577 EXPORT_SYMBOL(bitmap_scnlistprintf);
580 * __bitmap_parselist - convert list format ASCII string to bitmap
581 * @buf: read nul-terminated user string from this buffer
582 * @buflen: buffer size in bytes. If string is smaller than this
583 * then it must be terminated with a \0.
584 * @is_user: location of buffer, 0 indicates kernel space
585 * @maskp: write resulting mask here
586 * @nmaskbits: number of bits in mask to be written
588 * Input format is a comma-separated list of decimal numbers and
589 * ranges. Consecutively set bits are shown as two hyphen-separated
590 * decimal numbers, the smallest and largest bit numbers set in
593 * Returns 0 on success, -errno on invalid input strings.
595 * %-EINVAL: second number in range smaller than first
596 * %-EINVAL: invalid character in string
597 * %-ERANGE: bit number specified too large for mask
599 static int __bitmap_parselist(const char *buf, unsigned int buflen,
600 int is_user, unsigned long *maskp,
604 int c, old_c, totaldigits;
605 const char __user __force *ubuf = (const char __user __force *)buf;
606 int exp_digit, in_range;
609 bitmap_zero(maskp, nmaskbits);
615 /* Get the next cpu# or a range of cpu#'s */
619 if (__get_user(c, ubuf++))
628 * If the last character was a space and the current
629 * character isn't '\0', we've got embedded whitespace.
630 * This is a no-no, so throw an error.
632 if (totaldigits && c && isspace(old_c))
635 /* A '\0' or a ',' signal the end of a cpu# or range */
636 if (c == '\0' || c == ',')
640 if (exp_digit || in_range)
651 b = b * 10 + (c - '0');
665 } while (buflen && c == ',');
669 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
671 char *nl = strchr(bp, '\n');
679 return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
681 EXPORT_SYMBOL(bitmap_parselist);
685 * bitmap_parselist_user()
687 * @ubuf: pointer to user buffer containing string.
688 * @ulen: buffer size in bytes. If string is smaller than this
689 * then it must be terminated with a \0.
690 * @maskp: pointer to bitmap array that will contain result.
691 * @nmaskbits: size of bitmap, in bits.
693 * Wrapper for bitmap_parselist(), providing it with user buffer.
695 * We cannot have this as an inline function in bitmap.h because it needs
696 * linux/uaccess.h to get the access_ok() declaration and this causes
697 * cyclic dependencies.
699 int bitmap_parselist_user(const char __user *ubuf,
700 unsigned int ulen, unsigned long *maskp,
703 if (!access_ok(VERIFY_READ, ubuf, ulen))
705 return __bitmap_parselist((const char __force *)ubuf,
706 ulen, 1, maskp, nmaskbits);
708 EXPORT_SYMBOL(bitmap_parselist_user);
712 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
713 * @buf: pointer to a bitmap
714 * @pos: a bit position in @buf (0 <= @pos < @bits)
715 * @bits: number of valid bit positions in @buf
717 * Map the bit at position @pos in @buf (of length @bits) to the
718 * ordinal of which set bit it is. If it is not set or if @pos
719 * is not a valid bit position, map to -1.
721 * If for example, just bits 4 through 7 are set in @buf, then @pos
722 * values 4 through 7 will get mapped to 0 through 3, respectively,
723 * and other @pos values will get mapped to 0. When @pos value 7
724 * gets mapped to (returns) @ord value 3 in this example, that means
725 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
727 * The bit positions 0 through @bits are valid positions in @buf.
729 static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits)
733 if (pos < 0 || pos >= bits || !test_bit(pos, buf))
736 i = find_first_bit(buf, bits);
739 i = find_next_bit(buf, bits, i + 1);
748 * bitmap_ord_to_pos - find position of n-th set bit in bitmap
749 * @buf: pointer to bitmap
750 * @ord: ordinal bit position (n-th set bit, n >= 0)
751 * @bits: number of valid bit positions in @buf
753 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
754 * Value of @ord should be in range 0 <= @ord < weight(buf), else
755 * results are undefined.
757 * If for example, just bits 4 through 7 are set in @buf, then @ord
758 * values 0 through 3 will get mapped to 4 through 7, respectively,
759 * and all other @ord values return undefined values. When @ord value 3
760 * gets mapped to (returns) @pos value 7 in this example, that means
761 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
763 * The bit positions 0 through @bits are valid positions in @buf.
765 int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits)
769 if (ord >= 0 && ord < bits) {
772 for (i = find_first_bit(buf, bits);
774 i = find_next_bit(buf, bits, i + 1))
776 if (i < bits && ord == 0)
784 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
785 * @dst: remapped result
786 * @src: subset to be remapped
787 * @old: defines domain of map
788 * @new: defines range of map
789 * @bits: number of bits in each of these bitmaps
791 * Let @old and @new define a mapping of bit positions, such that
792 * whatever position is held by the n-th set bit in @old is mapped
793 * to the n-th set bit in @new. In the more general case, allowing
794 * for the possibility that the weight 'w' of @new is less than the
795 * weight of @old, map the position of the n-th set bit in @old to
796 * the position of the m-th set bit in @new, where m == n % w.
798 * If either of the @old and @new bitmaps are empty, or if @src and
799 * @dst point to the same location, then this routine copies @src
802 * The positions of unset bits in @old are mapped to themselves
803 * (the identify map).
805 * Apply the above specified mapping to @src, placing the result in
806 * @dst, clearing any bits previously set in @dst.
808 * For example, lets say that @old has bits 4 through 7 set, and
809 * @new has bits 12 through 15 set. This defines the mapping of bit
810 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
811 * bit positions unchanged. So if say @src comes into this routine
812 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
815 void bitmap_remap(unsigned long *dst, const unsigned long *src,
816 const unsigned long *old, const unsigned long *new,
821 if (dst == src) /* following doesn't handle inplace remaps */
823 bitmap_zero(dst, bits);
825 w = bitmap_weight(new, bits);
826 for_each_set_bit(oldbit, src, bits) {
827 int n = bitmap_pos_to_ord(old, oldbit, bits);
830 set_bit(oldbit, dst); /* identity map */
832 set_bit(bitmap_ord_to_pos(new, n % w, bits), dst);
835 EXPORT_SYMBOL(bitmap_remap);
838 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
839 * @oldbit: bit position to be mapped
840 * @old: defines domain of map
841 * @new: defines range of map
842 * @bits: number of bits in each of these bitmaps
844 * Let @old and @new define a mapping of bit positions, such that
845 * whatever position is held by the n-th set bit in @old is mapped
846 * to the n-th set bit in @new. In the more general case, allowing
847 * for the possibility that the weight 'w' of @new is less than the
848 * weight of @old, map the position of the n-th set bit in @old to
849 * the position of the m-th set bit in @new, where m == n % w.
851 * The positions of unset bits in @old are mapped to themselves
852 * (the identify map).
854 * Apply the above specified mapping to bit position @oldbit, returning
855 * the new bit position.
857 * For example, lets say that @old has bits 4 through 7 set, and
858 * @new has bits 12 through 15 set. This defines the mapping of bit
859 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
860 * bit positions unchanged. So if say @oldbit is 5, then this routine
863 int bitmap_bitremap(int oldbit, const unsigned long *old,
864 const unsigned long *new, int bits)
866 int w = bitmap_weight(new, bits);
867 int n = bitmap_pos_to_ord(old, oldbit, bits);
871 return bitmap_ord_to_pos(new, n % w, bits);
873 EXPORT_SYMBOL(bitmap_bitremap);
876 * bitmap_onto - translate one bitmap relative to another
877 * @dst: resulting translated bitmap
878 * @orig: original untranslated bitmap
879 * @relmap: bitmap relative to which translated
880 * @bits: number of bits in each of these bitmaps
882 * Set the n-th bit of @dst iff there exists some m such that the
883 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
884 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
885 * (If you understood the previous sentence the first time your
886 * read it, you're overqualified for your current job.)
888 * In other words, @orig is mapped onto (surjectively) @dst,
889 * using the the map { <n, m> | the n-th bit of @relmap is the
890 * m-th set bit of @relmap }.
892 * Any set bits in @orig above bit number W, where W is the
893 * weight of (number of set bits in) @relmap are mapped nowhere.
894 * In particular, if for all bits m set in @orig, m >= W, then
895 * @dst will end up empty. In situations where the possibility
896 * of such an empty result is not desired, one way to avoid it is
897 * to use the bitmap_fold() operator, below, to first fold the
898 * @orig bitmap over itself so that all its set bits x are in the
899 * range 0 <= x < W. The bitmap_fold() operator does this by
900 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
902 * Example [1] for bitmap_onto():
903 * Let's say @relmap has bits 30-39 set, and @orig has bits
904 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,
905 * @dst will have bits 31, 33, 35, 37 and 39 set.
907 * When bit 0 is set in @orig, it means turn on the bit in
908 * @dst corresponding to whatever is the first bit (if any)
909 * that is turned on in @relmap. Since bit 0 was off in the
910 * above example, we leave off that bit (bit 30) in @dst.
912 * When bit 1 is set in @orig (as in the above example), it
913 * means turn on the bit in @dst corresponding to whatever
914 * is the second bit that is turned on in @relmap. The second
915 * bit in @relmap that was turned on in the above example was
916 * bit 31, so we turned on bit 31 in @dst.
918 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
919 * because they were the 4th, 6th, 8th and 10th set bits
920 * set in @relmap, and the 4th, 6th, 8th and 10th bits of
921 * @orig (i.e. bits 3, 5, 7 and 9) were also set.
923 * When bit 11 is set in @orig, it means turn on the bit in
924 * @dst corresponding to whatever is the twelfth bit that is
925 * turned on in @relmap. In the above example, there were
926 * only ten bits turned on in @relmap (30..39), so that bit
927 * 11 was set in @orig had no affect on @dst.
929 * Example [2] for bitmap_fold() + bitmap_onto():
930 * Let's say @relmap has these ten bits set:
931 * 40 41 42 43 45 48 53 61 74 95
932 * (for the curious, that's 40 plus the first ten terms of the
933 * Fibonacci sequence.)
935 * Further lets say we use the following code, invoking
936 * bitmap_fold() then bitmap_onto, as suggested above to
937 * avoid the possitility of an empty @dst result:
939 * unsigned long *tmp; // a temporary bitmap's bits
941 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
942 * bitmap_onto(dst, tmp, relmap, bits);
944 * Then this table shows what various values of @dst would be, for
945 * various @orig's. I list the zero-based positions of each set bit.
946 * The tmp column shows the intermediate result, as computed by
947 * using bitmap_fold() to fold the @orig bitmap modulo ten
948 * (the weight of @relmap).
955 * 1 3 5 7 1 3 5 7 41 43 48 61
956 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45
957 * 0 9 18 27 0 9 8 7 40 61 74 95
959 * 0 11 22 33 0 1 2 3 40 41 42 43
960 * 0 12 24 36 0 2 4 6 40 42 45 53
961 * 78 102 211 1 2 8 41 42 74 (*)
963 * (*) For these marked lines, if we hadn't first done bitmap_fold()
964 * into tmp, then the @dst result would have been empty.
966 * If either of @orig or @relmap is empty (no set bits), then @dst
967 * will be returned empty.
969 * If (as explained above) the only set bits in @orig are in positions
970 * m where m >= W, (where W is the weight of @relmap) then @dst will
971 * once again be returned empty.
973 * All bits in @dst not set by the above rule are cleared.
975 void bitmap_onto(unsigned long *dst, const unsigned long *orig,
976 const unsigned long *relmap, int bits)
978 int n, m; /* same meaning as in above comment */
980 if (dst == orig) /* following doesn't handle inplace mappings */
982 bitmap_zero(dst, bits);
985 * The following code is a more efficient, but less
986 * obvious, equivalent to the loop:
987 * for (m = 0; m < bitmap_weight(relmap, bits); m++) {
988 * n = bitmap_ord_to_pos(orig, m, bits);
989 * if (test_bit(m, orig))
995 for_each_set_bit(n, relmap, bits) {
996 /* m == bitmap_pos_to_ord(relmap, n, bits) */
997 if (test_bit(m, orig))
1002 EXPORT_SYMBOL(bitmap_onto);
1005 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
1006 * @dst: resulting smaller bitmap
1007 * @orig: original larger bitmap
1008 * @sz: specified size
1009 * @bits: number of bits in each of these bitmaps
1011 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
1012 * Clear all other bits in @dst. See further the comment and
1013 * Example [2] for bitmap_onto() for why and how to use this.
1015 void bitmap_fold(unsigned long *dst, const unsigned long *orig,
1020 if (dst == orig) /* following doesn't handle inplace mappings */
1022 bitmap_zero(dst, bits);
1024 for_each_set_bit(oldbit, orig, bits)
1025 set_bit(oldbit % sz, dst);
1027 EXPORT_SYMBOL(bitmap_fold);
1030 * Common code for bitmap_*_region() routines.
1031 * bitmap: array of unsigned longs corresponding to the bitmap
1032 * pos: the beginning of the region
1033 * order: region size (log base 2 of number of bits)
1034 * reg_op: operation(s) to perform on that region of bitmap
1036 * Can set, verify and/or release a region of bits in a bitmap,
1037 * depending on which combination of REG_OP_* flag bits is set.
1039 * A region of a bitmap is a sequence of bits in the bitmap, of
1040 * some size '1 << order' (a power of two), aligned to that same
1041 * '1 << order' power of two.
1043 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
1044 * Returns 0 in all other cases and reg_ops.
1048 REG_OP_ISFREE, /* true if region is all zero bits */
1049 REG_OP_ALLOC, /* set all bits in region */
1050 REG_OP_RELEASE, /* clear all bits in region */
1053 static int __reg_op(unsigned long *bitmap, int pos, int order, int reg_op)
1055 int nbits_reg; /* number of bits in region */
1056 int index; /* index first long of region in bitmap */
1057 int offset; /* bit offset region in bitmap[index] */
1058 int nlongs_reg; /* num longs spanned by region in bitmap */
1059 int nbitsinlong; /* num bits of region in each spanned long */
1060 unsigned long mask; /* bitmask for one long of region */
1061 int i; /* scans bitmap by longs */
1062 int ret = 0; /* return value */
1065 * Either nlongs_reg == 1 (for small orders that fit in one long)
1066 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
1068 nbits_reg = 1 << order;
1069 index = pos / BITS_PER_LONG;
1070 offset = pos - (index * BITS_PER_LONG);
1071 nlongs_reg = BITS_TO_LONGS(nbits_reg);
1072 nbitsinlong = min(nbits_reg, BITS_PER_LONG);
1075 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
1076 * overflows if nbitsinlong == BITS_PER_LONG.
1078 mask = (1UL << (nbitsinlong - 1));
1084 for (i = 0; i < nlongs_reg; i++) {
1085 if (bitmap[index + i] & mask)
1088 ret = 1; /* all bits in region free (zero) */
1092 for (i = 0; i < nlongs_reg; i++)
1093 bitmap[index + i] |= mask;
1096 case REG_OP_RELEASE:
1097 for (i = 0; i < nlongs_reg; i++)
1098 bitmap[index + i] &= ~mask;
1106 * bitmap_find_free_region - find a contiguous aligned mem region
1107 * @bitmap: array of unsigned longs corresponding to the bitmap
1108 * @bits: number of bits in the bitmap
1109 * @order: region size (log base 2 of number of bits) to find
1111 * Find a region of free (zero) bits in a @bitmap of @bits bits and
1112 * allocate them (set them to one). Only consider regions of length
1113 * a power (@order) of two, aligned to that power of two, which
1114 * makes the search algorithm much faster.
1116 * Return the bit offset in bitmap of the allocated region,
1117 * or -errno on failure.
1119 int bitmap_find_free_region(unsigned long *bitmap, int bits, int order)
1121 int pos, end; /* scans bitmap by regions of size order */
1123 for (pos = 0 ; (end = pos + (1 << order)) <= bits; pos = end) {
1124 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1126 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1131 EXPORT_SYMBOL(bitmap_find_free_region);
1134 * bitmap_release_region - release allocated bitmap region
1135 * @bitmap: array of unsigned longs corresponding to the bitmap
1136 * @pos: beginning of bit region to release
1137 * @order: region size (log base 2 of number of bits) to release
1139 * This is the complement to __bitmap_find_free_region() and releases
1140 * the found region (by clearing it in the bitmap).
1144 void bitmap_release_region(unsigned long *bitmap, int pos, int order)
1146 __reg_op(bitmap, pos, order, REG_OP_RELEASE);
1148 EXPORT_SYMBOL(bitmap_release_region);
1151 * bitmap_allocate_region - allocate bitmap region
1152 * @bitmap: array of unsigned longs corresponding to the bitmap
1153 * @pos: beginning of bit region to allocate
1154 * @order: region size (log base 2 of number of bits) to allocate
1156 * Allocate (set bits in) a specified region of a bitmap.
1158 * Return 0 on success, or %-EBUSY if specified region wasn't
1159 * free (not all bits were zero).
1161 int bitmap_allocate_region(unsigned long *bitmap, int pos, int order)
1163 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1165 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1168 EXPORT_SYMBOL(bitmap_allocate_region);
1171 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1172 * @dst: destination buffer
1173 * @src: bitmap to copy
1174 * @nbits: number of bits in the bitmap
1176 * Require nbits % BITS_PER_LONG == 0.
1178 void bitmap_copy_le(void *dst, const unsigned long *src, int nbits)
1180 unsigned long *d = dst;
1183 for (i = 0; i < nbits/BITS_PER_LONG; i++) {
1184 if (BITS_PER_LONG == 64)
1185 d[i] = cpu_to_le64(src[i]);
1187 d[i] = cpu_to_le32(src[i]);
1190 EXPORT_SYMBOL(bitmap_copy_le);