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, unsigned int bits)
45 unsigned 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, unsigned int bits)
60 unsigned 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, unsigned int bits)
76 unsigned 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, unsigned int bits)
91 unsigned int k, lim = bits/BITS_PER_LONG;
92 for (k = 0; k < lim; ++k)
95 if (bits % BITS_PER_LONG)
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] = upper << (BITS_PER_LONG - rem) | lower >> rem;
135 if (left && k == lim - 1)
139 memset(&dst[lim - off], 0, off*sizeof(unsigned long));
141 EXPORT_SYMBOL(__bitmap_shift_right);
145 * __bitmap_shift_left - logical left shift of the bits in a bitmap
146 * @dst : destination bitmap
147 * @src : source bitmap
148 * @shift : shift by this many bits
149 * @bits : bitmap size, in bits
151 * Shifting left (multiplying) means moving bits in the LS -> MS
152 * direction. Zeros are fed into the vacated LS bit positions
153 * and those MS bits shifted off the top are lost.
156 void __bitmap_shift_left(unsigned long *dst,
157 const unsigned long *src, int shift, int bits)
159 int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;
160 int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
161 for (k = lim - off - 1; k >= 0; --k) {
162 unsigned long upper, lower;
165 * If shift is not word aligned, take upper rem bits of
166 * word below and make them the bottom rem bits of result.
173 if (left && k == lim - 1)
174 upper &= (1UL << left) - 1;
175 dst[k + off] = lower >> (BITS_PER_LONG - rem) | upper << rem;
176 if (left && k + off == lim - 1)
177 dst[k + off] &= (1UL << left) - 1;
180 memset(dst, 0, off*sizeof(unsigned long));
182 EXPORT_SYMBOL(__bitmap_shift_left);
184 int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
185 const unsigned long *bitmap2, unsigned int bits)
188 unsigned int nr = BITS_TO_LONGS(bits);
189 unsigned long result = 0;
191 for (k = 0; k < nr; k++)
192 result |= (dst[k] = bitmap1[k] & bitmap2[k]);
195 EXPORT_SYMBOL(__bitmap_and);
197 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
198 const unsigned long *bitmap2, unsigned int bits)
201 unsigned int nr = BITS_TO_LONGS(bits);
203 for (k = 0; k < nr; k++)
204 dst[k] = bitmap1[k] | bitmap2[k];
206 EXPORT_SYMBOL(__bitmap_or);
208 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
209 const unsigned long *bitmap2, unsigned int bits)
212 unsigned int nr = BITS_TO_LONGS(bits);
214 for (k = 0; k < nr; k++)
215 dst[k] = bitmap1[k] ^ bitmap2[k];
217 EXPORT_SYMBOL(__bitmap_xor);
219 int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
220 const unsigned long *bitmap2, unsigned int bits)
223 unsigned int nr = BITS_TO_LONGS(bits);
224 unsigned long result = 0;
226 for (k = 0; k < nr; k++)
227 result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
230 EXPORT_SYMBOL(__bitmap_andnot);
232 int __bitmap_intersects(const unsigned long *bitmap1,
233 const unsigned long *bitmap2, unsigned int bits)
235 unsigned int k, lim = bits/BITS_PER_LONG;
236 for (k = 0; k < lim; ++k)
237 if (bitmap1[k] & bitmap2[k])
240 if (bits % BITS_PER_LONG)
241 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
245 EXPORT_SYMBOL(__bitmap_intersects);
247 int __bitmap_subset(const unsigned long *bitmap1,
248 const unsigned long *bitmap2, unsigned int bits)
250 unsigned int k, lim = bits/BITS_PER_LONG;
251 for (k = 0; k < lim; ++k)
252 if (bitmap1[k] & ~bitmap2[k])
255 if (bits % BITS_PER_LONG)
256 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
260 EXPORT_SYMBOL(__bitmap_subset);
262 int __bitmap_weight(const unsigned long *bitmap, unsigned int bits)
264 unsigned int k, lim = bits/BITS_PER_LONG;
267 for (k = 0; k < lim; k++)
268 w += hweight_long(bitmap[k]);
270 if (bits % BITS_PER_LONG)
271 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
275 EXPORT_SYMBOL(__bitmap_weight);
277 void bitmap_set(unsigned long *map, unsigned int start, int len)
279 unsigned long *p = map + BIT_WORD(start);
280 const unsigned int size = start + len;
281 int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
282 unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
284 while (len - bits_to_set >= 0) {
287 bits_to_set = BITS_PER_LONG;
292 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
296 EXPORT_SYMBOL(bitmap_set);
298 void bitmap_clear(unsigned long *map, int start, int nr)
300 unsigned long *p = map + BIT_WORD(start);
301 const int size = start + nr;
302 int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
303 unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
305 while (nr - bits_to_clear >= 0) {
306 *p &= ~mask_to_clear;
308 bits_to_clear = BITS_PER_LONG;
309 mask_to_clear = ~0UL;
313 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
314 *p &= ~mask_to_clear;
317 EXPORT_SYMBOL(bitmap_clear);
320 * bitmap_find_next_zero_area - find a contiguous aligned zero area
321 * @map: The address to base the search on
322 * @size: The bitmap size in bits
323 * @start: The bitnumber to start searching at
324 * @nr: The number of zeroed bits we're looking for
325 * @align_mask: Alignment mask 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 is multiples of that
329 * power of 2. A @align_mask of 0 means no alignment is required.
331 unsigned long bitmap_find_next_zero_area(unsigned long *map,
335 unsigned long align_mask)
337 unsigned long index, end, i;
339 index = find_next_zero_bit(map, size, start);
341 /* Align allocation */
342 index = __ALIGN_MASK(index, align_mask);
347 i = find_next_bit(map, end, index);
354 EXPORT_SYMBOL(bitmap_find_next_zero_area);
357 * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,
358 * second version by Paul Jackson, third by Joe Korty.
362 #define nbits_to_hold_value(val) fls(val)
363 #define BASEDEC 10 /* fancier cpuset lists input in decimal */
366 * bitmap_scnprintf - convert bitmap to an ASCII hex string.
367 * @buf: byte buffer into which string is placed
368 * @buflen: reserved size of @buf, in bytes
369 * @maskp: pointer to bitmap to convert
370 * @nmaskbits: size of bitmap, in bits
372 * Exactly @nmaskbits bits are displayed. Hex digits are grouped into
373 * comma-separated sets of eight digits per set. Returns the number of
374 * characters which were written to *buf, excluding the trailing \0.
376 int bitmap_scnprintf(char *buf, unsigned int buflen,
377 const unsigned long *maskp, int nmaskbits)
379 int i, word, bit, len = 0;
381 const char *sep = "";
385 chunksz = nmaskbits & (CHUNKSZ - 1);
389 i = ALIGN(nmaskbits, CHUNKSZ) - CHUNKSZ;
390 for (; i >= 0; i -= CHUNKSZ) {
391 chunkmask = ((1ULL << chunksz) - 1);
392 word = i / BITS_PER_LONG;
393 bit = i % BITS_PER_LONG;
394 val = (maskp[word] >> bit) & chunkmask;
395 len += scnprintf(buf+len, buflen-len, "%s%0*lx", sep,
402 EXPORT_SYMBOL(bitmap_scnprintf);
405 * __bitmap_parse - convert an ASCII hex string into a bitmap.
406 * @buf: pointer to buffer containing string.
407 * @buflen: buffer size in bytes. If string is smaller than this
408 * then it must be terminated with a \0.
409 * @is_user: location of buffer, 0 indicates kernel space
410 * @maskp: pointer to bitmap array that will contain result.
411 * @nmaskbits: size of bitmap, in bits.
413 * Commas group hex digits into chunks. Each chunk defines exactly 32
414 * bits of the resultant bitmask. No chunk may specify a value larger
415 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
416 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
417 * characters and for grouping errors such as "1,,5", ",44", "," and "".
418 * Leading and trailing whitespace accepted, but not embedded whitespace.
420 int __bitmap_parse(const char *buf, unsigned int buflen,
421 int is_user, unsigned long *maskp,
424 int c, old_c, totaldigits, ndigits, nchunks, nbits;
426 const char __user __force *ubuf = (const char __user __force *)buf;
428 bitmap_zero(maskp, nmaskbits);
430 nchunks = nbits = totaldigits = c = 0;
434 /* Get the next chunk of the bitmap */
438 if (__get_user(c, ubuf++))
448 * If the last character was a space and the current
449 * character isn't '\0', we've got embedded whitespace.
450 * This is a no-no, so throw an error.
452 if (totaldigits && c && isspace(old_c))
455 /* A '\0' or a ',' signal the end of the chunk */
456 if (c == '\0' || c == ',')
463 * Make sure there are at least 4 free bits in 'chunk'.
464 * If not, this hexdigit will overflow 'chunk', so
467 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
470 chunk = (chunk << 4) | hex_to_bin(c);
471 ndigits++; totaldigits++;
475 if (nchunks == 0 && chunk == 0)
478 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
481 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
482 if (nbits > nmaskbits)
484 } while (buflen && c == ',');
488 EXPORT_SYMBOL(__bitmap_parse);
491 * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
493 * @ubuf: pointer to user buffer containing string.
494 * @ulen: buffer size in bytes. If string is smaller than this
495 * then it must be terminated with a \0.
496 * @maskp: pointer to bitmap array that will contain result.
497 * @nmaskbits: size of bitmap, in bits.
499 * Wrapper for __bitmap_parse(), providing it with user buffer.
501 * We cannot have this as an inline function in bitmap.h because it needs
502 * linux/uaccess.h to get the access_ok() declaration and this causes
503 * cyclic dependencies.
505 int bitmap_parse_user(const char __user *ubuf,
506 unsigned int ulen, unsigned long *maskp,
509 if (!access_ok(VERIFY_READ, ubuf, ulen))
511 return __bitmap_parse((const char __force *)ubuf,
512 ulen, 1, maskp, nmaskbits);
515 EXPORT_SYMBOL(bitmap_parse_user);
518 * bscnl_emit(buf, buflen, rbot, rtop, bp)
520 * Helper routine for bitmap_scnlistprintf(). Write decimal number
521 * or range to buf, suppressing output past buf+buflen, with optional
522 * comma-prefix. Return len of what was written to *buf, excluding the
525 static inline int bscnl_emit(char *buf, int buflen, int rbot, int rtop, int len)
528 len += scnprintf(buf + len, buflen - len, ",");
530 len += scnprintf(buf + len, buflen - len, "%d", rbot);
532 len += scnprintf(buf + len, buflen - len, "%d-%d", rbot, rtop);
537 * bitmap_scnlistprintf - convert bitmap to list format ASCII string
538 * @buf: byte buffer into which string is placed
539 * @buflen: reserved size of @buf, in bytes
540 * @maskp: pointer to bitmap to convert
541 * @nmaskbits: size of bitmap, in bits
543 * Output format is a comma-separated list of decimal numbers and
544 * ranges. Consecutively set bits are shown as two hyphen-separated
545 * decimal numbers, the smallest and largest bit numbers set in
546 * the range. Output format is compatible with the format
547 * accepted as input by bitmap_parselist().
549 * The return value is the number of characters which were written to *buf
550 * excluding the trailing '\0', as per ISO C99's scnprintf.
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 * @buf: read nul-terminated user string from this buffer
579 * @buflen: buffer size in bytes. If string is smaller than this
580 * then it must be terminated with a \0.
581 * @is_user: location of buffer, 0 indicates kernel space
582 * @maskp: write resulting mask here
583 * @nmaskbits: number of bits in mask to be written
585 * Input format is a comma-separated list of decimal numbers and
586 * ranges. Consecutively set bits are shown as two hyphen-separated
587 * decimal numbers, the smallest and largest bit numbers set in
590 * Returns 0 on success, -errno on invalid input strings.
592 * %-EINVAL: second number in range smaller than first
593 * %-EINVAL: invalid character in string
594 * %-ERANGE: bit number specified too large for mask
596 static int __bitmap_parselist(const char *buf, unsigned int buflen,
597 int is_user, unsigned long *maskp,
601 int c, old_c, totaldigits;
602 const char __user __force *ubuf = (const char __user __force *)buf;
603 int exp_digit, in_range;
606 bitmap_zero(maskp, nmaskbits);
612 /* Get the next cpu# or a range of cpu#'s */
616 if (__get_user(c, ubuf++))
625 * If the last character was a space and the current
626 * character isn't '\0', we've got embedded whitespace.
627 * This is a no-no, so throw an error.
629 if (totaldigits && c && isspace(old_c))
632 /* A '\0' or a ',' signal the end of a cpu# or range */
633 if (c == '\0' || c == ',')
637 if (exp_digit || in_range)
648 b = b * 10 + (c - '0');
662 } while (buflen && c == ',');
666 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
668 char *nl = strchr(bp, '\n');
676 return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
678 EXPORT_SYMBOL(bitmap_parselist);
682 * bitmap_parselist_user()
684 * @ubuf: pointer to user buffer containing string.
685 * @ulen: buffer size in bytes. If string is smaller than this
686 * then it must be terminated with a \0.
687 * @maskp: pointer to bitmap array that will contain result.
688 * @nmaskbits: size of bitmap, in bits.
690 * Wrapper for bitmap_parselist(), providing it with user buffer.
692 * We cannot have this as an inline function in bitmap.h because it needs
693 * linux/uaccess.h to get the access_ok() declaration and this causes
694 * cyclic dependencies.
696 int bitmap_parselist_user(const char __user *ubuf,
697 unsigned int ulen, unsigned long *maskp,
700 if (!access_ok(VERIFY_READ, ubuf, ulen))
702 return __bitmap_parselist((const char __force *)ubuf,
703 ulen, 1, maskp, nmaskbits);
705 EXPORT_SYMBOL(bitmap_parselist_user);
709 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
710 * @buf: pointer to a bitmap
711 * @pos: a bit position in @buf (0 <= @pos < @bits)
712 * @bits: number of valid bit positions in @buf
714 * Map the bit at position @pos in @buf (of length @bits) to the
715 * ordinal of which set bit it is. If it is not set or if @pos
716 * is not a valid bit position, map to -1.
718 * If for example, just bits 4 through 7 are set in @buf, then @pos
719 * values 4 through 7 will get mapped to 0 through 3, respectively,
720 * and other @pos values will get mapped to 0. When @pos value 7
721 * gets mapped to (returns) @ord value 3 in this example, that means
722 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
724 * The bit positions 0 through @bits are valid positions in @buf.
726 static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits)
730 if (pos < 0 || pos >= bits || !test_bit(pos, buf))
733 i = find_first_bit(buf, bits);
736 i = find_next_bit(buf, bits, i + 1);
745 * bitmap_ord_to_pos - find position of n-th set bit in bitmap
746 * @buf: pointer to bitmap
747 * @ord: ordinal bit position (n-th set bit, n >= 0)
748 * @bits: number of valid bit positions in @buf
750 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
751 * Value of @ord should be in range 0 <= @ord < weight(buf), else
752 * results are undefined.
754 * If for example, just bits 4 through 7 are set in @buf, then @ord
755 * values 0 through 3 will get mapped to 4 through 7, respectively,
756 * and all other @ord values return undefined values. When @ord value 3
757 * gets mapped to (returns) @pos value 7 in this example, that means
758 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
760 * The bit positions 0 through @bits are valid positions in @buf.
762 int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits)
766 if (ord >= 0 && ord < bits) {
769 for (i = find_first_bit(buf, bits);
771 i = find_next_bit(buf, bits, i + 1))
773 if (i < bits && ord == 0)
781 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
782 * @dst: remapped result
783 * @src: subset to be remapped
784 * @old: defines domain of map
785 * @new: defines range of map
786 * @bits: number of bits in each of these bitmaps
788 * Let @old and @new define a mapping of bit positions, such that
789 * whatever position is held by the n-th set bit in @old is mapped
790 * to the n-th set bit in @new. In the more general case, allowing
791 * for the possibility that the weight 'w' of @new is less than the
792 * weight of @old, map the position of the n-th set bit in @old to
793 * the position of the m-th set bit in @new, where m == n % w.
795 * If either of the @old and @new bitmaps are empty, or if @src and
796 * @dst point to the same location, then this routine copies @src
799 * The positions of unset bits in @old are mapped to themselves
800 * (the identify map).
802 * Apply the above specified mapping to @src, placing the result in
803 * @dst, clearing any bits previously set in @dst.
805 * For example, lets say that @old has bits 4 through 7 set, and
806 * @new has bits 12 through 15 set. This defines the mapping of bit
807 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
808 * bit positions unchanged. So if say @src comes into this routine
809 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
812 void bitmap_remap(unsigned long *dst, const unsigned long *src,
813 const unsigned long *old, const unsigned long *new,
818 if (dst == src) /* following doesn't handle inplace remaps */
820 bitmap_zero(dst, bits);
822 w = bitmap_weight(new, bits);
823 for_each_set_bit(oldbit, src, bits) {
824 int n = bitmap_pos_to_ord(old, oldbit, bits);
827 set_bit(oldbit, dst); /* identity map */
829 set_bit(bitmap_ord_to_pos(new, n % w, bits), dst);
832 EXPORT_SYMBOL(bitmap_remap);
835 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
836 * @oldbit: bit position to be mapped
837 * @old: defines domain of map
838 * @new: defines range of map
839 * @bits: number of bits in each of these bitmaps
841 * Let @old and @new define a mapping of bit positions, such that
842 * whatever position is held by the n-th set bit in @old is mapped
843 * to the n-th set bit in @new. In the more general case, allowing
844 * for the possibility that the weight 'w' of @new is less than the
845 * weight of @old, map the position of the n-th set bit in @old to
846 * the position of the m-th set bit in @new, where m == n % w.
848 * The positions of unset bits in @old are mapped to themselves
849 * (the identify map).
851 * Apply the above specified mapping to bit position @oldbit, returning
852 * the new bit position.
854 * For example, lets say that @old has bits 4 through 7 set, and
855 * @new has bits 12 through 15 set. This defines the mapping of bit
856 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
857 * bit positions unchanged. So if say @oldbit is 5, then this routine
860 int bitmap_bitremap(int oldbit, const unsigned long *old,
861 const unsigned long *new, int bits)
863 int w = bitmap_weight(new, bits);
864 int n = bitmap_pos_to_ord(old, oldbit, bits);
868 return bitmap_ord_to_pos(new, n % w, bits);
870 EXPORT_SYMBOL(bitmap_bitremap);
873 * bitmap_onto - translate one bitmap relative to another
874 * @dst: resulting translated bitmap
875 * @orig: original untranslated bitmap
876 * @relmap: bitmap relative to which translated
877 * @bits: number of bits in each of these bitmaps
879 * Set the n-th bit of @dst iff there exists some m such that the
880 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
881 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
882 * (If you understood the previous sentence the first time your
883 * read it, you're overqualified for your current job.)
885 * In other words, @orig is mapped onto (surjectively) @dst,
886 * using the the map { <n, m> | the n-th bit of @relmap is the
887 * m-th set bit of @relmap }.
889 * Any set bits in @orig above bit number W, where W is the
890 * weight of (number of set bits in) @relmap are mapped nowhere.
891 * In particular, if for all bits m set in @orig, m >= W, then
892 * @dst will end up empty. In situations where the possibility
893 * of such an empty result is not desired, one way to avoid it is
894 * to use the bitmap_fold() operator, below, to first fold the
895 * @orig bitmap over itself so that all its set bits x are in the
896 * range 0 <= x < W. The bitmap_fold() operator does this by
897 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
899 * Example [1] for bitmap_onto():
900 * Let's say @relmap has bits 30-39 set, and @orig has bits
901 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,
902 * @dst will have bits 31, 33, 35, 37 and 39 set.
904 * When bit 0 is set in @orig, it means turn on the bit in
905 * @dst corresponding to whatever is the first bit (if any)
906 * that is turned on in @relmap. Since bit 0 was off in the
907 * above example, we leave off that bit (bit 30) in @dst.
909 * When bit 1 is set in @orig (as in the above example), it
910 * means turn on the bit in @dst corresponding to whatever
911 * is the second bit that is turned on in @relmap. The second
912 * bit in @relmap that was turned on in the above example was
913 * bit 31, so we turned on bit 31 in @dst.
915 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
916 * because they were the 4th, 6th, 8th and 10th set bits
917 * set in @relmap, and the 4th, 6th, 8th and 10th bits of
918 * @orig (i.e. bits 3, 5, 7 and 9) were also set.
920 * When bit 11 is set in @orig, it means turn on the bit in
921 * @dst corresponding to whatever is the twelfth bit that is
922 * turned on in @relmap. In the above example, there were
923 * only ten bits turned on in @relmap (30..39), so that bit
924 * 11 was set in @orig had no affect on @dst.
926 * Example [2] for bitmap_fold() + bitmap_onto():
927 * Let's say @relmap has these ten bits set:
928 * 40 41 42 43 45 48 53 61 74 95
929 * (for the curious, that's 40 plus the first ten terms of the
930 * Fibonacci sequence.)
932 * Further lets say we use the following code, invoking
933 * bitmap_fold() then bitmap_onto, as suggested above to
934 * avoid the possitility of an empty @dst result:
936 * unsigned long *tmp; // a temporary bitmap's bits
938 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
939 * bitmap_onto(dst, tmp, relmap, bits);
941 * Then this table shows what various values of @dst would be, for
942 * various @orig's. I list the zero-based positions of each set bit.
943 * The tmp column shows the intermediate result, as computed by
944 * using bitmap_fold() to fold the @orig bitmap modulo ten
945 * (the weight of @relmap).
952 * 1 3 5 7 1 3 5 7 41 43 48 61
953 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45
954 * 0 9 18 27 0 9 8 7 40 61 74 95
956 * 0 11 22 33 0 1 2 3 40 41 42 43
957 * 0 12 24 36 0 2 4 6 40 42 45 53
958 * 78 102 211 1 2 8 41 42 74 (*)
960 * (*) For these marked lines, if we hadn't first done bitmap_fold()
961 * into tmp, then the @dst result would have been empty.
963 * If either of @orig or @relmap is empty (no set bits), then @dst
964 * will be returned empty.
966 * If (as explained above) the only set bits in @orig are in positions
967 * m where m >= W, (where W is the weight of @relmap) then @dst will
968 * once again be returned empty.
970 * All bits in @dst not set by the above rule are cleared.
972 void bitmap_onto(unsigned long *dst, const unsigned long *orig,
973 const unsigned long *relmap, int bits)
975 int n, m; /* same meaning as in above comment */
977 if (dst == orig) /* following doesn't handle inplace mappings */
979 bitmap_zero(dst, bits);
982 * The following code is a more efficient, but less
983 * obvious, equivalent to the loop:
984 * for (m = 0; m < bitmap_weight(relmap, bits); m++) {
985 * n = bitmap_ord_to_pos(orig, m, bits);
986 * if (test_bit(m, orig))
992 for_each_set_bit(n, relmap, bits) {
993 /* m == bitmap_pos_to_ord(relmap, n, bits) */
994 if (test_bit(m, orig))
999 EXPORT_SYMBOL(bitmap_onto);
1002 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
1003 * @dst: resulting smaller bitmap
1004 * @orig: original larger bitmap
1005 * @sz: specified size
1006 * @bits: number of bits in each of these bitmaps
1008 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
1009 * Clear all other bits in @dst. See further the comment and
1010 * Example [2] for bitmap_onto() for why and how to use this.
1012 void bitmap_fold(unsigned long *dst, const unsigned long *orig,
1017 if (dst == orig) /* following doesn't handle inplace mappings */
1019 bitmap_zero(dst, bits);
1021 for_each_set_bit(oldbit, orig, bits)
1022 set_bit(oldbit % sz, dst);
1024 EXPORT_SYMBOL(bitmap_fold);
1027 * Common code for bitmap_*_region() routines.
1028 * bitmap: array of unsigned longs corresponding to the bitmap
1029 * pos: the beginning of the region
1030 * order: region size (log base 2 of number of bits)
1031 * reg_op: operation(s) to perform on that region of bitmap
1033 * Can set, verify and/or release a region of bits in a bitmap,
1034 * depending on which combination of REG_OP_* flag bits is set.
1036 * A region of a bitmap is a sequence of bits in the bitmap, of
1037 * some size '1 << order' (a power of two), aligned to that same
1038 * '1 << order' power of two.
1040 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
1041 * Returns 0 in all other cases and reg_ops.
1045 REG_OP_ISFREE, /* true if region is all zero bits */
1046 REG_OP_ALLOC, /* set all bits in region */
1047 REG_OP_RELEASE, /* clear all bits in region */
1050 static int __reg_op(unsigned long *bitmap, int pos, int order, int reg_op)
1052 int nbits_reg; /* number of bits in region */
1053 int index; /* index first long of region in bitmap */
1054 int offset; /* bit offset region in bitmap[index] */
1055 int nlongs_reg; /* num longs spanned by region in bitmap */
1056 int nbitsinlong; /* num bits of region in each spanned long */
1057 unsigned long mask; /* bitmask for one long of region */
1058 int i; /* scans bitmap by longs */
1059 int ret = 0; /* return value */
1062 * Either nlongs_reg == 1 (for small orders that fit in one long)
1063 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
1065 nbits_reg = 1 << order;
1066 index = pos / BITS_PER_LONG;
1067 offset = pos - (index * BITS_PER_LONG);
1068 nlongs_reg = BITS_TO_LONGS(nbits_reg);
1069 nbitsinlong = min(nbits_reg, BITS_PER_LONG);
1072 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
1073 * overflows if nbitsinlong == BITS_PER_LONG.
1075 mask = (1UL << (nbitsinlong - 1));
1081 for (i = 0; i < nlongs_reg; i++) {
1082 if (bitmap[index + i] & mask)
1085 ret = 1; /* all bits in region free (zero) */
1089 for (i = 0; i < nlongs_reg; i++)
1090 bitmap[index + i] |= mask;
1093 case REG_OP_RELEASE:
1094 for (i = 0; i < nlongs_reg; i++)
1095 bitmap[index + i] &= ~mask;
1103 * bitmap_find_free_region - find a contiguous aligned mem region
1104 * @bitmap: array of unsigned longs corresponding to the bitmap
1105 * @bits: number of bits in the bitmap
1106 * @order: region size (log base 2 of number of bits) to find
1108 * Find a region of free (zero) bits in a @bitmap of @bits bits and
1109 * allocate them (set them to one). Only consider regions of length
1110 * a power (@order) of two, aligned to that power of two, which
1111 * makes the search algorithm much faster.
1113 * Return the bit offset in bitmap of the allocated region,
1114 * or -errno on failure.
1116 int bitmap_find_free_region(unsigned long *bitmap, int bits, int order)
1118 int pos, end; /* scans bitmap by regions of size order */
1120 for (pos = 0 ; (end = pos + (1 << order)) <= bits; pos = end) {
1121 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1123 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1128 EXPORT_SYMBOL(bitmap_find_free_region);
1131 * bitmap_release_region - release allocated bitmap region
1132 * @bitmap: array of unsigned longs corresponding to the bitmap
1133 * @pos: beginning of bit region to release
1134 * @order: region size (log base 2 of number of bits) to release
1136 * This is the complement to __bitmap_find_free_region() and releases
1137 * the found region (by clearing it in the bitmap).
1141 void bitmap_release_region(unsigned long *bitmap, int pos, int order)
1143 __reg_op(bitmap, pos, order, REG_OP_RELEASE);
1145 EXPORT_SYMBOL(bitmap_release_region);
1148 * bitmap_allocate_region - allocate bitmap region
1149 * @bitmap: array of unsigned longs corresponding to the bitmap
1150 * @pos: beginning of bit region to allocate
1151 * @order: region size (log base 2 of number of bits) to allocate
1153 * Allocate (set bits in) a specified region of a bitmap.
1155 * Return 0 on success, or %-EBUSY if specified region wasn't
1156 * free (not all bits were zero).
1158 int bitmap_allocate_region(unsigned long *bitmap, int pos, int order)
1160 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1162 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1165 EXPORT_SYMBOL(bitmap_allocate_region);
1168 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1169 * @dst: destination buffer
1170 * @src: bitmap to copy
1171 * @nbits: number of bits in the bitmap
1173 * Require nbits % BITS_PER_LONG == 0.
1175 void bitmap_copy_le(void *dst, const unsigned long *src, int nbits)
1177 unsigned long *d = dst;
1180 for (i = 0; i < nbits/BITS_PER_LONG; i++) {
1181 if (BITS_PER_LONG == 64)
1182 d[i] = cpu_to_le64(src[i]);
1184 d[i] = cpu_to_le32(src[i]);
1187 EXPORT_SYMBOL(bitmap_copy_le);