3 * Helper functions for bitmap.h.
5 * This source code is licensed under the GNU General Public License,
6 * Version 2. See the file COPYING for more details.
8 #include <linux/export.h>
9 #include <linux/thread_info.h>
10 #include <linux/ctype.h>
11 #include <linux/errno.h>
12 #include <linux/bitmap.h>
13 #include <linux/bitops.h>
14 #include <linux/bug.h>
17 #include <asm/uaccess.h>
20 * bitmaps provide an array of bits, implemented using an an
21 * array of unsigned longs. The number of valid bits in a
22 * given bitmap does _not_ need to be an exact multiple of
25 * The possible unused bits in the last, partially used word
26 * of a bitmap are 'don't care'. The implementation makes
27 * no particular effort to keep them zero. It ensures that
28 * their value will not affect the results of any operation.
29 * The bitmap operations that return Boolean (bitmap_empty,
30 * for example) or scalar (bitmap_weight, for example) results
31 * carefully filter out these unused bits from impacting their
34 * These operations actually hold to a slightly stronger rule:
35 * if you don't input any bitmaps to these ops that have some
36 * unused bits set, then they won't output any set unused bits
39 * The byte ordering of bitmaps is more natural on little
40 * endian architectures. See the big-endian headers
41 * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
42 * for the best explanations of this ordering.
45 int __bitmap_empty(const unsigned long *bitmap, unsigned int bits)
47 unsigned int k, lim = bits/BITS_PER_LONG;
48 for (k = 0; k < lim; ++k)
52 if (bits % BITS_PER_LONG)
53 if (bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
58 EXPORT_SYMBOL(__bitmap_empty);
60 int __bitmap_full(const unsigned long *bitmap, unsigned int bits)
62 unsigned int k, lim = bits/BITS_PER_LONG;
63 for (k = 0; k < lim; ++k)
67 if (bits % BITS_PER_LONG)
68 if (~bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
73 EXPORT_SYMBOL(__bitmap_full);
75 int __bitmap_equal(const unsigned long *bitmap1,
76 const unsigned long *bitmap2, unsigned int bits)
78 unsigned int k, lim = bits/BITS_PER_LONG;
79 for (k = 0; k < lim; ++k)
80 if (bitmap1[k] != bitmap2[k])
83 if (bits % BITS_PER_LONG)
84 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
89 EXPORT_SYMBOL(__bitmap_equal);
91 void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits)
93 unsigned int k, lim = bits/BITS_PER_LONG;
94 for (k = 0; k < lim; ++k)
97 if (bits % BITS_PER_LONG)
100 EXPORT_SYMBOL(__bitmap_complement);
103 * __bitmap_shift_right - logical right shift of the bits in a bitmap
104 * @dst : destination bitmap
105 * @src : source bitmap
106 * @shift : shift by this many bits
107 * @nbits : bitmap size, in bits
109 * Shifting right (dividing) means moving bits in the MS -> LS bit
110 * direction. Zeros are fed into the vacated MS positions and the
111 * LS bits shifted off the bottom are lost.
113 void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
114 unsigned shift, unsigned nbits)
116 unsigned k, lim = BITS_TO_LONGS(nbits);
117 unsigned off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
118 unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);
119 for (k = 0; off + k < lim; ++k) {
120 unsigned long upper, lower;
123 * If shift is not word aligned, take lower rem bits of
124 * word above and make them the top rem bits of result.
126 if (!rem || off + k + 1 >= lim)
129 upper = src[off + k + 1];
130 if (off + k + 1 == lim - 1)
132 upper <<= (BITS_PER_LONG - rem);
134 lower = src[off + k];
135 if (off + k == lim - 1)
138 dst[k] = lower | upper;
141 memset(&dst[lim - off], 0, off*sizeof(unsigned long));
143 EXPORT_SYMBOL(__bitmap_shift_right);
147 * __bitmap_shift_left - logical left shift of the bits in a bitmap
148 * @dst : destination bitmap
149 * @src : source bitmap
150 * @shift : shift by this many bits
151 * @nbits : bitmap size, in bits
153 * Shifting left (multiplying) means moving bits in the LS -> MS
154 * direction. Zeros are fed into the vacated LS bit positions
155 * and those MS bits shifted off the top are lost.
158 void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
159 unsigned int shift, unsigned int nbits)
162 unsigned int lim = BITS_TO_LONGS(nbits), left = nbits % BITS_PER_LONG;
163 unsigned int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
164 for (k = lim - off - 1; k >= 0; --k) {
165 unsigned long upper, lower;
168 * If shift is not word aligned, take upper rem bits of
169 * word below and make them the bottom rem bits of result.
176 if (left && k == lim - 1)
177 upper &= (1UL << left) - 1;
178 dst[k + off] = upper << rem;
180 dst[k + off] |= lower >> (BITS_PER_LONG - rem);
181 if (left && k + off == lim - 1)
182 dst[k + off] &= (1UL << left) - 1;
185 memset(dst, 0, off*sizeof(unsigned long));
187 EXPORT_SYMBOL(__bitmap_shift_left);
189 int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
190 const unsigned long *bitmap2, unsigned int bits)
193 unsigned int lim = bits/BITS_PER_LONG;
194 unsigned long result = 0;
196 for (k = 0; k < lim; k++)
197 result |= (dst[k] = bitmap1[k] & bitmap2[k]);
198 if (bits % BITS_PER_LONG)
199 result |= (dst[k] = bitmap1[k] & bitmap2[k] &
200 BITMAP_LAST_WORD_MASK(bits));
203 EXPORT_SYMBOL(__bitmap_and);
205 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
206 const unsigned long *bitmap2, unsigned int bits)
209 unsigned int nr = BITS_TO_LONGS(bits);
211 for (k = 0; k < nr; k++)
212 dst[k] = bitmap1[k] | bitmap2[k];
214 EXPORT_SYMBOL(__bitmap_or);
216 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
217 const unsigned long *bitmap2, unsigned int bits)
220 unsigned int nr = BITS_TO_LONGS(bits);
222 for (k = 0; k < nr; k++)
223 dst[k] = bitmap1[k] ^ bitmap2[k];
225 EXPORT_SYMBOL(__bitmap_xor);
227 int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
228 const unsigned long *bitmap2, unsigned int bits)
231 unsigned int lim = bits/BITS_PER_LONG;
232 unsigned long result = 0;
234 for (k = 0; k < lim; k++)
235 result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
236 if (bits % BITS_PER_LONG)
237 result |= (dst[k] = bitmap1[k] & ~bitmap2[k] &
238 BITMAP_LAST_WORD_MASK(bits));
241 EXPORT_SYMBOL(__bitmap_andnot);
243 int __bitmap_intersects(const unsigned long *bitmap1,
244 const unsigned long *bitmap2, unsigned int bits)
246 unsigned int k, lim = bits/BITS_PER_LONG;
247 for (k = 0; k < lim; ++k)
248 if (bitmap1[k] & bitmap2[k])
251 if (bits % BITS_PER_LONG)
252 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
256 EXPORT_SYMBOL(__bitmap_intersects);
258 int __bitmap_subset(const unsigned long *bitmap1,
259 const unsigned long *bitmap2, unsigned int bits)
261 unsigned int k, lim = bits/BITS_PER_LONG;
262 for (k = 0; k < lim; ++k)
263 if (bitmap1[k] & ~bitmap2[k])
266 if (bits % BITS_PER_LONG)
267 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
271 EXPORT_SYMBOL(__bitmap_subset);
273 int __bitmap_weight(const unsigned long *bitmap, unsigned int bits)
275 unsigned int k, lim = bits/BITS_PER_LONG;
278 for (k = 0; k < lim; k++)
279 w += hweight_long(bitmap[k]);
281 if (bits % BITS_PER_LONG)
282 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
286 EXPORT_SYMBOL(__bitmap_weight);
288 void bitmap_set(unsigned long *map, unsigned int start, int len)
290 unsigned long *p = map + BIT_WORD(start);
291 const unsigned int size = start + len;
292 int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
293 unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
295 while (len - bits_to_set >= 0) {
298 bits_to_set = BITS_PER_LONG;
303 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
307 EXPORT_SYMBOL(bitmap_set);
309 void bitmap_clear(unsigned long *map, unsigned int start, int len)
311 unsigned long *p = map + BIT_WORD(start);
312 const unsigned int size = start + len;
313 int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
314 unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
316 while (len - bits_to_clear >= 0) {
317 *p &= ~mask_to_clear;
318 len -= bits_to_clear;
319 bits_to_clear = BITS_PER_LONG;
320 mask_to_clear = ~0UL;
324 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
325 *p &= ~mask_to_clear;
328 EXPORT_SYMBOL(bitmap_clear);
331 * bitmap_find_next_zero_area_off - find a contiguous aligned zero area
332 * @map: The address to base the search on
333 * @size: The bitmap size in bits
334 * @start: The bitnumber to start searching at
335 * @nr: The number of zeroed bits we're looking for
336 * @align_mask: Alignment mask for zero area
337 * @align_offset: Alignment offset for zero area.
339 * The @align_mask should be one less than a power of 2; the effect is that
340 * the bit offset of all zero areas this function finds plus @align_offset
341 * is multiple of that power of 2.
343 unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
347 unsigned long align_mask,
348 unsigned long align_offset)
350 unsigned long index, end, i;
352 index = find_next_zero_bit(map, size, start);
354 /* Align allocation */
355 index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset;
360 i = find_next_bit(map, end, index);
367 EXPORT_SYMBOL(bitmap_find_next_zero_area_off);
370 * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,
371 * second version by Paul Jackson, third by Joe Korty.
375 #define nbits_to_hold_value(val) fls(val)
376 #define BASEDEC 10 /* fancier cpuset lists input in decimal */
379 * bitmap_scnprintf - convert bitmap to an ASCII hex string.
380 * @buf: byte buffer into which string is placed
381 * @buflen: reserved size of @buf, in bytes
382 * @maskp: pointer to bitmap to convert
383 * @nmaskbits: size of bitmap, in bits
385 * Exactly @nmaskbits bits are displayed. Hex digits are grouped into
386 * comma-separated sets of eight digits per set. Returns the number of
387 * characters which were written to *buf, excluding the trailing \0.
389 int bitmap_scnprintf(char *buf, unsigned int buflen,
390 const unsigned long *maskp, int nmaskbits)
392 int i, word, bit, len = 0;
394 const char *sep = "";
398 chunksz = nmaskbits & (CHUNKSZ - 1);
402 i = ALIGN(nmaskbits, CHUNKSZ) - CHUNKSZ;
403 for (; i >= 0; i -= CHUNKSZ) {
404 chunkmask = ((1ULL << chunksz) - 1);
405 word = i / BITS_PER_LONG;
406 bit = i % BITS_PER_LONG;
407 val = (maskp[word] >> bit) & chunkmask;
408 len += scnprintf(buf+len, buflen-len, "%s%0*lx", sep,
415 EXPORT_SYMBOL(bitmap_scnprintf);
418 * __bitmap_parse - convert an ASCII hex string into a bitmap.
419 * @buf: pointer to buffer containing string.
420 * @buflen: buffer size in bytes. If string is smaller than this
421 * then it must be terminated with a \0.
422 * @is_user: location of buffer, 0 indicates kernel space
423 * @maskp: pointer to bitmap array that will contain result.
424 * @nmaskbits: size of bitmap, in bits.
426 * Commas group hex digits into chunks. Each chunk defines exactly 32
427 * bits of the resultant bitmask. No chunk may specify a value larger
428 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
429 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
430 * characters and for grouping errors such as "1,,5", ",44", "," and "".
431 * Leading and trailing whitespace accepted, but not embedded whitespace.
433 int __bitmap_parse(const char *buf, unsigned int buflen,
434 int is_user, unsigned long *maskp,
437 int c, old_c, totaldigits, ndigits, nchunks, nbits;
439 const char __user __force *ubuf = (const char __user __force *)buf;
441 bitmap_zero(maskp, nmaskbits);
443 nchunks = nbits = totaldigits = c = 0;
447 /* Get the next chunk of the bitmap */
451 if (__get_user(c, ubuf++))
461 * If the last character was a space and the current
462 * character isn't '\0', we've got embedded whitespace.
463 * This is a no-no, so throw an error.
465 if (totaldigits && c && isspace(old_c))
468 /* A '\0' or a ',' signal the end of the chunk */
469 if (c == '\0' || c == ',')
476 * Make sure there are at least 4 free bits in 'chunk'.
477 * If not, this hexdigit will overflow 'chunk', so
480 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
483 chunk = (chunk << 4) | hex_to_bin(c);
484 ndigits++; totaldigits++;
488 if (nchunks == 0 && chunk == 0)
491 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
494 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
495 if (nbits > nmaskbits)
497 } while (buflen && c == ',');
501 EXPORT_SYMBOL(__bitmap_parse);
504 * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
506 * @ubuf: pointer to user buffer containing string.
507 * @ulen: buffer size in bytes. If string is smaller than this
508 * then it must be terminated with a \0.
509 * @maskp: pointer to bitmap array that will contain result.
510 * @nmaskbits: size of bitmap, in bits.
512 * Wrapper for __bitmap_parse(), providing it with user buffer.
514 * We cannot have this as an inline function in bitmap.h because it needs
515 * linux/uaccess.h to get the access_ok() declaration and this causes
516 * cyclic dependencies.
518 int bitmap_parse_user(const char __user *ubuf,
519 unsigned int ulen, unsigned long *maskp,
522 if (!access_ok(VERIFY_READ, ubuf, ulen))
524 return __bitmap_parse((const char __force *)ubuf,
525 ulen, 1, maskp, nmaskbits);
528 EXPORT_SYMBOL(bitmap_parse_user);
531 * bscnl_emit(buf, buflen, rbot, rtop, bp)
533 * Helper routine for bitmap_scnlistprintf(). Write decimal number
534 * or range to buf, suppressing output past buf+buflen, with optional
535 * comma-prefix. Return len of what was written to *buf, excluding the
538 static inline int bscnl_emit(char *buf, int buflen, int rbot, int rtop, int len)
541 len += scnprintf(buf + len, buflen - len, ",");
543 len += scnprintf(buf + len, buflen - len, "%d", rbot);
545 len += scnprintf(buf + len, buflen - len, "%d-%d", rbot, rtop);
550 * bitmap_scnlistprintf - convert bitmap to list format ASCII string
551 * @buf: byte buffer into which string is placed
552 * @buflen: reserved size of @buf, in bytes
553 * @maskp: pointer to bitmap to convert
554 * @nmaskbits: size of bitmap, in bits
556 * Output format is a comma-separated list of decimal numbers and
557 * ranges. Consecutively set bits are shown as two hyphen-separated
558 * decimal numbers, the smallest and largest bit numbers set in
559 * the range. Output format is compatible with the format
560 * accepted as input by bitmap_parselist().
562 * The return value is the number of characters which were written to *buf
563 * excluding the trailing '\0', as per ISO C99's scnprintf.
565 int bitmap_scnlistprintf(char *buf, unsigned int buflen,
566 const unsigned long *maskp, int nmaskbits)
569 /* current bit is 'cur', most recently seen range is [rbot, rtop] */
576 rbot = cur = find_first_bit(maskp, nmaskbits);
577 while (cur < nmaskbits) {
579 cur = find_next_bit(maskp, nmaskbits, cur+1);
580 if (cur >= nmaskbits || cur > rtop + 1) {
581 len = bscnl_emit(buf, buflen, rbot, rtop, len);
587 EXPORT_SYMBOL(bitmap_scnlistprintf);
590 * bitmap_print_to_pagebuf - convert bitmap to list or hex format ASCII string
591 * @list: indicates whether the bitmap must be list
592 * @buf: page aligned buffer into which string is placed
593 * @maskp: pointer to bitmap to convert
594 * @nmaskbits: size of bitmap, in bits
596 * Output format is a comma-separated list of decimal numbers and
597 * ranges if list is specified or hex digits grouped into comma-separated
598 * sets of 8 digits/set. Returns the number of characters written to buf.
600 int bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp,
603 ptrdiff_t len = PTR_ALIGN(buf + PAGE_SIZE - 1, PAGE_SIZE) - buf - 2;
607 n = list ? bitmap_scnlistprintf(buf, len, maskp, nmaskbits) :
608 bitmap_scnprintf(buf, len, maskp, nmaskbits);
614 EXPORT_SYMBOL(bitmap_print_to_pagebuf);
617 * __bitmap_parselist - convert list format ASCII string to bitmap
618 * @buf: read nul-terminated user string from this buffer
619 * @buflen: buffer size in bytes. If string is smaller than this
620 * then it must be terminated with a \0.
621 * @is_user: location of buffer, 0 indicates kernel space
622 * @maskp: write resulting mask here
623 * @nmaskbits: number of bits in mask to be written
625 * Input format is a comma-separated list of decimal numbers and
626 * ranges. Consecutively set bits are shown as two hyphen-separated
627 * decimal numbers, the smallest and largest bit numbers set in
630 * Returns 0 on success, -errno on invalid input strings.
632 * %-EINVAL: second number in range smaller than first
633 * %-EINVAL: invalid character in string
634 * %-ERANGE: bit number specified too large for mask
636 static int __bitmap_parselist(const char *buf, unsigned int buflen,
637 int is_user, unsigned long *maskp,
641 int c, old_c, totaldigits;
642 const char __user __force *ubuf = (const char __user __force *)buf;
643 int exp_digit, in_range;
646 bitmap_zero(maskp, nmaskbits);
652 /* Get the next cpu# or a range of cpu#'s */
656 if (__get_user(c, ubuf++))
665 * If the last character was a space and the current
666 * character isn't '\0', we've got embedded whitespace.
667 * This is a no-no, so throw an error.
669 if (totaldigits && c && isspace(old_c))
672 /* A '\0' or a ',' signal the end of a cpu# or range */
673 if (c == '\0' || c == ',')
677 if (exp_digit || in_range)
688 b = b * 10 + (c - '0');
702 } while (buflen && c == ',');
706 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
708 char *nl = strchrnul(bp, '\n');
711 return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
713 EXPORT_SYMBOL(bitmap_parselist);
717 * bitmap_parselist_user()
719 * @ubuf: pointer to user buffer containing string.
720 * @ulen: buffer size in bytes. If string is smaller than this
721 * then it must be terminated with a \0.
722 * @maskp: pointer to bitmap array that will contain result.
723 * @nmaskbits: size of bitmap, in bits.
725 * Wrapper for bitmap_parselist(), providing it with user buffer.
727 * We cannot have this as an inline function in bitmap.h because it needs
728 * linux/uaccess.h to get the access_ok() declaration and this causes
729 * cyclic dependencies.
731 int bitmap_parselist_user(const char __user *ubuf,
732 unsigned int ulen, unsigned long *maskp,
735 if (!access_ok(VERIFY_READ, ubuf, ulen))
737 return __bitmap_parselist((const char __force *)ubuf,
738 ulen, 1, maskp, nmaskbits);
740 EXPORT_SYMBOL(bitmap_parselist_user);
744 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
745 * @buf: pointer to a bitmap
746 * @pos: a bit position in @buf (0 <= @pos < @nbits)
747 * @nbits: number of valid bit positions in @buf
749 * Map the bit at position @pos in @buf (of length @nbits) to the
750 * ordinal of which set bit it is. If it is not set or if @pos
751 * is not a valid bit position, map to -1.
753 * If for example, just bits 4 through 7 are set in @buf, then @pos
754 * values 4 through 7 will get mapped to 0 through 3, respectively,
755 * and other @pos values will get mapped to -1. When @pos value 7
756 * gets mapped to (returns) @ord value 3 in this example, that means
757 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
759 * The bit positions 0 through @bits are valid positions in @buf.
761 static int bitmap_pos_to_ord(const unsigned long *buf, unsigned int pos, unsigned int nbits)
763 if (pos >= nbits || !test_bit(pos, buf))
766 return __bitmap_weight(buf, pos);
770 * bitmap_ord_to_pos - find position of n-th set bit in bitmap
771 * @buf: pointer to bitmap
772 * @ord: ordinal bit position (n-th set bit, n >= 0)
773 * @nbits: number of valid bit positions in @buf
775 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
776 * Value of @ord should be in range 0 <= @ord < weight(buf). If @ord
777 * >= weight(buf), returns @nbits.
779 * If for example, just bits 4 through 7 are set in @buf, then @ord
780 * values 0 through 3 will get mapped to 4 through 7, respectively,
781 * and all other @ord values returns @nbits. When @ord value 3
782 * gets mapped to (returns) @pos value 7 in this example, that means
783 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
785 * The bit positions 0 through @nbits-1 are valid positions in @buf.
787 unsigned int bitmap_ord_to_pos(const unsigned long *buf, unsigned int ord, unsigned int nbits)
791 for (pos = find_first_bit(buf, nbits);
793 pos = find_next_bit(buf, nbits, pos + 1))
800 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
801 * @dst: remapped result
802 * @src: subset to be remapped
803 * @old: defines domain of map
804 * @new: defines range of map
805 * @nbits: number of bits in each of these bitmaps
807 * Let @old and @new define a mapping of bit positions, such that
808 * whatever position is held by the n-th set bit in @old is mapped
809 * to the n-th set bit in @new. In the more general case, allowing
810 * for the possibility that the weight 'w' of @new is less than the
811 * weight of @old, map the position of the n-th set bit in @old to
812 * the position of the m-th set bit in @new, where m == n % w.
814 * If either of the @old and @new bitmaps are empty, or if @src and
815 * @dst point to the same location, then this routine copies @src
818 * The positions of unset bits in @old are mapped to themselves
819 * (the identify map).
821 * Apply the above specified mapping to @src, placing the result in
822 * @dst, clearing any bits previously set in @dst.
824 * For example, lets say that @old has bits 4 through 7 set, and
825 * @new has bits 12 through 15 set. This defines the mapping of bit
826 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
827 * bit positions unchanged. So if say @src comes into this routine
828 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
831 void bitmap_remap(unsigned long *dst, const unsigned long *src,
832 const unsigned long *old, const unsigned long *new,
835 unsigned int oldbit, w;
837 if (dst == src) /* following doesn't handle inplace remaps */
839 bitmap_zero(dst, nbits);
841 w = bitmap_weight(new, nbits);
842 for_each_set_bit(oldbit, src, nbits) {
843 int n = bitmap_pos_to_ord(old, oldbit, nbits);
846 set_bit(oldbit, dst); /* identity map */
848 set_bit(bitmap_ord_to_pos(new, n % w, nbits), dst);
851 EXPORT_SYMBOL(bitmap_remap);
854 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
855 * @oldbit: bit position to be mapped
856 * @old: defines domain of map
857 * @new: defines range of map
858 * @bits: number of bits in each of these bitmaps
860 * Let @old and @new define a mapping of bit positions, such that
861 * whatever position is held by the n-th set bit in @old is mapped
862 * to the n-th set bit in @new. In the more general case, allowing
863 * for the possibility that the weight 'w' of @new is less than the
864 * weight of @old, map the position of the n-th set bit in @old to
865 * the position of the m-th set bit in @new, where m == n % w.
867 * The positions of unset bits in @old are mapped to themselves
868 * (the identify map).
870 * Apply the above specified mapping to bit position @oldbit, returning
871 * the new bit position.
873 * For example, lets say that @old has bits 4 through 7 set, and
874 * @new has bits 12 through 15 set. This defines the mapping of bit
875 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
876 * bit positions unchanged. So if say @oldbit is 5, then this routine
879 int bitmap_bitremap(int oldbit, const unsigned long *old,
880 const unsigned long *new, int bits)
882 int w = bitmap_weight(new, bits);
883 int n = bitmap_pos_to_ord(old, oldbit, bits);
887 return bitmap_ord_to_pos(new, n % w, bits);
889 EXPORT_SYMBOL(bitmap_bitremap);
892 * bitmap_onto - translate one bitmap relative to another
893 * @dst: resulting translated bitmap
894 * @orig: original untranslated bitmap
895 * @relmap: bitmap relative to which translated
896 * @bits: number of bits in each of these bitmaps
898 * Set the n-th bit of @dst iff there exists some m such that the
899 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
900 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
901 * (If you understood the previous sentence the first time your
902 * read it, you're overqualified for your current job.)
904 * In other words, @orig is mapped onto (surjectively) @dst,
905 * using the map { <n, m> | the n-th bit of @relmap is the
906 * m-th set bit of @relmap }.
908 * Any set bits in @orig above bit number W, where W is the
909 * weight of (number of set bits in) @relmap are mapped nowhere.
910 * In particular, if for all bits m set in @orig, m >= W, then
911 * @dst will end up empty. In situations where the possibility
912 * of such an empty result is not desired, one way to avoid it is
913 * to use the bitmap_fold() operator, below, to first fold the
914 * @orig bitmap over itself so that all its set bits x are in the
915 * range 0 <= x < W. The bitmap_fold() operator does this by
916 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
918 * Example [1] for bitmap_onto():
919 * Let's say @relmap has bits 30-39 set, and @orig has bits
920 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,
921 * @dst will have bits 31, 33, 35, 37 and 39 set.
923 * When bit 0 is set in @orig, it means turn on the bit in
924 * @dst corresponding to whatever is the first bit (if any)
925 * that is turned on in @relmap. Since bit 0 was off in the
926 * above example, we leave off that bit (bit 30) in @dst.
928 * When bit 1 is set in @orig (as in the above example), it
929 * means turn on the bit in @dst corresponding to whatever
930 * is the second bit that is turned on in @relmap. The second
931 * bit in @relmap that was turned on in the above example was
932 * bit 31, so we turned on bit 31 in @dst.
934 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
935 * because they were the 4th, 6th, 8th and 10th set bits
936 * set in @relmap, and the 4th, 6th, 8th and 10th bits of
937 * @orig (i.e. bits 3, 5, 7 and 9) were also set.
939 * When bit 11 is set in @orig, it means turn on the bit in
940 * @dst corresponding to whatever is the twelfth bit that is
941 * turned on in @relmap. In the above example, there were
942 * only ten bits turned on in @relmap (30..39), so that bit
943 * 11 was set in @orig had no affect on @dst.
945 * Example [2] for bitmap_fold() + bitmap_onto():
946 * Let's say @relmap has these ten bits set:
947 * 40 41 42 43 45 48 53 61 74 95
948 * (for the curious, that's 40 plus the first ten terms of the
949 * Fibonacci sequence.)
951 * Further lets say we use the following code, invoking
952 * bitmap_fold() then bitmap_onto, as suggested above to
953 * avoid the possibility of an empty @dst result:
955 * unsigned long *tmp; // a temporary bitmap's bits
957 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
958 * bitmap_onto(dst, tmp, relmap, bits);
960 * Then this table shows what various values of @dst would be, for
961 * various @orig's. I list the zero-based positions of each set bit.
962 * The tmp column shows the intermediate result, as computed by
963 * using bitmap_fold() to fold the @orig bitmap modulo ten
964 * (the weight of @relmap).
971 * 1 3 5 7 1 3 5 7 41 43 48 61
972 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45
973 * 0 9 18 27 0 9 8 7 40 61 74 95
975 * 0 11 22 33 0 1 2 3 40 41 42 43
976 * 0 12 24 36 0 2 4 6 40 42 45 53
977 * 78 102 211 1 2 8 41 42 74 (*)
979 * (*) For these marked lines, if we hadn't first done bitmap_fold()
980 * into tmp, then the @dst result would have been empty.
982 * If either of @orig or @relmap is empty (no set bits), then @dst
983 * will be returned empty.
985 * If (as explained above) the only set bits in @orig are in positions
986 * m where m >= W, (where W is the weight of @relmap) then @dst will
987 * once again be returned empty.
989 * All bits in @dst not set by the above rule are cleared.
991 void bitmap_onto(unsigned long *dst, const unsigned long *orig,
992 const unsigned long *relmap, unsigned int bits)
994 unsigned int n, m; /* same meaning as in above comment */
996 if (dst == orig) /* following doesn't handle inplace mappings */
998 bitmap_zero(dst, bits);
1001 * The following code is a more efficient, but less
1002 * obvious, equivalent to the loop:
1003 * for (m = 0; m < bitmap_weight(relmap, bits); m++) {
1004 * n = bitmap_ord_to_pos(orig, m, bits);
1005 * if (test_bit(m, orig))
1011 for_each_set_bit(n, relmap, bits) {
1012 /* m == bitmap_pos_to_ord(relmap, n, bits) */
1013 if (test_bit(m, orig))
1018 EXPORT_SYMBOL(bitmap_onto);
1021 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
1022 * @dst: resulting smaller bitmap
1023 * @orig: original larger bitmap
1024 * @sz: specified size
1025 * @nbits: number of bits in each of these bitmaps
1027 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
1028 * Clear all other bits in @dst. See further the comment and
1029 * Example [2] for bitmap_onto() for why and how to use this.
1031 void bitmap_fold(unsigned long *dst, const unsigned long *orig,
1032 unsigned int sz, unsigned int nbits)
1034 unsigned int oldbit;
1036 if (dst == orig) /* following doesn't handle inplace mappings */
1038 bitmap_zero(dst, nbits);
1040 for_each_set_bit(oldbit, orig, nbits)
1041 set_bit(oldbit % sz, dst);
1043 EXPORT_SYMBOL(bitmap_fold);
1046 * Common code for bitmap_*_region() routines.
1047 * bitmap: array of unsigned longs corresponding to the bitmap
1048 * pos: the beginning of the region
1049 * order: region size (log base 2 of number of bits)
1050 * reg_op: operation(s) to perform on that region of bitmap
1052 * Can set, verify and/or release a region of bits in a bitmap,
1053 * depending on which combination of REG_OP_* flag bits is set.
1055 * A region of a bitmap is a sequence of bits in the bitmap, of
1056 * some size '1 << order' (a power of two), aligned to that same
1057 * '1 << order' power of two.
1059 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
1060 * Returns 0 in all other cases and reg_ops.
1064 REG_OP_ISFREE, /* true if region is all zero bits */
1065 REG_OP_ALLOC, /* set all bits in region */
1066 REG_OP_RELEASE, /* clear all bits in region */
1069 static int __reg_op(unsigned long *bitmap, unsigned int pos, int order, int reg_op)
1071 int nbits_reg; /* number of bits in region */
1072 int index; /* index first long of region in bitmap */
1073 int offset; /* bit offset region in bitmap[index] */
1074 int nlongs_reg; /* num longs spanned by region in bitmap */
1075 int nbitsinlong; /* num bits of region in each spanned long */
1076 unsigned long mask; /* bitmask for one long of region */
1077 int i; /* scans bitmap by longs */
1078 int ret = 0; /* return value */
1081 * Either nlongs_reg == 1 (for small orders that fit in one long)
1082 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
1084 nbits_reg = 1 << order;
1085 index = pos / BITS_PER_LONG;
1086 offset = pos - (index * BITS_PER_LONG);
1087 nlongs_reg = BITS_TO_LONGS(nbits_reg);
1088 nbitsinlong = min(nbits_reg, BITS_PER_LONG);
1091 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
1092 * overflows if nbitsinlong == BITS_PER_LONG.
1094 mask = (1UL << (nbitsinlong - 1));
1100 for (i = 0; i < nlongs_reg; i++) {
1101 if (bitmap[index + i] & mask)
1104 ret = 1; /* all bits in region free (zero) */
1108 for (i = 0; i < nlongs_reg; i++)
1109 bitmap[index + i] |= mask;
1112 case REG_OP_RELEASE:
1113 for (i = 0; i < nlongs_reg; i++)
1114 bitmap[index + i] &= ~mask;
1122 * bitmap_find_free_region - find a contiguous aligned mem region
1123 * @bitmap: array of unsigned longs corresponding to the bitmap
1124 * @bits: number of bits in the bitmap
1125 * @order: region size (log base 2 of number of bits) to find
1127 * Find a region of free (zero) bits in a @bitmap of @bits bits and
1128 * allocate them (set them to one). Only consider regions of length
1129 * a power (@order) of two, aligned to that power of two, which
1130 * makes the search algorithm much faster.
1132 * Return the bit offset in bitmap of the allocated region,
1133 * or -errno on failure.
1135 int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order)
1137 unsigned int pos, end; /* scans bitmap by regions of size order */
1139 for (pos = 0 ; (end = pos + (1U << order)) <= bits; pos = end) {
1140 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1142 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1147 EXPORT_SYMBOL(bitmap_find_free_region);
1150 * bitmap_release_region - release allocated bitmap region
1151 * @bitmap: array of unsigned longs corresponding to the bitmap
1152 * @pos: beginning of bit region to release
1153 * @order: region size (log base 2 of number of bits) to release
1155 * This is the complement to __bitmap_find_free_region() and releases
1156 * the found region (by clearing it in the bitmap).
1160 void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order)
1162 __reg_op(bitmap, pos, order, REG_OP_RELEASE);
1164 EXPORT_SYMBOL(bitmap_release_region);
1167 * bitmap_allocate_region - allocate bitmap region
1168 * @bitmap: array of unsigned longs corresponding to the bitmap
1169 * @pos: beginning of bit region to allocate
1170 * @order: region size (log base 2 of number of bits) to allocate
1172 * Allocate (set bits in) a specified region of a bitmap.
1174 * Return 0 on success, or %-EBUSY if specified region wasn't
1175 * free (not all bits were zero).
1177 int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order)
1179 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1181 return __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1183 EXPORT_SYMBOL(bitmap_allocate_region);
1186 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1187 * @dst: destination buffer
1188 * @src: bitmap to copy
1189 * @nbits: number of bits in the bitmap
1191 * Require nbits % BITS_PER_LONG == 0.
1194 void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits)
1198 for (i = 0; i < nbits/BITS_PER_LONG; i++) {
1199 if (BITS_PER_LONG == 64)
1200 dst[i] = cpu_to_le64(src[i]);
1202 dst[i] = cpu_to_le32(src[i]);
1205 EXPORT_SYMBOL(bitmap_copy_le);