3 * Helper functions for bitmap.h.
5 * This source code is licensed under the GNU General Public License,
6 * Version 2. See the file COPYING for more details.
8 #include <linux/module.h>
9 #include <linux/ctype.h>
10 #include <linux/errno.h>
11 #include <linux/bitmap.h>
12 #include <linux/bitops.h>
13 #include <linux/bug.h>
14 #include <asm/uaccess.h>
17 * bitmaps provide an array of bits, implemented using an an
18 * array of unsigned longs. The number of valid bits in a
19 * given bitmap does _not_ need to be an exact multiple of
22 * The possible unused bits in the last, partially used word
23 * of a bitmap are 'don't care'. The implementation makes
24 * no particular effort to keep them zero. It ensures that
25 * their value will not affect the results of any operation.
26 * The bitmap operations that return Boolean (bitmap_empty,
27 * for example) or scalar (bitmap_weight, for example) results
28 * carefully filter out these unused bits from impacting their
31 * These operations actually hold to a slightly stronger rule:
32 * if you don't input any bitmaps to these ops that have some
33 * unused bits set, then they won't output any set unused bits
36 * The byte ordering of bitmaps is more natural on little
37 * endian architectures. See the big-endian headers
38 * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
39 * for the best explanations of this ordering.
42 int __bitmap_empty(const unsigned long *bitmap, int bits)
44 int k, lim = bits/BITS_PER_LONG;
45 for (k = 0; k < lim; ++k)
49 if (bits % BITS_PER_LONG)
50 if (bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
55 EXPORT_SYMBOL(__bitmap_empty);
57 int __bitmap_full(const unsigned long *bitmap, int bits)
59 int k, lim = bits/BITS_PER_LONG;
60 for (k = 0; k < lim; ++k)
64 if (bits % BITS_PER_LONG)
65 if (~bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
70 EXPORT_SYMBOL(__bitmap_full);
72 int __bitmap_equal(const unsigned long *bitmap1,
73 const unsigned long *bitmap2, int bits)
75 int k, lim = bits/BITS_PER_LONG;
76 for (k = 0; k < lim; ++k)
77 if (bitmap1[k] != bitmap2[k])
80 if (bits % BITS_PER_LONG)
81 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
86 EXPORT_SYMBOL(__bitmap_equal);
88 void __bitmap_complement(unsigned long *dst, const unsigned long *src, int bits)
90 int k, lim = bits/BITS_PER_LONG;
91 for (k = 0; k < lim; ++k)
94 if (bits % BITS_PER_LONG)
95 dst[k] = ~src[k] & BITMAP_LAST_WORD_MASK(bits);
97 EXPORT_SYMBOL(__bitmap_complement);
100 * __bitmap_shift_right - logical right shift of the bits in a bitmap
101 * @dst : destination bitmap
102 * @src : source bitmap
103 * @shift : shift by this many bits
104 * @bits : bitmap size, in bits
106 * Shifting right (dividing) means moving bits in the MS -> LS bit
107 * direction. Zeros are fed into the vacated MS positions and the
108 * LS bits shifted off the bottom are lost.
110 void __bitmap_shift_right(unsigned long *dst,
111 const unsigned long *src, int shift, int bits)
113 int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;
114 int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
115 unsigned long mask = (1UL << left) - 1;
116 for (k = 0; off + k < lim; ++k) {
117 unsigned long upper, lower;
120 * If shift is not word aligned, take lower rem bits of
121 * word above and make them the top rem bits of result.
123 if (!rem || off + k + 1 >= lim)
126 upper = src[off + k + 1];
127 if (off + k + 1 == lim - 1 && left)
130 lower = src[off + k];
131 if (left && off + k == lim - 1)
133 dst[k] = upper << (BITS_PER_LONG - rem) | lower >> rem;
134 if (left && k == lim - 1)
138 memset(&dst[lim - off], 0, off*sizeof(unsigned long));
140 EXPORT_SYMBOL(__bitmap_shift_right);
144 * __bitmap_shift_left - logical left shift of the bits in a bitmap
145 * @dst : destination bitmap
146 * @src : source bitmap
147 * @shift : shift by this many bits
148 * @bits : bitmap size, in bits
150 * Shifting left (multiplying) means moving bits in the LS -> MS
151 * direction. Zeros are fed into the vacated LS bit positions
152 * and those MS bits shifted off the top are lost.
155 void __bitmap_shift_left(unsigned long *dst,
156 const unsigned long *src, int shift, int bits)
158 int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;
159 int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
160 for (k = lim - off - 1; k >= 0; --k) {
161 unsigned long upper, lower;
164 * If shift is not word aligned, take upper rem bits of
165 * word below and make them the bottom rem bits of result.
172 if (left && k == lim - 1)
173 upper &= (1UL << left) - 1;
174 dst[k + off] = lower >> (BITS_PER_LONG - rem) | upper << rem;
175 if (left && k + off == lim - 1)
176 dst[k + off] &= (1UL << left) - 1;
179 memset(dst, 0, off*sizeof(unsigned long));
181 EXPORT_SYMBOL(__bitmap_shift_left);
183 int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
184 const unsigned long *bitmap2, int bits)
187 int nr = BITS_TO_LONGS(bits);
188 unsigned long result = 0;
190 for (k = 0; k < nr; k++)
191 result |= (dst[k] = bitmap1[k] & bitmap2[k]);
194 EXPORT_SYMBOL(__bitmap_and);
196 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
197 const unsigned long *bitmap2, int bits)
200 int nr = BITS_TO_LONGS(bits);
202 for (k = 0; k < nr; k++)
203 dst[k] = bitmap1[k] | bitmap2[k];
205 EXPORT_SYMBOL(__bitmap_or);
207 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
208 const unsigned long *bitmap2, int bits)
211 int nr = BITS_TO_LONGS(bits);
213 for (k = 0; k < nr; k++)
214 dst[k] = bitmap1[k] ^ bitmap2[k];
216 EXPORT_SYMBOL(__bitmap_xor);
218 int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
219 const unsigned long *bitmap2, int bits)
222 int nr = BITS_TO_LONGS(bits);
223 unsigned long result = 0;
225 for (k = 0; k < nr; k++)
226 result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
229 EXPORT_SYMBOL(__bitmap_andnot);
231 int __bitmap_intersects(const unsigned long *bitmap1,
232 const unsigned long *bitmap2, int bits)
234 int k, lim = bits/BITS_PER_LONG;
235 for (k = 0; k < lim; ++k)
236 if (bitmap1[k] & bitmap2[k])
239 if (bits % BITS_PER_LONG)
240 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
244 EXPORT_SYMBOL(__bitmap_intersects);
246 int __bitmap_subset(const unsigned long *bitmap1,
247 const unsigned long *bitmap2, int bits)
249 int k, lim = bits/BITS_PER_LONG;
250 for (k = 0; k < lim; ++k)
251 if (bitmap1[k] & ~bitmap2[k])
254 if (bits % BITS_PER_LONG)
255 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
259 EXPORT_SYMBOL(__bitmap_subset);
261 int __bitmap_weight(const unsigned long *bitmap, int bits)
263 int k, w = 0, lim = bits/BITS_PER_LONG;
265 for (k = 0; k < lim; k++)
266 w += hweight_long(bitmap[k]);
268 if (bits % BITS_PER_LONG)
269 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
273 EXPORT_SYMBOL(__bitmap_weight);
275 void bitmap_set(unsigned long *map, int start, int nr)
277 unsigned long *p = map + BIT_WORD(start);
278 const int size = start + nr;
279 int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
280 unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
282 while (nr - bits_to_set >= 0) {
285 bits_to_set = BITS_PER_LONG;
290 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
294 EXPORT_SYMBOL(bitmap_set);
296 void bitmap_clear(unsigned long *map, int start, int nr)
298 unsigned long *p = map + BIT_WORD(start);
299 const int size = start + nr;
300 int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
301 unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
303 while (nr - bits_to_clear >= 0) {
304 *p &= ~mask_to_clear;
306 bits_to_clear = BITS_PER_LONG;
307 mask_to_clear = ~0UL;
311 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
312 *p &= ~mask_to_clear;
315 EXPORT_SYMBOL(bitmap_clear);
318 * bitmap_find_next_zero_area - find a contiguous aligned zero area
319 * @map: The address to base the search on
320 * @size: The bitmap size in bits
321 * @start: The bitnumber to start searching at
322 * @nr: The number of zeroed bits we're looking for
323 * @align_mask: Alignment mask for zero area
325 * The @align_mask should be one less than a power of 2; the effect is that
326 * the bit offset of all zero areas this function finds is multiples of that
327 * power of 2. A @align_mask of 0 means no alignment is required.
329 unsigned long bitmap_find_next_zero_area(unsigned long *map,
333 unsigned long align_mask)
335 unsigned long index, end, i;
337 index = find_next_zero_bit(map, size, start);
339 /* Align allocation */
340 index = __ALIGN_MASK(index, align_mask);
345 i = find_next_bit(map, end, index);
352 EXPORT_SYMBOL(bitmap_find_next_zero_area);
355 * Bitmap printing & parsing functions: first version by Bill Irwin,
356 * second version by Paul Jackson, third by Joe Korty.
360 #define nbits_to_hold_value(val) fls(val)
361 #define BASEDEC 10 /* fancier cpuset lists input in decimal */
364 * bitmap_scnprintf - convert bitmap to an ASCII hex string.
365 * @buf: byte buffer into which string is placed
366 * @buflen: reserved size of @buf, in bytes
367 * @maskp: pointer to bitmap to convert
368 * @nmaskbits: size of bitmap, in bits
370 * Exactly @nmaskbits bits are displayed. Hex digits are grouped into
371 * comma-separated sets of eight digits per set.
373 int bitmap_scnprintf(char *buf, unsigned int buflen,
374 const unsigned long *maskp, int nmaskbits)
376 int i, word, bit, len = 0;
378 const char *sep = "";
382 chunksz = nmaskbits & (CHUNKSZ - 1);
386 i = ALIGN(nmaskbits, CHUNKSZ) - CHUNKSZ;
387 for (; i >= 0; i -= CHUNKSZ) {
388 chunkmask = ((1ULL << chunksz) - 1);
389 word = i / BITS_PER_LONG;
390 bit = i % BITS_PER_LONG;
391 val = (maskp[word] >> bit) & chunkmask;
392 len += scnprintf(buf+len, buflen-len, "%s%0*lx", sep,
399 EXPORT_SYMBOL(bitmap_scnprintf);
402 * __bitmap_parse - convert an ASCII hex string into a bitmap.
403 * @buf: pointer to buffer containing string.
404 * @buflen: buffer size in bytes. If string is smaller than this
405 * then it must be terminated with a \0.
406 * @is_user: location of buffer, 0 indicates kernel space
407 * @maskp: pointer to bitmap array that will contain result.
408 * @nmaskbits: size of bitmap, in bits.
410 * Commas group hex digits into chunks. Each chunk defines exactly 32
411 * bits of the resultant bitmask. No chunk may specify a value larger
412 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
413 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
414 * characters and for grouping errors such as "1,,5", ",44", "," and "".
415 * Leading and trailing whitespace accepted, but not embedded whitespace.
417 int __bitmap_parse(const char *buf, unsigned int buflen,
418 int is_user, unsigned long *maskp,
421 int c, old_c, totaldigits, ndigits, nchunks, nbits;
423 const char __user __force *ubuf = (const char __user __force *)buf;
425 bitmap_zero(maskp, nmaskbits);
427 nchunks = nbits = totaldigits = c = 0;
431 /* Get the next chunk of the bitmap */
435 if (__get_user(c, ubuf++))
445 * If the last character was a space and the current
446 * character isn't '\0', we've got embedded whitespace.
447 * This is a no-no, so throw an error.
449 if (totaldigits && c && isspace(old_c))
452 /* A '\0' or a ',' signal the end of the chunk */
453 if (c == '\0' || c == ',')
460 * Make sure there are at least 4 free bits in 'chunk'.
461 * If not, this hexdigit will overflow 'chunk', so
464 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
467 chunk = (chunk << 4) | hex_to_bin(c);
468 ndigits++; totaldigits++;
472 if (nchunks == 0 && chunk == 0)
475 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
478 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
479 if (nbits > nmaskbits)
481 } while (buflen && c == ',');
485 EXPORT_SYMBOL(__bitmap_parse);
488 * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
490 * @ubuf: pointer to user buffer containing string.
491 * @ulen: buffer size in bytes. If string is smaller than this
492 * then it must be terminated with a \0.
493 * @maskp: pointer to bitmap array that will contain result.
494 * @nmaskbits: size of bitmap, in bits.
496 * Wrapper for __bitmap_parse(), providing it with user buffer.
498 * We cannot have this as an inline function in bitmap.h because it needs
499 * linux/uaccess.h to get the access_ok() declaration and this causes
500 * cyclic dependencies.
502 int bitmap_parse_user(const char __user *ubuf,
503 unsigned int ulen, unsigned long *maskp,
506 if (!access_ok(VERIFY_READ, ubuf, ulen))
508 return __bitmap_parse((const char __force *)ubuf,
509 ulen, 1, maskp, nmaskbits);
512 EXPORT_SYMBOL(bitmap_parse_user);
515 * bscnl_emit(buf, buflen, rbot, rtop, bp)
517 * Helper routine for bitmap_scnlistprintf(). Write decimal number
518 * or range to buf, suppressing output past buf+buflen, with optional
519 * comma-prefix. Return len of what would be written to buf, if it
522 static inline int bscnl_emit(char *buf, int buflen, int rbot, int rtop, int len)
525 len += scnprintf(buf + len, buflen - len, ",");
527 len += scnprintf(buf + len, buflen - len, "%d", rbot);
529 len += scnprintf(buf + len, buflen - len, "%d-%d", rbot, rtop);
534 * bitmap_scnlistprintf - convert bitmap to list format ASCII string
535 * @buf: byte buffer into which string is placed
536 * @buflen: reserved size of @buf, in bytes
537 * @maskp: pointer to bitmap to convert
538 * @nmaskbits: size of bitmap, in bits
540 * Output format is a comma-separated list of decimal numbers and
541 * ranges. Consecutively set bits are shown as two hyphen-separated
542 * decimal numbers, the smallest and largest bit numbers set in
543 * the range. Output format is compatible with the format
544 * accepted as input by bitmap_parselist().
546 * The return value is the number of characters which would be
547 * generated for the given input, excluding the trailing '\0', as
550 int bitmap_scnlistprintf(char *buf, unsigned int buflen,
551 const unsigned long *maskp, int nmaskbits)
554 /* current bit is 'cur', most recently seen range is [rbot, rtop] */
561 rbot = cur = find_first_bit(maskp, nmaskbits);
562 while (cur < nmaskbits) {
564 cur = find_next_bit(maskp, nmaskbits, cur+1);
565 if (cur >= nmaskbits || cur > rtop + 1) {
566 len = bscnl_emit(buf, buflen, rbot, rtop, len);
572 EXPORT_SYMBOL(bitmap_scnlistprintf);
575 * __bitmap_parselist - convert list format ASCII string to bitmap
576 * @buf: read nul-terminated user string from this buffer
577 * @buflen: buffer size in bytes. If string is smaller than this
578 * then it must be terminated with a \0.
579 * @is_user: location of buffer, 0 indicates kernel space
580 * @maskp: write resulting mask here
581 * @nmaskbits: number of bits in mask to be written
583 * Input format is a comma-separated list of decimal numbers and
584 * ranges. Consecutively set bits are shown as two hyphen-separated
585 * decimal numbers, the smallest and largest bit numbers set in
588 * Returns 0 on success, -errno on invalid input strings.
590 * %-EINVAL: second number in range smaller than first
591 * %-EINVAL: invalid character in string
592 * %-ERANGE: bit number specified too large for mask
594 static int __bitmap_parselist(const char *buf, unsigned int buflen,
595 int is_user, unsigned long *maskp,
599 int c, old_c, totaldigits;
600 const char __user __force *ubuf = (const char __user __force *)buf;
601 int exp_digit, in_range;
604 bitmap_zero(maskp, nmaskbits);
610 /* Get the next cpu# or a range of cpu#'s */
614 if (__get_user(c, ubuf++))
623 * If the last character was a space and the current
624 * character isn't '\0', we've got embedded whitespace.
625 * This is a no-no, so throw an error.
627 if (totaldigits && c && isspace(old_c))
630 /* A '\0' or a ',' signal the end of a cpu# or range */
631 if (c == '\0' || c == ',')
635 if (exp_digit || in_range)
646 b = b * 10 + (c - '0');
660 } while (buflen && c == ',');
664 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
666 char *nl = strchr(bp, '\n');
674 return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
676 EXPORT_SYMBOL(bitmap_parselist);
680 * bitmap_parselist_user()
682 * @ubuf: pointer to user buffer containing string.
683 * @ulen: buffer size in bytes. If string is smaller than this
684 * then it must be terminated with a \0.
685 * @maskp: pointer to bitmap array that will contain result.
686 * @nmaskbits: size of bitmap, in bits.
688 * Wrapper for bitmap_parselist(), providing it with user buffer.
690 * We cannot have this as an inline function in bitmap.h because it needs
691 * linux/uaccess.h to get the access_ok() declaration and this causes
692 * cyclic dependencies.
694 int bitmap_parselist_user(const char __user *ubuf,
695 unsigned int ulen, unsigned long *maskp,
698 if (!access_ok(VERIFY_READ, ubuf, ulen))
700 return __bitmap_parselist((const char __force *)ubuf,
701 ulen, 1, maskp, nmaskbits);
703 EXPORT_SYMBOL(bitmap_parselist_user);
707 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
708 * @buf: pointer to a bitmap
709 * @pos: a bit position in @buf (0 <= @pos < @bits)
710 * @bits: number of valid bit positions in @buf
712 * Map the bit at position @pos in @buf (of length @bits) to the
713 * ordinal of which set bit it is. If it is not set or if @pos
714 * is not a valid bit position, map to -1.
716 * If for example, just bits 4 through 7 are set in @buf, then @pos
717 * values 4 through 7 will get mapped to 0 through 3, respectively,
718 * and other @pos values will get mapped to 0. When @pos value 7
719 * gets mapped to (returns) @ord value 3 in this example, that means
720 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
722 * The bit positions 0 through @bits are valid positions in @buf.
724 static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits)
728 if (pos < 0 || pos >= bits || !test_bit(pos, buf))
731 i = find_first_bit(buf, bits);
734 i = find_next_bit(buf, bits, i + 1);
743 * bitmap_ord_to_pos - find position of n-th set bit in bitmap
744 * @buf: pointer to bitmap
745 * @ord: ordinal bit position (n-th set bit, n >= 0)
746 * @bits: number of valid bit positions in @buf
748 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
749 * Value of @ord should be in range 0 <= @ord < weight(buf), else
750 * results are undefined.
752 * If for example, just bits 4 through 7 are set in @buf, then @ord
753 * values 0 through 3 will get mapped to 4 through 7, respectively,
754 * and all other @ord values return undefined values. When @ord value 3
755 * gets mapped to (returns) @pos value 7 in this example, that means
756 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
758 * The bit positions 0 through @bits are valid positions in @buf.
760 int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits)
764 if (ord >= 0 && ord < bits) {
767 for (i = find_first_bit(buf, bits);
769 i = find_next_bit(buf, bits, i + 1))
771 if (i < bits && ord == 0)
779 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
780 * @dst: remapped result
781 * @src: subset to be remapped
782 * @old: defines domain of map
783 * @new: defines range of map
784 * @bits: number of bits in each of these bitmaps
786 * Let @old and @new define a mapping of bit positions, such that
787 * whatever position is held by the n-th set bit in @old is mapped
788 * to the n-th set bit in @new. In the more general case, allowing
789 * for the possibility that the weight 'w' of @new is less than the
790 * weight of @old, map the position of the n-th set bit in @old to
791 * the position of the m-th set bit in @new, where m == n % w.
793 * If either of the @old and @new bitmaps are empty, or if @src and
794 * @dst point to the same location, then this routine copies @src
797 * The positions of unset bits in @old are mapped to themselves
798 * (the identify map).
800 * Apply the above specified mapping to @src, placing the result in
801 * @dst, clearing any bits previously set in @dst.
803 * For example, lets say that @old has bits 4 through 7 set, and
804 * @new has bits 12 through 15 set. This defines the mapping of bit
805 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
806 * bit positions unchanged. So if say @src comes into this routine
807 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
810 void bitmap_remap(unsigned long *dst, const unsigned long *src,
811 const unsigned long *old, const unsigned long *new,
816 if (dst == src) /* following doesn't handle inplace remaps */
818 bitmap_zero(dst, bits);
820 w = bitmap_weight(new, bits);
821 for_each_set_bit(oldbit, src, bits) {
822 int n = bitmap_pos_to_ord(old, oldbit, bits);
825 set_bit(oldbit, dst); /* identity map */
827 set_bit(bitmap_ord_to_pos(new, n % w, bits), dst);
830 EXPORT_SYMBOL(bitmap_remap);
833 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
834 * @oldbit: bit position to be mapped
835 * @old: defines domain of map
836 * @new: defines range of map
837 * @bits: number of bits in each of these bitmaps
839 * Let @old and @new define a mapping of bit positions, such that
840 * whatever position is held by the n-th set bit in @old is mapped
841 * to the n-th set bit in @new. In the more general case, allowing
842 * for the possibility that the weight 'w' of @new is less than the
843 * weight of @old, map the position of the n-th set bit in @old to
844 * the position of the m-th set bit in @new, where m == n % w.
846 * The positions of unset bits in @old are mapped to themselves
847 * (the identify map).
849 * Apply the above specified mapping to bit position @oldbit, returning
850 * the new bit position.
852 * For example, lets say that @old has bits 4 through 7 set, and
853 * @new has bits 12 through 15 set. This defines the mapping of bit
854 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
855 * bit positions unchanged. So if say @oldbit is 5, then this routine
858 int bitmap_bitremap(int oldbit, const unsigned long *old,
859 const unsigned long *new, int bits)
861 int w = bitmap_weight(new, bits);
862 int n = bitmap_pos_to_ord(old, oldbit, bits);
866 return bitmap_ord_to_pos(new, n % w, bits);
868 EXPORT_SYMBOL(bitmap_bitremap);
871 * bitmap_onto - translate one bitmap relative to another
872 * @dst: resulting translated bitmap
873 * @orig: original untranslated bitmap
874 * @relmap: bitmap relative to which translated
875 * @bits: number of bits in each of these bitmaps
877 * Set the n-th bit of @dst iff there exists some m such that the
878 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
879 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
880 * (If you understood the previous sentence the first time your
881 * read it, you're overqualified for your current job.)
883 * In other words, @orig is mapped onto (surjectively) @dst,
884 * using the the map { <n, m> | the n-th bit of @relmap is the
885 * m-th set bit of @relmap }.
887 * Any set bits in @orig above bit number W, where W is the
888 * weight of (number of set bits in) @relmap are mapped nowhere.
889 * In particular, if for all bits m set in @orig, m >= W, then
890 * @dst will end up empty. In situations where the possibility
891 * of such an empty result is not desired, one way to avoid it is
892 * to use the bitmap_fold() operator, below, to first fold the
893 * @orig bitmap over itself so that all its set bits x are in the
894 * range 0 <= x < W. The bitmap_fold() operator does this by
895 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
897 * Example [1] for bitmap_onto():
898 * Let's say @relmap has bits 30-39 set, and @orig has bits
899 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,
900 * @dst will have bits 31, 33, 35, 37 and 39 set.
902 * When bit 0 is set in @orig, it means turn on the bit in
903 * @dst corresponding to whatever is the first bit (if any)
904 * that is turned on in @relmap. Since bit 0 was off in the
905 * above example, we leave off that bit (bit 30) in @dst.
907 * When bit 1 is set in @orig (as in the above example), it
908 * means turn on the bit in @dst corresponding to whatever
909 * is the second bit that is turned on in @relmap. The second
910 * bit in @relmap that was turned on in the above example was
911 * bit 31, so we turned on bit 31 in @dst.
913 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
914 * because they were the 4th, 6th, 8th and 10th set bits
915 * set in @relmap, and the 4th, 6th, 8th and 10th bits of
916 * @orig (i.e. bits 3, 5, 7 and 9) were also set.
918 * When bit 11 is set in @orig, it means turn on the bit in
919 * @dst corresponding to whatever is the twelfth bit that is
920 * turned on in @relmap. In the above example, there were
921 * only ten bits turned on in @relmap (30..39), so that bit
922 * 11 was set in @orig had no affect on @dst.
924 * Example [2] for bitmap_fold() + bitmap_onto():
925 * Let's say @relmap has these ten bits set:
926 * 40 41 42 43 45 48 53 61 74 95
927 * (for the curious, that's 40 plus the first ten terms of the
928 * Fibonacci sequence.)
930 * Further lets say we use the following code, invoking
931 * bitmap_fold() then bitmap_onto, as suggested above to
932 * avoid the possitility of an empty @dst result:
934 * unsigned long *tmp; // a temporary bitmap's bits
936 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
937 * bitmap_onto(dst, tmp, relmap, bits);
939 * Then this table shows what various values of @dst would be, for
940 * various @orig's. I list the zero-based positions of each set bit.
941 * The tmp column shows the intermediate result, as computed by
942 * using bitmap_fold() to fold the @orig bitmap modulo ten
943 * (the weight of @relmap).
950 * 1 3 5 7 1 3 5 7 41 43 48 61
951 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45
952 * 0 9 18 27 0 9 8 7 40 61 74 95
954 * 0 11 22 33 0 1 2 3 40 41 42 43
955 * 0 12 24 36 0 2 4 6 40 42 45 53
956 * 78 102 211 1 2 8 41 42 74 (*)
958 * (*) For these marked lines, if we hadn't first done bitmap_fold()
959 * into tmp, then the @dst result would have been empty.
961 * If either of @orig or @relmap is empty (no set bits), then @dst
962 * will be returned empty.
964 * If (as explained above) the only set bits in @orig are in positions
965 * m where m >= W, (where W is the weight of @relmap) then @dst will
966 * once again be returned empty.
968 * All bits in @dst not set by the above rule are cleared.
970 void bitmap_onto(unsigned long *dst, const unsigned long *orig,
971 const unsigned long *relmap, int bits)
973 int n, m; /* same meaning as in above comment */
975 if (dst == orig) /* following doesn't handle inplace mappings */
977 bitmap_zero(dst, bits);
980 * The following code is a more efficient, but less
981 * obvious, equivalent to the loop:
982 * for (m = 0; m < bitmap_weight(relmap, bits); m++) {
983 * n = bitmap_ord_to_pos(orig, m, bits);
984 * if (test_bit(m, orig))
990 for_each_set_bit(n, relmap, bits) {
991 /* m == bitmap_pos_to_ord(relmap, n, bits) */
992 if (test_bit(m, orig))
997 EXPORT_SYMBOL(bitmap_onto);
1000 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
1001 * @dst: resulting smaller bitmap
1002 * @orig: original larger bitmap
1003 * @sz: specified size
1004 * @bits: number of bits in each of these bitmaps
1006 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
1007 * Clear all other bits in @dst. See further the comment and
1008 * Example [2] for bitmap_onto() for why and how to use this.
1010 void bitmap_fold(unsigned long *dst, const unsigned long *orig,
1015 if (dst == orig) /* following doesn't handle inplace mappings */
1017 bitmap_zero(dst, bits);
1019 for_each_set_bit(oldbit, orig, bits)
1020 set_bit(oldbit % sz, dst);
1022 EXPORT_SYMBOL(bitmap_fold);
1025 * Common code for bitmap_*_region() routines.
1026 * bitmap: array of unsigned longs corresponding to the bitmap
1027 * pos: the beginning of the region
1028 * order: region size (log base 2 of number of bits)
1029 * reg_op: operation(s) to perform on that region of bitmap
1031 * Can set, verify and/or release a region of bits in a bitmap,
1032 * depending on which combination of REG_OP_* flag bits is set.
1034 * A region of a bitmap is a sequence of bits in the bitmap, of
1035 * some size '1 << order' (a power of two), aligned to that same
1036 * '1 << order' power of two.
1038 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
1039 * Returns 0 in all other cases and reg_ops.
1043 REG_OP_ISFREE, /* true if region is all zero bits */
1044 REG_OP_ALLOC, /* set all bits in region */
1045 REG_OP_RELEASE, /* clear all bits in region */
1048 static int __reg_op(unsigned long *bitmap, int pos, int order, int reg_op)
1050 int nbits_reg; /* number of bits in region */
1051 int index; /* index first long of region in bitmap */
1052 int offset; /* bit offset region in bitmap[index] */
1053 int nlongs_reg; /* num longs spanned by region in bitmap */
1054 int nbitsinlong; /* num bits of region in each spanned long */
1055 unsigned long mask; /* bitmask for one long of region */
1056 int i; /* scans bitmap by longs */
1057 int ret = 0; /* return value */
1060 * Either nlongs_reg == 1 (for small orders that fit in one long)
1061 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
1063 nbits_reg = 1 << order;
1064 index = pos / BITS_PER_LONG;
1065 offset = pos - (index * BITS_PER_LONG);
1066 nlongs_reg = BITS_TO_LONGS(nbits_reg);
1067 nbitsinlong = min(nbits_reg, BITS_PER_LONG);
1070 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
1071 * overflows if nbitsinlong == BITS_PER_LONG.
1073 mask = (1UL << (nbitsinlong - 1));
1079 for (i = 0; i < nlongs_reg; i++) {
1080 if (bitmap[index + i] & mask)
1083 ret = 1; /* all bits in region free (zero) */
1087 for (i = 0; i < nlongs_reg; i++)
1088 bitmap[index + i] |= mask;
1091 case REG_OP_RELEASE:
1092 for (i = 0; i < nlongs_reg; i++)
1093 bitmap[index + i] &= ~mask;
1101 * bitmap_find_free_region - find a contiguous aligned mem region
1102 * @bitmap: array of unsigned longs corresponding to the bitmap
1103 * @bits: number of bits in the bitmap
1104 * @order: region size (log base 2 of number of bits) to find
1106 * Find a region of free (zero) bits in a @bitmap of @bits bits and
1107 * allocate them (set them to one). Only consider regions of length
1108 * a power (@order) of two, aligned to that power of two, which
1109 * makes the search algorithm much faster.
1111 * Return the bit offset in bitmap of the allocated region,
1112 * or -errno on failure.
1114 int bitmap_find_free_region(unsigned long *bitmap, int bits, int order)
1116 int pos, end; /* scans bitmap by regions of size order */
1118 for (pos = 0 ; (end = pos + (1 << order)) <= bits; pos = end) {
1119 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1121 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1126 EXPORT_SYMBOL(bitmap_find_free_region);
1129 * bitmap_release_region - release allocated bitmap region
1130 * @bitmap: array of unsigned longs corresponding to the bitmap
1131 * @pos: beginning of bit region to release
1132 * @order: region size (log base 2 of number of bits) to release
1134 * This is the complement to __bitmap_find_free_region() and releases
1135 * the found region (by clearing it in the bitmap).
1139 void bitmap_release_region(unsigned long *bitmap, int pos, int order)
1141 __reg_op(bitmap, pos, order, REG_OP_RELEASE);
1143 EXPORT_SYMBOL(bitmap_release_region);
1146 * bitmap_allocate_region - allocate bitmap region
1147 * @bitmap: array of unsigned longs corresponding to the bitmap
1148 * @pos: beginning of bit region to allocate
1149 * @order: region size (log base 2 of number of bits) to allocate
1151 * Allocate (set bits in) a specified region of a bitmap.
1153 * Return 0 on success, or %-EBUSY if specified region wasn't
1154 * free (not all bits were zero).
1156 int bitmap_allocate_region(unsigned long *bitmap, int pos, int order)
1158 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1160 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1163 EXPORT_SYMBOL(bitmap_allocate_region);
1166 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1167 * @dst: destination buffer
1168 * @src: bitmap to copy
1169 * @nbits: number of bits in the bitmap
1171 * Require nbits % BITS_PER_LONG == 0.
1173 void bitmap_copy_le(void *dst, const unsigned long *src, int nbits)
1175 unsigned long *d = dst;
1178 for (i = 0; i < nbits/BITS_PER_LONG; i++) {
1179 if (BITS_PER_LONG == 64)
1180 d[i] = cpu_to_le64(src[i]);
1182 d[i] = cpu_to_le32(src[i]);
1185 EXPORT_SYMBOL(bitmap_copy_le);