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 <asm/uaccess.h>
16 * bitmaps provide an array of bits, implemented using an an
17 * array of unsigned longs. The number of valid bits in a
18 * given bitmap does _not_ need to be an exact multiple of
21 * The possible unused bits in the last, partially used word
22 * of a bitmap are 'don't care'. The implementation makes
23 * no particular effort to keep them zero. It ensures that
24 * their value will not affect the results of any operation.
25 * The bitmap operations that return Boolean (bitmap_empty,
26 * for example) or scalar (bitmap_weight, for example) results
27 * carefully filter out these unused bits from impacting their
30 * These operations actually hold to a slightly stronger rule:
31 * if you don't input any bitmaps to these ops that have some
32 * unused bits set, then they won't output any set unused bits
35 * The byte ordering of bitmaps is more natural on little
36 * endian architectures. See the big-endian headers
37 * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
38 * for the best explanations of this ordering.
41 int __bitmap_empty(const unsigned long *bitmap, int bits)
43 int k, lim = bits/BITS_PER_LONG;
44 for (k = 0; k < lim; ++k)
48 if (bits % BITS_PER_LONG)
49 if (bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
54 EXPORT_SYMBOL(__bitmap_empty);
56 int __bitmap_full(const unsigned long *bitmap, int bits)
58 int k, lim = bits/BITS_PER_LONG;
59 for (k = 0; k < lim; ++k)
63 if (bits % BITS_PER_LONG)
64 if (~bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
69 EXPORT_SYMBOL(__bitmap_full);
71 int __bitmap_equal(const unsigned long *bitmap1,
72 const unsigned long *bitmap2, int bits)
74 int k, lim = bits/BITS_PER_LONG;
75 for (k = 0; k < lim; ++k)
76 if (bitmap1[k] != bitmap2[k])
79 if (bits % BITS_PER_LONG)
80 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
85 EXPORT_SYMBOL(__bitmap_equal);
87 void __bitmap_complement(unsigned long *dst, const unsigned long *src, int bits)
89 int k, lim = bits/BITS_PER_LONG;
90 for (k = 0; k < lim; ++k)
93 if (bits % BITS_PER_LONG)
94 dst[k] = ~src[k] & BITMAP_LAST_WORD_MASK(bits);
96 EXPORT_SYMBOL(__bitmap_complement);
99 * __bitmap_shift_right - logical right shift of the bits in a bitmap
100 * @dst : destination bitmap
101 * @src : source bitmap
102 * @shift : shift by this many bits
103 * @bits : bitmap size, in bits
105 * Shifting right (dividing) means moving bits in the MS -> LS bit
106 * direction. Zeros are fed into the vacated MS positions and the
107 * LS bits shifted off the bottom are lost.
109 void __bitmap_shift_right(unsigned long *dst,
110 const unsigned long *src, int shift, int bits)
112 int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;
113 int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
114 unsigned long mask = (1UL << left) - 1;
115 for (k = 0; off + k < lim; ++k) {
116 unsigned long upper, lower;
119 * If shift is not word aligned, take lower rem bits of
120 * word above and make them the top rem bits of result.
122 if (!rem || off + k + 1 >= lim)
125 upper = src[off + k + 1];
126 if (off + k + 1 == lim - 1 && left)
129 lower = src[off + k];
130 if (left && off + k == lim - 1)
132 dst[k] = lower >> rem;
134 dst[k] |= upper << (BITS_PER_LONG - 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] = upper << rem;
177 dst[k + off] |= lower >> (BITS_PER_LONG - rem);
178 if (left && k + off == lim - 1)
179 dst[k + off] &= (1UL << left) - 1;
182 memset(dst, 0, off*sizeof(unsigned long));
184 EXPORT_SYMBOL(__bitmap_shift_left);
186 int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
187 const unsigned long *bitmap2, int bits)
190 int nr = BITS_TO_LONGS(bits);
191 unsigned long result = 0;
193 for (k = 0; k < nr; k++)
194 result |= (dst[k] = bitmap1[k] & bitmap2[k]);
197 EXPORT_SYMBOL(__bitmap_and);
199 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
200 const unsigned long *bitmap2, int bits)
203 int nr = BITS_TO_LONGS(bits);
205 for (k = 0; k < nr; k++)
206 dst[k] = bitmap1[k] | bitmap2[k];
208 EXPORT_SYMBOL(__bitmap_or);
210 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
211 const unsigned long *bitmap2, int bits)
214 int nr = BITS_TO_LONGS(bits);
216 for (k = 0; k < nr; k++)
217 dst[k] = bitmap1[k] ^ bitmap2[k];
219 EXPORT_SYMBOL(__bitmap_xor);
221 int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
222 const unsigned long *bitmap2, int bits)
225 int nr = BITS_TO_LONGS(bits);
226 unsigned long result = 0;
228 for (k = 0; k < nr; k++)
229 result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
232 EXPORT_SYMBOL(__bitmap_andnot);
234 int __bitmap_intersects(const unsigned long *bitmap1,
235 const unsigned long *bitmap2, int bits)
237 int k, lim = bits/BITS_PER_LONG;
238 for (k = 0; k < lim; ++k)
239 if (bitmap1[k] & bitmap2[k])
242 if (bits % BITS_PER_LONG)
243 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
247 EXPORT_SYMBOL(__bitmap_intersects);
249 int __bitmap_subset(const unsigned long *bitmap1,
250 const unsigned long *bitmap2, int bits)
252 int k, lim = bits/BITS_PER_LONG;
253 for (k = 0; k < lim; ++k)
254 if (bitmap1[k] & ~bitmap2[k])
257 if (bits % BITS_PER_LONG)
258 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
262 EXPORT_SYMBOL(__bitmap_subset);
264 int __bitmap_weight(const unsigned long *bitmap, int bits)
266 int k, w = 0, lim = bits/BITS_PER_LONG;
268 for (k = 0; k < lim; k++)
269 w += hweight_long(bitmap[k]);
271 if (bits % BITS_PER_LONG)
272 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
276 EXPORT_SYMBOL(__bitmap_weight);
278 void bitmap_set(unsigned long *map, int start, int nr)
280 unsigned long *p = map + BIT_WORD(start);
281 const int size = start + nr;
282 int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
283 unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
285 while (nr - bits_to_set >= 0) {
288 bits_to_set = BITS_PER_LONG;
293 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
297 EXPORT_SYMBOL(bitmap_set);
299 void bitmap_clear(unsigned long *map, int start, int nr)
301 unsigned long *p = map + BIT_WORD(start);
302 const int size = start + nr;
303 int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
304 unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
306 while (nr - bits_to_clear >= 0) {
307 *p &= ~mask_to_clear;
309 bits_to_clear = BITS_PER_LONG;
310 mask_to_clear = ~0UL;
314 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
315 *p &= ~mask_to_clear;
318 EXPORT_SYMBOL(bitmap_clear);
321 * bitmap_find_next_zero_area - find a contiguous aligned zero area
322 * @map: The address to base the search on
323 * @size: The bitmap size in bits
324 * @start: The bitnumber to start searching at
325 * @nr: The number of zeroed bits we're looking for
326 * @align_mask: Alignment mask for zero area
328 * The @align_mask should be one less than a power of 2; the effect is that
329 * the bit offset of all zero areas this function finds is multiples of that
330 * power of 2. A @align_mask of 0 means no alignment is required.
332 unsigned long bitmap_find_next_zero_area(unsigned long *map,
336 unsigned long align_mask)
338 unsigned long index, end, i;
340 index = find_next_zero_bit(map, size, start);
342 /* Align allocation */
343 index = __ALIGN_MASK(index, align_mask);
348 i = find_next_bit(map, end, index);
355 EXPORT_SYMBOL(bitmap_find_next_zero_area);
358 * Bitmap printing & parsing functions: first version by Bill Irwin,
359 * second version by Paul Jackson, third by Joe Korty.
363 #define nbits_to_hold_value(val) fls(val)
364 #define BASEDEC 10 /* fancier cpuset lists input in decimal */
367 * bitmap_scnprintf - convert bitmap to an ASCII hex string.
368 * @buf: byte buffer into which string is placed
369 * @buflen: reserved size of @buf, in bytes
370 * @maskp: pointer to bitmap to convert
371 * @nmaskbits: size of bitmap, in bits
373 * Exactly @nmaskbits bits are displayed. Hex digits are grouped into
374 * comma-separated sets of eight digits per set.
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 would be written to buf, if it
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 would be
550 * generated for the given input, excluding the trailing '\0', as
553 int bitmap_scnlistprintf(char *buf, unsigned int buflen,
554 const unsigned long *maskp, int nmaskbits)
557 /* current bit is 'cur', most recently seen range is [rbot, rtop] */
564 rbot = cur = find_first_bit(maskp, nmaskbits);
565 while (cur < nmaskbits) {
567 cur = find_next_bit(maskp, nmaskbits, cur+1);
568 if (cur >= nmaskbits || cur > rtop + 1) {
569 len = bscnl_emit(buf, buflen, rbot, rtop, len);
575 EXPORT_SYMBOL(bitmap_scnlistprintf);
578 * __bitmap_parselist - convert list format ASCII string to bitmap
579 * @buf: read nul-terminated user string from this buffer
580 * @buflen: buffer size in bytes. If string is smaller than this
581 * then it must be terminated with a \0.
582 * @is_user: location of buffer, 0 indicates kernel space
583 * @maskp: write resulting mask here
584 * @nmaskbits: number of bits in mask to be written
586 * Input format is a comma-separated list of decimal numbers and
587 * ranges. Consecutively set bits are shown as two hyphen-separated
588 * decimal numbers, the smallest and largest bit numbers set in
591 * Returns 0 on success, -errno on invalid input strings.
593 * %-EINVAL: second number in range smaller than first
594 * %-EINVAL: invalid character in string
595 * %-ERANGE: bit number specified too large for mask
597 static int __bitmap_parselist(const char *buf, unsigned int buflen,
598 int is_user, unsigned long *maskp,
602 int c, old_c, totaldigits;
603 const char __user __force *ubuf = (const char __user __force *)buf;
604 int exp_digit, in_range;
607 bitmap_zero(maskp, nmaskbits);
613 /* Get the next cpu# or a range of cpu#'s */
617 if (__get_user(c, ubuf++))
626 * If the last character was a space and the current
627 * character isn't '\0', we've got embedded whitespace.
628 * This is a no-no, so throw an error.
630 if (totaldigits && c && isspace(old_c))
633 /* A '\0' or a ',' signal the end of a cpu# or range */
634 if (c == '\0' || c == ',')
638 if (exp_digit || in_range)
649 b = b * 10 + (c - '0');
663 } while (buflen && c == ',');
667 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
669 char *nl = strchr(bp, '\n');
677 return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
679 EXPORT_SYMBOL(bitmap_parselist);
683 * bitmap_parselist_user()
685 * @ubuf: pointer to user buffer containing string.
686 * @ulen: buffer size in bytes. If string is smaller than this
687 * then it must be terminated with a \0.
688 * @maskp: pointer to bitmap array that will contain result.
689 * @nmaskbits: size of bitmap, in bits.
691 * Wrapper for bitmap_parselist(), providing it with user buffer.
693 * We cannot have this as an inline function in bitmap.h because it needs
694 * linux/uaccess.h to get the access_ok() declaration and this causes
695 * cyclic dependencies.
697 int bitmap_parselist_user(const char __user *ubuf,
698 unsigned int ulen, unsigned long *maskp,
701 if (!access_ok(VERIFY_READ, ubuf, ulen))
703 return __bitmap_parselist((const char __force *)ubuf,
704 ulen, 1, maskp, nmaskbits);
706 EXPORT_SYMBOL(bitmap_parselist_user);
710 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
711 * @buf: pointer to a bitmap
712 * @pos: a bit position in @buf (0 <= @pos < @bits)
713 * @bits: number of valid bit positions in @buf
715 * Map the bit at position @pos in @buf (of length @bits) to the
716 * ordinal of which set bit it is. If it is not set or if @pos
717 * is not a valid bit position, map to -1.
719 * If for example, just bits 4 through 7 are set in @buf, then @pos
720 * values 4 through 7 will get mapped to 0 through 3, respectively,
721 * and other @pos values will get mapped to 0. When @pos value 7
722 * gets mapped to (returns) @ord value 3 in this example, that means
723 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
725 * The bit positions 0 through @bits are valid positions in @buf.
727 static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits)
731 if (pos < 0 || pos >= bits || !test_bit(pos, buf))
734 i = find_first_bit(buf, bits);
737 i = find_next_bit(buf, bits, i + 1);
746 * bitmap_ord_to_pos - find position of n-th set bit in bitmap
747 * @buf: pointer to bitmap
748 * @ord: ordinal bit position (n-th set bit, n >= 0)
749 * @bits: number of valid bit positions in @buf
751 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
752 * Value of @ord should be in range 0 <= @ord < weight(buf), else
753 * results are undefined.
755 * If for example, just bits 4 through 7 are set in @buf, then @ord
756 * values 0 through 3 will get mapped to 4 through 7, respectively,
757 * and all other @ord values return undefined values. When @ord value 3
758 * gets mapped to (returns) @pos value 7 in this example, that means
759 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
761 * The bit positions 0 through @bits are valid positions in @buf.
763 int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits)
767 if (ord >= 0 && ord < bits) {
770 for (i = find_first_bit(buf, bits);
772 i = find_next_bit(buf, bits, i + 1))
774 if (i < bits && ord == 0)
782 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
783 * @dst: remapped result
784 * @src: subset to be remapped
785 * @old: defines domain of map
786 * @new: defines range of map
787 * @bits: number of bits in each of these bitmaps
789 * Let @old and @new define a mapping of bit positions, such that
790 * whatever position is held by the n-th set bit in @old is mapped
791 * to the n-th set bit in @new. In the more general case, allowing
792 * for the possibility that the weight 'w' of @new is less than the
793 * weight of @old, map the position of the n-th set bit in @old to
794 * the position of the m-th set bit in @new, where m == n % w.
796 * If either of the @old and @new bitmaps are empty, or if @src and
797 * @dst point to the same location, then this routine copies @src
800 * The positions of unset bits in @old are mapped to themselves
801 * (the identify map).
803 * Apply the above specified mapping to @src, placing the result in
804 * @dst, clearing any bits previously set in @dst.
806 * For example, lets say that @old has bits 4 through 7 set, and
807 * @new has bits 12 through 15 set. This defines the mapping of bit
808 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
809 * bit positions unchanged. So if say @src comes into this routine
810 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
813 void bitmap_remap(unsigned long *dst, const unsigned long *src,
814 const unsigned long *old, const unsigned long *new,
819 if (dst == src) /* following doesn't handle inplace remaps */
821 bitmap_zero(dst, bits);
823 w = bitmap_weight(new, bits);
824 for_each_set_bit(oldbit, src, bits) {
825 int n = bitmap_pos_to_ord(old, oldbit, bits);
828 set_bit(oldbit, dst); /* identity map */
830 set_bit(bitmap_ord_to_pos(new, n % w, bits), dst);
833 EXPORT_SYMBOL(bitmap_remap);
836 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
837 * @oldbit: bit position to be mapped
838 * @old: defines domain of map
839 * @new: defines range of map
840 * @bits: number of bits in each of these bitmaps
842 * Let @old and @new define a mapping of bit positions, such that
843 * whatever position is held by the n-th set bit in @old is mapped
844 * to the n-th set bit in @new. In the more general case, allowing
845 * for the possibility that the weight 'w' of @new is less than the
846 * weight of @old, map the position of the n-th set bit in @old to
847 * the position of the m-th set bit in @new, where m == n % w.
849 * The positions of unset bits in @old are mapped to themselves
850 * (the identify map).
852 * Apply the above specified mapping to bit position @oldbit, returning
853 * the new bit position.
855 * For example, lets say that @old has bits 4 through 7 set, and
856 * @new has bits 12 through 15 set. This defines the mapping of bit
857 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
858 * bit positions unchanged. So if say @oldbit is 5, then this routine
861 int bitmap_bitremap(int oldbit, const unsigned long *old,
862 const unsigned long *new, int bits)
864 int w = bitmap_weight(new, bits);
865 int n = bitmap_pos_to_ord(old, oldbit, bits);
869 return bitmap_ord_to_pos(new, n % w, bits);
871 EXPORT_SYMBOL(bitmap_bitremap);
874 * bitmap_onto - translate one bitmap relative to another
875 * @dst: resulting translated bitmap
876 * @orig: original untranslated bitmap
877 * @relmap: bitmap relative to which translated
878 * @bits: number of bits in each of these bitmaps
880 * Set the n-th bit of @dst iff there exists some m such that the
881 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
882 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
883 * (If you understood the previous sentence the first time your
884 * read it, you're overqualified for your current job.)
886 * In other words, @orig is mapped onto (surjectively) @dst,
887 * using the the map { <n, m> | the n-th bit of @relmap is the
888 * m-th set bit of @relmap }.
890 * Any set bits in @orig above bit number W, where W is the
891 * weight of (number of set bits in) @relmap are mapped nowhere.
892 * In particular, if for all bits m set in @orig, m >= W, then
893 * @dst will end up empty. In situations where the possibility
894 * of such an empty result is not desired, one way to avoid it is
895 * to use the bitmap_fold() operator, below, to first fold the
896 * @orig bitmap over itself so that all its set bits x are in the
897 * range 0 <= x < W. The bitmap_fold() operator does this by
898 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
900 * Example [1] for bitmap_onto():
901 * Let's say @relmap has bits 30-39 set, and @orig has bits
902 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,
903 * @dst will have bits 31, 33, 35, 37 and 39 set.
905 * When bit 0 is set in @orig, it means turn on the bit in
906 * @dst corresponding to whatever is the first bit (if any)
907 * that is turned on in @relmap. Since bit 0 was off in the
908 * above example, we leave off that bit (bit 30) in @dst.
910 * When bit 1 is set in @orig (as in the above example), it
911 * means turn on the bit in @dst corresponding to whatever
912 * is the second bit that is turned on in @relmap. The second
913 * bit in @relmap that was turned on in the above example was
914 * bit 31, so we turned on bit 31 in @dst.
916 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
917 * because they were the 4th, 6th, 8th and 10th set bits
918 * set in @relmap, and the 4th, 6th, 8th and 10th bits of
919 * @orig (i.e. bits 3, 5, 7 and 9) were also set.
921 * When bit 11 is set in @orig, it means turn on the bit in
922 * @dst corresponding to whatever is the twelfth bit that is
923 * turned on in @relmap. In the above example, there were
924 * only ten bits turned on in @relmap (30..39), so that bit
925 * 11 was set in @orig had no affect on @dst.
927 * Example [2] for bitmap_fold() + bitmap_onto():
928 * Let's say @relmap has these ten bits set:
929 * 40 41 42 43 45 48 53 61 74 95
930 * (for the curious, that's 40 plus the first ten terms of the
931 * Fibonacci sequence.)
933 * Further lets say we use the following code, invoking
934 * bitmap_fold() then bitmap_onto, as suggested above to
935 * avoid the possitility of an empty @dst result:
937 * unsigned long *tmp; // a temporary bitmap's bits
939 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
940 * bitmap_onto(dst, tmp, relmap, bits);
942 * Then this table shows what various values of @dst would be, for
943 * various @orig's. I list the zero-based positions of each set bit.
944 * The tmp column shows the intermediate result, as computed by
945 * using bitmap_fold() to fold the @orig bitmap modulo ten
946 * (the weight of @relmap).
953 * 1 3 5 7 1 3 5 7 41 43 48 61
954 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45
955 * 0 9 18 27 0 9 8 7 40 61 74 95
957 * 0 11 22 33 0 1 2 3 40 41 42 43
958 * 0 12 24 36 0 2 4 6 40 42 45 53
959 * 78 102 211 1 2 8 41 42 74 (*)
961 * (*) For these marked lines, if we hadn't first done bitmap_fold()
962 * into tmp, then the @dst result would have been empty.
964 * If either of @orig or @relmap is empty (no set bits), then @dst
965 * will be returned empty.
967 * If (as explained above) the only set bits in @orig are in positions
968 * m where m >= W, (where W is the weight of @relmap) then @dst will
969 * once again be returned empty.
971 * All bits in @dst not set by the above rule are cleared.
973 void bitmap_onto(unsigned long *dst, const unsigned long *orig,
974 const unsigned long *relmap, int bits)
976 int n, m; /* same meaning as in above comment */
978 if (dst == orig) /* following doesn't handle inplace mappings */
980 bitmap_zero(dst, bits);
983 * The following code is a more efficient, but less
984 * obvious, equivalent to the loop:
985 * for (m = 0; m < bitmap_weight(relmap, bits); m++) {
986 * n = bitmap_ord_to_pos(orig, m, bits);
987 * if (test_bit(m, orig))
993 for_each_set_bit(n, relmap, bits) {
994 /* m == bitmap_pos_to_ord(relmap, n, bits) */
995 if (test_bit(m, orig))
1000 EXPORT_SYMBOL(bitmap_onto);
1003 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
1004 * @dst: resulting smaller bitmap
1005 * @orig: original larger bitmap
1006 * @sz: specified size
1007 * @bits: number of bits in each of these bitmaps
1009 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
1010 * Clear all other bits in @dst. See further the comment and
1011 * Example [2] for bitmap_onto() for why and how to use this.
1013 void bitmap_fold(unsigned long *dst, const unsigned long *orig,
1018 if (dst == orig) /* following doesn't handle inplace mappings */
1020 bitmap_zero(dst, bits);
1022 for_each_set_bit(oldbit, orig, bits)
1023 set_bit(oldbit % sz, dst);
1025 EXPORT_SYMBOL(bitmap_fold);
1028 * Common code for bitmap_*_region() routines.
1029 * bitmap: array of unsigned longs corresponding to the bitmap
1030 * pos: the beginning of the region
1031 * order: region size (log base 2 of number of bits)
1032 * reg_op: operation(s) to perform on that region of bitmap
1034 * Can set, verify and/or release a region of bits in a bitmap,
1035 * depending on which combination of REG_OP_* flag bits is set.
1037 * A region of a bitmap is a sequence of bits in the bitmap, of
1038 * some size '1 << order' (a power of two), aligned to that same
1039 * '1 << order' power of two.
1041 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
1042 * Returns 0 in all other cases and reg_ops.
1046 REG_OP_ISFREE, /* true if region is all zero bits */
1047 REG_OP_ALLOC, /* set all bits in region */
1048 REG_OP_RELEASE, /* clear all bits in region */
1051 static int __reg_op(unsigned long *bitmap, int pos, int order, int reg_op)
1053 int nbits_reg; /* number of bits in region */
1054 int index; /* index first long of region in bitmap */
1055 int offset; /* bit offset region in bitmap[index] */
1056 int nlongs_reg; /* num longs spanned by region in bitmap */
1057 int nbitsinlong; /* num bits of region in each spanned long */
1058 unsigned long mask; /* bitmask for one long of region */
1059 int i; /* scans bitmap by longs */
1060 int ret = 0; /* return value */
1063 * Either nlongs_reg == 1 (for small orders that fit in one long)
1064 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
1066 nbits_reg = 1 << order;
1067 index = pos / BITS_PER_LONG;
1068 offset = pos - (index * BITS_PER_LONG);
1069 nlongs_reg = BITS_TO_LONGS(nbits_reg);
1070 nbitsinlong = min(nbits_reg, BITS_PER_LONG);
1073 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
1074 * overflows if nbitsinlong == BITS_PER_LONG.
1076 mask = (1UL << (nbitsinlong - 1));
1082 for (i = 0; i < nlongs_reg; i++) {
1083 if (bitmap[index + i] & mask)
1086 ret = 1; /* all bits in region free (zero) */
1090 for (i = 0; i < nlongs_reg; i++)
1091 bitmap[index + i] |= mask;
1094 case REG_OP_RELEASE:
1095 for (i = 0; i < nlongs_reg; i++)
1096 bitmap[index + i] &= ~mask;
1104 * bitmap_find_free_region - find a contiguous aligned mem region
1105 * @bitmap: array of unsigned longs corresponding to the bitmap
1106 * @bits: number of bits in the bitmap
1107 * @order: region size (log base 2 of number of bits) to find
1109 * Find a region of free (zero) bits in a @bitmap of @bits bits and
1110 * allocate them (set them to one). Only consider regions of length
1111 * a power (@order) of two, aligned to that power of two, which
1112 * makes the search algorithm much faster.
1114 * Return the bit offset in bitmap of the allocated region,
1115 * or -errno on failure.
1117 int bitmap_find_free_region(unsigned long *bitmap, int bits, int order)
1119 int pos, end; /* scans bitmap by regions of size order */
1121 for (pos = 0 ; (end = pos + (1 << order)) <= bits; pos = end) {
1122 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1124 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1129 EXPORT_SYMBOL(bitmap_find_free_region);
1132 * bitmap_release_region - release allocated bitmap region
1133 * @bitmap: array of unsigned longs corresponding to the bitmap
1134 * @pos: beginning of bit region to release
1135 * @order: region size (log base 2 of number of bits) to release
1137 * This is the complement to __bitmap_find_free_region() and releases
1138 * the found region (by clearing it in the bitmap).
1142 void bitmap_release_region(unsigned long *bitmap, int pos, int order)
1144 __reg_op(bitmap, pos, order, REG_OP_RELEASE);
1146 EXPORT_SYMBOL(bitmap_release_region);
1149 * bitmap_allocate_region - allocate bitmap region
1150 * @bitmap: array of unsigned longs corresponding to the bitmap
1151 * @pos: beginning of bit region to allocate
1152 * @order: region size (log base 2 of number of bits) to allocate
1154 * Allocate (set bits in) a specified region of a bitmap.
1156 * Return 0 on success, or %-EBUSY if specified region wasn't
1157 * free (not all bits were zero).
1159 int bitmap_allocate_region(unsigned long *bitmap, int pos, int order)
1161 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1163 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1166 EXPORT_SYMBOL(bitmap_allocate_region);
1169 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1170 * @dst: destination buffer
1171 * @src: bitmap to copy
1172 * @nbits: number of bits in the bitmap
1174 * Require nbits % BITS_PER_LONG == 0.
1176 void bitmap_copy_le(void *dst, const unsigned long *src, int nbits)
1178 unsigned long *d = dst;
1181 for (i = 0; i < nbits/BITS_PER_LONG; i++) {
1182 if (BITS_PER_LONG == 64)
1183 d[i] = cpu_to_le64(src[i]);
1185 d[i] = cpu_to_le32(src[i]);
1188 EXPORT_SYMBOL(bitmap_copy_le);