Btrfs: tweak the delayed inode reservations again
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / lib / bitmap.c
blob2f4412e4d0719c25ca1d4948d489eee8c998f444
1 /*
2 * lib/bitmap.c
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.
7 */
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
19 * BITS_PER_LONG.
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
28 * results.
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
33 * in output bitmaps.
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)
45 if (bitmap[k])
46 return 0;
48 if (bits % BITS_PER_LONG)
49 if (bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
50 return 0;
52 return 1;
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)
60 if (~bitmap[k])
61 return 0;
63 if (bits % BITS_PER_LONG)
64 if (~bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
65 return 0;
67 return 1;
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])
77 return 0;
79 if (bits % BITS_PER_LONG)
80 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
81 return 0;
83 return 1;
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)
91 dst[k] = ~src[k];
93 if (bits % BITS_PER_LONG)
94 dst[k] = ~src[k] & BITMAP_LAST_WORD_MASK(bits);
96 EXPORT_SYMBOL(__bitmap_complement);
98 /**
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)
123 upper = 0;
124 else {
125 upper = src[off + k + 1];
126 if (off + k + 1 == lim - 1 && left)
127 upper &= mask;
129 lower = src[off + k];
130 if (left && off + k == lim - 1)
131 lower &= mask;
132 dst[k] = upper << (BITS_PER_LONG - rem) | lower >> rem;
133 if (left && k == lim - 1)
134 dst[k] &= mask;
136 if (off)
137 memset(&dst[lim - off], 0, off*sizeof(unsigned long));
139 EXPORT_SYMBOL(__bitmap_shift_right);
143 * __bitmap_shift_left - logical left shift of the bits in a bitmap
144 * @dst : destination bitmap
145 * @src : source bitmap
146 * @shift : shift by this many bits
147 * @bits : bitmap size, in bits
149 * Shifting left (multiplying) means moving bits in the LS -> MS
150 * direction. Zeros are fed into the vacated LS bit positions
151 * and those MS bits shifted off the top are lost.
154 void __bitmap_shift_left(unsigned long *dst,
155 const unsigned long *src, int shift, int bits)
157 int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;
158 int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
159 for (k = lim - off - 1; k >= 0; --k) {
160 unsigned long upper, lower;
163 * If shift is not word aligned, take upper rem bits of
164 * word below and make them the bottom rem bits of result.
166 if (rem && k > 0)
167 lower = src[k - 1];
168 else
169 lower = 0;
170 upper = src[k];
171 if (left && k == lim - 1)
172 upper &= (1UL << left) - 1;
173 dst[k + off] = lower >> (BITS_PER_LONG - rem) | upper << rem;
174 if (left && k + off == lim - 1)
175 dst[k + off] &= (1UL << left) - 1;
177 if (off)
178 memset(dst, 0, off*sizeof(unsigned long));
180 EXPORT_SYMBOL(__bitmap_shift_left);
182 int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
183 const unsigned long *bitmap2, int bits)
185 int k;
186 int nr = BITS_TO_LONGS(bits);
187 unsigned long result = 0;
189 for (k = 0; k < nr; k++)
190 result |= (dst[k] = bitmap1[k] & bitmap2[k]);
191 return result != 0;
193 EXPORT_SYMBOL(__bitmap_and);
195 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
196 const unsigned long *bitmap2, int bits)
198 int k;
199 int nr = BITS_TO_LONGS(bits);
201 for (k = 0; k < nr; k++)
202 dst[k] = bitmap1[k] | bitmap2[k];
204 EXPORT_SYMBOL(__bitmap_or);
206 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
207 const unsigned long *bitmap2, int bits)
209 int k;
210 int nr = BITS_TO_LONGS(bits);
212 for (k = 0; k < nr; k++)
213 dst[k] = bitmap1[k] ^ bitmap2[k];
215 EXPORT_SYMBOL(__bitmap_xor);
217 int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
218 const unsigned long *bitmap2, int bits)
220 int k;
221 int nr = BITS_TO_LONGS(bits);
222 unsigned long result = 0;
224 for (k = 0; k < nr; k++)
225 result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
226 return result != 0;
228 EXPORT_SYMBOL(__bitmap_andnot);
230 int __bitmap_intersects(const unsigned long *bitmap1,
231 const unsigned long *bitmap2, int bits)
233 int k, lim = bits/BITS_PER_LONG;
234 for (k = 0; k < lim; ++k)
235 if (bitmap1[k] & bitmap2[k])
236 return 1;
238 if (bits % BITS_PER_LONG)
239 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
240 return 1;
241 return 0;
243 EXPORT_SYMBOL(__bitmap_intersects);
245 int __bitmap_subset(const unsigned long *bitmap1,
246 const unsigned long *bitmap2, int bits)
248 int k, lim = bits/BITS_PER_LONG;
249 for (k = 0; k < lim; ++k)
250 if (bitmap1[k] & ~bitmap2[k])
251 return 0;
253 if (bits % BITS_PER_LONG)
254 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
255 return 0;
256 return 1;
258 EXPORT_SYMBOL(__bitmap_subset);
260 int __bitmap_weight(const unsigned long *bitmap, int bits)
262 int k, w = 0, lim = bits/BITS_PER_LONG;
264 for (k = 0; k < lim; k++)
265 w += hweight_long(bitmap[k]);
267 if (bits % BITS_PER_LONG)
268 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
270 return w;
272 EXPORT_SYMBOL(__bitmap_weight);
274 void bitmap_set(unsigned long *map, int start, int nr)
276 unsigned long *p = map + BIT_WORD(start);
277 const int size = start + nr;
278 int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
279 unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
281 while (nr - bits_to_set >= 0) {
282 *p |= mask_to_set;
283 nr -= bits_to_set;
284 bits_to_set = BITS_PER_LONG;
285 mask_to_set = ~0UL;
286 p++;
288 if (nr) {
289 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
290 *p |= mask_to_set;
293 EXPORT_SYMBOL(bitmap_set);
295 void bitmap_clear(unsigned long *map, int start, int nr)
297 unsigned long *p = map + BIT_WORD(start);
298 const int size = start + nr;
299 int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
300 unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
302 while (nr - bits_to_clear >= 0) {
303 *p &= ~mask_to_clear;
304 nr -= bits_to_clear;
305 bits_to_clear = BITS_PER_LONG;
306 mask_to_clear = ~0UL;
307 p++;
309 if (nr) {
310 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
311 *p &= ~mask_to_clear;
314 EXPORT_SYMBOL(bitmap_clear);
317 * bitmap_find_next_zero_area - find a contiguous aligned zero area
318 * @map: The address to base the search on
319 * @size: The bitmap size in bits
320 * @start: The bitnumber to start searching at
321 * @nr: The number of zeroed bits we're looking for
322 * @align_mask: Alignment mask for zero area
324 * The @align_mask should be one less than a power of 2; the effect is that
325 * the bit offset of all zero areas this function finds is multiples of that
326 * power of 2. A @align_mask of 0 means no alignment is required.
328 unsigned long bitmap_find_next_zero_area(unsigned long *map,
329 unsigned long size,
330 unsigned long start,
331 unsigned int nr,
332 unsigned long align_mask)
334 unsigned long index, end, i;
335 again:
336 index = find_next_zero_bit(map, size, start);
338 /* Align allocation */
339 index = __ALIGN_MASK(index, align_mask);
341 end = index + nr;
342 if (end > size)
343 return end;
344 i = find_next_bit(map, end, index);
345 if (i < end) {
346 start = i + 1;
347 goto again;
349 return index;
351 EXPORT_SYMBOL(bitmap_find_next_zero_area);
354 * Bitmap printing & parsing functions: first version by Bill Irwin,
355 * second version by Paul Jackson, third by Joe Korty.
358 #define CHUNKSZ 32
359 #define nbits_to_hold_value(val) fls(val)
360 #define BASEDEC 10 /* fancier cpuset lists input in decimal */
363 * bitmap_scnprintf - convert bitmap to an ASCII hex string.
364 * @buf: byte buffer into which string is placed
365 * @buflen: reserved size of @buf, in bytes
366 * @maskp: pointer to bitmap to convert
367 * @nmaskbits: size of bitmap, in bits
369 * Exactly @nmaskbits bits are displayed. Hex digits are grouped into
370 * comma-separated sets of eight digits per set.
372 int bitmap_scnprintf(char *buf, unsigned int buflen,
373 const unsigned long *maskp, int nmaskbits)
375 int i, word, bit, len = 0;
376 unsigned long val;
377 const char *sep = "";
378 int chunksz;
379 u32 chunkmask;
381 chunksz = nmaskbits & (CHUNKSZ - 1);
382 if (chunksz == 0)
383 chunksz = CHUNKSZ;
385 i = ALIGN(nmaskbits, CHUNKSZ) - CHUNKSZ;
386 for (; i >= 0; i -= CHUNKSZ) {
387 chunkmask = ((1ULL << chunksz) - 1);
388 word = i / BITS_PER_LONG;
389 bit = i % BITS_PER_LONG;
390 val = (maskp[word] >> bit) & chunkmask;
391 len += scnprintf(buf+len, buflen-len, "%s%0*lx", sep,
392 (chunksz+3)/4, val);
393 chunksz = CHUNKSZ;
394 sep = ",";
396 return len;
398 EXPORT_SYMBOL(bitmap_scnprintf);
401 * __bitmap_parse - convert an ASCII hex string into a bitmap.
402 * @buf: pointer to buffer containing string.
403 * @buflen: buffer size in bytes. If string is smaller than this
404 * then it must be terminated with a \0.
405 * @is_user: location of buffer, 0 indicates kernel space
406 * @maskp: pointer to bitmap array that will contain result.
407 * @nmaskbits: size of bitmap, in bits.
409 * Commas group hex digits into chunks. Each chunk defines exactly 32
410 * bits of the resultant bitmask. No chunk may specify a value larger
411 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
412 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
413 * characters and for grouping errors such as "1,,5", ",44", "," and "".
414 * Leading and trailing whitespace accepted, but not embedded whitespace.
416 int __bitmap_parse(const char *buf, unsigned int buflen,
417 int is_user, unsigned long *maskp,
418 int nmaskbits)
420 int c, old_c, totaldigits, ndigits, nchunks, nbits;
421 u32 chunk;
422 const char __user *ubuf = buf;
424 bitmap_zero(maskp, nmaskbits);
426 nchunks = nbits = totaldigits = c = 0;
427 do {
428 chunk = ndigits = 0;
430 /* Get the next chunk of the bitmap */
431 while (buflen) {
432 old_c = c;
433 if (is_user) {
434 if (__get_user(c, ubuf++))
435 return -EFAULT;
437 else
438 c = *buf++;
439 buflen--;
440 if (isspace(c))
441 continue;
444 * If the last character was a space and the current
445 * character isn't '\0', we've got embedded whitespace.
446 * This is a no-no, so throw an error.
448 if (totaldigits && c && isspace(old_c))
449 return -EINVAL;
451 /* A '\0' or a ',' signal the end of the chunk */
452 if (c == '\0' || c == ',')
453 break;
455 if (!isxdigit(c))
456 return -EINVAL;
459 * Make sure there are at least 4 free bits in 'chunk'.
460 * If not, this hexdigit will overflow 'chunk', so
461 * throw an error.
463 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
464 return -EOVERFLOW;
466 chunk = (chunk << 4) | hex_to_bin(c);
467 ndigits++; totaldigits++;
469 if (ndigits == 0)
470 return -EINVAL;
471 if (nchunks == 0 && chunk == 0)
472 continue;
474 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
475 *maskp |= chunk;
476 nchunks++;
477 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
478 if (nbits > nmaskbits)
479 return -EOVERFLOW;
480 } while (buflen && c == ',');
482 return 0;
484 EXPORT_SYMBOL(__bitmap_parse);
487 * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
489 * @ubuf: pointer to user buffer containing string.
490 * @ulen: buffer size in bytes. If string is smaller than this
491 * then it must be terminated with a \0.
492 * @maskp: pointer to bitmap array that will contain result.
493 * @nmaskbits: size of bitmap, in bits.
495 * Wrapper for __bitmap_parse(), providing it with user buffer.
497 * We cannot have this as an inline function in bitmap.h because it needs
498 * linux/uaccess.h to get the access_ok() declaration and this causes
499 * cyclic dependencies.
501 int bitmap_parse_user(const char __user *ubuf,
502 unsigned int ulen, unsigned long *maskp,
503 int nmaskbits)
505 if (!access_ok(VERIFY_READ, ubuf, ulen))
506 return -EFAULT;
507 return __bitmap_parse((const char *)ubuf, ulen, 1, maskp, nmaskbits);
509 EXPORT_SYMBOL(bitmap_parse_user);
512 * bscnl_emit(buf, buflen, rbot, rtop, bp)
514 * Helper routine for bitmap_scnlistprintf(). Write decimal number
515 * or range to buf, suppressing output past buf+buflen, with optional
516 * comma-prefix. Return len of what would be written to buf, if it
517 * all fit.
519 static inline int bscnl_emit(char *buf, int buflen, int rbot, int rtop, int len)
521 if (len > 0)
522 len += scnprintf(buf + len, buflen - len, ",");
523 if (rbot == rtop)
524 len += scnprintf(buf + len, buflen - len, "%d", rbot);
525 else
526 len += scnprintf(buf + len, buflen - len, "%d-%d", rbot, rtop);
527 return len;
531 * bitmap_scnlistprintf - convert bitmap to list format ASCII string
532 * @buf: byte buffer into which string is placed
533 * @buflen: reserved size of @buf, in bytes
534 * @maskp: pointer to bitmap to convert
535 * @nmaskbits: size of bitmap, in bits
537 * Output format is a comma-separated list of decimal numbers and
538 * ranges. Consecutively set bits are shown as two hyphen-separated
539 * decimal numbers, the smallest and largest bit numbers set in
540 * the range. Output format is compatible with the format
541 * accepted as input by bitmap_parselist().
543 * The return value is the number of characters which would be
544 * generated for the given input, excluding the trailing '\0', as
545 * per ISO C99.
547 int bitmap_scnlistprintf(char *buf, unsigned int buflen,
548 const unsigned long *maskp, int nmaskbits)
550 int len = 0;
551 /* current bit is 'cur', most recently seen range is [rbot, rtop] */
552 int cur, rbot, rtop;
554 if (buflen == 0)
555 return 0;
556 buf[0] = 0;
558 rbot = cur = find_first_bit(maskp, nmaskbits);
559 while (cur < nmaskbits) {
560 rtop = cur;
561 cur = find_next_bit(maskp, nmaskbits, cur+1);
562 if (cur >= nmaskbits || cur > rtop + 1) {
563 len = bscnl_emit(buf, buflen, rbot, rtop, len);
564 rbot = cur;
567 return len;
569 EXPORT_SYMBOL(bitmap_scnlistprintf);
572 * __bitmap_parselist - convert list format ASCII string to bitmap
573 * @buf: read nul-terminated user string from this buffer
574 * @buflen: buffer size in bytes. If string is smaller than this
575 * then it must be terminated with a \0.
576 * @is_user: location of buffer, 0 indicates kernel space
577 * @maskp: write resulting mask here
578 * @nmaskbits: number of bits in mask to be written
580 * Input format is a comma-separated list of decimal numbers and
581 * ranges. Consecutively set bits are shown as two hyphen-separated
582 * decimal numbers, the smallest and largest bit numbers set in
583 * the range.
585 * Returns 0 on success, -errno on invalid input strings.
586 * Error values:
587 * %-EINVAL: second number in range smaller than first
588 * %-EINVAL: invalid character in string
589 * %-ERANGE: bit number specified too large for mask
591 static int __bitmap_parselist(const char *buf, unsigned int buflen,
592 int is_user, unsigned long *maskp,
593 int nmaskbits)
595 unsigned a, b;
596 int c, old_c, totaldigits;
597 const char __user *ubuf = buf;
598 int exp_digit, in_range;
600 totaldigits = c = 0;
601 bitmap_zero(maskp, nmaskbits);
602 do {
603 exp_digit = 1;
604 in_range = 0;
605 a = b = 0;
607 /* Get the next cpu# or a range of cpu#'s */
608 while (buflen) {
609 old_c = c;
610 if (is_user) {
611 if (__get_user(c, ubuf++))
612 return -EFAULT;
613 } else
614 c = *buf++;
615 buflen--;
616 if (isspace(c))
617 continue;
620 * If the last character was a space and the current
621 * character isn't '\0', we've got embedded whitespace.
622 * This is a no-no, so throw an error.
624 if (totaldigits && c && isspace(old_c))
625 return -EINVAL;
627 /* A '\0' or a ',' signal the end of a cpu# or range */
628 if (c == '\0' || c == ',')
629 break;
631 if (c == '-') {
632 if (exp_digit || in_range)
633 return -EINVAL;
634 b = 0;
635 in_range = 1;
636 exp_digit = 1;
637 continue;
640 if (!isdigit(c))
641 return -EINVAL;
643 b = b * 10 + (c - '0');
644 if (!in_range)
645 a = b;
646 exp_digit = 0;
647 totaldigits++;
649 if (!(a <= b))
650 return -EINVAL;
651 if (b >= nmaskbits)
652 return -ERANGE;
653 while (a <= b) {
654 set_bit(a, maskp);
655 a++;
657 } while (buflen && c == ',');
658 return 0;
661 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
663 char *nl = strchr(bp, '\n');
664 int len;
666 if (nl)
667 len = nl - bp;
668 else
669 len = strlen(bp);
671 return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
673 EXPORT_SYMBOL(bitmap_parselist);
677 * bitmap_parselist_user()
679 * @ubuf: pointer to user buffer containing string.
680 * @ulen: buffer size in bytes. If string is smaller than this
681 * then it must be terminated with a \0.
682 * @maskp: pointer to bitmap array that will contain result.
683 * @nmaskbits: size of bitmap, in bits.
685 * Wrapper for bitmap_parselist(), providing it with user buffer.
687 * We cannot have this as an inline function in bitmap.h because it needs
688 * linux/uaccess.h to get the access_ok() declaration and this causes
689 * cyclic dependencies.
691 int bitmap_parselist_user(const char __user *ubuf,
692 unsigned int ulen, unsigned long *maskp,
693 int nmaskbits)
695 if (!access_ok(VERIFY_READ, ubuf, ulen))
696 return -EFAULT;
697 return __bitmap_parselist((const char *)ubuf,
698 ulen, 1, maskp, nmaskbits);
700 EXPORT_SYMBOL(bitmap_parselist_user);
704 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
705 * @buf: pointer to a bitmap
706 * @pos: a bit position in @buf (0 <= @pos < @bits)
707 * @bits: number of valid bit positions in @buf
709 * Map the bit at position @pos in @buf (of length @bits) to the
710 * ordinal of which set bit it is. If it is not set or if @pos
711 * is not a valid bit position, map to -1.
713 * If for example, just bits 4 through 7 are set in @buf, then @pos
714 * values 4 through 7 will get mapped to 0 through 3, respectively,
715 * and other @pos values will get mapped to 0. When @pos value 7
716 * gets mapped to (returns) @ord value 3 in this example, that means
717 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
719 * The bit positions 0 through @bits are valid positions in @buf.
721 static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits)
723 int i, ord;
725 if (pos < 0 || pos >= bits || !test_bit(pos, buf))
726 return -1;
728 i = find_first_bit(buf, bits);
729 ord = 0;
730 while (i < pos) {
731 i = find_next_bit(buf, bits, i + 1);
732 ord++;
734 BUG_ON(i != pos);
736 return ord;
740 * bitmap_ord_to_pos - find position of n-th set bit in bitmap
741 * @buf: pointer to bitmap
742 * @ord: ordinal bit position (n-th set bit, n >= 0)
743 * @bits: number of valid bit positions in @buf
745 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
746 * Value of @ord should be in range 0 <= @ord < weight(buf), else
747 * results are undefined.
749 * If for example, just bits 4 through 7 are set in @buf, then @ord
750 * values 0 through 3 will get mapped to 4 through 7, respectively,
751 * and all other @ord values return undefined values. When @ord value 3
752 * gets mapped to (returns) @pos value 7 in this example, that means
753 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
755 * The bit positions 0 through @bits are valid positions in @buf.
757 int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits)
759 int pos = 0;
761 if (ord >= 0 && ord < bits) {
762 int i;
764 for (i = find_first_bit(buf, bits);
765 i < bits && ord > 0;
766 i = find_next_bit(buf, bits, i + 1))
767 ord--;
768 if (i < bits && ord == 0)
769 pos = i;
772 return pos;
776 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
777 * @dst: remapped result
778 * @src: subset to be remapped
779 * @old: defines domain of map
780 * @new: defines range of map
781 * @bits: number of bits in each of these bitmaps
783 * Let @old and @new define a mapping of bit positions, such that
784 * whatever position is held by the n-th set bit in @old is mapped
785 * to the n-th set bit in @new. In the more general case, allowing
786 * for the possibility that the weight 'w' of @new is less than the
787 * weight of @old, map the position of the n-th set bit in @old to
788 * the position of the m-th set bit in @new, where m == n % w.
790 * If either of the @old and @new bitmaps are empty, or if @src and
791 * @dst point to the same location, then this routine copies @src
792 * to @dst.
794 * The positions of unset bits in @old are mapped to themselves
795 * (the identify map).
797 * Apply the above specified mapping to @src, placing the result in
798 * @dst, clearing any bits previously set in @dst.
800 * For example, lets say that @old has bits 4 through 7 set, and
801 * @new has bits 12 through 15 set. This defines the mapping of bit
802 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
803 * bit positions unchanged. So if say @src comes into this routine
804 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
805 * 13 and 15 set.
807 void bitmap_remap(unsigned long *dst, const unsigned long *src,
808 const unsigned long *old, const unsigned long *new,
809 int bits)
811 int oldbit, w;
813 if (dst == src) /* following doesn't handle inplace remaps */
814 return;
815 bitmap_zero(dst, bits);
817 w = bitmap_weight(new, bits);
818 for_each_set_bit(oldbit, src, bits) {
819 int n = bitmap_pos_to_ord(old, oldbit, bits);
821 if (n < 0 || w == 0)
822 set_bit(oldbit, dst); /* identity map */
823 else
824 set_bit(bitmap_ord_to_pos(new, n % w, bits), dst);
827 EXPORT_SYMBOL(bitmap_remap);
830 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
831 * @oldbit: bit position to be mapped
832 * @old: defines domain of map
833 * @new: defines range of map
834 * @bits: number of bits in each of these bitmaps
836 * Let @old and @new define a mapping of bit positions, such that
837 * whatever position is held by the n-th set bit in @old is mapped
838 * to the n-th set bit in @new. In the more general case, allowing
839 * for the possibility that the weight 'w' of @new is less than the
840 * weight of @old, map the position of the n-th set bit in @old to
841 * the position of the m-th set bit in @new, where m == n % w.
843 * The positions of unset bits in @old are mapped to themselves
844 * (the identify map).
846 * Apply the above specified mapping to bit position @oldbit, returning
847 * the new bit position.
849 * For example, lets say that @old has bits 4 through 7 set, and
850 * @new has bits 12 through 15 set. This defines the mapping of bit
851 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
852 * bit positions unchanged. So if say @oldbit is 5, then this routine
853 * returns 13.
855 int bitmap_bitremap(int oldbit, const unsigned long *old,
856 const unsigned long *new, int bits)
858 int w = bitmap_weight(new, bits);
859 int n = bitmap_pos_to_ord(old, oldbit, bits);
860 if (n < 0 || w == 0)
861 return oldbit;
862 else
863 return bitmap_ord_to_pos(new, n % w, bits);
865 EXPORT_SYMBOL(bitmap_bitremap);
868 * bitmap_onto - translate one bitmap relative to another
869 * @dst: resulting translated bitmap
870 * @orig: original untranslated bitmap
871 * @relmap: bitmap relative to which translated
872 * @bits: number of bits in each of these bitmaps
874 * Set the n-th bit of @dst iff there exists some m such that the
875 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
876 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
877 * (If you understood the previous sentence the first time your
878 * read it, you're overqualified for your current job.)
880 * In other words, @orig is mapped onto (surjectively) @dst,
881 * using the the map { <n, m> | the n-th bit of @relmap is the
882 * m-th set bit of @relmap }.
884 * Any set bits in @orig above bit number W, where W is the
885 * weight of (number of set bits in) @relmap are mapped nowhere.
886 * In particular, if for all bits m set in @orig, m >= W, then
887 * @dst will end up empty. In situations where the possibility
888 * of such an empty result is not desired, one way to avoid it is
889 * to use the bitmap_fold() operator, below, to first fold the
890 * @orig bitmap over itself so that all its set bits x are in the
891 * range 0 <= x < W. The bitmap_fold() operator does this by
892 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
894 * Example [1] for bitmap_onto():
895 * Let's say @relmap has bits 30-39 set, and @orig has bits
896 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,
897 * @dst will have bits 31, 33, 35, 37 and 39 set.
899 * When bit 0 is set in @orig, it means turn on the bit in
900 * @dst corresponding to whatever is the first bit (if any)
901 * that is turned on in @relmap. Since bit 0 was off in the
902 * above example, we leave off that bit (bit 30) in @dst.
904 * When bit 1 is set in @orig (as in the above example), it
905 * means turn on the bit in @dst corresponding to whatever
906 * is the second bit that is turned on in @relmap. The second
907 * bit in @relmap that was turned on in the above example was
908 * bit 31, so we turned on bit 31 in @dst.
910 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
911 * because they were the 4th, 6th, 8th and 10th set bits
912 * set in @relmap, and the 4th, 6th, 8th and 10th bits of
913 * @orig (i.e. bits 3, 5, 7 and 9) were also set.
915 * When bit 11 is set in @orig, it means turn on the bit in
916 * @dst corresponding to whatever is the twelfth bit that is
917 * turned on in @relmap. In the above example, there were
918 * only ten bits turned on in @relmap (30..39), so that bit
919 * 11 was set in @orig had no affect on @dst.
921 * Example [2] for bitmap_fold() + bitmap_onto():
922 * Let's say @relmap has these ten bits set:
923 * 40 41 42 43 45 48 53 61 74 95
924 * (for the curious, that's 40 plus the first ten terms of the
925 * Fibonacci sequence.)
927 * Further lets say we use the following code, invoking
928 * bitmap_fold() then bitmap_onto, as suggested above to
929 * avoid the possitility of an empty @dst result:
931 * unsigned long *tmp; // a temporary bitmap's bits
933 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
934 * bitmap_onto(dst, tmp, relmap, bits);
936 * Then this table shows what various values of @dst would be, for
937 * various @orig's. I list the zero-based positions of each set bit.
938 * The tmp column shows the intermediate result, as computed by
939 * using bitmap_fold() to fold the @orig bitmap modulo ten
940 * (the weight of @relmap).
942 * @orig tmp @dst
943 * 0 0 40
944 * 1 1 41
945 * 9 9 95
946 * 10 0 40 (*)
947 * 1 3 5 7 1 3 5 7 41 43 48 61
948 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45
949 * 0 9 18 27 0 9 8 7 40 61 74 95
950 * 0 10 20 30 0 40
951 * 0 11 22 33 0 1 2 3 40 41 42 43
952 * 0 12 24 36 0 2 4 6 40 42 45 53
953 * 78 102 211 1 2 8 41 42 74 (*)
955 * (*) For these marked lines, if we hadn't first done bitmap_fold()
956 * into tmp, then the @dst result would have been empty.
958 * If either of @orig or @relmap is empty (no set bits), then @dst
959 * will be returned empty.
961 * If (as explained above) the only set bits in @orig are in positions
962 * m where m >= W, (where W is the weight of @relmap) then @dst will
963 * once again be returned empty.
965 * All bits in @dst not set by the above rule are cleared.
967 void bitmap_onto(unsigned long *dst, const unsigned long *orig,
968 const unsigned long *relmap, int bits)
970 int n, m; /* same meaning as in above comment */
972 if (dst == orig) /* following doesn't handle inplace mappings */
973 return;
974 bitmap_zero(dst, bits);
977 * The following code is a more efficient, but less
978 * obvious, equivalent to the loop:
979 * for (m = 0; m < bitmap_weight(relmap, bits); m++) {
980 * n = bitmap_ord_to_pos(orig, m, bits);
981 * if (test_bit(m, orig))
982 * set_bit(n, dst);
986 m = 0;
987 for_each_set_bit(n, relmap, bits) {
988 /* m == bitmap_pos_to_ord(relmap, n, bits) */
989 if (test_bit(m, orig))
990 set_bit(n, dst);
991 m++;
994 EXPORT_SYMBOL(bitmap_onto);
997 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
998 * @dst: resulting smaller bitmap
999 * @orig: original larger bitmap
1000 * @sz: specified size
1001 * @bits: number of bits in each of these bitmaps
1003 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
1004 * Clear all other bits in @dst. See further the comment and
1005 * Example [2] for bitmap_onto() for why and how to use this.
1007 void bitmap_fold(unsigned long *dst, const unsigned long *orig,
1008 int sz, int bits)
1010 int oldbit;
1012 if (dst == orig) /* following doesn't handle inplace mappings */
1013 return;
1014 bitmap_zero(dst, bits);
1016 for_each_set_bit(oldbit, orig, bits)
1017 set_bit(oldbit % sz, dst);
1019 EXPORT_SYMBOL(bitmap_fold);
1022 * Common code for bitmap_*_region() routines.
1023 * bitmap: array of unsigned longs corresponding to the bitmap
1024 * pos: the beginning of the region
1025 * order: region size (log base 2 of number of bits)
1026 * reg_op: operation(s) to perform on that region of bitmap
1028 * Can set, verify and/or release a region of bits in a bitmap,
1029 * depending on which combination of REG_OP_* flag bits is set.
1031 * A region of a bitmap is a sequence of bits in the bitmap, of
1032 * some size '1 << order' (a power of two), aligned to that same
1033 * '1 << order' power of two.
1035 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
1036 * Returns 0 in all other cases and reg_ops.
1039 enum {
1040 REG_OP_ISFREE, /* true if region is all zero bits */
1041 REG_OP_ALLOC, /* set all bits in region */
1042 REG_OP_RELEASE, /* clear all bits in region */
1045 static int __reg_op(unsigned long *bitmap, int pos, int order, int reg_op)
1047 int nbits_reg; /* number of bits in region */
1048 int index; /* index first long of region in bitmap */
1049 int offset; /* bit offset region in bitmap[index] */
1050 int nlongs_reg; /* num longs spanned by region in bitmap */
1051 int nbitsinlong; /* num bits of region in each spanned long */
1052 unsigned long mask; /* bitmask for one long of region */
1053 int i; /* scans bitmap by longs */
1054 int ret = 0; /* return value */
1057 * Either nlongs_reg == 1 (for small orders that fit in one long)
1058 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
1060 nbits_reg = 1 << order;
1061 index = pos / BITS_PER_LONG;
1062 offset = pos - (index * BITS_PER_LONG);
1063 nlongs_reg = BITS_TO_LONGS(nbits_reg);
1064 nbitsinlong = min(nbits_reg, BITS_PER_LONG);
1067 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
1068 * overflows if nbitsinlong == BITS_PER_LONG.
1070 mask = (1UL << (nbitsinlong - 1));
1071 mask += mask - 1;
1072 mask <<= offset;
1074 switch (reg_op) {
1075 case REG_OP_ISFREE:
1076 for (i = 0; i < nlongs_reg; i++) {
1077 if (bitmap[index + i] & mask)
1078 goto done;
1080 ret = 1; /* all bits in region free (zero) */
1081 break;
1083 case REG_OP_ALLOC:
1084 for (i = 0; i < nlongs_reg; i++)
1085 bitmap[index + i] |= mask;
1086 break;
1088 case REG_OP_RELEASE:
1089 for (i = 0; i < nlongs_reg; i++)
1090 bitmap[index + i] &= ~mask;
1091 break;
1093 done:
1094 return ret;
1098 * bitmap_find_free_region - find a contiguous aligned mem region
1099 * @bitmap: array of unsigned longs corresponding to the bitmap
1100 * @bits: number of bits in the bitmap
1101 * @order: region size (log base 2 of number of bits) to find
1103 * Find a region of free (zero) bits in a @bitmap of @bits bits and
1104 * allocate them (set them to one). Only consider regions of length
1105 * a power (@order) of two, aligned to that power of two, which
1106 * makes the search algorithm much faster.
1108 * Return the bit offset in bitmap of the allocated region,
1109 * or -errno on failure.
1111 int bitmap_find_free_region(unsigned long *bitmap, int bits, int order)
1113 int pos, end; /* scans bitmap by regions of size order */
1115 for (pos = 0 ; (end = pos + (1 << order)) <= bits; pos = end) {
1116 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1117 continue;
1118 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1119 return pos;
1121 return -ENOMEM;
1123 EXPORT_SYMBOL(bitmap_find_free_region);
1126 * bitmap_release_region - release allocated bitmap region
1127 * @bitmap: array of unsigned longs corresponding to the bitmap
1128 * @pos: beginning of bit region to release
1129 * @order: region size (log base 2 of number of bits) to release
1131 * This is the complement to __bitmap_find_free_region() and releases
1132 * the found region (by clearing it in the bitmap).
1134 * No return value.
1136 void bitmap_release_region(unsigned long *bitmap, int pos, int order)
1138 __reg_op(bitmap, pos, order, REG_OP_RELEASE);
1140 EXPORT_SYMBOL(bitmap_release_region);
1143 * bitmap_allocate_region - allocate bitmap region
1144 * @bitmap: array of unsigned longs corresponding to the bitmap
1145 * @pos: beginning of bit region to allocate
1146 * @order: region size (log base 2 of number of bits) to allocate
1148 * Allocate (set bits in) a specified region of a bitmap.
1150 * Return 0 on success, or %-EBUSY if specified region wasn't
1151 * free (not all bits were zero).
1153 int bitmap_allocate_region(unsigned long *bitmap, int pos, int order)
1155 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1156 return -EBUSY;
1157 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1158 return 0;
1160 EXPORT_SYMBOL(bitmap_allocate_region);
1163 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1164 * @dst: destination buffer
1165 * @src: bitmap to copy
1166 * @nbits: number of bits in the bitmap
1168 * Require nbits % BITS_PER_LONG == 0.
1170 void bitmap_copy_le(void *dst, const unsigned long *src, int nbits)
1172 unsigned long *d = dst;
1173 int i;
1175 for (i = 0; i < nbits/BITS_PER_LONG; i++) {
1176 if (BITS_PER_LONG == 64)
1177 d[i] = cpu_to_le64(src[i]);
1178 else
1179 d[i] = cpu_to_le32(src[i]);
1182 EXPORT_SYMBOL(bitmap_copy_le);