fed up with those stupid warnings
[mmotm.git] / lib / bitmap.c
blob95070fa1cee83873026e9ee26f6c145746763bf2
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 i, int len)
276 int end = i + len;
278 while (i < end) {
279 __set_bit(i, map);
280 i++;
283 EXPORT_SYMBOL(bitmap_set);
285 void bitmap_clear(unsigned long *map, int start, int nr)
287 int end = start + nr;
289 while (start < end) {
290 __clear_bit(start, map);
291 start++;
294 EXPORT_SYMBOL(bitmap_clear);
296 unsigned long bitmap_find_next_zero_area(unsigned long *map,
297 unsigned long size,
298 unsigned long start,
299 unsigned int nr,
300 unsigned long align_mask)
302 unsigned long index, end, i;
303 again:
304 index = find_next_zero_bit(map, size, start);
306 /* Align allocation */
307 index = (index + align_mask) & ~align_mask;
309 end = index + nr;
310 if (end >= size)
311 return end;
312 i = find_next_bit(map, end, index);
313 if (i < end) {
314 start = i + 1;
315 goto again;
317 return index;
319 EXPORT_SYMBOL(bitmap_find_next_zero_area);
322 * Bitmap printing & parsing functions: first version by Bill Irwin,
323 * second version by Paul Jackson, third by Joe Korty.
326 #define CHUNKSZ 32
327 #define nbits_to_hold_value(val) fls(val)
328 #define unhex(c) (isdigit(c) ? (c - '0') : (toupper(c) - 'A' + 10))
329 #define BASEDEC 10 /* fancier cpuset lists input in decimal */
332 * bitmap_scnprintf - convert bitmap to an ASCII hex string.
333 * @buf: byte buffer into which string is placed
334 * @buflen: reserved size of @buf, in bytes
335 * @maskp: pointer to bitmap to convert
336 * @nmaskbits: size of bitmap, in bits
338 * Exactly @nmaskbits bits are displayed. Hex digits are grouped into
339 * comma-separated sets of eight digits per set.
341 int bitmap_scnprintf(char *buf, unsigned int buflen,
342 const unsigned long *maskp, int nmaskbits)
344 int i, word, bit, len = 0;
345 unsigned long val;
346 const char *sep = "";
347 int chunksz;
348 u32 chunkmask;
350 chunksz = nmaskbits & (CHUNKSZ - 1);
351 if (chunksz == 0)
352 chunksz = CHUNKSZ;
354 i = ALIGN(nmaskbits, CHUNKSZ) - CHUNKSZ;
355 for (; i >= 0; i -= CHUNKSZ) {
356 chunkmask = ((1ULL << chunksz) - 1);
357 word = i / BITS_PER_LONG;
358 bit = i % BITS_PER_LONG;
359 val = (maskp[word] >> bit) & chunkmask;
360 len += scnprintf(buf+len, buflen-len, "%s%0*lx", sep,
361 (chunksz+3)/4, val);
362 chunksz = CHUNKSZ;
363 sep = ",";
365 return len;
367 EXPORT_SYMBOL(bitmap_scnprintf);
370 * __bitmap_parse - convert an ASCII hex string into a bitmap.
371 * @buf: pointer to buffer containing string.
372 * @buflen: buffer size in bytes. If string is smaller than this
373 * then it must be terminated with a \0.
374 * @is_user: location of buffer, 0 indicates kernel space
375 * @maskp: pointer to bitmap array that will contain result.
376 * @nmaskbits: size of bitmap, in bits.
378 * Commas group hex digits into chunks. Each chunk defines exactly 32
379 * bits of the resultant bitmask. No chunk may specify a value larger
380 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
381 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
382 * characters and for grouping errors such as "1,,5", ",44", "," and "".
383 * Leading and trailing whitespace accepted, but not embedded whitespace.
385 int __bitmap_parse(const char *buf, unsigned int buflen,
386 int is_user, unsigned long *maskp,
387 int nmaskbits)
389 int c, old_c, totaldigits, ndigits, nchunks, nbits;
390 u32 chunk;
391 const char __user *ubuf = buf;
393 bitmap_zero(maskp, nmaskbits);
395 nchunks = nbits = totaldigits = c = 0;
396 do {
397 chunk = ndigits = 0;
399 /* Get the next chunk of the bitmap */
400 while (buflen) {
401 old_c = c;
402 if (is_user) {
403 if (__get_user(c, ubuf++))
404 return -EFAULT;
406 else
407 c = *buf++;
408 buflen--;
409 if (isspace(c))
410 continue;
413 * If the last character was a space and the current
414 * character isn't '\0', we've got embedded whitespace.
415 * This is a no-no, so throw an error.
417 if (totaldigits && c && isspace(old_c))
418 return -EINVAL;
420 /* A '\0' or a ',' signal the end of the chunk */
421 if (c == '\0' || c == ',')
422 break;
424 if (!isxdigit(c))
425 return -EINVAL;
428 * Make sure there are at least 4 free bits in 'chunk'.
429 * If not, this hexdigit will overflow 'chunk', so
430 * throw an error.
432 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
433 return -EOVERFLOW;
435 chunk = (chunk << 4) | unhex(c);
436 ndigits++; totaldigits++;
438 if (ndigits == 0)
439 return -EINVAL;
440 if (nchunks == 0 && chunk == 0)
441 continue;
443 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
444 *maskp |= chunk;
445 nchunks++;
446 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
447 if (nbits > nmaskbits)
448 return -EOVERFLOW;
449 } while (buflen && c == ',');
451 return 0;
453 EXPORT_SYMBOL(__bitmap_parse);
456 * bitmap_parse_user()
458 * @ubuf: pointer to user buffer containing string.
459 * @ulen: buffer size in bytes. If string is smaller than this
460 * then it must be terminated with a \0.
461 * @maskp: pointer to bitmap array that will contain result.
462 * @nmaskbits: size of bitmap, in bits.
464 * Wrapper for __bitmap_parse(), providing it with user buffer.
466 * We cannot have this as an inline function in bitmap.h because it needs
467 * linux/uaccess.h to get the access_ok() declaration and this causes
468 * cyclic dependencies.
470 int bitmap_parse_user(const char __user *ubuf,
471 unsigned int ulen, unsigned long *maskp,
472 int nmaskbits)
474 if (!access_ok(VERIFY_READ, ubuf, ulen))
475 return -EFAULT;
476 return __bitmap_parse((const char *)ubuf, ulen, 1, maskp, nmaskbits);
478 EXPORT_SYMBOL(bitmap_parse_user);
481 * bscnl_emit(buf, buflen, rbot, rtop, bp)
483 * Helper routine for bitmap_scnlistprintf(). Write decimal number
484 * or range to buf, suppressing output past buf+buflen, with optional
485 * comma-prefix. Return len of what would be written to buf, if it
486 * all fit.
488 static inline int bscnl_emit(char *buf, int buflen, int rbot, int rtop, int len)
490 if (len > 0)
491 len += scnprintf(buf + len, buflen - len, ",");
492 if (rbot == rtop)
493 len += scnprintf(buf + len, buflen - len, "%d", rbot);
494 else
495 len += scnprintf(buf + len, buflen - len, "%d-%d", rbot, rtop);
496 return len;
500 * bitmap_scnlistprintf - convert bitmap to list format ASCII string
501 * @buf: byte buffer into which string is placed
502 * @buflen: reserved size of @buf, in bytes
503 * @maskp: pointer to bitmap to convert
504 * @nmaskbits: size of bitmap, in bits
506 * Output format is a comma-separated list of decimal numbers and
507 * ranges. Consecutively set bits are shown as two hyphen-separated
508 * decimal numbers, the smallest and largest bit numbers set in
509 * the range. Output format is compatible with the format
510 * accepted as input by bitmap_parselist().
512 * The return value is the number of characters which would be
513 * generated for the given input, excluding the trailing '\0', as
514 * per ISO C99.
516 int bitmap_scnlistprintf(char *buf, unsigned int buflen,
517 const unsigned long *maskp, int nmaskbits)
519 int len = 0;
520 /* current bit is 'cur', most recently seen range is [rbot, rtop] */
521 int cur, rbot, rtop;
523 if (buflen == 0)
524 return 0;
525 buf[0] = 0;
527 rbot = cur = find_first_bit(maskp, nmaskbits);
528 while (cur < nmaskbits) {
529 rtop = cur;
530 cur = find_next_bit(maskp, nmaskbits, cur+1);
531 if (cur >= nmaskbits || cur > rtop + 1) {
532 len = bscnl_emit(buf, buflen, rbot, rtop, len);
533 rbot = cur;
536 return len;
538 EXPORT_SYMBOL(bitmap_scnlistprintf);
541 * bitmap_parselist - convert list format ASCII string to bitmap
542 * @bp: read nul-terminated user string from this buffer
543 * @maskp: write resulting mask here
544 * @nmaskbits: number of bits in mask to be written
546 * Input format is a comma-separated list of decimal numbers and
547 * ranges. Consecutively set bits are shown as two hyphen-separated
548 * decimal numbers, the smallest and largest bit numbers set in
549 * the range.
551 * Returns 0 on success, -errno on invalid input strings.
552 * Error values:
553 * %-EINVAL: second number in range smaller than first
554 * %-EINVAL: invalid character in string
555 * %-ERANGE: bit number specified too large for mask
557 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
559 unsigned a, b;
561 bitmap_zero(maskp, nmaskbits);
562 do {
563 if (!isdigit(*bp))
564 return -EINVAL;
565 b = a = simple_strtoul(bp, (char **)&bp, BASEDEC);
566 if (*bp == '-') {
567 bp++;
568 if (!isdigit(*bp))
569 return -EINVAL;
570 b = simple_strtoul(bp, (char **)&bp, BASEDEC);
572 if (!(a <= b))
573 return -EINVAL;
574 if (b >= nmaskbits)
575 return -ERANGE;
576 while (a <= b) {
577 set_bit(a, maskp);
578 a++;
580 if (*bp == ',')
581 bp++;
582 } while (*bp != '\0' && *bp != '\n');
583 return 0;
585 EXPORT_SYMBOL(bitmap_parselist);
588 * bitmap_pos_to_ord(buf, pos, bits)
589 * @buf: pointer to a bitmap
590 * @pos: a bit position in @buf (0 <= @pos < @bits)
591 * @bits: number of valid bit positions in @buf
593 * Map the bit at position @pos in @buf (of length @bits) to the
594 * ordinal of which set bit it is. If it is not set or if @pos
595 * is not a valid bit position, map to -1.
597 * If for example, just bits 4 through 7 are set in @buf, then @pos
598 * values 4 through 7 will get mapped to 0 through 3, respectively,
599 * and other @pos values will get mapped to 0. When @pos value 7
600 * gets mapped to (returns) @ord value 3 in this example, that means
601 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
603 * The bit positions 0 through @bits are valid positions in @buf.
605 static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits)
607 int i, ord;
609 if (pos < 0 || pos >= bits || !test_bit(pos, buf))
610 return -1;
612 i = find_first_bit(buf, bits);
613 ord = 0;
614 while (i < pos) {
615 i = find_next_bit(buf, bits, i + 1);
616 ord++;
618 BUG_ON(i != pos);
620 return ord;
624 * bitmap_ord_to_pos(buf, ord, bits)
625 * @buf: pointer to bitmap
626 * @ord: ordinal bit position (n-th set bit, n >= 0)
627 * @bits: number of valid bit positions in @buf
629 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
630 * Value of @ord should be in range 0 <= @ord < weight(buf), else
631 * results are undefined.
633 * If for example, just bits 4 through 7 are set in @buf, then @ord
634 * values 0 through 3 will get mapped to 4 through 7, respectively,
635 * and all other @ord values return undefined values. When @ord value 3
636 * gets mapped to (returns) @pos value 7 in this example, that means
637 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
639 * The bit positions 0 through @bits are valid positions in @buf.
641 static int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits)
643 int pos = 0;
645 if (ord >= 0 && ord < bits) {
646 int i;
648 for (i = find_first_bit(buf, bits);
649 i < bits && ord > 0;
650 i = find_next_bit(buf, bits, i + 1))
651 ord--;
652 if (i < bits && ord == 0)
653 pos = i;
656 return pos;
660 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
661 * @dst: remapped result
662 * @src: subset to be remapped
663 * @old: defines domain of map
664 * @new: defines range of map
665 * @bits: number of bits in each of these bitmaps
667 * Let @old and @new define a mapping of bit positions, such that
668 * whatever position is held by the n-th set bit in @old is mapped
669 * to the n-th set bit in @new. In the more general case, allowing
670 * for the possibility that the weight 'w' of @new is less than the
671 * weight of @old, map the position of the n-th set bit in @old to
672 * the position of the m-th set bit in @new, where m == n % w.
674 * If either of the @old and @new bitmaps are empty, or if @src and
675 * @dst point to the same location, then this routine copies @src
676 * to @dst.
678 * The positions of unset bits in @old are mapped to themselves
679 * (the identify map).
681 * Apply the above specified mapping to @src, placing the result in
682 * @dst, clearing any bits previously set in @dst.
684 * For example, lets say that @old has bits 4 through 7 set, and
685 * @new has bits 12 through 15 set. This defines the mapping of bit
686 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
687 * bit positions unchanged. So if say @src comes into this routine
688 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
689 * 13 and 15 set.
691 void bitmap_remap(unsigned long *dst, const unsigned long *src,
692 const unsigned long *old, const unsigned long *new,
693 int bits)
695 int oldbit, w;
697 if (dst == src) /* following doesn't handle inplace remaps */
698 return;
699 bitmap_zero(dst, bits);
701 w = bitmap_weight(new, bits);
702 for (oldbit = find_first_bit(src, bits);
703 oldbit < bits;
704 oldbit = find_next_bit(src, bits, oldbit + 1)) {
705 int n = bitmap_pos_to_ord(old, oldbit, bits);
706 if (n < 0 || w == 0)
707 set_bit(oldbit, dst); /* identity map */
708 else
709 set_bit(bitmap_ord_to_pos(new, n % w, bits), dst);
712 EXPORT_SYMBOL(bitmap_remap);
715 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
716 * @oldbit: bit position to be mapped
717 * @old: defines domain of map
718 * @new: defines range of map
719 * @bits: number of bits in each of these bitmaps
721 * Let @old and @new define a mapping of bit positions, such that
722 * whatever position is held by the n-th set bit in @old is mapped
723 * to the n-th set bit in @new. In the more general case, allowing
724 * for the possibility that the weight 'w' of @new is less than the
725 * weight of @old, map the position of the n-th set bit in @old to
726 * the position of the m-th set bit in @new, where m == n % w.
728 * The positions of unset bits in @old are mapped to themselves
729 * (the identify map).
731 * Apply the above specified mapping to bit position @oldbit, returning
732 * the new bit position.
734 * For example, lets say that @old has bits 4 through 7 set, and
735 * @new has bits 12 through 15 set. This defines the mapping of bit
736 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
737 * bit positions unchanged. So if say @oldbit is 5, then this routine
738 * returns 13.
740 int bitmap_bitremap(int oldbit, const unsigned long *old,
741 const unsigned long *new, int bits)
743 int w = bitmap_weight(new, bits);
744 int n = bitmap_pos_to_ord(old, oldbit, bits);
745 if (n < 0 || w == 0)
746 return oldbit;
747 else
748 return bitmap_ord_to_pos(new, n % w, bits);
750 EXPORT_SYMBOL(bitmap_bitremap);
753 * bitmap_onto - translate one bitmap relative to another
754 * @dst: resulting translated bitmap
755 * @orig: original untranslated bitmap
756 * @relmap: bitmap relative to which translated
757 * @bits: number of bits in each of these bitmaps
759 * Set the n-th bit of @dst iff there exists some m such that the
760 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
761 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
762 * (If you understood the previous sentence the first time your
763 * read it, you're overqualified for your current job.)
765 * In other words, @orig is mapped onto (surjectively) @dst,
766 * using the the map { <n, m> | the n-th bit of @relmap is the
767 * m-th set bit of @relmap }.
769 * Any set bits in @orig above bit number W, where W is the
770 * weight of (number of set bits in) @relmap are mapped nowhere.
771 * In particular, if for all bits m set in @orig, m >= W, then
772 * @dst will end up empty. In situations where the possibility
773 * of such an empty result is not desired, one way to avoid it is
774 * to use the bitmap_fold() operator, below, to first fold the
775 * @orig bitmap over itself so that all its set bits x are in the
776 * range 0 <= x < W. The bitmap_fold() operator does this by
777 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
779 * Example [1] for bitmap_onto():
780 * Let's say @relmap has bits 30-39 set, and @orig has bits
781 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,
782 * @dst will have bits 31, 33, 35, 37 and 39 set.
784 * When bit 0 is set in @orig, it means turn on the bit in
785 * @dst corresponding to whatever is the first bit (if any)
786 * that is turned on in @relmap. Since bit 0 was off in the
787 * above example, we leave off that bit (bit 30) in @dst.
789 * When bit 1 is set in @orig (as in the above example), it
790 * means turn on the bit in @dst corresponding to whatever
791 * is the second bit that is turned on in @relmap. The second
792 * bit in @relmap that was turned on in the above example was
793 * bit 31, so we turned on bit 31 in @dst.
795 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
796 * because they were the 4th, 6th, 8th and 10th set bits
797 * set in @relmap, and the 4th, 6th, 8th and 10th bits of
798 * @orig (i.e. bits 3, 5, 7 and 9) were also set.
800 * When bit 11 is set in @orig, it means turn on the bit in
801 * @dst corresponding to whatever is the twelth bit that is
802 * turned on in @relmap. In the above example, there were
803 * only ten bits turned on in @relmap (30..39), so that bit
804 * 11 was set in @orig had no affect on @dst.
806 * Example [2] for bitmap_fold() + bitmap_onto():
807 * Let's say @relmap has these ten bits set:
808 * 40 41 42 43 45 48 53 61 74 95
809 * (for the curious, that's 40 plus the first ten terms of the
810 * Fibonacci sequence.)
812 * Further lets say we use the following code, invoking
813 * bitmap_fold() then bitmap_onto, as suggested above to
814 * avoid the possitility of an empty @dst result:
816 * unsigned long *tmp; // a temporary bitmap's bits
818 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
819 * bitmap_onto(dst, tmp, relmap, bits);
821 * Then this table shows what various values of @dst would be, for
822 * various @orig's. I list the zero-based positions of each set bit.
823 * The tmp column shows the intermediate result, as computed by
824 * using bitmap_fold() to fold the @orig bitmap modulo ten
825 * (the weight of @relmap).
827 * @orig tmp @dst
828 * 0 0 40
829 * 1 1 41
830 * 9 9 95
831 * 10 0 40 (*)
832 * 1 3 5 7 1 3 5 7 41 43 48 61
833 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45
834 * 0 9 18 27 0 9 8 7 40 61 74 95
835 * 0 10 20 30 0 40
836 * 0 11 22 33 0 1 2 3 40 41 42 43
837 * 0 12 24 36 0 2 4 6 40 42 45 53
838 * 78 102 211 1 2 8 41 42 74 (*)
840 * (*) For these marked lines, if we hadn't first done bitmap_fold()
841 * into tmp, then the @dst result would have been empty.
843 * If either of @orig or @relmap is empty (no set bits), then @dst
844 * will be returned empty.
846 * If (as explained above) the only set bits in @orig are in positions
847 * m where m >= W, (where W is the weight of @relmap) then @dst will
848 * once again be returned empty.
850 * All bits in @dst not set by the above rule are cleared.
852 void bitmap_onto(unsigned long *dst, const unsigned long *orig,
853 const unsigned long *relmap, int bits)
855 int n, m; /* same meaning as in above comment */
857 if (dst == orig) /* following doesn't handle inplace mappings */
858 return;
859 bitmap_zero(dst, bits);
862 * The following code is a more efficient, but less
863 * obvious, equivalent to the loop:
864 * for (m = 0; m < bitmap_weight(relmap, bits); m++) {
865 * n = bitmap_ord_to_pos(orig, m, bits);
866 * if (test_bit(m, orig))
867 * set_bit(n, dst);
871 m = 0;
872 for (n = find_first_bit(relmap, bits);
873 n < bits;
874 n = find_next_bit(relmap, bits, n + 1)) {
875 /* m == bitmap_pos_to_ord(relmap, n, bits) */
876 if (test_bit(m, orig))
877 set_bit(n, dst);
878 m++;
881 EXPORT_SYMBOL(bitmap_onto);
884 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
885 * @dst: resulting smaller bitmap
886 * @orig: original larger bitmap
887 * @sz: specified size
888 * @bits: number of bits in each of these bitmaps
890 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
891 * Clear all other bits in @dst. See further the comment and
892 * Example [2] for bitmap_onto() for why and how to use this.
894 void bitmap_fold(unsigned long *dst, const unsigned long *orig,
895 int sz, int bits)
897 int oldbit;
899 if (dst == orig) /* following doesn't handle inplace mappings */
900 return;
901 bitmap_zero(dst, bits);
903 for (oldbit = find_first_bit(orig, bits);
904 oldbit < bits;
905 oldbit = find_next_bit(orig, bits, oldbit + 1))
906 set_bit(oldbit % sz, dst);
908 EXPORT_SYMBOL(bitmap_fold);
911 * Common code for bitmap_*_region() routines.
912 * bitmap: array of unsigned longs corresponding to the bitmap
913 * pos: the beginning of the region
914 * order: region size (log base 2 of number of bits)
915 * reg_op: operation(s) to perform on that region of bitmap
917 * Can set, verify and/or release a region of bits in a bitmap,
918 * depending on which combination of REG_OP_* flag bits is set.
920 * A region of a bitmap is a sequence of bits in the bitmap, of
921 * some size '1 << order' (a power of two), aligned to that same
922 * '1 << order' power of two.
924 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
925 * Returns 0 in all other cases and reg_ops.
928 enum {
929 REG_OP_ISFREE, /* true if region is all zero bits */
930 REG_OP_ALLOC, /* set all bits in region */
931 REG_OP_RELEASE, /* clear all bits in region */
934 static int __reg_op(unsigned long *bitmap, int pos, int order, int reg_op)
936 int nbits_reg; /* number of bits in region */
937 int index; /* index first long of region in bitmap */
938 int offset; /* bit offset region in bitmap[index] */
939 int nlongs_reg; /* num longs spanned by region in bitmap */
940 int nbitsinlong; /* num bits of region in each spanned long */
941 unsigned long mask; /* bitmask for one long of region */
942 int i; /* scans bitmap by longs */
943 int ret = 0; /* return value */
946 * Either nlongs_reg == 1 (for small orders that fit in one long)
947 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
949 nbits_reg = 1 << order;
950 index = pos / BITS_PER_LONG;
951 offset = pos - (index * BITS_PER_LONG);
952 nlongs_reg = BITS_TO_LONGS(nbits_reg);
953 nbitsinlong = min(nbits_reg, BITS_PER_LONG);
956 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
957 * overflows if nbitsinlong == BITS_PER_LONG.
959 mask = (1UL << (nbitsinlong - 1));
960 mask += mask - 1;
961 mask <<= offset;
963 switch (reg_op) {
964 case REG_OP_ISFREE:
965 for (i = 0; i < nlongs_reg; i++) {
966 if (bitmap[index + i] & mask)
967 goto done;
969 ret = 1; /* all bits in region free (zero) */
970 break;
972 case REG_OP_ALLOC:
973 for (i = 0; i < nlongs_reg; i++)
974 bitmap[index + i] |= mask;
975 break;
977 case REG_OP_RELEASE:
978 for (i = 0; i < nlongs_reg; i++)
979 bitmap[index + i] &= ~mask;
980 break;
982 done:
983 return ret;
987 * bitmap_find_free_region - find a contiguous aligned mem region
988 * @bitmap: array of unsigned longs corresponding to the bitmap
989 * @bits: number of bits in the bitmap
990 * @order: region size (log base 2 of number of bits) to find
992 * Find a region of free (zero) bits in a @bitmap of @bits bits and
993 * allocate them (set them to one). Only consider regions of length
994 * a power (@order) of two, aligned to that power of two, which
995 * makes the search algorithm much faster.
997 * Return the bit offset in bitmap of the allocated region,
998 * or -errno on failure.
1000 int bitmap_find_free_region(unsigned long *bitmap, int bits, int order)
1002 int pos, end; /* scans bitmap by regions of size order */
1004 for (pos = 0 ; (end = pos + (1 << order)) <= bits; pos = end) {
1005 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1006 continue;
1007 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1008 return pos;
1010 return -ENOMEM;
1012 EXPORT_SYMBOL(bitmap_find_free_region);
1015 * bitmap_release_region - release allocated bitmap region
1016 * @bitmap: array of unsigned longs corresponding to the bitmap
1017 * @pos: beginning of bit region to release
1018 * @order: region size (log base 2 of number of bits) to release
1020 * This is the complement to __bitmap_find_free_region() and releases
1021 * the found region (by clearing it in the bitmap).
1023 * No return value.
1025 void bitmap_release_region(unsigned long *bitmap, int pos, int order)
1027 __reg_op(bitmap, pos, order, REG_OP_RELEASE);
1029 EXPORT_SYMBOL(bitmap_release_region);
1032 * bitmap_allocate_region - allocate bitmap region
1033 * @bitmap: array of unsigned longs corresponding to the bitmap
1034 * @pos: beginning of bit region to allocate
1035 * @order: region size (log base 2 of number of bits) to allocate
1037 * Allocate (set bits in) a specified region of a bitmap.
1039 * Return 0 on success, or %-EBUSY if specified region wasn't
1040 * free (not all bits were zero).
1042 int bitmap_allocate_region(unsigned long *bitmap, int pos, int order)
1044 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1045 return -EBUSY;
1046 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1047 return 0;
1049 EXPORT_SYMBOL(bitmap_allocate_region);
1052 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1053 * @dst: destination buffer
1054 * @src: bitmap to copy
1055 * @nbits: number of bits in the bitmap
1057 * Require nbits % BITS_PER_LONG == 0.
1059 void bitmap_copy_le(void *dst, const unsigned long *src, int nbits)
1061 unsigned long *d = dst;
1062 int i;
1064 for (i = 0; i < nbits/BITS_PER_LONG; i++) {
1065 if (BITS_PER_LONG == 64)
1066 d[i] = cpu_to_le64(src[i]);
1067 else
1068 d[i] = cpu_to_le32(src[i]);
1071 EXPORT_SYMBOL(bitmap_copy_le);