projects/linux·blob v2.6.23 · refs

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1/*
2 * lib/bitmap.c
3 * Helper functions for bitmap.h.
4 *
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>
14
15/*
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.
20 *
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.
29 *
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.
34 *
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.
39 */
40
41int __bitmap_empty(const unsigned long *bitmap, int bits)
42{
43 int k, lim = bits/BITS_PER_LONG;
44 for (k = 0; k < lim; ++k)
45 if (bitmap[k])
46 return 0;
47
48 if (bits % BITS_PER_LONG)
49 if (bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
50 return 0;
51
52 return 1;
53}
54EXPORT_SYMBOL(__bitmap_empty);
55
56int __bitmap_full(const unsigned long *bitmap, int bits)
57{
58 int k, lim = bits/BITS_PER_LONG;
59 for (k = 0; k < lim; ++k)
60 if (~bitmap[k])
61 return 0;
62
63 if (bits % BITS_PER_LONG)
64 if (~bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
65 return 0;
66
67 return 1;
68}
69EXPORT_SYMBOL(__bitmap_full);
70
71int __bitmap_equal(const unsigned long *bitmap1,
72 const unsigned long *bitmap2, int bits)
73{
74 int k, lim = bits/BITS_PER_LONG;
75 for (k = 0; k < lim; ++k)
76 if (bitmap1[k] != bitmap2[k])
77 return 0;
78
79 if (bits % BITS_PER_LONG)
80 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
81 return 0;
82
83 return 1;
84}
85EXPORT_SYMBOL(__bitmap_equal);
86
87void __bitmap_complement(unsigned long *dst, const unsigned long *src, int bits)
88{
89 int k, lim = bits/BITS_PER_LONG;
90 for (k = 0; k < lim; ++k)
91 dst[k] = ~src[k];
92
93 if (bits % BITS_PER_LONG)
94 dst[k] = ~src[k] & BITMAP_LAST_WORD_MASK(bits);
95}
96EXPORT_SYMBOL(__bitmap_complement);
97
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
104 *
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.
108 */
109void __bitmap_shift_right(unsigned long *dst,
110 const unsigned long *src, int shift, int bits)
111{
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;
117
118 /*
119 * If shift is not word aligned, take lower rem bits of
120 * word above and make them the top rem bits of result.
121 */
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;
128 }
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;
135 }
136 if (off)
137 memset(&dst[lim - off], 0, off*sizeof(unsigned long));
138}
139EXPORT_SYMBOL(__bitmap_shift_right);
140
141
142/**
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
148 *
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.
152 */
153
154void __bitmap_shift_left(unsigned long *dst,
155 const unsigned long *src, int shift, int bits)
156{
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;
161
162 /*
163 * If shift is not word aligned, take upper rem bits of
164 * word below and make them the bottom rem bits of result.
165 */
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;
176 }
177 if (off)
178 memset(dst, 0, off*sizeof(unsigned long));
179}
180EXPORT_SYMBOL(__bitmap_shift_left);
181
182void __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
183 const unsigned long *bitmap2, int bits)
184{
185 int k;
186 int nr = BITS_TO_LONGS(bits);
187
188 for (k = 0; k < nr; k++)
189 dst[k] = bitmap1[k] & bitmap2[k];
190}
191EXPORT_SYMBOL(__bitmap_and);
192
193void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
194 const unsigned long *bitmap2, int bits)
195{
196 int k;
197 int nr = BITS_TO_LONGS(bits);
198
199 for (k = 0; k < nr; k++)
200 dst[k] = bitmap1[k] | bitmap2[k];
201}
202EXPORT_SYMBOL(__bitmap_or);
203
204void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
205 const unsigned long *bitmap2, int bits)
206{
207 int k;
208 int nr = BITS_TO_LONGS(bits);
209
210 for (k = 0; k < nr; k++)
211 dst[k] = bitmap1[k] ^ bitmap2[k];
212}
213EXPORT_SYMBOL(__bitmap_xor);
214
215void __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
216 const unsigned long *bitmap2, int bits)
217{
218 int k;
219 int nr = BITS_TO_LONGS(bits);
220
221 for (k = 0; k < nr; k++)
222 dst[k] = bitmap1[k] & ~bitmap2[k];
223}
224EXPORT_SYMBOL(__bitmap_andnot);
225
226int __bitmap_intersects(const unsigned long *bitmap1,
227 const unsigned long *bitmap2, int bits)
228{
229 int k, lim = bits/BITS_PER_LONG;
230 for (k = 0; k < lim; ++k)
231 if (bitmap1[k] & bitmap2[k])
232 return 1;
233
234 if (bits % BITS_PER_LONG)
235 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
236 return 1;
237 return 0;
238}
239EXPORT_SYMBOL(__bitmap_intersects);
240
241int __bitmap_subset(const unsigned long *bitmap1,
242 const unsigned long *bitmap2, int bits)
243{
244 int k, lim = bits/BITS_PER_LONG;
245 for (k = 0; k < lim; ++k)
246 if (bitmap1[k] & ~bitmap2[k])
247 return 0;
248
249 if (bits % BITS_PER_LONG)
250 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
251 return 0;
252 return 1;
253}
254EXPORT_SYMBOL(__bitmap_subset);
255
256int __bitmap_weight(const unsigned long *bitmap, int bits)
257{
258 int k, w = 0, lim = bits/BITS_PER_LONG;
259
260 for (k = 0; k < lim; k++)
261 w += hweight_long(bitmap[k]);
262
263 if (bits % BITS_PER_LONG)
264 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
265
266 return w;
267}
268EXPORT_SYMBOL(__bitmap_weight);
269
270/*
271 * Bitmap printing & parsing functions: first version by Bill Irwin,
272 * second version by Paul Jackson, third by Joe Korty.
273 */
274
275#define CHUNKSZ 32
276#define nbits_to_hold_value(val) fls(val)
277#define unhex(c) (isdigit(c) ? (c - '0') : (toupper(c) - 'A' + 10))
278#define BASEDEC 10 /* fancier cpuset lists input in decimal */
279
280/**
281 * bitmap_scnprintf - convert bitmap to an ASCII hex string.
282 * @buf: byte buffer into which string is placed
283 * @buflen: reserved size of @buf, in bytes
284 * @maskp: pointer to bitmap to convert
285 * @nmaskbits: size of bitmap, in bits
286 *
287 * Exactly @nmaskbits bits are displayed. Hex digits are grouped into
288 * comma-separated sets of eight digits per set.
289 */
290int bitmap_scnprintf(char *buf, unsigned int buflen,
291 const unsigned long *maskp, int nmaskbits)
292{
293 int i, word, bit, len = 0;
294 unsigned long val;
295 const char *sep = "";
296 int chunksz;
297 u32 chunkmask;
298
299 chunksz = nmaskbits & (CHUNKSZ - 1);
300 if (chunksz == 0)
301 chunksz = CHUNKSZ;
302
303 i = ALIGN(nmaskbits, CHUNKSZ) - CHUNKSZ;
304 for (; i >= 0; i -= CHUNKSZ) {
305 chunkmask = ((1ULL << chunksz) - 1);
306 word = i / BITS_PER_LONG;
307 bit = i % BITS_PER_LONG;
308 val = (maskp[word] >> bit) & chunkmask;
309 len += scnprintf(buf+len, buflen-len, "%s%0*lx", sep,
310 (chunksz+3)/4, val);
311 chunksz = CHUNKSZ;
312 sep = ",";
313 }
314 return len;
315}
316EXPORT_SYMBOL(bitmap_scnprintf);
317
318/**
319 * __bitmap_parse - convert an ASCII hex string into a bitmap.
320 * @buf: pointer to buffer containing string.
321 * @buflen: buffer size in bytes. If string is smaller than this
322 * then it must be terminated with a \0.
323 * @is_user: location of buffer, 0 indicates kernel space
324 * @maskp: pointer to bitmap array that will contain result.
325 * @nmaskbits: size of bitmap, in bits.
326 *
327 * Commas group hex digits into chunks. Each chunk defines exactly 32
328 * bits of the resultant bitmask. No chunk may specify a value larger
329 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
330 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
331 * characters and for grouping errors such as "1,,5", ",44", "," and "".
332 * Leading and trailing whitespace accepted, but not embedded whitespace.
333 */
334int __bitmap_parse(const char *buf, unsigned int buflen,
335 int is_user, unsigned long *maskp,
336 int nmaskbits)
337{
338 int c, old_c, totaldigits, ndigits, nchunks, nbits;
339 u32 chunk;
340 const char __user *ubuf = buf;
341
342 bitmap_zero(maskp, nmaskbits);
343
344 nchunks = nbits = totaldigits = c = 0;
345 do {
346 chunk = ndigits = 0;
347
348 /* Get the next chunk of the bitmap */
349 while (buflen) {
350 old_c = c;
351 if (is_user) {
352 if (__get_user(c, ubuf++))
353 return -EFAULT;
354 }
355 else
356 c = *buf++;
357 buflen--;
358 if (isspace(c))
359 continue;
360
361 /*
362 * If the last character was a space and the current
363 * character isn't '\0', we've got embedded whitespace.
364 * This is a no-no, so throw an error.
365 */
366 if (totaldigits && c && isspace(old_c))
367 return -EINVAL;
368
369 /* A '\0' or a ',' signal the end of the chunk */
370 if (c == '\0' || c == ',')
371 break;
372
373 if (!isxdigit(c))
374 return -EINVAL;
375
376 /*
377 * Make sure there are at least 4 free bits in 'chunk'.
378 * If not, this hexdigit will overflow 'chunk', so
379 * throw an error.
380 */
381 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
382 return -EOVERFLOW;
383
384 chunk = (chunk << 4) | unhex(c);
385 ndigits++; totaldigits++;
386 }
387 if (ndigits == 0)
388 return -EINVAL;
389 if (nchunks == 0 && chunk == 0)
390 continue;
391
392 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
393 *maskp |= chunk;
394 nchunks++;
395 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
396 if (nbits > nmaskbits)
397 return -EOVERFLOW;
398 } while (buflen && c == ',');
399
400 return 0;
401}
402EXPORT_SYMBOL(__bitmap_parse);
403
404/**
405 * bitmap_parse_user()
406 *
407 * @ubuf: pointer to user buffer containing string.
408 * @ulen: buffer size in bytes. If string is smaller than this
409 * then it must be terminated with a \0.
410 * @maskp: pointer to bitmap array that will contain result.
411 * @nmaskbits: size of bitmap, in bits.
412 *
413 * Wrapper for __bitmap_parse(), providing it with user buffer.
414 *
415 * We cannot have this as an inline function in bitmap.h because it needs
416 * linux/uaccess.h to get the access_ok() declaration and this causes
417 * cyclic dependencies.
418 */
419int bitmap_parse_user(const char __user *ubuf,
420 unsigned int ulen, unsigned long *maskp,
421 int nmaskbits)
422{
423 if (!access_ok(VERIFY_READ, ubuf, ulen))
424 return -EFAULT;
425 return __bitmap_parse((const char *)ubuf, ulen, 1, maskp, nmaskbits);
426}
427EXPORT_SYMBOL(bitmap_parse_user);
428
429/*
430 * bscnl_emit(buf, buflen, rbot, rtop, bp)
431 *
432 * Helper routine for bitmap_scnlistprintf(). Write decimal number
433 * or range to buf, suppressing output past buf+buflen, with optional
434 * comma-prefix. Return len of what would be written to buf, if it
435 * all fit.
436 */
437static inline int bscnl_emit(char *buf, int buflen, int rbot, int rtop, int len)
438{
439 if (len > 0)
440 len += scnprintf(buf + len, buflen - len, ",");
441 if (rbot == rtop)
442 len += scnprintf(buf + len, buflen - len, "%d", rbot);
443 else
444 len += scnprintf(buf + len, buflen - len, "%d-%d", rbot, rtop);
445 return len;
446}
447
448/**
449 * bitmap_scnlistprintf - convert bitmap to list format ASCII string
450 * @buf: byte buffer into which string is placed
451 * @buflen: reserved size of @buf, in bytes
452 * @maskp: pointer to bitmap to convert
453 * @nmaskbits: size of bitmap, in bits
454 *
455 * Output format is a comma-separated list of decimal numbers and
456 * ranges. Consecutively set bits are shown as two hyphen-separated
457 * decimal numbers, the smallest and largest bit numbers set in
458 * the range. Output format is compatible with the format
459 * accepted as input by bitmap_parselist().
460 *
461 * The return value is the number of characters which would be
462 * generated for the given input, excluding the trailing '\0', as
463 * per ISO C99.
464 */
465int bitmap_scnlistprintf(char *buf, unsigned int buflen,
466 const unsigned long *maskp, int nmaskbits)
467{
468 int len = 0;
469 /* current bit is 'cur', most recently seen range is [rbot, rtop] */
470 int cur, rbot, rtop;
471
472 rbot = cur = find_first_bit(maskp, nmaskbits);
473 while (cur < nmaskbits) {
474 rtop = cur;
475 cur = find_next_bit(maskp, nmaskbits, cur+1);
476 if (cur >= nmaskbits || cur > rtop + 1) {
477 len = bscnl_emit(buf, buflen, rbot, rtop, len);
478 rbot = cur;
479 }
480 }
481 return len;
482}
483EXPORT_SYMBOL(bitmap_scnlistprintf);
484
485/**
486 * bitmap_parselist - convert list format ASCII string to bitmap
487 * @bp: read nul-terminated user string from this buffer
488 * @maskp: write resulting mask here
489 * @nmaskbits: number of bits in mask to be written
490 *
491 * Input format is a comma-separated list of decimal numbers and
492 * ranges. Consecutively set bits are shown as two hyphen-separated
493 * decimal numbers, the smallest and largest bit numbers set in
494 * the range.
495 *
496 * Returns 0 on success, -errno on invalid input strings.
497 * Error values:
498 * %-EINVAL: second number in range smaller than first
499 * %-EINVAL: invalid character in string
500 * %-ERANGE: bit number specified too large for mask
501 */
502int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
503{
504 unsigned a, b;
505
506 bitmap_zero(maskp, nmaskbits);
507 do {
508 if (!isdigit(*bp))
509 return -EINVAL;
510 b = a = simple_strtoul(bp, (char **)&bp, BASEDEC);
511 if (*bp == '-') {
512 bp++;
513 if (!isdigit(*bp))
514 return -EINVAL;
515 b = simple_strtoul(bp, (char **)&bp, BASEDEC);
516 }
517 if (!(a <= b))
518 return -EINVAL;
519 if (b >= nmaskbits)
520 return -ERANGE;
521 while (a <= b) {
522 set_bit(a, maskp);
523 a++;
524 }
525 if (*bp == ',')
526 bp++;
527 } while (*bp != '\0' && *bp != '\n');
528 return 0;
529}
530EXPORT_SYMBOL(bitmap_parselist);
531
532/**
533 * bitmap_pos_to_ord(buf, pos, bits)
534 * @buf: pointer to a bitmap
535 * @pos: a bit position in @buf (0 <= @pos < @bits)
536 * @bits: number of valid bit positions in @buf
537 *
538 * Map the bit at position @pos in @buf (of length @bits) to the
539 * ordinal of which set bit it is. If it is not set or if @pos
540 * is not a valid bit position, map to -1.
541 *
542 * If for example, just bits 4 through 7 are set in @buf, then @pos
543 * values 4 through 7 will get mapped to 0 through 3, respectively,
544 * and other @pos values will get mapped to 0. When @pos value 7
545 * gets mapped to (returns) @ord value 3 in this example, that means
546 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
547 *
548 * The bit positions 0 through @bits are valid positions in @buf.
549 */
550static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits)
551{
552 int i, ord;
553
554 if (pos < 0 || pos >= bits || !test_bit(pos, buf))
555 return -1;
556
557 i = find_first_bit(buf, bits);
558 ord = 0;
559 while (i < pos) {
560 i = find_next_bit(buf, bits, i + 1);
561 ord++;
562 }
563 BUG_ON(i != pos);
564
565 return ord;
566}
567
568/**
569 * bitmap_ord_to_pos(buf, ord, bits)
570 * @buf: pointer to bitmap
571 * @ord: ordinal bit position (n-th set bit, n >= 0)
572 * @bits: number of valid bit positions in @buf
573 *
574 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
575 * Value of @ord should be in range 0 <= @ord < weight(buf), else
576 * results are undefined.
577 *
578 * If for example, just bits 4 through 7 are set in @buf, then @ord
579 * values 0 through 3 will get mapped to 4 through 7, respectively,
580 * and all other @ord values return undefined values. When @ord value 3
581 * gets mapped to (returns) @pos value 7 in this example, that means
582 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
583 *
584 * The bit positions 0 through @bits are valid positions in @buf.
585 */
586static int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits)
587{
588 int pos = 0;
589
590 if (ord >= 0 && ord < bits) {
591 int i;
592
593 for (i = find_first_bit(buf, bits);
594 i < bits && ord > 0;
595 i = find_next_bit(buf, bits, i + 1))
596 ord--;
597 if (i < bits && ord == 0)
598 pos = i;
599 }
600
601 return pos;
602}
603
604/**
605 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
606 * @dst: remapped result
607 * @src: subset to be remapped
608 * @old: defines domain of map
609 * @new: defines range of map
610 * @bits: number of bits in each of these bitmaps
611 *
612 * Let @old and @new define a mapping of bit positions, such that
613 * whatever position is held by the n-th set bit in @old is mapped
614 * to the n-th set bit in @new. In the more general case, allowing
615 * for the possibility that the weight 'w' of @new is less than the
616 * weight of @old, map the position of the n-th set bit in @old to
617 * the position of the m-th set bit in @new, where m == n % w.
618 *
619 * If either of the @old and @new bitmaps are empty, or if @src and
620 * @dst point to the same location, then this routine copies @src
621 * to @dst.
622 *
623 * The positions of unset bits in @old are mapped to themselves
624 * (the identify map).
625 *
626 * Apply the above specified mapping to @src, placing the result in
627 * @dst, clearing any bits previously set in @dst.
628 *
629 * For example, lets say that @old has bits 4 through 7 set, and
630 * @new has bits 12 through 15 set. This defines the mapping of bit
631 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
632 * bit positions unchanged. So if say @src comes into this routine
633 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
634 * 13 and 15 set.
635 */
636void bitmap_remap(unsigned long *dst, const unsigned long *src,
637 const unsigned long *old, const unsigned long *new,
638 int bits)
639{
640 int oldbit, w;
641
642 if (dst == src) /* following doesn't handle inplace remaps */
643 return;
644 bitmap_zero(dst, bits);
645
646 w = bitmap_weight(new, bits);
647 for (oldbit = find_first_bit(src, bits);
648 oldbit < bits;
649 oldbit = find_next_bit(src, bits, oldbit + 1)) {
650 int n = bitmap_pos_to_ord(old, oldbit, bits);
651 if (n < 0 || w == 0)
652 set_bit(oldbit, dst); /* identity map */
653 else
654 set_bit(bitmap_ord_to_pos(new, n % w, bits), dst);
655 }
656}
657EXPORT_SYMBOL(bitmap_remap);
658
659/**
660 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
661 * @oldbit: bit position to be mapped
662 * @old: defines domain of map
663 * @new: defines range of map
664 * @bits: number of bits in each of these bitmaps
665 *
666 * Let @old and @new define a mapping of bit positions, such that
667 * whatever position is held by the n-th set bit in @old is mapped
668 * to the n-th set bit in @new. In the more general case, allowing
669 * for the possibility that the weight 'w' of @new is less than the
670 * weight of @old, map the position of the n-th set bit in @old to
671 * the position of the m-th set bit in @new, where m == n % w.
672 *
673 * The positions of unset bits in @old are mapped to themselves
674 * (the identify map).
675 *
676 * Apply the above specified mapping to bit position @oldbit, returning
677 * the new bit position.
678 *
679 * For example, lets say that @old has bits 4 through 7 set, and
680 * @new has bits 12 through 15 set. This defines the mapping of bit
681 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
682 * bit positions unchanged. So if say @oldbit is 5, then this routine
683 * returns 13.
684 */
685int bitmap_bitremap(int oldbit, const unsigned long *old,
686 const unsigned long *new, int bits)
687{
688 int w = bitmap_weight(new, bits);
689 int n = bitmap_pos_to_ord(old, oldbit, bits);
690 if (n < 0 || w == 0)
691 return oldbit;
692 else
693 return bitmap_ord_to_pos(new, n % w, bits);
694}
695EXPORT_SYMBOL(bitmap_bitremap);
696
697/*
698 * Common code for bitmap_*_region() routines.
699 * bitmap: array of unsigned longs corresponding to the bitmap
700 * pos: the beginning of the region
701 * order: region size (log base 2 of number of bits)
702 * reg_op: operation(s) to perform on that region of bitmap
703 *
704 * Can set, verify and/or release a region of bits in a bitmap,
705 * depending on which combination of REG_OP_* flag bits is set.
706 *
707 * A region of a bitmap is a sequence of bits in the bitmap, of
708 * some size '1 << order' (a power of two), aligned to that same
709 * '1 << order' power of two.
710 *
711 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
712 * Returns 0 in all other cases and reg_ops.
713 */
714
715enum {
716 REG_OP_ISFREE, /* true if region is all zero bits */
717 REG_OP_ALLOC, /* set all bits in region */
718 REG_OP_RELEASE, /* clear all bits in region */
719};
720
721static int __reg_op(unsigned long *bitmap, int pos, int order, int reg_op)
722{
723 int nbits_reg; /* number of bits in region */
724 int index; /* index first long of region in bitmap */
725 int offset; /* bit offset region in bitmap[index] */
726 int nlongs_reg; /* num longs spanned by region in bitmap */
727 int nbitsinlong; /* num bits of region in each spanned long */
728 unsigned long mask; /* bitmask for one long of region */
729 int i; /* scans bitmap by longs */
730 int ret = 0; /* return value */
731
732 /*
733 * Either nlongs_reg == 1 (for small orders that fit in one long)
734 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
735 */
736 nbits_reg = 1 << order;
737 index = pos / BITS_PER_LONG;
738 offset = pos - (index * BITS_PER_LONG);
739 nlongs_reg = BITS_TO_LONGS(nbits_reg);
740 nbitsinlong = min(nbits_reg, BITS_PER_LONG);
741
742 /*
743 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
744 * overflows if nbitsinlong == BITS_PER_LONG.
745 */
746 mask = (1UL << (nbitsinlong - 1));
747 mask += mask - 1;
748 mask <<= offset;
749
750 switch (reg_op) {
751 case REG_OP_ISFREE:
752 for (i = 0; i < nlongs_reg; i++) {
753 if (bitmap[index + i] & mask)
754 goto done;
755 }
756 ret = 1; /* all bits in region free (zero) */
757 break;
758
759 case REG_OP_ALLOC:
760 for (i = 0; i < nlongs_reg; i++)
761 bitmap[index + i] |= mask;
762 break;
763
764 case REG_OP_RELEASE:
765 for (i = 0; i < nlongs_reg; i++)
766 bitmap[index + i] &= ~mask;
767 break;
768 }
769done:
770 return ret;
771}
772
773/**
774 * bitmap_find_free_region - find a contiguous aligned mem region
775 * @bitmap: array of unsigned longs corresponding to the bitmap
776 * @bits: number of bits in the bitmap
777 * @order: region size (log base 2 of number of bits) to find
778 *
779 * Find a region of free (zero) bits in a @bitmap of @bits bits and
780 * allocate them (set them to one). Only consider regions of length
781 * a power (@order) of two, aligned to that power of two, which
782 * makes the search algorithm much faster.
783 *
784 * Return the bit offset in bitmap of the allocated region,
785 * or -errno on failure.
786 */
787int bitmap_find_free_region(unsigned long *bitmap, int bits, int order)
788{
789 int pos; /* scans bitmap by regions of size order */
790
791 for (pos = 0; pos < bits; pos += (1 << order))
792 if (__reg_op(bitmap, pos, order, REG_OP_ISFREE))
793 break;
794 if (pos == bits)
795 return -ENOMEM;
796 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
797 return pos;
798}
799EXPORT_SYMBOL(bitmap_find_free_region);
800
801/**
802 * bitmap_release_region - release allocated bitmap region
803 * @bitmap: array of unsigned longs corresponding to the bitmap
804 * @pos: beginning of bit region to release
805 * @order: region size (log base 2 of number of bits) to release
806 *
807 * This is the complement to __bitmap_find_free_region() and releases
808 * the found region (by clearing it in the bitmap).
809 *
810 * No return value.
811 */
812void bitmap_release_region(unsigned long *bitmap, int pos, int order)
813{
814 __reg_op(bitmap, pos, order, REG_OP_RELEASE);
815}
816EXPORT_SYMBOL(bitmap_release_region);
817
818/**
819 * bitmap_allocate_region - allocate bitmap region
820 * @bitmap: array of unsigned longs corresponding to the bitmap
821 * @pos: beginning of bit region to allocate
822 * @order: region size (log base 2 of number of bits) to allocate
823 *
824 * Allocate (set bits in) a specified region of a bitmap.
825 *
826 * Return 0 on success, or %-EBUSY if specified region wasn't
827 * free (not all bits were zero).
828 */
829int bitmap_allocate_region(unsigned long *bitmap, int pos, int order)
830{
831 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
832 return -EBUSY;
833 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
834 return 0;
835}
836EXPORT_SYMBOL(bitmap_allocate_region);