blob: a6939e18d7bb3bc4f8d0caba8004e6b075bd3983 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
Robert P. J. Day72fd4a32007-02-10 01:45:59 -080098/**
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 * __bitmap_shift_right - logical right shift of the bits in a bitmap
Randy Dunlap05fb6bf2007-02-28 20:12:13 -0800100 * @dst : destination bitmap
101 * @src : source bitmap
102 * @shift : shift by this many bits
103 * @bits : bitmap size, in bits
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 *
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
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800142/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 * __bitmap_shift_left - logical left shift of the bits in a bitmap
Randy Dunlap05fb6bf2007-02-28 20:12:13 -0800144 * @dst : destination bitmap
145 * @src : source bitmap
146 * @shift : shift by this many bits
147 * @bits : bitmap size, in bits
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148 *
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
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256int __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++)
Akinobu Mita37d54112006-03-26 01:39:56 -0800261 w += hweight_long(bitmap[k]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262
263 if (bits % BITS_PER_LONG)
Akinobu Mita37d54112006-03-26 01:39:56 -0800264 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265
266 return w;
267}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700268EXPORT_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)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700277#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
Nick Wilson8c0e33c2005-06-25 14:59:00 -0700303 i = ALIGN(nmaskbits, CHUNKSZ) - CHUNKSZ;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304 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/**
Mike Travis30ca60c2008-03-25 15:06:55 -0700319 * bitmap_scnprintf_len - return buffer length needed to convert
320 * bitmap to an ASCII hex string.
321 * @len: number of bits to be converted
322 */
323int bitmap_scnprintf_len(unsigned int len)
324{
325 /* we need 9 chars per word for 32 bit words (8 hexdigits + sep/null) */
326 int bitslen = ALIGN(len, CHUNKSZ);
327 int wordlen = CHUNKSZ / 4;
328 int buflen = (bitslen / wordlen) * (wordlen + 1) * sizeof(char);
329
330 return buflen;
331}
332EXPORT_SYMBOL(bitmap_scnprintf_len);
333
334/**
Reinette Chatre01a3ee22006-10-11 01:21:55 -0700335 * __bitmap_parse - convert an ASCII hex string into a bitmap.
336 * @buf: pointer to buffer containing string.
337 * @buflen: buffer size in bytes. If string is smaller than this
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338 * then it must be terminated with a \0.
Reinette Chatre01a3ee22006-10-11 01:21:55 -0700339 * @is_user: location of buffer, 0 indicates kernel space
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340 * @maskp: pointer to bitmap array that will contain result.
341 * @nmaskbits: size of bitmap, in bits.
342 *
343 * Commas group hex digits into chunks. Each chunk defines exactly 32
344 * bits of the resultant bitmask. No chunk may specify a value larger
Randy Dunlap6e1907ff2006-06-25 05:48:57 -0700345 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
346 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347 * characters and for grouping errors such as "1,,5", ",44", "," and "".
348 * Leading and trailing whitespace accepted, but not embedded whitespace.
349 */
Reinette Chatre01a3ee22006-10-11 01:21:55 -0700350int __bitmap_parse(const char *buf, unsigned int buflen,
351 int is_user, unsigned long *maskp,
352 int nmaskbits)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700353{
354 int c, old_c, totaldigits, ndigits, nchunks, nbits;
355 u32 chunk;
Reinette Chatre01a3ee22006-10-11 01:21:55 -0700356 const char __user *ubuf = buf;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357
358 bitmap_zero(maskp, nmaskbits);
359
360 nchunks = nbits = totaldigits = c = 0;
361 do {
362 chunk = ndigits = 0;
363
364 /* Get the next chunk of the bitmap */
Reinette Chatre01a3ee22006-10-11 01:21:55 -0700365 while (buflen) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366 old_c = c;
Reinette Chatre01a3ee22006-10-11 01:21:55 -0700367 if (is_user) {
368 if (__get_user(c, ubuf++))
369 return -EFAULT;
370 }
371 else
372 c = *buf++;
373 buflen--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374 if (isspace(c))
375 continue;
376
377 /*
378 * If the last character was a space and the current
379 * character isn't '\0', we've got embedded whitespace.
380 * This is a no-no, so throw an error.
381 */
382 if (totaldigits && c && isspace(old_c))
383 return -EINVAL;
384
385 /* A '\0' or a ',' signal the end of the chunk */
386 if (c == '\0' || c == ',')
387 break;
388
389 if (!isxdigit(c))
390 return -EINVAL;
391
392 /*
393 * Make sure there are at least 4 free bits in 'chunk'.
394 * If not, this hexdigit will overflow 'chunk', so
395 * throw an error.
396 */
397 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
398 return -EOVERFLOW;
399
400 chunk = (chunk << 4) | unhex(c);
401 ndigits++; totaldigits++;
402 }
403 if (ndigits == 0)
404 return -EINVAL;
405 if (nchunks == 0 && chunk == 0)
406 continue;
407
408 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
409 *maskp |= chunk;
410 nchunks++;
411 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
412 if (nbits > nmaskbits)
413 return -EOVERFLOW;
Reinette Chatre01a3ee22006-10-11 01:21:55 -0700414 } while (buflen && c == ',');
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415
416 return 0;
417}
Reinette Chatre01a3ee22006-10-11 01:21:55 -0700418EXPORT_SYMBOL(__bitmap_parse);
419
420/**
421 * bitmap_parse_user()
422 *
423 * @ubuf: pointer to user buffer containing string.
424 * @ulen: buffer size in bytes. If string is smaller than this
425 * then it must be terminated with a \0.
426 * @maskp: pointer to bitmap array that will contain result.
427 * @nmaskbits: size of bitmap, in bits.
428 *
429 * Wrapper for __bitmap_parse(), providing it with user buffer.
430 *
431 * We cannot have this as an inline function in bitmap.h because it needs
432 * linux/uaccess.h to get the access_ok() declaration and this causes
433 * cyclic dependencies.
434 */
435int bitmap_parse_user(const char __user *ubuf,
436 unsigned int ulen, unsigned long *maskp,
437 int nmaskbits)
438{
439 if (!access_ok(VERIFY_READ, ubuf, ulen))
440 return -EFAULT;
441 return __bitmap_parse((const char *)ubuf, ulen, 1, maskp, nmaskbits);
442}
443EXPORT_SYMBOL(bitmap_parse_user);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700444
445/*
446 * bscnl_emit(buf, buflen, rbot, rtop, bp)
447 *
448 * Helper routine for bitmap_scnlistprintf(). Write decimal number
449 * or range to buf, suppressing output past buf+buflen, with optional
450 * comma-prefix. Return len of what would be written to buf, if it
451 * all fit.
452 */
453static inline int bscnl_emit(char *buf, int buflen, int rbot, int rtop, int len)
454{
455 if (len > 0)
456 len += scnprintf(buf + len, buflen - len, ",");
457 if (rbot == rtop)
458 len += scnprintf(buf + len, buflen - len, "%d", rbot);
459 else
460 len += scnprintf(buf + len, buflen - len, "%d-%d", rbot, rtop);
461 return len;
462}
463
464/**
465 * bitmap_scnlistprintf - convert bitmap to list format ASCII string
466 * @buf: byte buffer into which string is placed
467 * @buflen: reserved size of @buf, in bytes
468 * @maskp: pointer to bitmap to convert
469 * @nmaskbits: size of bitmap, in bits
470 *
471 * Output format is a comma-separated list of decimal numbers and
472 * ranges. Consecutively set bits are shown as two hyphen-separated
473 * decimal numbers, the smallest and largest bit numbers set in
474 * the range. Output format is compatible with the format
475 * accepted as input by bitmap_parselist().
476 *
477 * The return value is the number of characters which would be
478 * generated for the given input, excluding the trailing '\0', as
479 * per ISO C99.
480 */
481int bitmap_scnlistprintf(char *buf, unsigned int buflen,
482 const unsigned long *maskp, int nmaskbits)
483{
484 int len = 0;
485 /* current bit is 'cur', most recently seen range is [rbot, rtop] */
486 int cur, rbot, rtop;
487
Andi Kleen0b030c22007-11-05 14:50:56 -0800488 if (buflen == 0)
489 return 0;
490 buf[0] = 0;
491
Linus Torvalds1da177e2005-04-16 15:20:36 -0700492 rbot = cur = find_first_bit(maskp, nmaskbits);
493 while (cur < nmaskbits) {
494 rtop = cur;
495 cur = find_next_bit(maskp, nmaskbits, cur+1);
496 if (cur >= nmaskbits || cur > rtop + 1) {
497 len = bscnl_emit(buf, buflen, rbot, rtop, len);
498 rbot = cur;
499 }
500 }
501 return len;
502}
503EXPORT_SYMBOL(bitmap_scnlistprintf);
504
505/**
506 * bitmap_parselist - convert list format ASCII string to bitmap
Randy Dunlap6e1907ff2006-06-25 05:48:57 -0700507 * @bp: read nul-terminated user string from this buffer
508 * @maskp: write resulting mask here
Linus Torvalds1da177e2005-04-16 15:20:36 -0700509 * @nmaskbits: number of bits in mask to be written
510 *
511 * Input format is a comma-separated list of decimal numbers and
512 * ranges. Consecutively set bits are shown as two hyphen-separated
513 * decimal numbers, the smallest and largest bit numbers set in
514 * the range.
515 *
Randy Dunlap6e1907ff2006-06-25 05:48:57 -0700516 * Returns 0 on success, -errno on invalid input strings.
517 * Error values:
518 * %-EINVAL: second number in range smaller than first
519 * %-EINVAL: invalid character in string
520 * %-ERANGE: bit number specified too large for mask
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521 */
522int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
523{
524 unsigned a, b;
525
526 bitmap_zero(maskp, nmaskbits);
527 do {
528 if (!isdigit(*bp))
529 return -EINVAL;
530 b = a = simple_strtoul(bp, (char **)&bp, BASEDEC);
531 if (*bp == '-') {
532 bp++;
533 if (!isdigit(*bp))
534 return -EINVAL;
535 b = simple_strtoul(bp, (char **)&bp, BASEDEC);
536 }
537 if (!(a <= b))
538 return -EINVAL;
539 if (b >= nmaskbits)
540 return -ERANGE;
541 while (a <= b) {
542 set_bit(a, maskp);
543 a++;
544 }
545 if (*bp == ',')
546 bp++;
547 } while (*bp != '\0' && *bp != '\n');
548 return 0;
549}
550EXPORT_SYMBOL(bitmap_parselist);
551
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800552/**
Paul Jacksonfb5eeee2005-10-30 15:02:33 -0800553 * bitmap_pos_to_ord(buf, pos, bits)
554 * @buf: pointer to a bitmap
555 * @pos: a bit position in @buf (0 <= @pos < @bits)
556 * @bits: number of valid bit positions in @buf
557 *
558 * Map the bit at position @pos in @buf (of length @bits) to the
559 * ordinal of which set bit it is. If it is not set or if @pos
Paul Jackson96b7f342006-01-08 01:01:46 -0800560 * is not a valid bit position, map to -1.
Paul Jacksonfb5eeee2005-10-30 15:02:33 -0800561 *
562 * If for example, just bits 4 through 7 are set in @buf, then @pos
563 * values 4 through 7 will get mapped to 0 through 3, respectively,
564 * and other @pos values will get mapped to 0. When @pos value 7
565 * gets mapped to (returns) @ord value 3 in this example, that means
566 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
567 *
568 * The bit positions 0 through @bits are valid positions in @buf.
569 */
570static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits)
571{
Paul Jackson96b7f342006-01-08 01:01:46 -0800572 int i, ord;
Paul Jacksonfb5eeee2005-10-30 15:02:33 -0800573
Paul Jackson96b7f342006-01-08 01:01:46 -0800574 if (pos < 0 || pos >= bits || !test_bit(pos, buf))
575 return -1;
Paul Jacksonfb5eeee2005-10-30 15:02:33 -0800576
Paul Jackson96b7f342006-01-08 01:01:46 -0800577 i = find_first_bit(buf, bits);
578 ord = 0;
579 while (i < pos) {
580 i = find_next_bit(buf, bits, i + 1);
581 ord++;
Paul Jacksonfb5eeee2005-10-30 15:02:33 -0800582 }
Paul Jackson96b7f342006-01-08 01:01:46 -0800583 BUG_ON(i != pos);
584
Paul Jacksonfb5eeee2005-10-30 15:02:33 -0800585 return ord;
586}
587
588/**
589 * bitmap_ord_to_pos(buf, ord, bits)
590 * @buf: pointer to bitmap
591 * @ord: ordinal bit position (n-th set bit, n >= 0)
592 * @bits: number of valid bit positions in @buf
593 *
594 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
Paul Jackson96b7f342006-01-08 01:01:46 -0800595 * Value of @ord should be in range 0 <= @ord < weight(buf), else
596 * results are undefined.
Paul Jacksonfb5eeee2005-10-30 15:02:33 -0800597 *
598 * If for example, just bits 4 through 7 are set in @buf, then @ord
599 * values 0 through 3 will get mapped to 4 through 7, respectively,
Paul Jackson96b7f342006-01-08 01:01:46 -0800600 * and all other @ord values return undefined values. When @ord value 3
Paul Jacksonfb5eeee2005-10-30 15:02:33 -0800601 * gets mapped to (returns) @pos value 7 in this example, that means
602 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
603 *
604 * The bit positions 0 through @bits are valid positions in @buf.
605 */
606static int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits)
607{
608 int pos = 0;
609
610 if (ord >= 0 && ord < bits) {
611 int i;
612
613 for (i = find_first_bit(buf, bits);
614 i < bits && ord > 0;
615 i = find_next_bit(buf, bits, i + 1))
616 ord--;
617 if (i < bits && ord == 0)
618 pos = i;
619 }
620
621 return pos;
622}
623
624/**
625 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
Paul Jacksonfb5eeee2005-10-30 15:02:33 -0800626 * @dst: remapped result
Paul Jackson96b7f342006-01-08 01:01:46 -0800627 * @src: subset to be remapped
Paul Jacksonfb5eeee2005-10-30 15:02:33 -0800628 * @old: defines domain of map
629 * @new: defines range of map
630 * @bits: number of bits in each of these bitmaps
631 *
632 * Let @old and @new define a mapping of bit positions, such that
633 * whatever position is held by the n-th set bit in @old is mapped
634 * to the n-th set bit in @new. In the more general case, allowing
635 * for the possibility that the weight 'w' of @new is less than the
636 * weight of @old, map the position of the n-th set bit in @old to
637 * the position of the m-th set bit in @new, where m == n % w.
638 *
Paul Jackson96b7f342006-01-08 01:01:46 -0800639 * If either of the @old and @new bitmaps are empty, or if @src and
640 * @dst point to the same location, then this routine copies @src
641 * to @dst.
Paul Jacksonfb5eeee2005-10-30 15:02:33 -0800642 *
Paul Jackson96b7f342006-01-08 01:01:46 -0800643 * The positions of unset bits in @old are mapped to themselves
644 * (the identify map).
Paul Jacksonfb5eeee2005-10-30 15:02:33 -0800645 *
646 * Apply the above specified mapping to @src, placing the result in
647 * @dst, clearing any bits previously set in @dst.
648 *
Paul Jacksonfb5eeee2005-10-30 15:02:33 -0800649 * For example, lets say that @old has bits 4 through 7 set, and
650 * @new has bits 12 through 15 set. This defines the mapping of bit
651 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
Paul Jackson96b7f342006-01-08 01:01:46 -0800652 * bit positions unchanged. So if say @src comes into this routine
653 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
654 * 13 and 15 set.
Paul Jacksonfb5eeee2005-10-30 15:02:33 -0800655 */
656void bitmap_remap(unsigned long *dst, const unsigned long *src,
657 const unsigned long *old, const unsigned long *new,
658 int bits)
659{
Paul Jackson96b7f342006-01-08 01:01:46 -0800660 int oldbit, w;
Paul Jacksonfb5eeee2005-10-30 15:02:33 -0800661
Paul Jacksonfb5eeee2005-10-30 15:02:33 -0800662 if (dst == src) /* following doesn't handle inplace remaps */
663 return;
Paul Jacksonfb5eeee2005-10-30 15:02:33 -0800664 bitmap_zero(dst, bits);
Paul Jackson96b7f342006-01-08 01:01:46 -0800665
666 w = bitmap_weight(new, bits);
667 for (oldbit = find_first_bit(src, bits);
668 oldbit < bits;
669 oldbit = find_next_bit(src, bits, oldbit + 1)) {
670 int n = bitmap_pos_to_ord(old, oldbit, bits);
671 if (n < 0 || w == 0)
672 set_bit(oldbit, dst); /* identity map */
673 else
674 set_bit(bitmap_ord_to_pos(new, n % w, bits), dst);
Paul Jacksonfb5eeee2005-10-30 15:02:33 -0800675 }
676}
677EXPORT_SYMBOL(bitmap_remap);
678
679/**
680 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
Randy Dunlap6e1907ff2006-06-25 05:48:57 -0700681 * @oldbit: bit position to be mapped
682 * @old: defines domain of map
683 * @new: defines range of map
684 * @bits: number of bits in each of these bitmaps
Paul Jacksonfb5eeee2005-10-30 15:02:33 -0800685 *
686 * Let @old and @new define a mapping of bit positions, such that
687 * whatever position is held by the n-th set bit in @old is mapped
688 * to the n-th set bit in @new. In the more general case, allowing
689 * for the possibility that the weight 'w' of @new is less than the
690 * weight of @old, map the position of the n-th set bit in @old to
691 * the position of the m-th set bit in @new, where m == n % w.
692 *
Paul Jackson96b7f342006-01-08 01:01:46 -0800693 * The positions of unset bits in @old are mapped to themselves
694 * (the identify map).
Paul Jacksonfb5eeee2005-10-30 15:02:33 -0800695 *
696 * Apply the above specified mapping to bit position @oldbit, returning
697 * the new bit position.
698 *
699 * For example, lets say that @old has bits 4 through 7 set, and
700 * @new has bits 12 through 15 set. This defines the mapping of bit
701 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
Paul Jackson96b7f342006-01-08 01:01:46 -0800702 * bit positions unchanged. So if say @oldbit is 5, then this routine
703 * returns 13.
Paul Jacksonfb5eeee2005-10-30 15:02:33 -0800704 */
705int bitmap_bitremap(int oldbit, const unsigned long *old,
706 const unsigned long *new, int bits)
707{
Paul Jackson96b7f342006-01-08 01:01:46 -0800708 int w = bitmap_weight(new, bits);
709 int n = bitmap_pos_to_ord(old, oldbit, bits);
710 if (n < 0 || w == 0)
711 return oldbit;
712 else
713 return bitmap_ord_to_pos(new, n % w, bits);
Paul Jacksonfb5eeee2005-10-30 15:02:33 -0800714}
715EXPORT_SYMBOL(bitmap_bitremap);
716
Paul Jackson3cf64b92006-03-24 03:15:46 -0800717/*
718 * Common code for bitmap_*_region() routines.
719 * bitmap: array of unsigned longs corresponding to the bitmap
720 * pos: the beginning of the region
721 * order: region size (log base 2 of number of bits)
722 * reg_op: operation(s) to perform on that region of bitmap
723 *
724 * Can set, verify and/or release a region of bits in a bitmap,
725 * depending on which combination of REG_OP_* flag bits is set.
726 *
727 * A region of a bitmap is a sequence of bits in the bitmap, of
728 * some size '1 << order' (a power of two), aligned to that same
729 * '1 << order' power of two.
730 *
731 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
732 * Returns 0 in all other cases and reg_ops.
733 */
734
735enum {
736 REG_OP_ISFREE, /* true if region is all zero bits */
737 REG_OP_ALLOC, /* set all bits in region */
738 REG_OP_RELEASE, /* clear all bits in region */
739};
740
741static int __reg_op(unsigned long *bitmap, int pos, int order, int reg_op)
742{
743 int nbits_reg; /* number of bits in region */
744 int index; /* index first long of region in bitmap */
745 int offset; /* bit offset region in bitmap[index] */
746 int nlongs_reg; /* num longs spanned by region in bitmap */
747 int nbitsinlong; /* num bits of region in each spanned long */
748 unsigned long mask; /* bitmask for one long of region */
749 int i; /* scans bitmap by longs */
750 int ret = 0; /* return value */
751
752 /*
753 * Either nlongs_reg == 1 (for small orders that fit in one long)
754 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
755 */
756 nbits_reg = 1 << order;
757 index = pos / BITS_PER_LONG;
758 offset = pos - (index * BITS_PER_LONG);
759 nlongs_reg = BITS_TO_LONGS(nbits_reg);
760 nbitsinlong = min(nbits_reg, BITS_PER_LONG);
761
762 /*
763 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
764 * overflows if nbitsinlong == BITS_PER_LONG.
765 */
766 mask = (1UL << (nbitsinlong - 1));
767 mask += mask - 1;
768 mask <<= offset;
769
770 switch (reg_op) {
771 case REG_OP_ISFREE:
772 for (i = 0; i < nlongs_reg; i++) {
773 if (bitmap[index + i] & mask)
774 goto done;
775 }
776 ret = 1; /* all bits in region free (zero) */
777 break;
778
779 case REG_OP_ALLOC:
780 for (i = 0; i < nlongs_reg; i++)
781 bitmap[index + i] |= mask;
782 break;
783
784 case REG_OP_RELEASE:
785 for (i = 0; i < nlongs_reg; i++)
786 bitmap[index + i] &= ~mask;
787 break;
788 }
789done:
790 return ret;
791}
792
Linus Torvalds1da177e2005-04-16 15:20:36 -0700793/**
Paul Jackson87e24802006-03-24 03:15:44 -0800794 * bitmap_find_free_region - find a contiguous aligned mem region
Paul Jackson3cf64b92006-03-24 03:15:46 -0800795 * @bitmap: array of unsigned longs corresponding to the bitmap
Linus Torvalds1da177e2005-04-16 15:20:36 -0700796 * @bits: number of bits in the bitmap
Paul Jackson3cf64b92006-03-24 03:15:46 -0800797 * @order: region size (log base 2 of number of bits) to find
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798 *
Paul Jackson3cf64b92006-03-24 03:15:46 -0800799 * Find a region of free (zero) bits in a @bitmap of @bits bits and
800 * allocate them (set them to one). Only consider regions of length
801 * a power (@order) of two, aligned to that power of two, which
Paul Jackson87e24802006-03-24 03:15:44 -0800802 * makes the search algorithm much faster.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700803 *
Paul Jackson3cf64b92006-03-24 03:15:46 -0800804 * Return the bit offset in bitmap of the allocated region,
Paul Jackson87e24802006-03-24 03:15:44 -0800805 * or -errno on failure.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806 */
807int bitmap_find_free_region(unsigned long *bitmap, int bits, int order)
808{
Paul Jackson3cf64b92006-03-24 03:15:46 -0800809 int pos; /* scans bitmap by regions of size order */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700810
Paul Jackson3cf64b92006-03-24 03:15:46 -0800811 for (pos = 0; pos < bits; pos += (1 << order))
812 if (__reg_op(bitmap, pos, order, REG_OP_ISFREE))
813 break;
814 if (pos == bits)
815 return -ENOMEM;
816 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
817 return pos;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818}
819EXPORT_SYMBOL(bitmap_find_free_region);
820
821/**
Paul Jackson87e24802006-03-24 03:15:44 -0800822 * bitmap_release_region - release allocated bitmap region
Paul Jackson3cf64b92006-03-24 03:15:46 -0800823 * @bitmap: array of unsigned longs corresponding to the bitmap
824 * @pos: beginning of bit region to release
825 * @order: region size (log base 2 of number of bits) to release
Linus Torvalds1da177e2005-04-16 15:20:36 -0700826 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800827 * This is the complement to __bitmap_find_free_region() and releases
Linus Torvalds1da177e2005-04-16 15:20:36 -0700828 * the found region (by clearing it in the bitmap).
Paul Jackson3cf64b92006-03-24 03:15:46 -0800829 *
830 * No return value.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700831 */
832void bitmap_release_region(unsigned long *bitmap, int pos, int order)
833{
Paul Jackson3cf64b92006-03-24 03:15:46 -0800834 __reg_op(bitmap, pos, order, REG_OP_RELEASE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700835}
836EXPORT_SYMBOL(bitmap_release_region);
837
Paul Jackson87e24802006-03-24 03:15:44 -0800838/**
839 * bitmap_allocate_region - allocate bitmap region
Paul Jackson3cf64b92006-03-24 03:15:46 -0800840 * @bitmap: array of unsigned longs corresponding to the bitmap
841 * @pos: beginning of bit region to allocate
842 * @order: region size (log base 2 of number of bits) to allocate
Paul Jackson87e24802006-03-24 03:15:44 -0800843 *
844 * Allocate (set bits in) a specified region of a bitmap.
Paul Jackson3cf64b92006-03-24 03:15:46 -0800845 *
Randy Dunlap6e1907ff2006-06-25 05:48:57 -0700846 * Return 0 on success, or %-EBUSY if specified region wasn't
Paul Jackson87e24802006-03-24 03:15:44 -0800847 * free (not all bits were zero).
848 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700849int bitmap_allocate_region(unsigned long *bitmap, int pos, int order)
850{
Paul Jackson3cf64b92006-03-24 03:15:46 -0800851 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
852 return -EBUSY;
853 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700854 return 0;
855}
856EXPORT_SYMBOL(bitmap_allocate_region);