ia64/linux-2.6.18-xen.hg

view lib/bitmap.c @ 782:9ab1c319531f

merge with linux-2.6.18-xen.hg
author Isaku Yamahata <yamahata@valinux.co.jp>
date Wed Jan 28 13:07:23 2009 +0900 (2009-01-28)
parents 831230e53067
children
line source
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>
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 */
41 int __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;
48 if (bits % BITS_PER_LONG)
49 if (bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
50 return 0;
52 return 1;
53 }
54 EXPORT_SYMBOL(__bitmap_empty);
56 int __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;
63 if (bits % BITS_PER_LONG)
64 if (~bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
65 return 0;
67 return 1;
68 }
69 EXPORT_SYMBOL(__bitmap_full);
71 int __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;
79 if (bits % BITS_PER_LONG)
80 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
81 return 0;
83 return 1;
84 }
85 EXPORT_SYMBOL(__bitmap_equal);
87 void __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];
93 if (bits % BITS_PER_LONG)
94 dst[k] = ~src[k] & BITMAP_LAST_WORD_MASK(bits);
95 }
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 * @nbits - 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 */
109 void __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;
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 }
139 EXPORT_SYMBOL(__bitmap_shift_right);
142 /*
143 * __bitmap_shift_left - logical left shift of the bits in a bitmap
144 * @dst - destination bitmap
145 * @src - source bitmap
146 * @nbits - 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 */
154 void __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;
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 }
180 EXPORT_SYMBOL(__bitmap_shift_left);
182 void __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);
188 for (k = 0; k < nr; k++)
189 dst[k] = bitmap1[k] & bitmap2[k];
190 }
191 EXPORT_SYMBOL(__bitmap_and);
193 void __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);
199 for (k = 0; k < nr; k++)
200 dst[k] = bitmap1[k] | bitmap2[k];
201 }
202 EXPORT_SYMBOL(__bitmap_or);
204 void __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);
210 for (k = 0; k < nr; k++)
211 dst[k] = bitmap1[k] ^ bitmap2[k];
212 }
213 EXPORT_SYMBOL(__bitmap_xor);
215 void __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);
221 for (k = 0; k < nr; k++)
222 dst[k] = bitmap1[k] & ~bitmap2[k];
223 }
224 EXPORT_SYMBOL(__bitmap_andnot);
226 int __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;
234 if (bits % BITS_PER_LONG)
235 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
236 return 1;
237 return 0;
238 }
239 EXPORT_SYMBOL(__bitmap_intersects);
241 int __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;
249 if (bits % BITS_PER_LONG)
250 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
251 return 0;
252 return 1;
253 }
254 EXPORT_SYMBOL(__bitmap_subset);
256 int __bitmap_weight(const unsigned long *bitmap, int bits)
257 {
258 int k, w = 0, lim = bits/BITS_PER_LONG;
260 for (k = 0; k < lim; k++)
261 w += hweight_long(bitmap[k]);
263 if (bits % BITS_PER_LONG)
264 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
266 return w;
267 }
268 EXPORT_SYMBOL(__bitmap_weight);
270 /*
271 * Bitmap printing & parsing functions: first version by Bill Irwin,
272 * second version by Paul Jackson, third by Joe Korty.
273 */
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 */
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 */
290 int 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;
299 chunksz = nmaskbits & (CHUNKSZ - 1);
300 if (chunksz == 0)
301 chunksz = CHUNKSZ;
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 }
316 EXPORT_SYMBOL(bitmap_scnprintf);
318 /**
319 * bitmap_parse - convert an ASCII hex string into a bitmap.
320 * @ubuf: pointer to buffer in user space containing string.
321 * @ubuflen: buffer size in bytes. If string is smaller than this
322 * then it must be terminated with a \0.
323 * @maskp: pointer to bitmap array that will contain result.
324 * @nmaskbits: size of bitmap, in bits.
325 *
326 * Commas group hex digits into chunks. Each chunk defines exactly 32
327 * bits of the resultant bitmask. No chunk may specify a value larger
328 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
329 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
330 * characters and for grouping errors such as "1,,5", ",44", "," and "".
331 * Leading and trailing whitespace accepted, but not embedded whitespace.
332 */
333 int bitmap_parse(const char __user *ubuf, unsigned int ubuflen,
334 unsigned long *maskp, int nmaskbits)
335 {
336 int c, old_c, totaldigits, ndigits, nchunks, nbits;
337 u32 chunk;
339 bitmap_zero(maskp, nmaskbits);
341 nchunks = nbits = totaldigits = c = 0;
342 do {
343 chunk = ndigits = 0;
345 /* Get the next chunk of the bitmap */
346 while (ubuflen) {
347 old_c = c;
348 if (get_user(c, ubuf++))
349 return -EFAULT;
350 ubuflen--;
351 if (isspace(c))
352 continue;
354 /*
355 * If the last character was a space and the current
356 * character isn't '\0', we've got embedded whitespace.
357 * This is a no-no, so throw an error.
358 */
359 if (totaldigits && c && isspace(old_c))
360 return -EINVAL;
362 /* A '\0' or a ',' signal the end of the chunk */
363 if (c == '\0' || c == ',')
364 break;
366 if (!isxdigit(c))
367 return -EINVAL;
369 /*
370 * Make sure there are at least 4 free bits in 'chunk'.
371 * If not, this hexdigit will overflow 'chunk', so
372 * throw an error.
373 */
374 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
375 return -EOVERFLOW;
377 chunk = (chunk << 4) | unhex(c);
378 ndigits++; totaldigits++;
379 }
380 if (ndigits == 0)
381 return -EINVAL;
382 if (nchunks == 0 && chunk == 0)
383 continue;
385 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
386 *maskp |= chunk;
387 nchunks++;
388 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
389 if (nbits > nmaskbits)
390 return -EOVERFLOW;
391 } while (ubuflen && c == ',');
393 return 0;
394 }
395 EXPORT_SYMBOL(bitmap_parse);
397 /*
398 * bscnl_emit(buf, buflen, rbot, rtop, bp)
399 *
400 * Helper routine for bitmap_scnlistprintf(). Write decimal number
401 * or range to buf, suppressing output past buf+buflen, with optional
402 * comma-prefix. Return len of what would be written to buf, if it
403 * all fit.
404 */
405 static inline int bscnl_emit(char *buf, int buflen, int rbot, int rtop, int len)
406 {
407 if (len > 0)
408 len += scnprintf(buf + len, buflen - len, ",");
409 if (rbot == rtop)
410 len += scnprintf(buf + len, buflen - len, "%d", rbot);
411 else
412 len += scnprintf(buf + len, buflen - len, "%d-%d", rbot, rtop);
413 return len;
414 }
416 /**
417 * bitmap_scnlistprintf - convert bitmap to list format ASCII string
418 * @buf: byte buffer into which string is placed
419 * @buflen: reserved size of @buf, in bytes
420 * @maskp: pointer to bitmap to convert
421 * @nmaskbits: size of bitmap, in bits
422 *
423 * Output format is a comma-separated list of decimal numbers and
424 * ranges. Consecutively set bits are shown as two hyphen-separated
425 * decimal numbers, the smallest and largest bit numbers set in
426 * the range. Output format is compatible with the format
427 * accepted as input by bitmap_parselist().
428 *
429 * The return value is the number of characters which would be
430 * generated for the given input, excluding the trailing '\0', as
431 * per ISO C99.
432 */
433 int bitmap_scnlistprintf(char *buf, unsigned int buflen,
434 const unsigned long *maskp, int nmaskbits)
435 {
436 int len = 0;
437 /* current bit is 'cur', most recently seen range is [rbot, rtop] */
438 int cur, rbot, rtop;
440 rbot = cur = find_first_bit(maskp, nmaskbits);
441 while (cur < nmaskbits) {
442 rtop = cur;
443 cur = find_next_bit(maskp, nmaskbits, cur+1);
444 if (cur >= nmaskbits || cur > rtop + 1) {
445 len = bscnl_emit(buf, buflen, rbot, rtop, len);
446 rbot = cur;
447 }
448 }
449 return len;
450 }
451 EXPORT_SYMBOL(bitmap_scnlistprintf);
453 /**
454 * bitmap_parselist - convert list format ASCII string to bitmap
455 * @bp: read nul-terminated user string from this buffer
456 * @maskp: write resulting mask here
457 * @nmaskbits: number of bits in mask to be written
458 *
459 * Input format is a comma-separated list of decimal numbers and
460 * ranges. Consecutively set bits are shown as two hyphen-separated
461 * decimal numbers, the smallest and largest bit numbers set in
462 * the range.
463 *
464 * Returns 0 on success, -errno on invalid input strings.
465 * Error values:
466 * %-EINVAL: second number in range smaller than first
467 * %-EINVAL: invalid character in string
468 * %-ERANGE: bit number specified too large for mask
469 */
470 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
471 {
472 unsigned a, b;
474 bitmap_zero(maskp, nmaskbits);
475 do {
476 if (!isdigit(*bp))
477 return -EINVAL;
478 b = a = simple_strtoul(bp, (char **)&bp, BASEDEC);
479 if (*bp == '-') {
480 bp++;
481 if (!isdigit(*bp))
482 return -EINVAL;
483 b = simple_strtoul(bp, (char **)&bp, BASEDEC);
484 }
485 if (!(a <= b))
486 return -EINVAL;
487 if (b >= nmaskbits)
488 return -ERANGE;
489 while (a <= b) {
490 set_bit(a, maskp);
491 a++;
492 }
493 if (*bp == ',')
494 bp++;
495 } while (*bp != '\0' && *bp != '\n');
496 return 0;
497 }
498 EXPORT_SYMBOL(bitmap_parselist);
500 /*
501 * bitmap_pos_to_ord(buf, pos, bits)
502 * @buf: pointer to a bitmap
503 * @pos: a bit position in @buf (0 <= @pos < @bits)
504 * @bits: number of valid bit positions in @buf
505 *
506 * Map the bit at position @pos in @buf (of length @bits) to the
507 * ordinal of which set bit it is. If it is not set or if @pos
508 * is not a valid bit position, map to -1.
509 *
510 * If for example, just bits 4 through 7 are set in @buf, then @pos
511 * values 4 through 7 will get mapped to 0 through 3, respectively,
512 * and other @pos values will get mapped to 0. When @pos value 7
513 * gets mapped to (returns) @ord value 3 in this example, that means
514 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
515 *
516 * The bit positions 0 through @bits are valid positions in @buf.
517 */
518 static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits)
519 {
520 int i, ord;
522 if (pos < 0 || pos >= bits || !test_bit(pos, buf))
523 return -1;
525 i = find_first_bit(buf, bits);
526 ord = 0;
527 while (i < pos) {
528 i = find_next_bit(buf, bits, i + 1);
529 ord++;
530 }
531 BUG_ON(i != pos);
533 return ord;
534 }
536 /**
537 * bitmap_ord_to_pos(buf, ord, bits)
538 * @buf: pointer to bitmap
539 * @ord: ordinal bit position (n-th set bit, n >= 0)
540 * @bits: number of valid bit positions in @buf
541 *
542 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
543 * Value of @ord should be in range 0 <= @ord < weight(buf), else
544 * results are undefined.
545 *
546 * If for example, just bits 4 through 7 are set in @buf, then @ord
547 * values 0 through 3 will get mapped to 4 through 7, respectively,
548 * and all other @ord values return undefined values. When @ord value 3
549 * gets mapped to (returns) @pos value 7 in this example, that means
550 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
551 *
552 * The bit positions 0 through @bits are valid positions in @buf.
553 */
554 static int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits)
555 {
556 int pos = 0;
558 if (ord >= 0 && ord < bits) {
559 int i;
561 for (i = find_first_bit(buf, bits);
562 i < bits && ord > 0;
563 i = find_next_bit(buf, bits, i + 1))
564 ord--;
565 if (i < bits && ord == 0)
566 pos = i;
567 }
569 return pos;
570 }
572 /**
573 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
574 * @dst: remapped result
575 * @src: subset to be remapped
576 * @old: defines domain of map
577 * @new: defines range of map
578 * @bits: number of bits in each of these bitmaps
579 *
580 * Let @old and @new define a mapping of bit positions, such that
581 * whatever position is held by the n-th set bit in @old is mapped
582 * to the n-th set bit in @new. In the more general case, allowing
583 * for the possibility that the weight 'w' of @new is less than the
584 * weight of @old, map the position of the n-th set bit in @old to
585 * the position of the m-th set bit in @new, where m == n % w.
586 *
587 * If either of the @old and @new bitmaps are empty, or if @src and
588 * @dst point to the same location, then this routine copies @src
589 * to @dst.
590 *
591 * The positions of unset bits in @old are mapped to themselves
592 * (the identify map).
593 *
594 * Apply the above specified mapping to @src, placing the result in
595 * @dst, clearing any bits previously set in @dst.
596 *
597 * For example, lets say that @old has bits 4 through 7 set, and
598 * @new has bits 12 through 15 set. This defines the mapping of bit
599 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
600 * bit positions unchanged. So if say @src comes into this routine
601 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
602 * 13 and 15 set.
603 */
604 void bitmap_remap(unsigned long *dst, const unsigned long *src,
605 const unsigned long *old, const unsigned long *new,
606 int bits)
607 {
608 int oldbit, w;
610 if (dst == src) /* following doesn't handle inplace remaps */
611 return;
612 bitmap_zero(dst, bits);
614 w = bitmap_weight(new, bits);
615 for (oldbit = find_first_bit(src, bits);
616 oldbit < bits;
617 oldbit = find_next_bit(src, bits, oldbit + 1)) {
618 int n = bitmap_pos_to_ord(old, oldbit, bits);
619 if (n < 0 || w == 0)
620 set_bit(oldbit, dst); /* identity map */
621 else
622 set_bit(bitmap_ord_to_pos(new, n % w, bits), dst);
623 }
624 }
625 EXPORT_SYMBOL(bitmap_remap);
627 /**
628 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
629 * @oldbit: bit position to be mapped
630 * @old: defines domain of map
631 * @new: defines range of map
632 * @bits: number of bits in each of these bitmaps
633 *
634 * Let @old and @new define a mapping of bit positions, such that
635 * whatever position is held by the n-th set bit in @old is mapped
636 * to the n-th set bit in @new. In the more general case, allowing
637 * for the possibility that the weight 'w' of @new is less than the
638 * weight of @old, map the position of the n-th set bit in @old to
639 * the position of the m-th set bit in @new, where m == n % w.
640 *
641 * The positions of unset bits in @old are mapped to themselves
642 * (the identify map).
643 *
644 * Apply the above specified mapping to bit position @oldbit, returning
645 * the new bit position.
646 *
647 * For example, lets say that @old has bits 4 through 7 set, and
648 * @new has bits 12 through 15 set. This defines the mapping of bit
649 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
650 * bit positions unchanged. So if say @oldbit is 5, then this routine
651 * returns 13.
652 */
653 int bitmap_bitremap(int oldbit, const unsigned long *old,
654 const unsigned long *new, int bits)
655 {
656 int w = bitmap_weight(new, bits);
657 int n = bitmap_pos_to_ord(old, oldbit, bits);
658 if (n < 0 || w == 0)
659 return oldbit;
660 else
661 return bitmap_ord_to_pos(new, n % w, bits);
662 }
663 EXPORT_SYMBOL(bitmap_bitremap);
665 /*
666 * Common code for bitmap_*_region() routines.
667 * bitmap: array of unsigned longs corresponding to the bitmap
668 * pos: the beginning of the region
669 * order: region size (log base 2 of number of bits)
670 * reg_op: operation(s) to perform on that region of bitmap
671 *
672 * Can set, verify and/or release a region of bits in a bitmap,
673 * depending on which combination of REG_OP_* flag bits is set.
674 *
675 * A region of a bitmap is a sequence of bits in the bitmap, of
676 * some size '1 << order' (a power of two), aligned to that same
677 * '1 << order' power of two.
678 *
679 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
680 * Returns 0 in all other cases and reg_ops.
681 */
683 enum {
684 REG_OP_ISFREE, /* true if region is all zero bits */
685 REG_OP_ALLOC, /* set all bits in region */
686 REG_OP_RELEASE, /* clear all bits in region */
687 };
689 static int __reg_op(unsigned long *bitmap, int pos, int order, int reg_op)
690 {
691 int nbits_reg; /* number of bits in region */
692 int index; /* index first long of region in bitmap */
693 int offset; /* bit offset region in bitmap[index] */
694 int nlongs_reg; /* num longs spanned by region in bitmap */
695 int nbitsinlong; /* num bits of region in each spanned long */
696 unsigned long mask; /* bitmask for one long of region */
697 int i; /* scans bitmap by longs */
698 int ret = 0; /* return value */
700 /*
701 * Either nlongs_reg == 1 (for small orders that fit in one long)
702 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
703 */
704 nbits_reg = 1 << order;
705 index = pos / BITS_PER_LONG;
706 offset = pos - (index * BITS_PER_LONG);
707 nlongs_reg = BITS_TO_LONGS(nbits_reg);
708 nbitsinlong = min(nbits_reg, BITS_PER_LONG);
710 /*
711 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
712 * overflows if nbitsinlong == BITS_PER_LONG.
713 */
714 mask = (1UL << (nbitsinlong - 1));
715 mask += mask - 1;
716 mask <<= offset;
718 switch (reg_op) {
719 case REG_OP_ISFREE:
720 for (i = 0; i < nlongs_reg; i++) {
721 if (bitmap[index + i] & mask)
722 goto done;
723 }
724 ret = 1; /* all bits in region free (zero) */
725 break;
727 case REG_OP_ALLOC:
728 for (i = 0; i < nlongs_reg; i++)
729 bitmap[index + i] |= mask;
730 break;
732 case REG_OP_RELEASE:
733 for (i = 0; i < nlongs_reg; i++)
734 bitmap[index + i] &= ~mask;
735 break;
736 }
737 done:
738 return ret;
739 }
741 /**
742 * bitmap_find_free_region - find a contiguous aligned mem region
743 * @bitmap: array of unsigned longs corresponding to the bitmap
744 * @bits: number of bits in the bitmap
745 * @order: region size (log base 2 of number of bits) to find
746 *
747 * Find a region of free (zero) bits in a @bitmap of @bits bits and
748 * allocate them (set them to one). Only consider regions of length
749 * a power (@order) of two, aligned to that power of two, which
750 * makes the search algorithm much faster.
751 *
752 * Return the bit offset in bitmap of the allocated region,
753 * or -errno on failure.
754 */
755 int bitmap_find_free_region(unsigned long *bitmap, int bits, int order)
756 {
757 int pos; /* scans bitmap by regions of size order */
759 for (pos = 0; pos < bits; pos += (1 << order))
760 if (__reg_op(bitmap, pos, order, REG_OP_ISFREE))
761 break;
762 if (pos == bits)
763 return -ENOMEM;
764 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
765 return pos;
766 }
767 EXPORT_SYMBOL(bitmap_find_free_region);
769 /**
770 * bitmap_release_region - release allocated bitmap region
771 * @bitmap: array of unsigned longs corresponding to the bitmap
772 * @pos: beginning of bit region to release
773 * @order: region size (log base 2 of number of bits) to release
774 *
775 * This is the complement to __bitmap_find_free_region and releases
776 * the found region (by clearing it in the bitmap).
777 *
778 * No return value.
779 */
780 void bitmap_release_region(unsigned long *bitmap, int pos, int order)
781 {
782 __reg_op(bitmap, pos, order, REG_OP_RELEASE);
783 }
784 EXPORT_SYMBOL(bitmap_release_region);
786 /**
787 * bitmap_allocate_region - allocate bitmap region
788 * @bitmap: array of unsigned longs corresponding to the bitmap
789 * @pos: beginning of bit region to allocate
790 * @order: region size (log base 2 of number of bits) to allocate
791 *
792 * Allocate (set bits in) a specified region of a bitmap.
793 *
794 * Return 0 on success, or %-EBUSY if specified region wasn't
795 * free (not all bits were zero).
796 */
797 int bitmap_allocate_region(unsigned long *bitmap, int pos, int order)
798 {
799 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
800 return -EBUSY;
801 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
802 return 0;
803 }
804 EXPORT_SYMBOL(bitmap_allocate_region);