Version:  2.0.40 2.2.26 2.4.37 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1

Linux/lib/bitmap.c

  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/export.h>
  9 #include <linux/thread_info.h>
 10 #include <linux/ctype.h>
 11 #include <linux/errno.h>
 12 #include <linux/bitmap.h>
 13 #include <linux/bitops.h>
 14 #include <linux/bug.h>
 15 
 16 #include <asm/page.h>
 17 #include <asm/uaccess.h>
 18 
 19 /*
 20  * bitmaps provide an array of bits, implemented using an an
 21  * array of unsigned longs.  The number of valid bits in a
 22  * given bitmap does _not_ need to be an exact multiple of
 23  * BITS_PER_LONG.
 24  *
 25  * The possible unused bits in the last, partially used word
 26  * of a bitmap are 'don't care'.  The implementation makes
 27  * no particular effort to keep them zero.  It ensures that
 28  * their value will not affect the results of any operation.
 29  * The bitmap operations that return Boolean (bitmap_empty,
 30  * for example) or scalar (bitmap_weight, for example) results
 31  * carefully filter out these unused bits from impacting their
 32  * results.
 33  *
 34  * These operations actually hold to a slightly stronger rule:
 35  * if you don't input any bitmaps to these ops that have some
 36  * unused bits set, then they won't output any set unused bits
 37  * in output bitmaps.
 38  *
 39  * The byte ordering of bitmaps is more natural on little
 40  * endian architectures.  See the big-endian headers
 41  * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
 42  * for the best explanations of this ordering.
 43  */
 44 
 45 int __bitmap_equal(const unsigned long *bitmap1,
 46                 const unsigned long *bitmap2, unsigned int bits)
 47 {
 48         unsigned int k, lim = bits/BITS_PER_LONG;
 49         for (k = 0; k < lim; ++k)
 50                 if (bitmap1[k] != bitmap2[k])
 51                         return 0;
 52 
 53         if (bits % BITS_PER_LONG)
 54                 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
 55                         return 0;
 56 
 57         return 1;
 58 }
 59 EXPORT_SYMBOL(__bitmap_equal);
 60 
 61 void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits)
 62 {
 63         unsigned int k, lim = bits/BITS_PER_LONG;
 64         for (k = 0; k < lim; ++k)
 65                 dst[k] = ~src[k];
 66 
 67         if (bits % BITS_PER_LONG)
 68                 dst[k] = ~src[k];
 69 }
 70 EXPORT_SYMBOL(__bitmap_complement);
 71 
 72 /**
 73  * __bitmap_shift_right - logical right shift of the bits in a bitmap
 74  *   @dst : destination bitmap
 75  *   @src : source bitmap
 76  *   @shift : shift by this many bits
 77  *   @nbits : bitmap size, in bits
 78  *
 79  * Shifting right (dividing) means moving bits in the MS -> LS bit
 80  * direction.  Zeros are fed into the vacated MS positions and the
 81  * LS bits shifted off the bottom are lost.
 82  */
 83 void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
 84                         unsigned shift, unsigned nbits)
 85 {
 86         unsigned k, lim = BITS_TO_LONGS(nbits);
 87         unsigned off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
 88         unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);
 89         for (k = 0; off + k < lim; ++k) {
 90                 unsigned long upper, lower;
 91 
 92                 /*
 93                  * If shift is not word aligned, take lower rem bits of
 94                  * word above and make them the top rem bits of result.
 95                  */
 96                 if (!rem || off + k + 1 >= lim)
 97                         upper = 0;
 98                 else {
 99                         upper = src[off + k + 1];
100                         if (off + k + 1 == lim - 1)
101                                 upper &= mask;
102                         upper <<= (BITS_PER_LONG - rem);
103                 }
104                 lower = src[off + k];
105                 if (off + k == lim - 1)
106                         lower &= mask;
107                 lower >>= rem;
108                 dst[k] = lower | upper;
109         }
110         if (off)
111                 memset(&dst[lim - off], 0, off*sizeof(unsigned long));
112 }
113 EXPORT_SYMBOL(__bitmap_shift_right);
114 
115 
116 /**
117  * __bitmap_shift_left - logical left shift of the bits in a bitmap
118  *   @dst : destination bitmap
119  *   @src : source bitmap
120  *   @shift : shift by this many bits
121  *   @nbits : bitmap size, in bits
122  *
123  * Shifting left (multiplying) means moving bits in the LS -> MS
124  * direction.  Zeros are fed into the vacated LS bit positions
125  * and those MS bits shifted off the top are lost.
126  */
127 
128 void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
129                         unsigned int shift, unsigned int nbits)
130 {
131         int k;
132         unsigned int lim = BITS_TO_LONGS(nbits);
133         unsigned int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
134         for (k = lim - off - 1; k >= 0; --k) {
135                 unsigned long upper, lower;
136 
137                 /*
138                  * If shift is not word aligned, take upper rem bits of
139                  * word below and make them the bottom rem bits of result.
140                  */
141                 if (rem && k > 0)
142                         lower = src[k - 1] >> (BITS_PER_LONG - rem);
143                 else
144                         lower = 0;
145                 upper = src[k] << rem;
146                 dst[k + off] = lower | upper;
147         }
148         if (off)
149                 memset(dst, 0, off*sizeof(unsigned long));
150 }
151 EXPORT_SYMBOL(__bitmap_shift_left);
152 
153 int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
154                                 const unsigned long *bitmap2, unsigned int bits)
155 {
156         unsigned int k;
157         unsigned int lim = bits/BITS_PER_LONG;
158         unsigned long result = 0;
159 
160         for (k = 0; k < lim; k++)
161                 result |= (dst[k] = bitmap1[k] & bitmap2[k]);
162         if (bits % BITS_PER_LONG)
163                 result |= (dst[k] = bitmap1[k] & bitmap2[k] &
164                            BITMAP_LAST_WORD_MASK(bits));
165         return result != 0;
166 }
167 EXPORT_SYMBOL(__bitmap_and);
168 
169 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
170                                 const unsigned long *bitmap2, unsigned int bits)
171 {
172         unsigned int k;
173         unsigned int nr = BITS_TO_LONGS(bits);
174 
175         for (k = 0; k < nr; k++)
176                 dst[k] = bitmap1[k] | bitmap2[k];
177 }
178 EXPORT_SYMBOL(__bitmap_or);
179 
180 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
181                                 const unsigned long *bitmap2, unsigned int bits)
182 {
183         unsigned int k;
184         unsigned int nr = BITS_TO_LONGS(bits);
185 
186         for (k = 0; k < nr; k++)
187                 dst[k] = bitmap1[k] ^ bitmap2[k];
188 }
189 EXPORT_SYMBOL(__bitmap_xor);
190 
191 int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
192                                 const unsigned long *bitmap2, unsigned int bits)
193 {
194         unsigned int k;
195         unsigned int lim = bits/BITS_PER_LONG;
196         unsigned long result = 0;
197 
198         for (k = 0; k < lim; k++)
199                 result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
200         if (bits % BITS_PER_LONG)
201                 result |= (dst[k] = bitmap1[k] & ~bitmap2[k] &
202                            BITMAP_LAST_WORD_MASK(bits));
203         return result != 0;
204 }
205 EXPORT_SYMBOL(__bitmap_andnot);
206 
207 int __bitmap_intersects(const unsigned long *bitmap1,
208                         const unsigned long *bitmap2, unsigned int bits)
209 {
210         unsigned int k, lim = bits/BITS_PER_LONG;
211         for (k = 0; k < lim; ++k)
212                 if (bitmap1[k] & bitmap2[k])
213                         return 1;
214 
215         if (bits % BITS_PER_LONG)
216                 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
217                         return 1;
218         return 0;
219 }
220 EXPORT_SYMBOL(__bitmap_intersects);
221 
222 int __bitmap_subset(const unsigned long *bitmap1,
223                     const unsigned long *bitmap2, unsigned int bits)
224 {
225         unsigned int k, lim = bits/BITS_PER_LONG;
226         for (k = 0; k < lim; ++k)
227                 if (bitmap1[k] & ~bitmap2[k])
228                         return 0;
229 
230         if (bits % BITS_PER_LONG)
231                 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
232                         return 0;
233         return 1;
234 }
235 EXPORT_SYMBOL(__bitmap_subset);
236 
237 int __bitmap_weight(const unsigned long *bitmap, unsigned int bits)
238 {
239         unsigned int k, lim = bits/BITS_PER_LONG;
240         int w = 0;
241 
242         for (k = 0; k < lim; k++)
243                 w += hweight_long(bitmap[k]);
244 
245         if (bits % BITS_PER_LONG)
246                 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
247 
248         return w;
249 }
250 EXPORT_SYMBOL(__bitmap_weight);
251 
252 void bitmap_set(unsigned long *map, unsigned int start, int len)
253 {
254         unsigned long *p = map + BIT_WORD(start);
255         const unsigned int size = start + len;
256         int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
257         unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
258 
259         while (len - bits_to_set >= 0) {
260                 *p |= mask_to_set;
261                 len -= bits_to_set;
262                 bits_to_set = BITS_PER_LONG;
263                 mask_to_set = ~0UL;
264                 p++;
265         }
266         if (len) {
267                 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
268                 *p |= mask_to_set;
269         }
270 }
271 EXPORT_SYMBOL(bitmap_set);
272 
273 void bitmap_clear(unsigned long *map, unsigned int start, int len)
274 {
275         unsigned long *p = map + BIT_WORD(start);
276         const unsigned int size = start + len;
277         int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
278         unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
279 
280         while (len - bits_to_clear >= 0) {
281                 *p &= ~mask_to_clear;
282                 len -= bits_to_clear;
283                 bits_to_clear = BITS_PER_LONG;
284                 mask_to_clear = ~0UL;
285                 p++;
286         }
287         if (len) {
288                 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
289                 *p &= ~mask_to_clear;
290         }
291 }
292 EXPORT_SYMBOL(bitmap_clear);
293 
294 /**
295  * bitmap_find_next_zero_area_off - find a contiguous aligned zero area
296  * @map: The address to base the search on
297  * @size: The bitmap size in bits
298  * @start: The bitnumber to start searching at
299  * @nr: The number of zeroed bits we're looking for
300  * @align_mask: Alignment mask for zero area
301  * @align_offset: Alignment offset for zero area.
302  *
303  * The @align_mask should be one less than a power of 2; the effect is that
304  * the bit offset of all zero areas this function finds plus @align_offset
305  * is multiple of that power of 2.
306  */
307 unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
308                                              unsigned long size,
309                                              unsigned long start,
310                                              unsigned int nr,
311                                              unsigned long align_mask,
312                                              unsigned long align_offset)
313 {
314         unsigned long index, end, i;
315 again:
316         index = find_next_zero_bit(map, size, start);
317 
318         /* Align allocation */
319         index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset;
320 
321         end = index + nr;
322         if (end > size)
323                 return end;
324         i = find_next_bit(map, end, index);
325         if (i < end) {
326                 start = i + 1;
327                 goto again;
328         }
329         return index;
330 }
331 EXPORT_SYMBOL(bitmap_find_next_zero_area_off);
332 
333 /*
334  * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,
335  * second version by Paul Jackson, third by Joe Korty.
336  */
337 
338 #define CHUNKSZ                         32
339 #define nbits_to_hold_value(val)        fls(val)
340 #define BASEDEC 10              /* fancier cpuset lists input in decimal */
341 
342 /**
343  * __bitmap_parse - convert an ASCII hex string into a bitmap.
344  * @buf: pointer to buffer containing string.
345  * @buflen: buffer size in bytes.  If string is smaller than this
346  *    then it must be terminated with a \0.
347  * @is_user: location of buffer, 0 indicates kernel space
348  * @maskp: pointer to bitmap array that will contain result.
349  * @nmaskbits: size of bitmap, in bits.
350  *
351  * Commas group hex digits into chunks.  Each chunk defines exactly 32
352  * bits of the resultant bitmask.  No chunk may specify a value larger
353  * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
354  * then leading 0-bits are prepended.  %-EINVAL is returned for illegal
355  * characters and for grouping errors such as "1,,5", ",44", "," and "".
356  * Leading and trailing whitespace accepted, but not embedded whitespace.
357  */
358 int __bitmap_parse(const char *buf, unsigned int buflen,
359                 int is_user, unsigned long *maskp,
360                 int nmaskbits)
361 {
362         int c, old_c, totaldigits, ndigits, nchunks, nbits;
363         u32 chunk;
364         const char __user __force *ubuf = (const char __user __force *)buf;
365 
366         bitmap_zero(maskp, nmaskbits);
367 
368         nchunks = nbits = totaldigits = c = 0;
369         do {
370                 chunk = ndigits = 0;
371 
372                 /* Get the next chunk of the bitmap */
373                 while (buflen) {
374                         old_c = c;
375                         if (is_user) {
376                                 if (__get_user(c, ubuf++))
377                                         return -EFAULT;
378                         }
379                         else
380                                 c = *buf++;
381                         buflen--;
382                         if (isspace(c))
383                                 continue;
384 
385                         /*
386                          * If the last character was a space and the current
387                          * character isn't '\0', we've got embedded whitespace.
388                          * This is a no-no, so throw an error.
389                          */
390                         if (totaldigits && c && isspace(old_c))
391                                 return -EINVAL;
392 
393                         /* A '\0' or a ',' signal the end of the chunk */
394                         if (c == '\0' || c == ',')
395                                 break;
396 
397                         if (!isxdigit(c))
398                                 return -EINVAL;
399 
400                         /*
401                          * Make sure there are at least 4 free bits in 'chunk'.
402                          * If not, this hexdigit will overflow 'chunk', so
403                          * throw an error.
404                          */
405                         if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
406                                 return -EOVERFLOW;
407 
408                         chunk = (chunk << 4) | hex_to_bin(c);
409                         ndigits++; totaldigits++;
410                 }
411                 if (ndigits == 0)
412                         return -EINVAL;
413                 if (nchunks == 0 && chunk == 0)
414                         continue;
415 
416                 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
417                 *maskp |= chunk;
418                 nchunks++;
419                 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
420                 if (nbits > nmaskbits)
421                         return -EOVERFLOW;
422         } while (buflen && c == ',');
423 
424         return 0;
425 }
426 EXPORT_SYMBOL(__bitmap_parse);
427 
428 /**
429  * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
430  *
431  * @ubuf: pointer to user buffer containing string.
432  * @ulen: buffer size in bytes.  If string is smaller than this
433  *    then it must be terminated with a \0.
434  * @maskp: pointer to bitmap array that will contain result.
435  * @nmaskbits: size of bitmap, in bits.
436  *
437  * Wrapper for __bitmap_parse(), providing it with user buffer.
438  *
439  * We cannot have this as an inline function in bitmap.h because it needs
440  * linux/uaccess.h to get the access_ok() declaration and this causes
441  * cyclic dependencies.
442  */
443 int bitmap_parse_user(const char __user *ubuf,
444                         unsigned int ulen, unsigned long *maskp,
445                         int nmaskbits)
446 {
447         if (!access_ok(VERIFY_READ, ubuf, ulen))
448                 return -EFAULT;
449         return __bitmap_parse((const char __force *)ubuf,
450                                 ulen, 1, maskp, nmaskbits);
451 
452 }
453 EXPORT_SYMBOL(bitmap_parse_user);
454 
455 /**
456  * bitmap_print_to_pagebuf - convert bitmap to list or hex format ASCII string
457  * @list: indicates whether the bitmap must be list
458  * @buf: page aligned buffer into which string is placed
459  * @maskp: pointer to bitmap to convert
460  * @nmaskbits: size of bitmap, in bits
461  *
462  * Output format is a comma-separated list of decimal numbers and
463  * ranges if list is specified or hex digits grouped into comma-separated
464  * sets of 8 digits/set. Returns the number of characters written to buf.
465  */
466 int bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp,
467                             int nmaskbits)
468 {
469         ptrdiff_t len = PTR_ALIGN(buf + PAGE_SIZE - 1, PAGE_SIZE) - buf - 2;
470         int n = 0;
471 
472         if (len > 1) {
473                 n = list ? scnprintf(buf, len, "%*pbl", nmaskbits, maskp) :
474                            scnprintf(buf, len, "%*pb", nmaskbits, maskp);
475                 buf[n++] = '\n';
476                 buf[n] = '\0';
477         }
478         return n;
479 }
480 EXPORT_SYMBOL(bitmap_print_to_pagebuf);
481 
482 /**
483  * __bitmap_parselist - convert list format ASCII string to bitmap
484  * @buf: read nul-terminated user string from this buffer
485  * @buflen: buffer size in bytes.  If string is smaller than this
486  *    then it must be terminated with a \0.
487  * @is_user: location of buffer, 0 indicates kernel space
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  */
502 static int __bitmap_parselist(const char *buf, unsigned int buflen,
503                 int is_user, unsigned long *maskp,
504                 int nmaskbits)
505 {
506         unsigned a, b;
507         int c, old_c, totaldigits;
508         const char __user __force *ubuf = (const char __user __force *)buf;
509         int exp_digit, in_range;
510 
511         totaldigits = c = 0;
512         bitmap_zero(maskp, nmaskbits);
513         do {
514                 exp_digit = 1;
515                 in_range = 0;
516                 a = b = 0;
517 
518                 /* Get the next cpu# or a range of cpu#'s */
519                 while (buflen) {
520                         old_c = c;
521                         if (is_user) {
522                                 if (__get_user(c, ubuf++))
523                                         return -EFAULT;
524                         } else
525                                 c = *buf++;
526                         buflen--;
527                         if (isspace(c))
528                                 continue;
529 
530                         /*
531                          * If the last character was a space and the current
532                          * character isn't '\0', we've got embedded whitespace.
533                          * This is a no-no, so throw an error.
534                          */
535                         if (totaldigits && c && isspace(old_c))
536                                 return -EINVAL;
537 
538                         /* A '\0' or a ',' signal the end of a cpu# or range */
539                         if (c == '\0' || c == ',')
540                                 break;
541 
542                         if (c == '-') {
543                                 if (exp_digit || in_range)
544                                         return -EINVAL;
545                                 b = 0;
546                                 in_range = 1;
547                                 exp_digit = 1;
548                                 continue;
549                         }
550 
551                         if (!isdigit(c))
552                                 return -EINVAL;
553 
554                         b = b * 10 + (c - '');
555                         if (!in_range)
556                                 a = b;
557                         exp_digit = 0;
558                         totaldigits++;
559                 }
560                 if (!(a <= b))
561                         return -EINVAL;
562                 if (b >= nmaskbits)
563                         return -ERANGE;
564                 while (a <= b) {
565                         set_bit(a, maskp);
566                         a++;
567                 }
568         } while (buflen && c == ',');
569         return 0;
570 }
571 
572 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
573 {
574         char *nl  = strchrnul(bp, '\n');
575         int len = nl - bp;
576 
577         return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
578 }
579 EXPORT_SYMBOL(bitmap_parselist);
580 
581 
582 /**
583  * bitmap_parselist_user()
584  *
585  * @ubuf: pointer to user buffer containing string.
586  * @ulen: buffer size in bytes.  If string is smaller than this
587  *    then it must be terminated with a \0.
588  * @maskp: pointer to bitmap array that will contain result.
589  * @nmaskbits: size of bitmap, in bits.
590  *
591  * Wrapper for bitmap_parselist(), providing it with user buffer.
592  *
593  * We cannot have this as an inline function in bitmap.h because it needs
594  * linux/uaccess.h to get the access_ok() declaration and this causes
595  * cyclic dependencies.
596  */
597 int bitmap_parselist_user(const char __user *ubuf,
598                         unsigned int ulen, unsigned long *maskp,
599                         int nmaskbits)
600 {
601         if (!access_ok(VERIFY_READ, ubuf, ulen))
602                 return -EFAULT;
603         return __bitmap_parselist((const char __force *)ubuf,
604                                         ulen, 1, maskp, nmaskbits);
605 }
606 EXPORT_SYMBOL(bitmap_parselist_user);
607 
608 
609 /**
610  * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
611  *      @buf: pointer to a bitmap
612  *      @pos: a bit position in @buf (0 <= @pos < @nbits)
613  *      @nbits: number of valid bit positions in @buf
614  *
615  * Map the bit at position @pos in @buf (of length @nbits) to the
616  * ordinal of which set bit it is.  If it is not set or if @pos
617  * is not a valid bit position, map to -1.
618  *
619  * If for example, just bits 4 through 7 are set in @buf, then @pos
620  * values 4 through 7 will get mapped to 0 through 3, respectively,
621  * and other @pos values will get mapped to -1.  When @pos value 7
622  * gets mapped to (returns) @ord value 3 in this example, that means
623  * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
624  *
625  * The bit positions 0 through @bits are valid positions in @buf.
626  */
627 static int bitmap_pos_to_ord(const unsigned long *buf, unsigned int pos, unsigned int nbits)
628 {
629         if (pos >= nbits || !test_bit(pos, buf))
630                 return -1;
631 
632         return __bitmap_weight(buf, pos);
633 }
634 
635 /**
636  * bitmap_ord_to_pos - find position of n-th set bit in bitmap
637  *      @buf: pointer to bitmap
638  *      @ord: ordinal bit position (n-th set bit, n >= 0)
639  *      @nbits: number of valid bit positions in @buf
640  *
641  * Map the ordinal offset of bit @ord in @buf to its position in @buf.
642  * Value of @ord should be in range 0 <= @ord < weight(buf). If @ord
643  * >= weight(buf), returns @nbits.
644  *
645  * If for example, just bits 4 through 7 are set in @buf, then @ord
646  * values 0 through 3 will get mapped to 4 through 7, respectively,
647  * and all other @ord values returns @nbits.  When @ord value 3
648  * gets mapped to (returns) @pos value 7 in this example, that means
649  * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
650  *
651  * The bit positions 0 through @nbits-1 are valid positions in @buf.
652  */
653 unsigned int bitmap_ord_to_pos(const unsigned long *buf, unsigned int ord, unsigned int nbits)
654 {
655         unsigned int pos;
656 
657         for (pos = find_first_bit(buf, nbits);
658              pos < nbits && ord;
659              pos = find_next_bit(buf, nbits, pos + 1))
660                 ord--;
661 
662         return pos;
663 }
664 
665 /**
666  * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
667  *      @dst: remapped result
668  *      @src: subset to be remapped
669  *      @old: defines domain of map
670  *      @new: defines range of map
671  *      @nbits: number of bits in each of these bitmaps
672  *
673  * Let @old and @new define a mapping of bit positions, such that
674  * whatever position is held by the n-th set bit in @old is mapped
675  * to the n-th set bit in @new.  In the more general case, allowing
676  * for the possibility that the weight 'w' of @new is less than the
677  * weight of @old, map the position of the n-th set bit in @old to
678  * the position of the m-th set bit in @new, where m == n % w.
679  *
680  * If either of the @old and @new bitmaps are empty, or if @src and
681  * @dst point to the same location, then this routine copies @src
682  * to @dst.
683  *
684  * The positions of unset bits in @old are mapped to themselves
685  * (the identify map).
686  *
687  * Apply the above specified mapping to @src, placing the result in
688  * @dst, clearing any bits previously set in @dst.
689  *
690  * For example, lets say that @old has bits 4 through 7 set, and
691  * @new has bits 12 through 15 set.  This defines the mapping of bit
692  * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
693  * bit positions unchanged.  So if say @src comes into this routine
694  * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
695  * 13 and 15 set.
696  */
697 void bitmap_remap(unsigned long *dst, const unsigned long *src,
698                 const unsigned long *old, const unsigned long *new,
699                 unsigned int nbits)
700 {
701         unsigned int oldbit, w;
702 
703         if (dst == src)         /* following doesn't handle inplace remaps */
704                 return;
705         bitmap_zero(dst, nbits);
706 
707         w = bitmap_weight(new, nbits);
708         for_each_set_bit(oldbit, src, nbits) {
709                 int n = bitmap_pos_to_ord(old, oldbit, nbits);
710 
711                 if (n < 0 || w == 0)
712                         set_bit(oldbit, dst);   /* identity map */
713                 else
714                         set_bit(bitmap_ord_to_pos(new, n % w, nbits), dst);
715         }
716 }
717 EXPORT_SYMBOL(bitmap_remap);
718 
719 /**
720  * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
721  *      @oldbit: bit position to be mapped
722  *      @old: defines domain of map
723  *      @new: defines range of map
724  *      @bits: number of bits in each of these bitmaps
725  *
726  * Let @old and @new define a mapping of bit positions, such that
727  * whatever position is held by the n-th set bit in @old is mapped
728  * to the n-th set bit in @new.  In the more general case, allowing
729  * for the possibility that the weight 'w' of @new is less than the
730  * weight of @old, map the position of the n-th set bit in @old to
731  * the position of the m-th set bit in @new, where m == n % w.
732  *
733  * The positions of unset bits in @old are mapped to themselves
734  * (the identify map).
735  *
736  * Apply the above specified mapping to bit position @oldbit, returning
737  * the new bit position.
738  *
739  * For example, lets say that @old has bits 4 through 7 set, and
740  * @new has bits 12 through 15 set.  This defines the mapping of bit
741  * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
742  * bit positions unchanged.  So if say @oldbit is 5, then this routine
743  * returns 13.
744  */
745 int bitmap_bitremap(int oldbit, const unsigned long *old,
746                                 const unsigned long *new, int bits)
747 {
748         int w = bitmap_weight(new, bits);
749         int n = bitmap_pos_to_ord(old, oldbit, bits);
750         if (n < 0 || w == 0)
751                 return oldbit;
752         else
753                 return bitmap_ord_to_pos(new, n % w, bits);
754 }
755 EXPORT_SYMBOL(bitmap_bitremap);
756 
757 /**
758  * bitmap_onto - translate one bitmap relative to another
759  *      @dst: resulting translated bitmap
760  *      @orig: original untranslated bitmap
761  *      @relmap: bitmap relative to which translated
762  *      @bits: number of bits in each of these bitmaps
763  *
764  * Set the n-th bit of @dst iff there exists some m such that the
765  * n-th bit of @relmap is set, the m-th bit of @orig is set, and
766  * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
767  * (If you understood the previous sentence the first time your
768  * read it, you're overqualified for your current job.)
769  *
770  * In other words, @orig is mapped onto (surjectively) @dst,
771  * using the map { <n, m> | the n-th bit of @relmap is the
772  * m-th set bit of @relmap }.
773  *
774  * Any set bits in @orig above bit number W, where W is the
775  * weight of (number of set bits in) @relmap are mapped nowhere.
776  * In particular, if for all bits m set in @orig, m >= W, then
777  * @dst will end up empty.  In situations where the possibility
778  * of such an empty result is not desired, one way to avoid it is
779  * to use the bitmap_fold() operator, below, to first fold the
780  * @orig bitmap over itself so that all its set bits x are in the
781  * range 0 <= x < W.  The bitmap_fold() operator does this by
782  * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
783  *
784  * Example [1] for bitmap_onto():
785  *  Let's say @relmap has bits 30-39 set, and @orig has bits
786  *  1, 3, 5, 7, 9 and 11 set.  Then on return from this routine,
787  *  @dst will have bits 31, 33, 35, 37 and 39 set.
788  *
789  *  When bit 0 is set in @orig, it means turn on the bit in
790  *  @dst corresponding to whatever is the first bit (if any)
791  *  that is turned on in @relmap.  Since bit 0 was off in the
792  *  above example, we leave off that bit (bit 30) in @dst.
793  *
794  *  When bit 1 is set in @orig (as in the above example), it
795  *  means turn on the bit in @dst corresponding to whatever
796  *  is the second bit that is turned on in @relmap.  The second
797  *  bit in @relmap that was turned on in the above example was
798  *  bit 31, so we turned on bit 31 in @dst.
799  *
800  *  Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
801  *  because they were the 4th, 6th, 8th and 10th set bits
802  *  set in @relmap, and the 4th, 6th, 8th and 10th bits of
803  *  @orig (i.e. bits 3, 5, 7 and 9) were also set.
804  *
805  *  When bit 11 is set in @orig, it means turn on the bit in
806  *  @dst corresponding to whatever is the twelfth bit that is
807  *  turned on in @relmap.  In the above example, there were
808  *  only ten bits turned on in @relmap (30..39), so that bit
809  *  11 was set in @orig had no affect on @dst.
810  *
811  * Example [2] for bitmap_fold() + bitmap_onto():
812  *  Let's say @relmap has these ten bits set:
813  *              40 41 42 43 45 48 53 61 74 95
814  *  (for the curious, that's 40 plus the first ten terms of the
815  *  Fibonacci sequence.)
816  *
817  *  Further lets say we use the following code, invoking
818  *  bitmap_fold() then bitmap_onto, as suggested above to
819  *  avoid the possibility of an empty @dst result:
820  *
821  *      unsigned long *tmp;     // a temporary bitmap's bits
822  *
823  *      bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
824  *      bitmap_onto(dst, tmp, relmap, bits);
825  *
826  *  Then this table shows what various values of @dst would be, for
827  *  various @orig's.  I list the zero-based positions of each set bit.
828  *  The tmp column shows the intermediate result, as computed by
829  *  using bitmap_fold() to fold the @orig bitmap modulo ten
830  *  (the weight of @relmap).
831  *
832  *      @orig           tmp            @dst
833  *      0                0             40
834  *      1                1             41
835  *      9                9             95
836  *      10               0             40 (*)
837  *      1 3 5 7          1 3 5 7       41 43 48 61
838  *      0 1 2 3 4        0 1 2 3 4     40 41 42 43 45
839  *      0 9 18 27        0 9 8 7       40 61 74 95
840  *      0 10 20 30       0             40
841  *      0 11 22 33       0 1 2 3       40 41 42 43
842  *      0 12 24 36       0 2 4 6       40 42 45 53
843  *      78 102 211       1 2 8         41 42 74 (*)
844  *
845  * (*) For these marked lines, if we hadn't first done bitmap_fold()
846  *     into tmp, then the @dst result would have been empty.
847  *
848  * If either of @orig or @relmap is empty (no set bits), then @dst
849  * will be returned empty.
850  *
851  * If (as explained above) the only set bits in @orig are in positions
852  * m where m >= W, (where W is the weight of @relmap) then @dst will
853  * once again be returned empty.
854  *
855  * All bits in @dst not set by the above rule are cleared.
856  */
857 void bitmap_onto(unsigned long *dst, const unsigned long *orig,
858                         const unsigned long *relmap, unsigned int bits)
859 {
860         unsigned int n, m;      /* same meaning as in above comment */
861 
862         if (dst == orig)        /* following doesn't handle inplace mappings */
863                 return;
864         bitmap_zero(dst, bits);
865 
866         /*
867          * The following code is a more efficient, but less
868          * obvious, equivalent to the loop:
869          *      for (m = 0; m < bitmap_weight(relmap, bits); m++) {
870          *              n = bitmap_ord_to_pos(orig, m, bits);
871          *              if (test_bit(m, orig))
872          *                      set_bit(n, dst);
873          *      }
874          */
875 
876         m = 0;
877         for_each_set_bit(n, relmap, bits) {
878                 /* m == bitmap_pos_to_ord(relmap, n, bits) */
879                 if (test_bit(m, orig))
880                         set_bit(n, dst);
881                 m++;
882         }
883 }
884 EXPORT_SYMBOL(bitmap_onto);
885 
886 /**
887  * bitmap_fold - fold larger bitmap into smaller, modulo specified size
888  *      @dst: resulting smaller bitmap
889  *      @orig: original larger bitmap
890  *      @sz: specified size
891  *      @nbits: number of bits in each of these bitmaps
892  *
893  * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
894  * Clear all other bits in @dst.  See further the comment and
895  * Example [2] for bitmap_onto() for why and how to use this.
896  */
897 void bitmap_fold(unsigned long *dst, const unsigned long *orig,
898                         unsigned int sz, unsigned int nbits)
899 {
900         unsigned int oldbit;
901 
902         if (dst == orig)        /* following doesn't handle inplace mappings */
903                 return;
904         bitmap_zero(dst, nbits);
905 
906         for_each_set_bit(oldbit, orig, nbits)
907                 set_bit(oldbit % sz, dst);
908 }
909 EXPORT_SYMBOL(bitmap_fold);
910 
911 /*
912  * Common code for bitmap_*_region() routines.
913  *      bitmap: array of unsigned longs corresponding to the bitmap
914  *      pos: the beginning of the region
915  *      order: region size (log base 2 of number of bits)
916  *      reg_op: operation(s) to perform on that region of bitmap
917  *
918  * Can set, verify and/or release a region of bits in a bitmap,
919  * depending on which combination of REG_OP_* flag bits is set.
920  *
921  * A region of a bitmap is a sequence of bits in the bitmap, of
922  * some size '1 << order' (a power of two), aligned to that same
923  * '1 << order' power of two.
924  *
925  * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
926  * Returns 0 in all other cases and reg_ops.
927  */
928 
929 enum {
930         REG_OP_ISFREE,          /* true if region is all zero bits */
931         REG_OP_ALLOC,           /* set all bits in region */
932         REG_OP_RELEASE,         /* clear all bits in region */
933 };
934 
935 static int __reg_op(unsigned long *bitmap, unsigned int pos, int order, int reg_op)
936 {
937         int nbits_reg;          /* number of bits in region */
938         int index;              /* index first long of region in bitmap */
939         int offset;             /* bit offset region in bitmap[index] */
940         int nlongs_reg;         /* num longs spanned by region in bitmap */
941         int nbitsinlong;        /* num bits of region in each spanned long */
942         unsigned long mask;     /* bitmask for one long of region */
943         int i;                  /* scans bitmap by longs */
944         int ret = 0;            /* return value */
945 
946         /*
947          * Either nlongs_reg == 1 (for small orders that fit in one long)
948          * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
949          */
950         nbits_reg = 1 << order;
951         index = pos / BITS_PER_LONG;
952         offset = pos - (index * BITS_PER_LONG);
953         nlongs_reg = BITS_TO_LONGS(nbits_reg);
954         nbitsinlong = min(nbits_reg,  BITS_PER_LONG);
955 
956         /*
957          * Can't do "mask = (1UL << nbitsinlong) - 1", as that
958          * overflows if nbitsinlong == BITS_PER_LONG.
959          */
960         mask = (1UL << (nbitsinlong - 1));
961         mask += mask - 1;
962         mask <<= offset;
963 
964         switch (reg_op) {
965         case REG_OP_ISFREE:
966                 for (i = 0; i < nlongs_reg; i++) {
967                         if (bitmap[index + i] & mask)
968                                 goto done;
969                 }
970                 ret = 1;        /* all bits in region free (zero) */
971                 break;
972 
973         case REG_OP_ALLOC:
974                 for (i = 0; i < nlongs_reg; i++)
975                         bitmap[index + i] |= mask;
976                 break;
977 
978         case REG_OP_RELEASE:
979                 for (i = 0; i < nlongs_reg; i++)
980                         bitmap[index + i] &= ~mask;
981                 break;
982         }
983 done:
984         return ret;
985 }
986 
987 /**
988  * bitmap_find_free_region - find a contiguous aligned mem region
989  *      @bitmap: array of unsigned longs corresponding to the bitmap
990  *      @bits: number of bits in the bitmap
991  *      @order: region size (log base 2 of number of bits) to find
992  *
993  * Find a region of free (zero) bits in a @bitmap of @bits bits and
994  * allocate them (set them to one).  Only consider regions of length
995  * a power (@order) of two, aligned to that power of two, which
996  * makes the search algorithm much faster.
997  *
998  * Return the bit offset in bitmap of the allocated region,
999  * or -errno on failure.
1000  */
1001 int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order)
1002 {
1003         unsigned int pos, end;          /* scans bitmap by regions of size order */
1004 
1005         for (pos = 0 ; (end = pos + (1U << order)) <= bits; pos = end) {
1006                 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1007                         continue;
1008                 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1009                 return pos;
1010         }
1011         return -ENOMEM;
1012 }
1013 EXPORT_SYMBOL(bitmap_find_free_region);
1014 
1015 /**
1016  * bitmap_release_region - release allocated bitmap region
1017  *      @bitmap: array of unsigned longs corresponding to the bitmap
1018  *      @pos: beginning of bit region to release
1019  *      @order: region size (log base 2 of number of bits) to release
1020  *
1021  * This is the complement to __bitmap_find_free_region() and releases
1022  * the found region (by clearing it in the bitmap).
1023  *
1024  * No return value.
1025  */
1026 void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order)
1027 {
1028         __reg_op(bitmap, pos, order, REG_OP_RELEASE);
1029 }
1030 EXPORT_SYMBOL(bitmap_release_region);
1031 
1032 /**
1033  * bitmap_allocate_region - allocate bitmap region
1034  *      @bitmap: array of unsigned longs corresponding to the bitmap
1035  *      @pos: beginning of bit region to allocate
1036  *      @order: region size (log base 2 of number of bits) to allocate
1037  *
1038  * Allocate (set bits in) a specified region of a bitmap.
1039  *
1040  * Return 0 on success, or %-EBUSY if specified region wasn't
1041  * free (not all bits were zero).
1042  */
1043 int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order)
1044 {
1045         if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1046                 return -EBUSY;
1047         return __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1048 }
1049 EXPORT_SYMBOL(bitmap_allocate_region);
1050 
1051 /**
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
1056  *
1057  * Require nbits % BITS_PER_LONG == 0.
1058  */
1059 #ifdef __BIG_ENDIAN
1060 void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits)
1061 {
1062         unsigned int i;
1063 
1064         for (i = 0; i < nbits/BITS_PER_LONG; i++) {
1065                 if (BITS_PER_LONG == 64)
1066                         dst[i] = cpu_to_le64(src[i]);
1067                 else
1068                         dst[i] = cpu_to_le32(src[i]);
1069         }
1070 }
1071 EXPORT_SYMBOL(bitmap_copy_le);
1072 #endif
1073 

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