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3 * Helper functions for bitmap.h.
5 * This source code is licensed under the GNU General Public License,
6 * Version 2. See the file COPYING for more details.
8 #include <linux/module.h>
9 #include <linux/ctype.h>
10 #include <linux/errno.h>
11 #include <linux/bitmap.h>
12 #include <linux/bitops.h>
13 #include <asm/uaccess.h>
16 * bitmaps provide an array of bits, implemented using an an
17 * array of unsigned longs. The number of valid bits in a
18 * given bitmap does _not_ need to be an exact multiple of
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
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
35 * The byte ordering of bitmaps is more natural on little
36 * endian architectures. See the big-endian headers
37 * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
38 * for the best explanations of this ordering.
41 int __bitmap_empty(const unsigned long *bitmap
, int bits
)
43 int k
, lim
= bits
/BITS_PER_LONG
;
44 for (k
= 0; k
< lim
; ++k
)
48 if (bits
% BITS_PER_LONG
)
49 if (bitmap
[k
] & BITMAP_LAST_WORD_MASK(bits
))
54 EXPORT_SYMBOL(__bitmap_empty
);
56 int __bitmap_full(const unsigned long *bitmap
, int bits
)
58 int k
, lim
= bits
/BITS_PER_LONG
;
59 for (k
= 0; k
< lim
; ++k
)
63 if (bits
% BITS_PER_LONG
)
64 if (~bitmap
[k
] & BITMAP_LAST_WORD_MASK(bits
))
69 EXPORT_SYMBOL(__bitmap_full
);
71 int __bitmap_equal(const unsigned long *bitmap1
,
72 const unsigned long *bitmap2
, int bits
)
74 int k
, lim
= bits
/BITS_PER_LONG
;
75 for (k
= 0; k
< lim
; ++k
)
76 if (bitmap1
[k
] != bitmap2
[k
])
79 if (bits
% BITS_PER_LONG
)
80 if ((bitmap1
[k
] ^ bitmap2
[k
]) & BITMAP_LAST_WORD_MASK(bits
))
85 EXPORT_SYMBOL(__bitmap_equal
);
87 void __bitmap_complement(unsigned long *dst
, const unsigned long *src
, int bits
)
89 int k
, lim
= bits
/BITS_PER_LONG
;
90 for (k
= 0; k
< lim
; ++k
)
93 if (bits
% BITS_PER_LONG
)
94 dst
[k
] = ~src
[k
] & BITMAP_LAST_WORD_MASK(bits
);
96 EXPORT_SYMBOL(__bitmap_complement
);
99 * __bitmap_shift_right - logical right shift of the bits in a bitmap
100 * @dst : destination bitmap
101 * @src : source bitmap
102 * @shift : shift by this many bits
103 * @bits : bitmap size, in bits
105 * Shifting right (dividing) means moving bits in the MS -> LS bit
106 * direction. Zeros are fed into the vacated MS positions and the
107 * LS bits shifted off the bottom are lost.
109 void __bitmap_shift_right(unsigned long *dst
,
110 const unsigned long *src
, int shift
, int bits
)
112 int k
, lim
= BITS_TO_LONGS(bits
), left
= bits
% BITS_PER_LONG
;
113 int off
= shift
/BITS_PER_LONG
, rem
= shift
% BITS_PER_LONG
;
114 unsigned long mask
= (1UL << left
) - 1;
115 for (k
= 0; off
+ k
< lim
; ++k
) {
116 unsigned long upper
, lower
;
119 * If shift is not word aligned, take lower rem bits of
120 * word above and make them the top rem bits of result.
122 if (!rem
|| off
+ k
+ 1 >= lim
)
125 upper
= src
[off
+ k
+ 1];
126 if (off
+ k
+ 1 == lim
- 1 && left
)
129 lower
= src
[off
+ k
];
130 if (left
&& off
+ k
== lim
- 1)
132 dst
[k
] = upper
<< (BITS_PER_LONG
- rem
) | lower
>> rem
;
133 if (left
&& k
== lim
- 1)
137 memset(&dst
[lim
- off
], 0, off
*sizeof(unsigned long));
139 EXPORT_SYMBOL(__bitmap_shift_right
);
143 * __bitmap_shift_left - logical left shift of the bits in a bitmap
144 * @dst : destination bitmap
145 * @src : source bitmap
146 * @shift : shift by this many bits
147 * @bits : bitmap size, in bits
149 * Shifting left (multiplying) means moving bits in the LS -> MS
150 * direction. Zeros are fed into the vacated LS bit positions
151 * and those MS bits shifted off the top are lost.
154 void __bitmap_shift_left(unsigned long *dst
,
155 const unsigned long *src
, int shift
, int bits
)
157 int k
, lim
= BITS_TO_LONGS(bits
), left
= bits
% BITS_PER_LONG
;
158 int off
= shift
/BITS_PER_LONG
, rem
= shift
% BITS_PER_LONG
;
159 for (k
= lim
- off
- 1; k
>= 0; --k
) {
160 unsigned long upper
, lower
;
163 * If shift is not word aligned, take upper rem bits of
164 * word below and make them the bottom rem bits of result.
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;
178 memset(dst
, 0, off
*sizeof(unsigned long));
180 EXPORT_SYMBOL(__bitmap_shift_left
);
182 void __bitmap_and(unsigned long *dst
, const unsigned long *bitmap1
,
183 const unsigned long *bitmap2
, int bits
)
186 int nr
= BITS_TO_LONGS(bits
);
188 for (k
= 0; k
< nr
; k
++)
189 dst
[k
] = bitmap1
[k
] & bitmap2
[k
];
191 EXPORT_SYMBOL(__bitmap_and
);
193 void __bitmap_or(unsigned long *dst
, const unsigned long *bitmap1
,
194 const unsigned long *bitmap2
, int bits
)
197 int nr
= BITS_TO_LONGS(bits
);
199 for (k
= 0; k
< nr
; k
++)
200 dst
[k
] = bitmap1
[k
] | bitmap2
[k
];
202 EXPORT_SYMBOL(__bitmap_or
);
204 void __bitmap_xor(unsigned long *dst
, const unsigned long *bitmap1
,
205 const unsigned long *bitmap2
, int bits
)
208 int nr
= BITS_TO_LONGS(bits
);
210 for (k
= 0; k
< nr
; k
++)
211 dst
[k
] = bitmap1
[k
] ^ bitmap2
[k
];
213 EXPORT_SYMBOL(__bitmap_xor
);
215 void __bitmap_andnot(unsigned long *dst
, const unsigned long *bitmap1
,
216 const unsigned long *bitmap2
, int bits
)
219 int nr
= BITS_TO_LONGS(bits
);
221 for (k
= 0; k
< nr
; k
++)
222 dst
[k
] = bitmap1
[k
] & ~bitmap2
[k
];
224 EXPORT_SYMBOL(__bitmap_andnot
);
226 int __bitmap_intersects(const unsigned long *bitmap1
,
227 const unsigned long *bitmap2
, int bits
)
229 int k
, lim
= bits
/BITS_PER_LONG
;
230 for (k
= 0; k
< lim
; ++k
)
231 if (bitmap1
[k
] & bitmap2
[k
])
234 if (bits
% BITS_PER_LONG
)
235 if ((bitmap1
[k
] & bitmap2
[k
]) & BITMAP_LAST_WORD_MASK(bits
))
239 EXPORT_SYMBOL(__bitmap_intersects
);
241 int __bitmap_subset(const unsigned long *bitmap1
,
242 const unsigned long *bitmap2
, int bits
)
244 int k
, lim
= bits
/BITS_PER_LONG
;
245 for (k
= 0; k
< lim
; ++k
)
246 if (bitmap1
[k
] & ~bitmap2
[k
])
249 if (bits
% BITS_PER_LONG
)
250 if ((bitmap1
[k
] & ~bitmap2
[k
]) & BITMAP_LAST_WORD_MASK(bits
))
254 EXPORT_SYMBOL(__bitmap_subset
);
256 int __bitmap_weight(const unsigned long *bitmap
, int bits
)
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
));
268 EXPORT_SYMBOL(__bitmap_weight
);
271 * Bitmap printing & parsing functions: first version by Bill Irwin,
272 * second version by Paul Jackson, third by Joe Korty.
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 */
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
287 * Exactly @nmaskbits bits are displayed. Hex digits are grouped into
288 * comma-separated sets of eight digits per set.
290 int bitmap_scnprintf(char *buf
, unsigned int buflen
,
291 const unsigned long *maskp
, int nmaskbits
)
293 int i
, word
, bit
, len
= 0;
295 const char *sep
= "";
299 chunksz
= nmaskbits
& (CHUNKSZ
- 1);
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
,
316 EXPORT_SYMBOL(bitmap_scnprintf
);
319 * bitmap_scnprintf_len - return buffer length needed to convert
320 * bitmap to an ASCII hex string
321 * @nr_bits: number of bits to be converted
323 int bitmap_scnprintf_len(unsigned int nr_bits
)
325 unsigned int nr_nibbles
= ALIGN(nr_bits
, 4) / 4;
326 return nr_nibbles
+ ALIGN(nr_nibbles
, CHUNKSZ
/ 4) / (CHUNKSZ
/ 4) - 1;
330 * __bitmap_parse - convert an ASCII hex string into a bitmap.
331 * @buf: pointer to buffer containing string.
332 * @buflen: buffer size in bytes. If string is smaller than this
333 * then it must be terminated with a \0.
334 * @is_user: location of buffer, 0 indicates kernel space
335 * @maskp: pointer to bitmap array that will contain result.
336 * @nmaskbits: size of bitmap, in bits.
338 * Commas group hex digits into chunks. Each chunk defines exactly 32
339 * bits of the resultant bitmask. No chunk may specify a value larger
340 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
341 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
342 * characters and for grouping errors such as "1,,5", ",44", "," and "".
343 * Leading and trailing whitespace accepted, but not embedded whitespace.
345 int __bitmap_parse(const char *buf
, unsigned int buflen
,
346 int is_user
, unsigned long *maskp
,
349 int c
, old_c
, totaldigits
, ndigits
, nchunks
, nbits
;
351 const char __user
*ubuf
= buf
;
353 bitmap_zero(maskp
, nmaskbits
);
355 nchunks
= nbits
= totaldigits
= c
= 0;
359 /* Get the next chunk of the bitmap */
363 if (__get_user(c
, ubuf
++))
373 * If the last character was a space and the current
374 * character isn't '\0', we've got embedded whitespace.
375 * This is a no-no, so throw an error.
377 if (totaldigits
&& c
&& isspace(old_c
))
380 /* A '\0' or a ',' signal the end of the chunk */
381 if (c
== '\0' || c
== ',')
388 * Make sure there are at least 4 free bits in 'chunk'.
389 * If not, this hexdigit will overflow 'chunk', so
392 if (chunk
& ~((1UL << (CHUNKSZ
- 4)) - 1))
395 chunk
= (chunk
<< 4) | unhex(c
);
396 ndigits
++; totaldigits
++;
400 if (nchunks
== 0 && chunk
== 0)
403 __bitmap_shift_left(maskp
, maskp
, CHUNKSZ
, nmaskbits
);
406 nbits
+= (nchunks
== 1) ? nbits_to_hold_value(chunk
) : CHUNKSZ
;
407 if (nbits
> nmaskbits
)
409 } while (buflen
&& c
== ',');
413 EXPORT_SYMBOL(__bitmap_parse
);
416 * bitmap_parse_user()
418 * @ubuf: pointer to user buffer containing string.
419 * @ulen: buffer size in bytes. If string is smaller than this
420 * then it must be terminated with a \0.
421 * @maskp: pointer to bitmap array that will contain result.
422 * @nmaskbits: size of bitmap, in bits.
424 * Wrapper for __bitmap_parse(), providing it with user buffer.
426 * We cannot have this as an inline function in bitmap.h because it needs
427 * linux/uaccess.h to get the access_ok() declaration and this causes
428 * cyclic dependencies.
430 int bitmap_parse_user(const char __user
*ubuf
,
431 unsigned int ulen
, unsigned long *maskp
,
434 if (!access_ok(VERIFY_READ
, ubuf
, ulen
))
436 return __bitmap_parse((const char *)ubuf
, ulen
, 1, maskp
, nmaskbits
);
438 EXPORT_SYMBOL(bitmap_parse_user
);
441 * bscnl_emit(buf, buflen, rbot, rtop, bp)
443 * Helper routine for bitmap_scnlistprintf(). Write decimal number
444 * or range to buf, suppressing output past buf+buflen, with optional
445 * comma-prefix. Return len of what would be written to buf, if it
448 static inline int bscnl_emit(char *buf
, int buflen
, int rbot
, int rtop
, int len
)
451 len
+= scnprintf(buf
+ len
, buflen
- len
, ",");
453 len
+= scnprintf(buf
+ len
, buflen
- len
, "%d", rbot
);
455 len
+= scnprintf(buf
+ len
, buflen
- len
, "%d-%d", rbot
, rtop
);
460 * bitmap_scnlistprintf - convert bitmap to list format ASCII string
461 * @buf: byte buffer into which string is placed
462 * @buflen: reserved size of @buf, in bytes
463 * @maskp: pointer to bitmap to convert
464 * @nmaskbits: size of bitmap, in bits
466 * Output format is a comma-separated list of decimal numbers and
467 * ranges. Consecutively set bits are shown as two hyphen-separated
468 * decimal numbers, the smallest and largest bit numbers set in
469 * the range. Output format is compatible with the format
470 * accepted as input by bitmap_parselist().
472 * The return value is the number of characters which would be
473 * generated for the given input, excluding the trailing '\0', as
476 int bitmap_scnlistprintf(char *buf
, unsigned int buflen
,
477 const unsigned long *maskp
, int nmaskbits
)
480 /* current bit is 'cur', most recently seen range is [rbot, rtop] */
487 rbot
= cur
= find_first_bit(maskp
, nmaskbits
);
488 while (cur
< nmaskbits
) {
490 cur
= find_next_bit(maskp
, nmaskbits
, cur
+1);
491 if (cur
>= nmaskbits
|| cur
> rtop
+ 1) {
492 len
= bscnl_emit(buf
, buflen
, rbot
, rtop
, len
);
498 EXPORT_SYMBOL(bitmap_scnlistprintf
);
501 * bitmap_parselist - convert list format ASCII string to bitmap
502 * @bp: read nul-terminated user string from this buffer
503 * @maskp: write resulting mask here
504 * @nmaskbits: number of bits in mask to be written
506 * Input format is a comma-separated list of decimal numbers and
507 * ranges. Consecutively set bits are shown as two hyphen-separated
508 * decimal numbers, the smallest and largest bit numbers set in
511 * Returns 0 on success, -errno on invalid input strings.
513 * %-EINVAL: second number in range smaller than first
514 * %-EINVAL: invalid character in string
515 * %-ERANGE: bit number specified too large for mask
517 int bitmap_parselist(const char *bp
, unsigned long *maskp
, int nmaskbits
)
521 bitmap_zero(maskp
, nmaskbits
);
525 b
= a
= simple_strtoul(bp
, (char **)&bp
, BASEDEC
);
530 b
= simple_strtoul(bp
, (char **)&bp
, BASEDEC
);
542 } while (*bp
!= '\0' && *bp
!= '\n');
545 EXPORT_SYMBOL(bitmap_parselist
);
548 * bitmap_pos_to_ord(buf, pos, bits)
549 * @buf: pointer to a bitmap
550 * @pos: a bit position in @buf (0 <= @pos < @bits)
551 * @bits: number of valid bit positions in @buf
553 * Map the bit at position @pos in @buf (of length @bits) to the
554 * ordinal of which set bit it is. If it is not set or if @pos
555 * is not a valid bit position, map to -1.
557 * If for example, just bits 4 through 7 are set in @buf, then @pos
558 * values 4 through 7 will get mapped to 0 through 3, respectively,
559 * and other @pos values will get mapped to 0. When @pos value 7
560 * gets mapped to (returns) @ord value 3 in this example, that means
561 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
563 * The bit positions 0 through @bits are valid positions in @buf.
565 static int bitmap_pos_to_ord(const unsigned long *buf
, int pos
, int bits
)
569 if (pos
< 0 || pos
>= bits
|| !test_bit(pos
, buf
))
572 i
= find_first_bit(buf
, bits
);
575 i
= find_next_bit(buf
, bits
, i
+ 1);
584 * bitmap_ord_to_pos(buf, ord, bits)
585 * @buf: pointer to bitmap
586 * @ord: ordinal bit position (n-th set bit, n >= 0)
587 * @bits: number of valid bit positions in @buf
589 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
590 * Value of @ord should be in range 0 <= @ord < weight(buf), else
591 * results are undefined.
593 * If for example, just bits 4 through 7 are set in @buf, then @ord
594 * values 0 through 3 will get mapped to 4 through 7, respectively,
595 * and all other @ord values return undefined values. When @ord value 3
596 * gets mapped to (returns) @pos value 7 in this example, that means
597 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
599 * The bit positions 0 through @bits are valid positions in @buf.
601 static int bitmap_ord_to_pos(const unsigned long *buf
, int ord
, int bits
)
605 if (ord
>= 0 && ord
< bits
) {
608 for (i
= find_first_bit(buf
, bits
);
610 i
= find_next_bit(buf
, bits
, i
+ 1))
612 if (i
< bits
&& ord
== 0)
620 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
621 * @dst: remapped result
622 * @src: subset to be remapped
623 * @old: defines domain of map
624 * @new: defines range of map
625 * @bits: number of bits in each of these bitmaps
627 * Let @old and @new define a mapping of bit positions, such that
628 * whatever position is held by the n-th set bit in @old is mapped
629 * to the n-th set bit in @new. In the more general case, allowing
630 * for the possibility that the weight 'w' of @new is less than the
631 * weight of @old, map the position of the n-th set bit in @old to
632 * the position of the m-th set bit in @new, where m == n % w.
634 * If either of the @old and @new bitmaps are empty, or if @src and
635 * @dst point to the same location, then this routine copies @src
638 * The positions of unset bits in @old are mapped to themselves
639 * (the identify map).
641 * Apply the above specified mapping to @src, placing the result in
642 * @dst, clearing any bits previously set in @dst.
644 * For example, lets say that @old has bits 4 through 7 set, and
645 * @new has bits 12 through 15 set. This defines the mapping of bit
646 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
647 * bit positions unchanged. So if say @src comes into this routine
648 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
651 void bitmap_remap(unsigned long *dst
, const unsigned long *src
,
652 const unsigned long *old
, const unsigned long *new,
657 if (dst
== src
) /* following doesn't handle inplace remaps */
659 bitmap_zero(dst
, bits
);
661 w
= bitmap_weight(new, bits
);
662 for (oldbit
= find_first_bit(src
, bits
);
664 oldbit
= find_next_bit(src
, bits
, oldbit
+ 1)) {
665 int n
= bitmap_pos_to_ord(old
, oldbit
, bits
);
667 set_bit(oldbit
, dst
); /* identity map */
669 set_bit(bitmap_ord_to_pos(new, n
% w
, bits
), dst
);
672 EXPORT_SYMBOL(bitmap_remap
);
675 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
676 * @oldbit: bit position to be mapped
677 * @old: defines domain of map
678 * @new: defines range of map
679 * @bits: number of bits in each of these bitmaps
681 * Let @old and @new define a mapping of bit positions, such that
682 * whatever position is held by the n-th set bit in @old is mapped
683 * to the n-th set bit in @new. In the more general case, allowing
684 * for the possibility that the weight 'w' of @new is less than the
685 * weight of @old, map the position of the n-th set bit in @old to
686 * the position of the m-th set bit in @new, where m == n % w.
688 * The positions of unset bits in @old are mapped to themselves
689 * (the identify map).
691 * Apply the above specified mapping to bit position @oldbit, returning
692 * the new bit position.
694 * For example, lets say that @old has bits 4 through 7 set, and
695 * @new has bits 12 through 15 set. This defines the mapping of bit
696 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
697 * bit positions unchanged. So if say @oldbit is 5, then this routine
700 int bitmap_bitremap(int oldbit
, const unsigned long *old
,
701 const unsigned long *new, int bits
)
703 int w
= bitmap_weight(new, bits
);
704 int n
= bitmap_pos_to_ord(old
, oldbit
, bits
);
708 return bitmap_ord_to_pos(new, n
% w
, bits
);
710 EXPORT_SYMBOL(bitmap_bitremap
);
713 * bitmap_onto - translate one bitmap relative to another
714 * @dst: resulting translated bitmap
715 * @orig: original untranslated bitmap
716 * @relmap: bitmap relative to which translated
717 * @bits: number of bits in each of these bitmaps
719 * Set the n-th bit of @dst iff there exists some m such that the
720 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
721 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
722 * (If you understood the previous sentence the first time your
723 * read it, you're overqualified for your current job.)
725 * In other words, @orig is mapped onto (surjectively) @dst,
726 * using the the map { <n, m> | the n-th bit of @relmap is the
727 * m-th set bit of @relmap }.
729 * Any set bits in @orig above bit number W, where W is the
730 * weight of (number of set bits in) @relmap are mapped nowhere.
731 * In particular, if for all bits m set in @orig, m >= W, then
732 * @dst will end up empty. In situations where the possibility
733 * of such an empty result is not desired, one way to avoid it is
734 * to use the bitmap_fold() operator, below, to first fold the
735 * @orig bitmap over itself so that all its set bits x are in the
736 * range 0 <= x < W. The bitmap_fold() operator does this by
737 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
739 * Example [1] for bitmap_onto():
740 * Let's say @relmap has bits 30-39 set, and @orig has bits
741 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,
742 * @dst will have bits 31, 33, 35, 37 and 39 set.
744 * When bit 0 is set in @orig, it means turn on the bit in
745 * @dst corresponding to whatever is the first bit (if any)
746 * that is turned on in @relmap. Since bit 0 was off in the
747 * above example, we leave off that bit (bit 30) in @dst.
749 * When bit 1 is set in @orig (as in the above example), it
750 * means turn on the bit in @dst corresponding to whatever
751 * is the second bit that is turned on in @relmap. The second
752 * bit in @relmap that was turned on in the above example was
753 * bit 31, so we turned on bit 31 in @dst.
755 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
756 * because they were the 4th, 6th, 8th and 10th set bits
757 * set in @relmap, and the 4th, 6th, 8th and 10th bits of
758 * @orig (i.e. bits 3, 5, 7 and 9) were also set.
760 * When bit 11 is set in @orig, it means turn on the bit in
761 * @dst corresponding to whatever is the twelth bit that is
762 * turned on in @relmap. In the above example, there were
763 * only ten bits turned on in @relmap (30..39), so that bit
764 * 11 was set in @orig had no affect on @dst.
766 * Example [2] for bitmap_fold() + bitmap_onto():
767 * Let's say @relmap has these ten bits set:
768 * 40 41 42 43 45 48 53 61 74 95
769 * (for the curious, that's 40 plus the first ten terms of the
770 * Fibonacci sequence.)
772 * Further lets say we use the following code, invoking
773 * bitmap_fold() then bitmap_onto, as suggested above to
774 * avoid the possitility of an empty @dst result:
776 * unsigned long *tmp; // a temporary bitmap's bits
778 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
779 * bitmap_onto(dst, tmp, relmap, bits);
781 * Then this table shows what various values of @dst would be, for
782 * various @orig's. I list the zero-based positions of each set bit.
783 * The tmp column shows the intermediate result, as computed by
784 * using bitmap_fold() to fold the @orig bitmap modulo ten
785 * (the weight of @relmap).
792 * 1 3 5 7 1 3 5 7 41 43 48 61
793 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45
794 * 0 9 18 27 0 9 8 7 40 61 74 95
796 * 0 11 22 33 0 1 2 3 40 41 42 43
797 * 0 12 24 36 0 2 4 6 40 42 45 53
798 * 78 102 211 1 2 8 41 42 74 (*)
800 * (*) For these marked lines, if we hadn't first done bitmap_fold()
801 * into tmp, then the @dst result would have been empty.
803 * If either of @orig or @relmap is empty (no set bits), then @dst
804 * will be returned empty.
806 * If (as explained above) the only set bits in @orig are in positions
807 * m where m >= W, (where W is the weight of @relmap) then @dst will
808 * once again be returned empty.
810 * All bits in @dst not set by the above rule are cleared.
812 void bitmap_onto(unsigned long *dst
, const unsigned long *orig
,
813 const unsigned long *relmap
, int bits
)
815 int n
, m
; /* same meaning as in above comment */
817 if (dst
== orig
) /* following doesn't handle inplace mappings */
819 bitmap_zero(dst
, bits
);
822 * The following code is a more efficient, but less
823 * obvious, equivalent to the loop:
824 * for (m = 0; m < bitmap_weight(relmap, bits); m++) {
825 * n = bitmap_ord_to_pos(orig, m, bits);
826 * if (test_bit(m, orig))
832 for (n
= find_first_bit(relmap
, bits
);
834 n
= find_next_bit(relmap
, bits
, n
+ 1)) {
835 /* m == bitmap_pos_to_ord(relmap, n, bits) */
836 if (test_bit(m
, orig
))
841 EXPORT_SYMBOL(bitmap_onto
);
844 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
845 * @dst: resulting smaller bitmap
846 * @orig: original larger bitmap
847 * @sz: specified size
848 * @bits: number of bits in each of these bitmaps
850 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
851 * Clear all other bits in @dst. See further the comment and
852 * Example [2] for bitmap_onto() for why and how to use this.
854 void bitmap_fold(unsigned long *dst
, const unsigned long *orig
,
859 if (dst
== orig
) /* following doesn't handle inplace mappings */
861 bitmap_zero(dst
, bits
);
863 for (oldbit
= find_first_bit(orig
, bits
);
865 oldbit
= find_next_bit(orig
, bits
, oldbit
+ 1))
866 set_bit(oldbit
% sz
, dst
);
868 EXPORT_SYMBOL(bitmap_fold
);
871 * Common code for bitmap_*_region() routines.
872 * bitmap: array of unsigned longs corresponding to the bitmap
873 * pos: the beginning of the region
874 * order: region size (log base 2 of number of bits)
875 * reg_op: operation(s) to perform on that region of bitmap
877 * Can set, verify and/or release a region of bits in a bitmap,
878 * depending on which combination of REG_OP_* flag bits is set.
880 * A region of a bitmap is a sequence of bits in the bitmap, of
881 * some size '1 << order' (a power of two), aligned to that same
882 * '1 << order' power of two.
884 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
885 * Returns 0 in all other cases and reg_ops.
889 REG_OP_ISFREE
, /* true if region is all zero bits */
890 REG_OP_ALLOC
, /* set all bits in region */
891 REG_OP_RELEASE
, /* clear all bits in region */
894 static int __reg_op(unsigned long *bitmap
, int pos
, int order
, int reg_op
)
896 int nbits_reg
; /* number of bits in region */
897 int index
; /* index first long of region in bitmap */
898 int offset
; /* bit offset region in bitmap[index] */
899 int nlongs_reg
; /* num longs spanned by region in bitmap */
900 int nbitsinlong
; /* num bits of region in each spanned long */
901 unsigned long mask
; /* bitmask for one long of region */
902 int i
; /* scans bitmap by longs */
903 int ret
= 0; /* return value */
906 * Either nlongs_reg == 1 (for small orders that fit in one long)
907 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
909 nbits_reg
= 1 << order
;
910 index
= pos
/ BITS_PER_LONG
;
911 offset
= pos
- (index
* BITS_PER_LONG
);
912 nlongs_reg
= BITS_TO_LONGS(nbits_reg
);
913 nbitsinlong
= min(nbits_reg
, BITS_PER_LONG
);
916 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
917 * overflows if nbitsinlong == BITS_PER_LONG.
919 mask
= (1UL << (nbitsinlong
- 1));
925 for (i
= 0; i
< nlongs_reg
; i
++) {
926 if (bitmap
[index
+ i
] & mask
)
929 ret
= 1; /* all bits in region free (zero) */
933 for (i
= 0; i
< nlongs_reg
; i
++)
934 bitmap
[index
+ i
] |= mask
;
938 for (i
= 0; i
< nlongs_reg
; i
++)
939 bitmap
[index
+ i
] &= ~mask
;
947 * bitmap_find_free_region - find a contiguous aligned mem region
948 * @bitmap: array of unsigned longs corresponding to the bitmap
949 * @bits: number of bits in the bitmap
950 * @order: region size (log base 2 of number of bits) to find
952 * Find a region of free (zero) bits in a @bitmap of @bits bits and
953 * allocate them (set them to one). Only consider regions of length
954 * a power (@order) of two, aligned to that power of two, which
955 * makes the search algorithm much faster.
957 * Return the bit offset in bitmap of the allocated region,
958 * or -errno on failure.
960 int bitmap_find_free_region(unsigned long *bitmap
, int bits
, int order
)
962 int pos
; /* scans bitmap by regions of size order */
964 for (pos
= 0; pos
< bits
; pos
+= (1 << order
))
965 if (__reg_op(bitmap
, pos
, order
, REG_OP_ISFREE
))
969 __reg_op(bitmap
, pos
, order
, REG_OP_ALLOC
);
972 EXPORT_SYMBOL(bitmap_find_free_region
);
975 * bitmap_release_region - release allocated bitmap region
976 * @bitmap: array of unsigned longs corresponding to the bitmap
977 * @pos: beginning of bit region to release
978 * @order: region size (log base 2 of number of bits) to release
980 * This is the complement to __bitmap_find_free_region() and releases
981 * the found region (by clearing it in the bitmap).
985 void bitmap_release_region(unsigned long *bitmap
, int pos
, int order
)
987 __reg_op(bitmap
, pos
, order
, REG_OP_RELEASE
);
989 EXPORT_SYMBOL(bitmap_release_region
);
992 * bitmap_allocate_region - allocate bitmap region
993 * @bitmap: array of unsigned longs corresponding to the bitmap
994 * @pos: beginning of bit region to allocate
995 * @order: region size (log base 2 of number of bits) to allocate
997 * Allocate (set bits in) a specified region of a bitmap.
999 * Return 0 on success, or %-EBUSY if specified region wasn't
1000 * free (not all bits were zero).
1002 int bitmap_allocate_region(unsigned long *bitmap
, int pos
, int order
)
1004 if (!__reg_op(bitmap
, pos
, order
, REG_OP_ISFREE
))
1006 __reg_op(bitmap
, pos
, order
, REG_OP_ALLOC
);
1009 EXPORT_SYMBOL(bitmap_allocate_region
);