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_parse - convert an ASCII hex string into a bitmap.
320 * @buf: pointer to buffer containing string.
321 * @buflen: buffer size in bytes. If string is smaller than this
322 * then it must be terminated with a \0.
323 * @is_user: location of buffer, 0 indicates kernel space
324 * @maskp: pointer to bitmap array that will contain result.
325 * @nmaskbits: size of bitmap, in bits.
327 * Commas group hex digits into chunks. Each chunk defines exactly 32
328 * bits of the resultant bitmask. No chunk may specify a value larger
329 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
330 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
331 * characters and for grouping errors such as "1,,5", ",44", "," and "".
332 * Leading and trailing whitespace accepted, but not embedded whitespace.
334 int __bitmap_parse(const char *buf
, unsigned int buflen
,
335 int is_user
, unsigned long *maskp
,
338 int c
, old_c
, totaldigits
, ndigits
, nchunks
, nbits
;
340 const char __user
*ubuf
= buf
;
342 bitmap_zero(maskp
, nmaskbits
);
344 nchunks
= nbits
= totaldigits
= c
= 0;
348 /* Get the next chunk of the bitmap */
352 if (__get_user(c
, ubuf
++))
362 * If the last character was a space and the current
363 * character isn't '\0', we've got embedded whitespace.
364 * This is a no-no, so throw an error.
366 if (totaldigits
&& c
&& isspace(old_c
))
369 /* A '\0' or a ',' signal the end of the chunk */
370 if (c
== '\0' || c
== ',')
377 * Make sure there are at least 4 free bits in 'chunk'.
378 * If not, this hexdigit will overflow 'chunk', so
381 if (chunk
& ~((1UL << (CHUNKSZ
- 4)) - 1))
384 chunk
= (chunk
<< 4) | unhex(c
);
385 ndigits
++; totaldigits
++;
389 if (nchunks
== 0 && chunk
== 0)
392 __bitmap_shift_left(maskp
, maskp
, CHUNKSZ
, nmaskbits
);
395 nbits
+= (nchunks
== 1) ? nbits_to_hold_value(chunk
) : CHUNKSZ
;
396 if (nbits
> nmaskbits
)
398 } while (buflen
&& c
== ',');
402 EXPORT_SYMBOL(__bitmap_parse
);
405 * bitmap_parse_user()
407 * @ubuf: pointer to user buffer containing string.
408 * @ulen: buffer size in bytes. If string is smaller than this
409 * then it must be terminated with a \0.
410 * @maskp: pointer to bitmap array that will contain result.
411 * @nmaskbits: size of bitmap, in bits.
413 * Wrapper for __bitmap_parse(), providing it with user buffer.
415 * We cannot have this as an inline function in bitmap.h because it needs
416 * linux/uaccess.h to get the access_ok() declaration and this causes
417 * cyclic dependencies.
419 int bitmap_parse_user(const char __user
*ubuf
,
420 unsigned int ulen
, unsigned long *maskp
,
423 if (!access_ok(VERIFY_READ
, ubuf
, ulen
))
425 return __bitmap_parse((const char *)ubuf
, ulen
, 1, maskp
, nmaskbits
);
427 EXPORT_SYMBOL(bitmap_parse_user
);
430 * bscnl_emit(buf, buflen, rbot, rtop, bp)
432 * Helper routine for bitmap_scnlistprintf(). Write decimal number
433 * or range to buf, suppressing output past buf+buflen, with optional
434 * comma-prefix. Return len of what would be written to buf, if it
437 static inline int bscnl_emit(char *buf
, int buflen
, int rbot
, int rtop
, int len
)
440 len
+= scnprintf(buf
+ len
, buflen
- len
, ",");
442 len
+= scnprintf(buf
+ len
, buflen
- len
, "%d", rbot
);
444 len
+= scnprintf(buf
+ len
, buflen
- len
, "%d-%d", rbot
, rtop
);
449 * bitmap_scnlistprintf - convert bitmap to list format ASCII string
450 * @buf: byte buffer into which string is placed
451 * @buflen: reserved size of @buf, in bytes
452 * @maskp: pointer to bitmap to convert
453 * @nmaskbits: size of bitmap, in bits
455 * Output format is a comma-separated list of decimal numbers and
456 * ranges. Consecutively set bits are shown as two hyphen-separated
457 * decimal numbers, the smallest and largest bit numbers set in
458 * the range. Output format is compatible with the format
459 * accepted as input by bitmap_parselist().
461 * The return value is the number of characters which would be
462 * generated for the given input, excluding the trailing '\0', as
465 int bitmap_scnlistprintf(char *buf
, unsigned int buflen
,
466 const unsigned long *maskp
, int nmaskbits
)
469 /* current bit is 'cur', most recently seen range is [rbot, rtop] */
476 rbot
= cur
= find_first_bit(maskp
, nmaskbits
);
477 while (cur
< nmaskbits
) {
479 cur
= find_next_bit(maskp
, nmaskbits
, cur
+1);
480 if (cur
>= nmaskbits
|| cur
> rtop
+ 1) {
481 len
= bscnl_emit(buf
, buflen
, rbot
, rtop
, len
);
487 EXPORT_SYMBOL(bitmap_scnlistprintf
);
490 * bitmap_parselist - convert list format ASCII string to bitmap
491 * @bp: read nul-terminated user string from this buffer
492 * @maskp: write resulting mask here
493 * @nmaskbits: number of bits in mask to be written
495 * Input format is a comma-separated list of decimal numbers and
496 * ranges. Consecutively set bits are shown as two hyphen-separated
497 * decimal numbers, the smallest and largest bit numbers set in
500 * Returns 0 on success, -errno on invalid input strings.
502 * %-EINVAL: second number in range smaller than first
503 * %-EINVAL: invalid character in string
504 * %-ERANGE: bit number specified too large for mask
506 int bitmap_parselist(const char *bp
, unsigned long *maskp
, int nmaskbits
)
510 bitmap_zero(maskp
, nmaskbits
);
514 b
= a
= simple_strtoul(bp
, (char **)&bp
, BASEDEC
);
519 b
= simple_strtoul(bp
, (char **)&bp
, BASEDEC
);
531 } while (*bp
!= '\0' && *bp
!= '\n');
534 EXPORT_SYMBOL(bitmap_parselist
);
537 * bitmap_pos_to_ord(buf, pos, bits)
538 * @buf: pointer to a bitmap
539 * @pos: a bit position in @buf (0 <= @pos < @bits)
540 * @bits: number of valid bit positions in @buf
542 * Map the bit at position @pos in @buf (of length @bits) to the
543 * ordinal of which set bit it is. If it is not set or if @pos
544 * is not a valid bit position, map to -1.
546 * If for example, just bits 4 through 7 are set in @buf, then @pos
547 * values 4 through 7 will get mapped to 0 through 3, respectively,
548 * and other @pos values will get mapped to 0. When @pos value 7
549 * gets mapped to (returns) @ord value 3 in this example, that means
550 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
552 * The bit positions 0 through @bits are valid positions in @buf.
554 static int bitmap_pos_to_ord(const unsigned long *buf
, int pos
, int bits
)
558 if (pos
< 0 || pos
>= bits
|| !test_bit(pos
, buf
))
561 i
= find_first_bit(buf
, bits
);
564 i
= find_next_bit(buf
, bits
, i
+ 1);
573 * bitmap_ord_to_pos(buf, ord, bits)
574 * @buf: pointer to bitmap
575 * @ord: ordinal bit position (n-th set bit, n >= 0)
576 * @bits: number of valid bit positions in @buf
578 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
579 * Value of @ord should be in range 0 <= @ord < weight(buf), else
580 * results are undefined.
582 * If for example, just bits 4 through 7 are set in @buf, then @ord
583 * values 0 through 3 will get mapped to 4 through 7, respectively,
584 * and all other @ord values return undefined values. When @ord value 3
585 * gets mapped to (returns) @pos value 7 in this example, that means
586 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
588 * The bit positions 0 through @bits are valid positions in @buf.
590 static int bitmap_ord_to_pos(const unsigned long *buf
, int ord
, int bits
)
594 if (ord
>= 0 && ord
< bits
) {
597 for (i
= find_first_bit(buf
, bits
);
599 i
= find_next_bit(buf
, bits
, i
+ 1))
601 if (i
< bits
&& ord
== 0)
609 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
610 * @dst: remapped result
611 * @src: subset to be remapped
612 * @old: defines domain of map
613 * @new: defines range of map
614 * @bits: number of bits in each of these bitmaps
616 * Let @old and @new define a mapping of bit positions, such that
617 * whatever position is held by the n-th set bit in @old is mapped
618 * to the n-th set bit in @new. In the more general case, allowing
619 * for the possibility that the weight 'w' of @new is less than the
620 * weight of @old, map the position of the n-th set bit in @old to
621 * the position of the m-th set bit in @new, where m == n % w.
623 * If either of the @old and @new bitmaps are empty, or if @src and
624 * @dst point to the same location, then this routine copies @src
627 * The positions of unset bits in @old are mapped to themselves
628 * (the identify map).
630 * Apply the above specified mapping to @src, placing the result in
631 * @dst, clearing any bits previously set in @dst.
633 * For example, lets say that @old has bits 4 through 7 set, and
634 * @new has bits 12 through 15 set. This defines the mapping of bit
635 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
636 * bit positions unchanged. So if say @src comes into this routine
637 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
640 void bitmap_remap(unsigned long *dst
, const unsigned long *src
,
641 const unsigned long *old
, const unsigned long *new,
646 if (dst
== src
) /* following doesn't handle inplace remaps */
648 bitmap_zero(dst
, bits
);
650 w
= bitmap_weight(new, bits
);
651 for (oldbit
= find_first_bit(src
, bits
);
653 oldbit
= find_next_bit(src
, bits
, oldbit
+ 1)) {
654 int n
= bitmap_pos_to_ord(old
, oldbit
, bits
);
656 set_bit(oldbit
, dst
); /* identity map */
658 set_bit(bitmap_ord_to_pos(new, n
% w
, bits
), dst
);
661 EXPORT_SYMBOL(bitmap_remap
);
664 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
665 * @oldbit: bit position to be mapped
666 * @old: defines domain of map
667 * @new: defines range of map
668 * @bits: number of bits in each of these bitmaps
670 * Let @old and @new define a mapping of bit positions, such that
671 * whatever position is held by the n-th set bit in @old is mapped
672 * to the n-th set bit in @new. In the more general case, allowing
673 * for the possibility that the weight 'w' of @new is less than the
674 * weight of @old, map the position of the n-th set bit in @old to
675 * the position of the m-th set bit in @new, where m == n % w.
677 * The positions of unset bits in @old are mapped to themselves
678 * (the identify map).
680 * Apply the above specified mapping to bit position @oldbit, returning
681 * the new bit position.
683 * For example, lets say that @old has bits 4 through 7 set, and
684 * @new has bits 12 through 15 set. This defines the mapping of bit
685 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
686 * bit positions unchanged. So if say @oldbit is 5, then this routine
689 int bitmap_bitremap(int oldbit
, const unsigned long *old
,
690 const unsigned long *new, int bits
)
692 int w
= bitmap_weight(new, bits
);
693 int n
= bitmap_pos_to_ord(old
, oldbit
, bits
);
697 return bitmap_ord_to_pos(new, n
% w
, bits
);
699 EXPORT_SYMBOL(bitmap_bitremap
);
702 * bitmap_onto - translate one bitmap relative to another
703 * @dst: resulting translated bitmap
704 * @orig: original untranslated bitmap
705 * @relmap: bitmap relative to which translated
706 * @bits: number of bits in each of these bitmaps
708 * Set the n-th bit of @dst iff there exists some m such that the
709 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
710 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
711 * (If you understood the previous sentence the first time your
712 * read it, you're overqualified for your current job.)
714 * In other words, @orig is mapped onto (surjectively) @dst,
715 * using the the map { <n, m> | the n-th bit of @relmap is the
716 * m-th set bit of @relmap }.
718 * Any set bits in @orig above bit number W, where W is the
719 * weight of (number of set bits in) @relmap are mapped nowhere.
720 * In particular, if for all bits m set in @orig, m >= W, then
721 * @dst will end up empty. In situations where the possibility
722 * of such an empty result is not desired, one way to avoid it is
723 * to use the bitmap_fold() operator, below, to first fold the
724 * @orig bitmap over itself so that all its set bits x are in the
725 * range 0 <= x < W. The bitmap_fold() operator does this by
726 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
728 * Example [1] for bitmap_onto():
729 * Let's say @relmap has bits 30-39 set, and @orig has bits
730 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,
731 * @dst will have bits 31, 33, 35, 37 and 39 set.
733 * When bit 0 is set in @orig, it means turn on the bit in
734 * @dst corresponding to whatever is the first bit (if any)
735 * that is turned on in @relmap. Since bit 0 was off in the
736 * above example, we leave off that bit (bit 30) in @dst.
738 * When bit 1 is set in @orig (as in the above example), it
739 * means turn on the bit in @dst corresponding to whatever
740 * is the second bit that is turned on in @relmap. The second
741 * bit in @relmap that was turned on in the above example was
742 * bit 31, so we turned on bit 31 in @dst.
744 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
745 * because they were the 4th, 6th, 8th and 10th set bits
746 * set in @relmap, and the 4th, 6th, 8th and 10th bits of
747 * @orig (i.e. bits 3, 5, 7 and 9) were also set.
749 * When bit 11 is set in @orig, it means turn on the bit in
750 * @dst corresponding to whatever is the twelth bit that is
751 * turned on in @relmap. In the above example, there were
752 * only ten bits turned on in @relmap (30..39), so that bit
753 * 11 was set in @orig had no affect on @dst.
755 * Example [2] for bitmap_fold() + bitmap_onto():
756 * Let's say @relmap has these ten bits set:
757 * 40 41 42 43 45 48 53 61 74 95
758 * (for the curious, that's 40 plus the first ten terms of the
759 * Fibonacci sequence.)
761 * Further lets say we use the following code, invoking
762 * bitmap_fold() then bitmap_onto, as suggested above to
763 * avoid the possitility of an empty @dst result:
765 * unsigned long *tmp; // a temporary bitmap's bits
767 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
768 * bitmap_onto(dst, tmp, relmap, bits);
770 * Then this table shows what various values of @dst would be, for
771 * various @orig's. I list the zero-based positions of each set bit.
772 * The tmp column shows the intermediate result, as computed by
773 * using bitmap_fold() to fold the @orig bitmap modulo ten
774 * (the weight of @relmap).
781 * 1 3 5 7 1 3 5 7 41 43 48 61
782 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45
783 * 0 9 18 27 0 9 8 7 40 61 74 95
785 * 0 11 22 33 0 1 2 3 40 41 42 43
786 * 0 12 24 36 0 2 4 6 40 42 45 53
787 * 78 102 211 1 2 8 41 42 74 (*)
789 * (*) For these marked lines, if we hadn't first done bitmap_fold()
790 * into tmp, then the @dst result would have been empty.
792 * If either of @orig or @relmap is empty (no set bits), then @dst
793 * will be returned empty.
795 * If (as explained above) the only set bits in @orig are in positions
796 * m where m >= W, (where W is the weight of @relmap) then @dst will
797 * once again be returned empty.
799 * All bits in @dst not set by the above rule are cleared.
801 void bitmap_onto(unsigned long *dst
, const unsigned long *orig
,
802 const unsigned long *relmap
, int bits
)
804 int n
, m
; /* same meaning as in above comment */
806 if (dst
== orig
) /* following doesn't handle inplace mappings */
808 bitmap_zero(dst
, bits
);
811 * The following code is a more efficient, but less
812 * obvious, equivalent to the loop:
813 * for (m = 0; m < bitmap_weight(relmap, bits); m++) {
814 * n = bitmap_ord_to_pos(orig, m, bits);
815 * if (test_bit(m, orig))
821 for (n
= find_first_bit(relmap
, bits
);
823 n
= find_next_bit(relmap
, bits
, n
+ 1)) {
824 /* m == bitmap_pos_to_ord(relmap, n, bits) */
825 if (test_bit(m
, orig
))
830 EXPORT_SYMBOL(bitmap_onto
);
833 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
834 * @dst: resulting smaller bitmap
835 * @orig: original larger bitmap
836 * @sz: specified size
837 * @bits: number of bits in each of these bitmaps
839 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
840 * Clear all other bits in @dst. See further the comment and
841 * Example [2] for bitmap_onto() for why and how to use this.
843 void bitmap_fold(unsigned long *dst
, const unsigned long *orig
,
848 if (dst
== orig
) /* following doesn't handle inplace mappings */
850 bitmap_zero(dst
, bits
);
852 for (oldbit
= find_first_bit(orig
, bits
);
854 oldbit
= find_next_bit(orig
, bits
, oldbit
+ 1))
855 set_bit(oldbit
% sz
, dst
);
857 EXPORT_SYMBOL(bitmap_fold
);
860 * Common code for bitmap_*_region() routines.
861 * bitmap: array of unsigned longs corresponding to the bitmap
862 * pos: the beginning of the region
863 * order: region size (log base 2 of number of bits)
864 * reg_op: operation(s) to perform on that region of bitmap
866 * Can set, verify and/or release a region of bits in a bitmap,
867 * depending on which combination of REG_OP_* flag bits is set.
869 * A region of a bitmap is a sequence of bits in the bitmap, of
870 * some size '1 << order' (a power of two), aligned to that same
871 * '1 << order' power of two.
873 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
874 * Returns 0 in all other cases and reg_ops.
878 REG_OP_ISFREE
, /* true if region is all zero bits */
879 REG_OP_ALLOC
, /* set all bits in region */
880 REG_OP_RELEASE
, /* clear all bits in region */
883 static int __reg_op(unsigned long *bitmap
, int pos
, int order
, int reg_op
)
885 int nbits_reg
; /* number of bits in region */
886 int index
; /* index first long of region in bitmap */
887 int offset
; /* bit offset region in bitmap[index] */
888 int nlongs_reg
; /* num longs spanned by region in bitmap */
889 int nbitsinlong
; /* num bits of region in each spanned long */
890 unsigned long mask
; /* bitmask for one long of region */
891 int i
; /* scans bitmap by longs */
892 int ret
= 0; /* return value */
895 * Either nlongs_reg == 1 (for small orders that fit in one long)
896 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
898 nbits_reg
= 1 << order
;
899 index
= pos
/ BITS_PER_LONG
;
900 offset
= pos
- (index
* BITS_PER_LONG
);
901 nlongs_reg
= BITS_TO_LONGS(nbits_reg
);
902 nbitsinlong
= min(nbits_reg
, BITS_PER_LONG
);
905 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
906 * overflows if nbitsinlong == BITS_PER_LONG.
908 mask
= (1UL << (nbitsinlong
- 1));
914 for (i
= 0; i
< nlongs_reg
; i
++) {
915 if (bitmap
[index
+ i
] & mask
)
918 ret
= 1; /* all bits in region free (zero) */
922 for (i
= 0; i
< nlongs_reg
; i
++)
923 bitmap
[index
+ i
] |= mask
;
927 for (i
= 0; i
< nlongs_reg
; i
++)
928 bitmap
[index
+ i
] &= ~mask
;
936 * bitmap_find_free_region - find a contiguous aligned mem region
937 * @bitmap: array of unsigned longs corresponding to the bitmap
938 * @bits: number of bits in the bitmap
939 * @order: region size (log base 2 of number of bits) to find
941 * Find a region of free (zero) bits in a @bitmap of @bits bits and
942 * allocate them (set them to one). Only consider regions of length
943 * a power (@order) of two, aligned to that power of two, which
944 * makes the search algorithm much faster.
946 * Return the bit offset in bitmap of the allocated region,
947 * or -errno on failure.
949 int bitmap_find_free_region(unsigned long *bitmap
, int bits
, int order
)
951 int pos
, end
; /* scans bitmap by regions of size order */
953 for (pos
= 0 ; (end
= pos
+ (1 << order
)) <= bits
; pos
= end
) {
954 if (!__reg_op(bitmap
, pos
, order
, REG_OP_ISFREE
))
956 __reg_op(bitmap
, pos
, order
, REG_OP_ALLOC
);
961 EXPORT_SYMBOL(bitmap_find_free_region
);
964 * bitmap_release_region - release allocated bitmap region
965 * @bitmap: array of unsigned longs corresponding to the bitmap
966 * @pos: beginning of bit region to release
967 * @order: region size (log base 2 of number of bits) to release
969 * This is the complement to __bitmap_find_free_region() and releases
970 * the found region (by clearing it in the bitmap).
974 void bitmap_release_region(unsigned long *bitmap
, int pos
, int order
)
976 __reg_op(bitmap
, pos
, order
, REG_OP_RELEASE
);
978 EXPORT_SYMBOL(bitmap_release_region
);
981 * bitmap_allocate_region - allocate bitmap region
982 * @bitmap: array of unsigned longs corresponding to the bitmap
983 * @pos: beginning of bit region to allocate
984 * @order: region size (log base 2 of number of bits) to allocate
986 * Allocate (set bits in) a specified region of a bitmap.
988 * Return 0 on success, or %-EBUSY if specified region wasn't
989 * free (not all bits were zero).
991 int bitmap_allocate_region(unsigned long *bitmap
, int pos
, int order
)
993 if (!__reg_op(bitmap
, pos
, order
, REG_OP_ISFREE
))
995 __reg_op(bitmap
, pos
, order
, REG_OP_ALLOC
);
998 EXPORT_SYMBOL(bitmap_allocate_region
);
1001 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1002 * @dst: destination buffer
1003 * @src: bitmap to copy
1004 * @nbits: number of bits in the bitmap
1006 * Require nbits % BITS_PER_LONG == 0.
1008 void bitmap_copy_le(void *dst
, const unsigned long *src
, int nbits
)
1010 unsigned long *d
= dst
;
1013 for (i
= 0; i
< nbits
/BITS_PER_LONG
; i
++) {
1014 if (BITS_PER_LONG
== 64)
1015 d
[i
] = cpu_to_le64(src
[i
]);
1017 d
[i
] = cpu_to_le32(src
[i
]);
1020 EXPORT_SYMBOL(bitmap_copy_le
);
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