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/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 #include <linux/kernel.h>
17 #include <linux/string.h>
18 #include <linux/uaccess.h>
23 * DOC: bitmap introduction
25 * bitmaps provide an array of bits, implemented using an an
26 * array of unsigned longs. The number of valid bits in a
27 * given bitmap does _not_ need to be an exact multiple of
30 * The possible unused bits in the last, partially used word
31 * of a bitmap are 'don't care'. The implementation makes
32 * no particular effort to keep them zero. It ensures that
33 * their value will not affect the results of any operation.
34 * The bitmap operations that return Boolean (bitmap_empty,
35 * for example) or scalar (bitmap_weight, for example) results
36 * carefully filter out these unused bits from impacting their
39 * These operations actually hold to a slightly stronger rule:
40 * if you don't input any bitmaps to these ops that have some
41 * unused bits set, then they won't output any set unused bits
44 * The byte ordering of bitmaps is more natural on little
45 * endian architectures. See the big-endian headers
46 * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
47 * for the best explanations of this ordering.
50 int __bitmap_equal(const unsigned long *bitmap1
,
51 const unsigned long *bitmap2
, unsigned int bits
)
53 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
54 for (k
= 0; k
< lim
; ++k
)
55 if (bitmap1
[k
] != bitmap2
[k
])
58 if (bits
% BITS_PER_LONG
)
59 if ((bitmap1
[k
] ^ bitmap2
[k
]) & BITMAP_LAST_WORD_MASK(bits
))
64 EXPORT_SYMBOL(__bitmap_equal
);
66 void __bitmap_complement(unsigned long *dst
, const unsigned long *src
, unsigned int bits
)
68 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
69 for (k
= 0; k
< lim
; ++k
)
72 if (bits
% BITS_PER_LONG
)
75 EXPORT_SYMBOL(__bitmap_complement
);
78 * __bitmap_shift_right - logical right shift of the bits in a bitmap
79 * @dst : destination bitmap
80 * @src : source bitmap
81 * @shift : shift by this many bits
82 * @nbits : bitmap size, in bits
84 * Shifting right (dividing) means moving bits in the MS -> LS bit
85 * direction. Zeros are fed into the vacated MS positions and the
86 * LS bits shifted off the bottom are lost.
88 void __bitmap_shift_right(unsigned long *dst
, const unsigned long *src
,
89 unsigned shift
, unsigned nbits
)
91 unsigned k
, lim
= BITS_TO_LONGS(nbits
);
92 unsigned off
= shift
/BITS_PER_LONG
, rem
= shift
% BITS_PER_LONG
;
93 unsigned long mask
= BITMAP_LAST_WORD_MASK(nbits
);
94 for (k
= 0; off
+ k
< lim
; ++k
) {
95 unsigned long upper
, lower
;
98 * If shift is not word aligned, take lower rem bits of
99 * word above and make them the top rem bits of result.
101 if (!rem
|| off
+ k
+ 1 >= lim
)
104 upper
= src
[off
+ k
+ 1];
105 if (off
+ k
+ 1 == lim
- 1)
107 upper
<<= (BITS_PER_LONG
- rem
);
109 lower
= src
[off
+ k
];
110 if (off
+ k
== lim
- 1)
113 dst
[k
] = lower
| upper
;
116 memset(&dst
[lim
- off
], 0, off
*sizeof(unsigned long));
118 EXPORT_SYMBOL(__bitmap_shift_right
);
122 * __bitmap_shift_left - logical left shift of the bits in a bitmap
123 * @dst : destination bitmap
124 * @src : source bitmap
125 * @shift : shift by this many bits
126 * @nbits : bitmap size, in bits
128 * Shifting left (multiplying) means moving bits in the LS -> MS
129 * direction. Zeros are fed into the vacated LS bit positions
130 * and those MS bits shifted off the top are lost.
133 void __bitmap_shift_left(unsigned long *dst
, const unsigned long *src
,
134 unsigned int shift
, unsigned int nbits
)
137 unsigned int lim
= BITS_TO_LONGS(nbits
);
138 unsigned int off
= shift
/BITS_PER_LONG
, rem
= shift
% BITS_PER_LONG
;
139 for (k
= lim
- off
- 1; k
>= 0; --k
) {
140 unsigned long upper
, lower
;
143 * If shift is not word aligned, take upper rem bits of
144 * word below and make them the bottom rem bits of result.
147 lower
= src
[k
- 1] >> (BITS_PER_LONG
- rem
);
150 upper
= src
[k
] << rem
;
151 dst
[k
+ off
] = lower
| upper
;
154 memset(dst
, 0, off
*sizeof(unsigned long));
156 EXPORT_SYMBOL(__bitmap_shift_left
);
158 int __bitmap_and(unsigned long *dst
, const unsigned long *bitmap1
,
159 const unsigned long *bitmap2
, unsigned int bits
)
162 unsigned int lim
= bits
/BITS_PER_LONG
;
163 unsigned long result
= 0;
165 for (k
= 0; k
< lim
; k
++)
166 result
|= (dst
[k
] = bitmap1
[k
] & bitmap2
[k
]);
167 if (bits
% BITS_PER_LONG
)
168 result
|= (dst
[k
] = bitmap1
[k
] & bitmap2
[k
] &
169 BITMAP_LAST_WORD_MASK(bits
));
172 EXPORT_SYMBOL(__bitmap_and
);
174 void __bitmap_or(unsigned long *dst
, const unsigned long *bitmap1
,
175 const unsigned long *bitmap2
, unsigned int bits
)
178 unsigned int nr
= BITS_TO_LONGS(bits
);
180 for (k
= 0; k
< nr
; k
++)
181 dst
[k
] = bitmap1
[k
] | bitmap2
[k
];
183 EXPORT_SYMBOL(__bitmap_or
);
185 void __bitmap_xor(unsigned long *dst
, const unsigned long *bitmap1
,
186 const unsigned long *bitmap2
, unsigned int bits
)
189 unsigned int nr
= BITS_TO_LONGS(bits
);
191 for (k
= 0; k
< nr
; k
++)
192 dst
[k
] = bitmap1
[k
] ^ bitmap2
[k
];
194 EXPORT_SYMBOL(__bitmap_xor
);
196 int __bitmap_andnot(unsigned long *dst
, const unsigned long *bitmap1
,
197 const unsigned long *bitmap2
, unsigned int bits
)
200 unsigned int lim
= bits
/BITS_PER_LONG
;
201 unsigned long result
= 0;
203 for (k
= 0; k
< lim
; k
++)
204 result
|= (dst
[k
] = bitmap1
[k
] & ~bitmap2
[k
]);
205 if (bits
% BITS_PER_LONG
)
206 result
|= (dst
[k
] = bitmap1
[k
] & ~bitmap2
[k
] &
207 BITMAP_LAST_WORD_MASK(bits
));
210 EXPORT_SYMBOL(__bitmap_andnot
);
212 int __bitmap_intersects(const unsigned long *bitmap1
,
213 const unsigned long *bitmap2
, unsigned int bits
)
215 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
216 for (k
= 0; k
< lim
; ++k
)
217 if (bitmap1
[k
] & bitmap2
[k
])
220 if (bits
% BITS_PER_LONG
)
221 if ((bitmap1
[k
] & bitmap2
[k
]) & BITMAP_LAST_WORD_MASK(bits
))
225 EXPORT_SYMBOL(__bitmap_intersects
);
227 int __bitmap_subset(const unsigned long *bitmap1
,
228 const unsigned long *bitmap2
, unsigned int bits
)
230 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
231 for (k
= 0; k
< lim
; ++k
)
232 if (bitmap1
[k
] & ~bitmap2
[k
])
235 if (bits
% BITS_PER_LONG
)
236 if ((bitmap1
[k
] & ~bitmap2
[k
]) & BITMAP_LAST_WORD_MASK(bits
))
240 EXPORT_SYMBOL(__bitmap_subset
);
242 int __bitmap_weight(const unsigned long *bitmap
, unsigned int bits
)
244 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
247 for (k
= 0; k
< lim
; k
++)
248 w
+= hweight_long(bitmap
[k
]);
250 if (bits
% BITS_PER_LONG
)
251 w
+= hweight_long(bitmap
[k
] & BITMAP_LAST_WORD_MASK(bits
));
255 EXPORT_SYMBOL(__bitmap_weight
);
257 void __bitmap_set(unsigned long *map
, unsigned int start
, int len
)
259 unsigned long *p
= map
+ BIT_WORD(start
);
260 const unsigned int size
= start
+ len
;
261 int bits_to_set
= BITS_PER_LONG
- (start
% BITS_PER_LONG
);
262 unsigned long mask_to_set
= BITMAP_FIRST_WORD_MASK(start
);
264 while (len
- bits_to_set
>= 0) {
267 bits_to_set
= BITS_PER_LONG
;
272 mask_to_set
&= BITMAP_LAST_WORD_MASK(size
);
276 EXPORT_SYMBOL(__bitmap_set
);
278 void __bitmap_clear(unsigned long *map
, unsigned int start
, int len
)
280 unsigned long *p
= map
+ BIT_WORD(start
);
281 const unsigned int size
= start
+ len
;
282 int bits_to_clear
= BITS_PER_LONG
- (start
% BITS_PER_LONG
);
283 unsigned long mask_to_clear
= BITMAP_FIRST_WORD_MASK(start
);
285 while (len
- bits_to_clear
>= 0) {
286 *p
&= ~mask_to_clear
;
287 len
-= bits_to_clear
;
288 bits_to_clear
= BITS_PER_LONG
;
289 mask_to_clear
= ~0UL;
293 mask_to_clear
&= BITMAP_LAST_WORD_MASK(size
);
294 *p
&= ~mask_to_clear
;
297 EXPORT_SYMBOL(__bitmap_clear
);
300 * bitmap_find_next_zero_area_off - find a contiguous aligned zero area
301 * @map: The address to base the search on
302 * @size: The bitmap size in bits
303 * @start: The bitnumber to start searching at
304 * @nr: The number of zeroed bits we're looking for
305 * @align_mask: Alignment mask for zero area
306 * @align_offset: Alignment offset for zero area.
308 * The @align_mask should be one less than a power of 2; the effect is that
309 * the bit offset of all zero areas this function finds plus @align_offset
310 * is multiple of that power of 2.
312 unsigned long bitmap_find_next_zero_area_off(unsigned long *map
,
316 unsigned long align_mask
,
317 unsigned long align_offset
)
319 unsigned long index
, end
, i
;
321 index
= find_next_zero_bit(map
, size
, start
);
323 /* Align allocation */
324 index
= __ALIGN_MASK(index
+ align_offset
, align_mask
) - align_offset
;
329 i
= find_next_bit(map
, end
, index
);
336 EXPORT_SYMBOL(bitmap_find_next_zero_area_off
);
339 * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,
340 * second version by Paul Jackson, third by Joe Korty.
344 #define nbits_to_hold_value(val) fls(val)
345 #define BASEDEC 10 /* fancier cpuset lists input in decimal */
348 * __bitmap_parse - convert an ASCII hex string into a bitmap.
349 * @buf: pointer to buffer containing string.
350 * @buflen: buffer size in bytes. If string is smaller than this
351 * then it must be terminated with a \0.
352 * @is_user: location of buffer, 0 indicates kernel space
353 * @maskp: pointer to bitmap array that will contain result.
354 * @nmaskbits: size of bitmap, in bits.
356 * Commas group hex digits into chunks. Each chunk defines exactly 32
357 * bits of the resultant bitmask. No chunk may specify a value larger
358 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
359 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
360 * characters and for grouping errors such as "1,,5", ",44", "," and "".
361 * Leading and trailing whitespace accepted, but not embedded whitespace.
363 int __bitmap_parse(const char *buf
, unsigned int buflen
,
364 int is_user
, unsigned long *maskp
,
367 int c
, old_c
, totaldigits
, ndigits
, nchunks
, nbits
;
369 const char __user __force
*ubuf
= (const char __user __force
*)buf
;
371 bitmap_zero(maskp
, nmaskbits
);
373 nchunks
= nbits
= totaldigits
= c
= 0;
376 ndigits
= totaldigits
;
378 /* Get the next chunk of the bitmap */
382 if (__get_user(c
, ubuf
++))
392 * If the last character was a space and the current
393 * character isn't '\0', we've got embedded whitespace.
394 * This is a no-no, so throw an error.
396 if (totaldigits
&& c
&& isspace(old_c
))
399 /* A '\0' or a ',' signal the end of the chunk */
400 if (c
== '\0' || c
== ',')
407 * Make sure there are at least 4 free bits in 'chunk'.
408 * If not, this hexdigit will overflow 'chunk', so
411 if (chunk
& ~((1UL << (CHUNKSZ
- 4)) - 1))
414 chunk
= (chunk
<< 4) | hex_to_bin(c
);
417 if (ndigits
== totaldigits
)
419 if (nchunks
== 0 && chunk
== 0)
422 __bitmap_shift_left(maskp
, maskp
, CHUNKSZ
, nmaskbits
);
425 nbits
+= (nchunks
== 1) ? nbits_to_hold_value(chunk
) : CHUNKSZ
;
426 if (nbits
> nmaskbits
)
428 } while (buflen
&& c
== ',');
432 EXPORT_SYMBOL(__bitmap_parse
);
435 * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
437 * @ubuf: pointer to user buffer containing string.
438 * @ulen: buffer size in bytes. If string is smaller than this
439 * then it must be terminated with a \0.
440 * @maskp: pointer to bitmap array that will contain result.
441 * @nmaskbits: size of bitmap, in bits.
443 * Wrapper for __bitmap_parse(), providing it with user buffer.
445 * We cannot have this as an inline function in bitmap.h because it needs
446 * linux/uaccess.h to get the access_ok() declaration and this causes
447 * cyclic dependencies.
449 int bitmap_parse_user(const char __user
*ubuf
,
450 unsigned int ulen
, unsigned long *maskp
,
453 if (!access_ok(VERIFY_READ
, ubuf
, ulen
))
455 return __bitmap_parse((const char __force
*)ubuf
,
456 ulen
, 1, maskp
, nmaskbits
);
459 EXPORT_SYMBOL(bitmap_parse_user
);
462 * bitmap_print_to_pagebuf - convert bitmap to list or hex format ASCII string
463 * @list: indicates whether the bitmap must be list
464 * @buf: page aligned buffer into which string is placed
465 * @maskp: pointer to bitmap to convert
466 * @nmaskbits: size of bitmap, in bits
468 * Output format is a comma-separated list of decimal numbers and
469 * ranges if list is specified or hex digits grouped into comma-separated
470 * sets of 8 digits/set. Returns the number of characters written to buf.
472 * It is assumed that @buf is a pointer into a PAGE_SIZE, page-aligned
473 * area and that sufficient storage remains at @buf to accommodate the
474 * bitmap_print_to_pagebuf() output. Returns the number of characters
475 * actually printed to @buf, excluding terminating '\0'.
477 int bitmap_print_to_pagebuf(bool list
, char *buf
, const unsigned long *maskp
,
480 ptrdiff_t len
= PAGE_SIZE
- offset_in_page(buf
);
484 n
= list
? scnprintf(buf
, len
, "%*pbl\n", nmaskbits
, maskp
) :
485 scnprintf(buf
, len
, "%*pb\n", nmaskbits
, maskp
);
488 EXPORT_SYMBOL(bitmap_print_to_pagebuf
);
491 * __bitmap_parselist - convert list format ASCII string to bitmap
492 * @buf: read nul-terminated user string from this buffer
493 * @buflen: buffer size in bytes. If string is smaller than this
494 * then it must be terminated with a \0.
495 * @is_user: location of buffer, 0 indicates kernel space
496 * @maskp: write resulting mask here
497 * @nmaskbits: number of bits in mask to be written
499 * Input format is a comma-separated list of decimal numbers and
500 * ranges. Consecutively set bits are shown as two hyphen-separated
501 * decimal numbers, the smallest and largest bit numbers set in
503 * Optionally each range can be postfixed to denote that only parts of it
504 * should be set. The range will divided to groups of specific size.
505 * From each group will be used only defined amount of bits.
506 * Syntax: range:used_size/group_size
507 * Example: 0-1023:2/256 ==> 0,1,256,257,512,513,768,769
509 * Returns: 0 on success, -errno on invalid input strings. Error values:
511 * - ``-EINVAL``: second number in range smaller than first
512 * - ``-EINVAL``: invalid character in string
513 * - ``-ERANGE``: bit number specified too large for mask
515 static int __bitmap_parselist(const char *buf
, unsigned int buflen
,
516 int is_user
, unsigned long *maskp
,
519 unsigned int a
, b
, old_a
, old_b
;
520 unsigned int group_size
, used_size
, off
;
521 int c
, old_c
, totaldigits
, ndigits
;
522 const char __user __force
*ubuf
= (const char __user __force
*)buf
;
523 int at_start
, in_range
, in_partial_range
;
527 group_size
= used_size
= 0;
528 bitmap_zero(maskp
, nmaskbits
);
532 in_partial_range
= 0;
534 ndigits
= totaldigits
;
536 /* Get the next cpu# or a range of cpu#'s */
540 if (__get_user(c
, ubuf
++))
548 /* A '\0' or a ',' signal the end of a cpu# or range */
549 if (c
== '\0' || c
== ',')
552 * whitespaces between digits are not allowed,
553 * but it's ok if whitespaces are on head or tail.
554 * when old_c is whilespace,
555 * if totaldigits == ndigits, whitespace is on head.
556 * if whitespace is on tail, it should not run here.
557 * as c was ',' or '\0',
558 * the last code line has broken the current loop.
560 if ((totaldigits
!= ndigits
) && isspace(old_c
))
576 in_partial_range
= 1;
582 if (at_start
|| in_range
)
593 b
= b
* 10 + (c
- '0');
599 if (ndigits
== totaldigits
)
601 if (in_partial_range
) {
607 used_size
= group_size
= b
- a
+ 1;
609 /* if no digit is after '-', it's wrong*/
610 if (at_start
&& in_range
)
612 if (!(a
<= b
) || group_size
== 0 || !(used_size
<= group_size
))
617 off
= min(b
- a
+ 1, used_size
);
618 bitmap_set(maskp
, a
, off
);
621 } while (buflen
&& c
== ',');
625 int bitmap_parselist(const char *bp
, unsigned long *maskp
, int nmaskbits
)
627 char *nl
= strchrnul(bp
, '\n');
630 return __bitmap_parselist(bp
, len
, 0, maskp
, nmaskbits
);
632 EXPORT_SYMBOL(bitmap_parselist
);
636 * bitmap_parselist_user()
638 * @ubuf: pointer to user buffer containing string.
639 * @ulen: buffer size in bytes. If string is smaller than this
640 * then it must be terminated with a \0.
641 * @maskp: pointer to bitmap array that will contain result.
642 * @nmaskbits: size of bitmap, in bits.
644 * Wrapper for bitmap_parselist(), providing it with user buffer.
646 * We cannot have this as an inline function in bitmap.h because it needs
647 * linux/uaccess.h to get the access_ok() declaration and this causes
648 * cyclic dependencies.
650 int bitmap_parselist_user(const char __user
*ubuf
,
651 unsigned int ulen
, unsigned long *maskp
,
654 if (!access_ok(VERIFY_READ
, ubuf
, ulen
))
656 return __bitmap_parselist((const char __force
*)ubuf
,
657 ulen
, 1, maskp
, nmaskbits
);
659 EXPORT_SYMBOL(bitmap_parselist_user
);
663 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
664 * @buf: pointer to a bitmap
665 * @pos: a bit position in @buf (0 <= @pos < @nbits)
666 * @nbits: number of valid bit positions in @buf
668 * Map the bit at position @pos in @buf (of length @nbits) to the
669 * ordinal of which set bit it is. If it is not set or if @pos
670 * is not a valid bit position, map to -1.
672 * If for example, just bits 4 through 7 are set in @buf, then @pos
673 * values 4 through 7 will get mapped to 0 through 3, respectively,
674 * and other @pos values will get mapped to -1. When @pos value 7
675 * gets mapped to (returns) @ord value 3 in this example, that means
676 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
678 * The bit positions 0 through @bits are valid positions in @buf.
680 static int bitmap_pos_to_ord(const unsigned long *buf
, unsigned int pos
, unsigned int nbits
)
682 if (pos
>= nbits
|| !test_bit(pos
, buf
))
685 return __bitmap_weight(buf
, pos
);
689 * bitmap_ord_to_pos - find position of n-th set bit in bitmap
690 * @buf: pointer to bitmap
691 * @ord: ordinal bit position (n-th set bit, n >= 0)
692 * @nbits: number of valid bit positions in @buf
694 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
695 * Value of @ord should be in range 0 <= @ord < weight(buf). If @ord
696 * >= weight(buf), returns @nbits.
698 * If for example, just bits 4 through 7 are set in @buf, then @ord
699 * values 0 through 3 will get mapped to 4 through 7, respectively,
700 * and all other @ord values returns @nbits. When @ord value 3
701 * gets mapped to (returns) @pos value 7 in this example, that means
702 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
704 * The bit positions 0 through @nbits-1 are valid positions in @buf.
706 unsigned int bitmap_ord_to_pos(const unsigned long *buf
, unsigned int ord
, unsigned int nbits
)
710 for (pos
= find_first_bit(buf
, nbits
);
712 pos
= find_next_bit(buf
, nbits
, pos
+ 1))
719 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
720 * @dst: remapped result
721 * @src: subset to be remapped
722 * @old: defines domain of map
723 * @new: defines range of map
724 * @nbits: number of bits in each of these bitmaps
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.
733 * If either of the @old and @new bitmaps are empty, or if @src and
734 * @dst point to the same location, then this routine copies @src
737 * The positions of unset bits in @old are mapped to themselves
738 * (the identify map).
740 * Apply the above specified mapping to @src, placing the result in
741 * @dst, clearing any bits previously set in @dst.
743 * For example, lets say that @old has bits 4 through 7 set, and
744 * @new has bits 12 through 15 set. This defines the mapping of bit
745 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
746 * bit positions unchanged. So if say @src comes into this routine
747 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
750 void bitmap_remap(unsigned long *dst
, const unsigned long *src
,
751 const unsigned long *old
, const unsigned long *new,
754 unsigned int oldbit
, w
;
756 if (dst
== src
) /* following doesn't handle inplace remaps */
758 bitmap_zero(dst
, nbits
);
760 w
= bitmap_weight(new, nbits
);
761 for_each_set_bit(oldbit
, src
, nbits
) {
762 int n
= bitmap_pos_to_ord(old
, oldbit
, nbits
);
765 set_bit(oldbit
, dst
); /* identity map */
767 set_bit(bitmap_ord_to_pos(new, n
% w
, nbits
), dst
);
770 EXPORT_SYMBOL(bitmap_remap
);
773 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
774 * @oldbit: bit position to be mapped
775 * @old: defines domain of map
776 * @new: defines range of map
777 * @bits: number of bits in each of these bitmaps
779 * Let @old and @new define a mapping of bit positions, such that
780 * whatever position is held by the n-th set bit in @old is mapped
781 * to the n-th set bit in @new. In the more general case, allowing
782 * for the possibility that the weight 'w' of @new is less than the
783 * weight of @old, map the position of the n-th set bit in @old to
784 * the position of the m-th set bit in @new, where m == n % w.
786 * The positions of unset bits in @old are mapped to themselves
787 * (the identify map).
789 * Apply the above specified mapping to bit position @oldbit, returning
790 * the new bit position.
792 * For example, lets say that @old has bits 4 through 7 set, and
793 * @new has bits 12 through 15 set. This defines the mapping of bit
794 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
795 * bit positions unchanged. So if say @oldbit is 5, then this routine
798 int bitmap_bitremap(int oldbit
, const unsigned long *old
,
799 const unsigned long *new, int bits
)
801 int w
= bitmap_weight(new, bits
);
802 int n
= bitmap_pos_to_ord(old
, oldbit
, bits
);
806 return bitmap_ord_to_pos(new, n
% w
, bits
);
808 EXPORT_SYMBOL(bitmap_bitremap
);
811 * bitmap_onto - translate one bitmap relative to another
812 * @dst: resulting translated bitmap
813 * @orig: original untranslated bitmap
814 * @relmap: bitmap relative to which translated
815 * @bits: number of bits in each of these bitmaps
817 * Set the n-th bit of @dst iff there exists some m such that the
818 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
819 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
820 * (If you understood the previous sentence the first time your
821 * read it, you're overqualified for your current job.)
823 * In other words, @orig is mapped onto (surjectively) @dst,
824 * using the map { <n, m> | the n-th bit of @relmap is the
825 * m-th set bit of @relmap }.
827 * Any set bits in @orig above bit number W, where W is the
828 * weight of (number of set bits in) @relmap are mapped nowhere.
829 * In particular, if for all bits m set in @orig, m >= W, then
830 * @dst will end up empty. In situations where the possibility
831 * of such an empty result is not desired, one way to avoid it is
832 * to use the bitmap_fold() operator, below, to first fold the
833 * @orig bitmap over itself so that all its set bits x are in the
834 * range 0 <= x < W. The bitmap_fold() operator does this by
835 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
837 * Example [1] for bitmap_onto():
838 * Let's say @relmap has bits 30-39 set, and @orig has bits
839 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,
840 * @dst will have bits 31, 33, 35, 37 and 39 set.
842 * When bit 0 is set in @orig, it means turn on the bit in
843 * @dst corresponding to whatever is the first bit (if any)
844 * that is turned on in @relmap. Since bit 0 was off in the
845 * above example, we leave off that bit (bit 30) in @dst.
847 * When bit 1 is set in @orig (as in the above example), it
848 * means turn on the bit in @dst corresponding to whatever
849 * is the second bit that is turned on in @relmap. The second
850 * bit in @relmap that was turned on in the above example was
851 * bit 31, so we turned on bit 31 in @dst.
853 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
854 * because they were the 4th, 6th, 8th and 10th set bits
855 * set in @relmap, and the 4th, 6th, 8th and 10th bits of
856 * @orig (i.e. bits 3, 5, 7 and 9) were also set.
858 * When bit 11 is set in @orig, it means turn on the bit in
859 * @dst corresponding to whatever is the twelfth bit that is
860 * turned on in @relmap. In the above example, there were
861 * only ten bits turned on in @relmap (30..39), so that bit
862 * 11 was set in @orig had no affect on @dst.
864 * Example [2] for bitmap_fold() + bitmap_onto():
865 * Let's say @relmap has these ten bits set::
867 * 40 41 42 43 45 48 53 61 74 95
869 * (for the curious, that's 40 plus the first ten terms of the
870 * Fibonacci sequence.)
872 * Further lets say we use the following code, invoking
873 * bitmap_fold() then bitmap_onto, as suggested above to
874 * avoid the possibility of an empty @dst result::
876 * unsigned long *tmp; // a temporary bitmap's bits
878 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
879 * bitmap_onto(dst, tmp, relmap, bits);
881 * Then this table shows what various values of @dst would be, for
882 * various @orig's. I list the zero-based positions of each set bit.
883 * The tmp column shows the intermediate result, as computed by
884 * using bitmap_fold() to fold the @orig bitmap modulo ten
885 * (the weight of @relmap):
887 * =============== ============== =================
893 * 1 3 5 7 1 3 5 7 41 43 48 61
894 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45
895 * 0 9 18 27 0 9 8 7 40 61 74 95
897 * 0 11 22 33 0 1 2 3 40 41 42 43
898 * 0 12 24 36 0 2 4 6 40 42 45 53
899 * 78 102 211 1 2 8 41 42 74 [#f1]_
900 * =============== ============== =================
904 * For these marked lines, if we hadn't first done bitmap_fold()
905 * into tmp, then the @dst result would have been empty.
907 * If either of @orig or @relmap is empty (no set bits), then @dst
908 * will be returned empty.
910 * If (as explained above) the only set bits in @orig are in positions
911 * m where m >= W, (where W is the weight of @relmap) then @dst will
912 * once again be returned empty.
914 * All bits in @dst not set by the above rule are cleared.
916 void bitmap_onto(unsigned long *dst
, const unsigned long *orig
,
917 const unsigned long *relmap
, unsigned int bits
)
919 unsigned int n
, m
; /* same meaning as in above comment */
921 if (dst
== orig
) /* following doesn't handle inplace mappings */
923 bitmap_zero(dst
, bits
);
926 * The following code is a more efficient, but less
927 * obvious, equivalent to the loop:
928 * for (m = 0; m < bitmap_weight(relmap, bits); m++) {
929 * n = bitmap_ord_to_pos(orig, m, bits);
930 * if (test_bit(m, orig))
936 for_each_set_bit(n
, relmap
, bits
) {
937 /* m == bitmap_pos_to_ord(relmap, n, bits) */
938 if (test_bit(m
, orig
))
943 EXPORT_SYMBOL(bitmap_onto
);
946 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
947 * @dst: resulting smaller bitmap
948 * @orig: original larger bitmap
949 * @sz: specified size
950 * @nbits: number of bits in each of these bitmaps
952 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
953 * Clear all other bits in @dst. See further the comment and
954 * Example [2] for bitmap_onto() for why and how to use this.
956 void bitmap_fold(unsigned long *dst
, const unsigned long *orig
,
957 unsigned int sz
, unsigned int nbits
)
961 if (dst
== orig
) /* following doesn't handle inplace mappings */
963 bitmap_zero(dst
, nbits
);
965 for_each_set_bit(oldbit
, orig
, nbits
)
966 set_bit(oldbit
% sz
, dst
);
968 EXPORT_SYMBOL(bitmap_fold
);
971 * Common code for bitmap_*_region() routines.
972 * bitmap: array of unsigned longs corresponding to the bitmap
973 * pos: the beginning of the region
974 * order: region size (log base 2 of number of bits)
975 * reg_op: operation(s) to perform on that region of bitmap
977 * Can set, verify and/or release a region of bits in a bitmap,
978 * depending on which combination of REG_OP_* flag bits is set.
980 * A region of a bitmap is a sequence of bits in the bitmap, of
981 * some size '1 << order' (a power of two), aligned to that same
982 * '1 << order' power of two.
984 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
985 * Returns 0 in all other cases and reg_ops.
989 REG_OP_ISFREE
, /* true if region is all zero bits */
990 REG_OP_ALLOC
, /* set all bits in region */
991 REG_OP_RELEASE
, /* clear all bits in region */
994 static int __reg_op(unsigned long *bitmap
, unsigned int pos
, int order
, int reg_op
)
996 int nbits_reg
; /* number of bits in region */
997 int index
; /* index first long of region in bitmap */
998 int offset
; /* bit offset region in bitmap[index] */
999 int nlongs_reg
; /* num longs spanned by region in bitmap */
1000 int nbitsinlong
; /* num bits of region in each spanned long */
1001 unsigned long mask
; /* bitmask for one long of region */
1002 int i
; /* scans bitmap by longs */
1003 int ret
= 0; /* return value */
1006 * Either nlongs_reg == 1 (for small orders that fit in one long)
1007 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
1009 nbits_reg
= 1 << order
;
1010 index
= pos
/ BITS_PER_LONG
;
1011 offset
= pos
- (index
* BITS_PER_LONG
);
1012 nlongs_reg
= BITS_TO_LONGS(nbits_reg
);
1013 nbitsinlong
= min(nbits_reg
, BITS_PER_LONG
);
1016 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
1017 * overflows if nbitsinlong == BITS_PER_LONG.
1019 mask
= (1UL << (nbitsinlong
- 1));
1025 for (i
= 0; i
< nlongs_reg
; i
++) {
1026 if (bitmap
[index
+ i
] & mask
)
1029 ret
= 1; /* all bits in region free (zero) */
1033 for (i
= 0; i
< nlongs_reg
; i
++)
1034 bitmap
[index
+ i
] |= mask
;
1037 case REG_OP_RELEASE
:
1038 for (i
= 0; i
< nlongs_reg
; i
++)
1039 bitmap
[index
+ i
] &= ~mask
;
1047 * bitmap_find_free_region - find a contiguous aligned mem region
1048 * @bitmap: array of unsigned longs corresponding to the bitmap
1049 * @bits: number of bits in the bitmap
1050 * @order: region size (log base 2 of number of bits) to find
1052 * Find a region of free (zero) bits in a @bitmap of @bits bits and
1053 * allocate them (set them to one). Only consider regions of length
1054 * a power (@order) of two, aligned to that power of two, which
1055 * makes the search algorithm much faster.
1057 * Return the bit offset in bitmap of the allocated region,
1058 * or -errno on failure.
1060 int bitmap_find_free_region(unsigned long *bitmap
, unsigned int bits
, int order
)
1062 unsigned int pos
, end
; /* scans bitmap by regions of size order */
1064 for (pos
= 0 ; (end
= pos
+ (1U << order
)) <= bits
; pos
= end
) {
1065 if (!__reg_op(bitmap
, pos
, order
, REG_OP_ISFREE
))
1067 __reg_op(bitmap
, pos
, order
, REG_OP_ALLOC
);
1072 EXPORT_SYMBOL(bitmap_find_free_region
);
1075 * bitmap_release_region - release allocated bitmap region
1076 * @bitmap: array of unsigned longs corresponding to the bitmap
1077 * @pos: beginning of bit region to release
1078 * @order: region size (log base 2 of number of bits) to release
1080 * This is the complement to __bitmap_find_free_region() and releases
1081 * the found region (by clearing it in the bitmap).
1085 void bitmap_release_region(unsigned long *bitmap
, unsigned int pos
, int order
)
1087 __reg_op(bitmap
, pos
, order
, REG_OP_RELEASE
);
1089 EXPORT_SYMBOL(bitmap_release_region
);
1092 * bitmap_allocate_region - allocate bitmap region
1093 * @bitmap: array of unsigned longs corresponding to the bitmap
1094 * @pos: beginning of bit region to allocate
1095 * @order: region size (log base 2 of number of bits) to allocate
1097 * Allocate (set bits in) a specified region of a bitmap.
1099 * Return 0 on success, or %-EBUSY if specified region wasn't
1100 * free (not all bits were zero).
1102 int bitmap_allocate_region(unsigned long *bitmap
, unsigned int pos
, int order
)
1104 if (!__reg_op(bitmap
, pos
, order
, REG_OP_ISFREE
))
1106 return __reg_op(bitmap
, pos
, order
, REG_OP_ALLOC
);
1108 EXPORT_SYMBOL(bitmap_allocate_region
);
1111 * bitmap_from_u32array - copy the contents of a u32 array of bits to bitmap
1112 * @bitmap: array of unsigned longs, the destination bitmap, non NULL
1113 * @nbits: number of bits in @bitmap
1114 * @buf: array of u32 (in host byte order), the source bitmap, non NULL
1115 * @nwords: number of u32 words in @buf
1117 * copy min(nbits, 32*nwords) bits from @buf to @bitmap, remaining
1118 * bits between nword and nbits in @bitmap (if any) are cleared. In
1119 * last word of @bitmap, the bits beyond nbits (if any) are kept
1122 * Return the number of bits effectively copied.
1125 bitmap_from_u32array(unsigned long *bitmap
, unsigned int nbits
,
1126 const u32
*buf
, unsigned int nwords
)
1128 unsigned int dst_idx
, src_idx
;
1130 for (src_idx
= dst_idx
= 0; dst_idx
< BITS_TO_LONGS(nbits
); ++dst_idx
) {
1131 unsigned long part
= 0;
1133 if (src_idx
< nwords
)
1134 part
= buf
[src_idx
++];
1136 #if BITS_PER_LONG == 64
1137 if (src_idx
< nwords
)
1138 part
|= ((unsigned long) buf
[src_idx
++]) << 32;
1141 if (dst_idx
< nbits
/BITS_PER_LONG
)
1142 bitmap
[dst_idx
] = part
;
1144 unsigned long mask
= BITMAP_LAST_WORD_MASK(nbits
);
1146 bitmap
[dst_idx
] = (bitmap
[dst_idx
] & ~mask
)
1151 return min_t(unsigned int, nbits
, 32*nwords
);
1153 EXPORT_SYMBOL(bitmap_from_u32array
);
1156 * bitmap_to_u32array - copy the contents of bitmap to a u32 array of bits
1157 * @buf: array of u32 (in host byte order), the dest bitmap, non NULL
1158 * @nwords: number of u32 words in @buf
1159 * @bitmap: array of unsigned longs, the source bitmap, non NULL
1160 * @nbits: number of bits in @bitmap
1162 * copy min(nbits, 32*nwords) bits from @bitmap to @buf. Remaining
1163 * bits after nbits in @buf (if any) are cleared.
1165 * Return the number of bits effectively copied.
1168 bitmap_to_u32array(u32
*buf
, unsigned int nwords
,
1169 const unsigned long *bitmap
, unsigned int nbits
)
1171 unsigned int dst_idx
= 0, src_idx
= 0;
1173 while (dst_idx
< nwords
) {
1174 unsigned long part
= 0;
1176 if (src_idx
< BITS_TO_LONGS(nbits
)) {
1177 part
= bitmap
[src_idx
];
1178 if (src_idx
>= nbits
/BITS_PER_LONG
)
1179 part
&= BITMAP_LAST_WORD_MASK(nbits
);
1183 buf
[dst_idx
++] = part
& 0xffffffffUL
;
1185 #if BITS_PER_LONG == 64
1186 if (dst_idx
< nwords
) {
1188 buf
[dst_idx
++] = part
& 0xffffffffUL
;
1193 return min_t(unsigned int, nbits
, 32*nwords
);
1195 EXPORT_SYMBOL(bitmap_to_u32array
);
1198 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1199 * @dst: destination buffer
1200 * @src: bitmap to copy
1201 * @nbits: number of bits in the bitmap
1203 * Require nbits % BITS_PER_LONG == 0.
1206 void bitmap_copy_le(unsigned long *dst
, const unsigned long *src
, unsigned int nbits
)
1210 for (i
= 0; i
< nbits
/BITS_PER_LONG
; i
++) {
1211 if (BITS_PER_LONG
== 64)
1212 dst
[i
] = cpu_to_le64(src
[i
]);
1214 dst
[i
] = cpu_to_le32(src
[i
]);
1217 EXPORT_SYMBOL(bitmap_copy_le
);