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>
17 #include <asm/uaccess.h>
20 * bitmaps provide an array of bits, implemented using an an
21 * array of unsigned longs. The number of valid bits in a
22 * given bitmap does _not_ need to be an exact multiple of
25 * The possible unused bits in the last, partially used word
26 * of a bitmap are 'don't care'. The implementation makes
27 * no particular effort to keep them zero. It ensures that
28 * their value will not affect the results of any operation.
29 * The bitmap operations that return Boolean (bitmap_empty,
30 * for example) or scalar (bitmap_weight, for example) results
31 * carefully filter out these unused bits from impacting their
34 * These operations actually hold to a slightly stronger rule:
35 * if you don't input any bitmaps to these ops that have some
36 * unused bits set, then they won't output any set unused bits
39 * The byte ordering of bitmaps is more natural on little
40 * endian architectures. See the big-endian headers
41 * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
42 * for the best explanations of this ordering.
45 int __bitmap_equal(const unsigned long *bitmap1
,
46 const unsigned long *bitmap2
, unsigned int bits
)
48 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
49 for (k
= 0; k
< lim
; ++k
)
50 if (bitmap1
[k
] != bitmap2
[k
])
53 if (bits
% BITS_PER_LONG
)
54 if ((bitmap1
[k
] ^ bitmap2
[k
]) & BITMAP_LAST_WORD_MASK(bits
))
59 EXPORT_SYMBOL(__bitmap_equal
);
61 void __bitmap_complement(unsigned long *dst
, const unsigned long *src
, unsigned int bits
)
63 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
64 for (k
= 0; k
< lim
; ++k
)
67 if (bits
% BITS_PER_LONG
)
70 EXPORT_SYMBOL(__bitmap_complement
);
73 * __bitmap_shift_right - logical right shift of the bits in a bitmap
74 * @dst : destination bitmap
75 * @src : source bitmap
76 * @shift : shift by this many bits
77 * @nbits : bitmap size, in bits
79 * Shifting right (dividing) means moving bits in the MS -> LS bit
80 * direction. Zeros are fed into the vacated MS positions and the
81 * LS bits shifted off the bottom are lost.
83 void __bitmap_shift_right(unsigned long *dst
, const unsigned long *src
,
84 unsigned shift
, unsigned nbits
)
86 unsigned k
, lim
= BITS_TO_LONGS(nbits
);
87 unsigned off
= shift
/BITS_PER_LONG
, rem
= shift
% BITS_PER_LONG
;
88 unsigned long mask
= BITMAP_LAST_WORD_MASK(nbits
);
89 for (k
= 0; off
+ k
< lim
; ++k
) {
90 unsigned long upper
, lower
;
93 * If shift is not word aligned, take lower rem bits of
94 * word above and make them the top rem bits of result.
96 if (!rem
|| off
+ k
+ 1 >= lim
)
99 upper
= src
[off
+ k
+ 1];
100 if (off
+ k
+ 1 == lim
- 1)
102 upper
<<= (BITS_PER_LONG
- rem
);
104 lower
= src
[off
+ k
];
105 if (off
+ k
== lim
- 1)
108 dst
[k
] = lower
| upper
;
111 memset(&dst
[lim
- off
], 0, off
*sizeof(unsigned long));
113 EXPORT_SYMBOL(__bitmap_shift_right
);
117 * __bitmap_shift_left - logical left shift of the bits in a bitmap
118 * @dst : destination bitmap
119 * @src : source bitmap
120 * @shift : shift by this many bits
121 * @nbits : bitmap size, in bits
123 * Shifting left (multiplying) means moving bits in the LS -> MS
124 * direction. Zeros are fed into the vacated LS bit positions
125 * and those MS bits shifted off the top are lost.
128 void __bitmap_shift_left(unsigned long *dst
, const unsigned long *src
,
129 unsigned int shift
, unsigned int nbits
)
132 unsigned int lim
= BITS_TO_LONGS(nbits
);
133 unsigned int off
= shift
/BITS_PER_LONG
, rem
= shift
% BITS_PER_LONG
;
134 for (k
= lim
- off
- 1; k
>= 0; --k
) {
135 unsigned long upper
, lower
;
138 * If shift is not word aligned, take upper rem bits of
139 * word below and make them the bottom rem bits of result.
142 lower
= src
[k
- 1] >> (BITS_PER_LONG
- rem
);
145 upper
= src
[k
] << rem
;
146 dst
[k
+ off
] = lower
| upper
;
149 memset(dst
, 0, off
*sizeof(unsigned long));
151 EXPORT_SYMBOL(__bitmap_shift_left
);
153 int __bitmap_and(unsigned long *dst
, const unsigned long *bitmap1
,
154 const unsigned long *bitmap2
, unsigned int bits
)
157 unsigned int lim
= bits
/BITS_PER_LONG
;
158 unsigned long result
= 0;
160 for (k
= 0; k
< lim
; k
++)
161 result
|= (dst
[k
] = bitmap1
[k
] & bitmap2
[k
]);
162 if (bits
% BITS_PER_LONG
)
163 result
|= (dst
[k
] = bitmap1
[k
] & bitmap2
[k
] &
164 BITMAP_LAST_WORD_MASK(bits
));
167 EXPORT_SYMBOL(__bitmap_and
);
169 void __bitmap_or(unsigned long *dst
, const unsigned long *bitmap1
,
170 const unsigned long *bitmap2
, unsigned int bits
)
173 unsigned int nr
= BITS_TO_LONGS(bits
);
175 for (k
= 0; k
< nr
; k
++)
176 dst
[k
] = bitmap1
[k
] | bitmap2
[k
];
178 EXPORT_SYMBOL(__bitmap_or
);
180 void __bitmap_xor(unsigned long *dst
, const unsigned long *bitmap1
,
181 const unsigned long *bitmap2
, unsigned int bits
)
184 unsigned int nr
= BITS_TO_LONGS(bits
);
186 for (k
= 0; k
< nr
; k
++)
187 dst
[k
] = bitmap1
[k
] ^ bitmap2
[k
];
189 EXPORT_SYMBOL(__bitmap_xor
);
191 int __bitmap_andnot(unsigned long *dst
, const unsigned long *bitmap1
,
192 const unsigned long *bitmap2
, unsigned int bits
)
195 unsigned int lim
= bits
/BITS_PER_LONG
;
196 unsigned long result
= 0;
198 for (k
= 0; k
< lim
; k
++)
199 result
|= (dst
[k
] = bitmap1
[k
] & ~bitmap2
[k
]);
200 if (bits
% BITS_PER_LONG
)
201 result
|= (dst
[k
] = bitmap1
[k
] & ~bitmap2
[k
] &
202 BITMAP_LAST_WORD_MASK(bits
));
205 EXPORT_SYMBOL(__bitmap_andnot
);
207 int __bitmap_intersects(const unsigned long *bitmap1
,
208 const unsigned long *bitmap2
, unsigned int bits
)
210 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
211 for (k
= 0; k
< lim
; ++k
)
212 if (bitmap1
[k
] & bitmap2
[k
])
215 if (bits
% BITS_PER_LONG
)
216 if ((bitmap1
[k
] & bitmap2
[k
]) & BITMAP_LAST_WORD_MASK(bits
))
220 EXPORT_SYMBOL(__bitmap_intersects
);
222 int __bitmap_subset(const unsigned long *bitmap1
,
223 const unsigned long *bitmap2
, unsigned int bits
)
225 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
226 for (k
= 0; k
< lim
; ++k
)
227 if (bitmap1
[k
] & ~bitmap2
[k
])
230 if (bits
% BITS_PER_LONG
)
231 if ((bitmap1
[k
] & ~bitmap2
[k
]) & BITMAP_LAST_WORD_MASK(bits
))
235 EXPORT_SYMBOL(__bitmap_subset
);
237 int __bitmap_weight(const unsigned long *bitmap
, unsigned int bits
)
239 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
242 for (k
= 0; k
< lim
; k
++)
243 w
+= hweight_long(bitmap
[k
]);
245 if (bits
% BITS_PER_LONG
)
246 w
+= hweight_long(bitmap
[k
] & BITMAP_LAST_WORD_MASK(bits
));
250 EXPORT_SYMBOL(__bitmap_weight
);
252 void bitmap_set(unsigned long *map
, unsigned int start
, int len
)
254 unsigned long *p
= map
+ BIT_WORD(start
);
255 const unsigned int size
= start
+ len
;
256 int bits_to_set
= BITS_PER_LONG
- (start
% BITS_PER_LONG
);
257 unsigned long mask_to_set
= BITMAP_FIRST_WORD_MASK(start
);
259 while (len
- bits_to_set
>= 0) {
262 bits_to_set
= BITS_PER_LONG
;
267 mask_to_set
&= BITMAP_LAST_WORD_MASK(size
);
271 EXPORT_SYMBOL(bitmap_set
);
273 void bitmap_clear(unsigned long *map
, unsigned int start
, int len
)
275 unsigned long *p
= map
+ BIT_WORD(start
);
276 const unsigned int size
= start
+ len
;
277 int bits_to_clear
= BITS_PER_LONG
- (start
% BITS_PER_LONG
);
278 unsigned long mask_to_clear
= BITMAP_FIRST_WORD_MASK(start
);
280 while (len
- bits_to_clear
>= 0) {
281 *p
&= ~mask_to_clear
;
282 len
-= bits_to_clear
;
283 bits_to_clear
= BITS_PER_LONG
;
284 mask_to_clear
= ~0UL;
288 mask_to_clear
&= BITMAP_LAST_WORD_MASK(size
);
289 *p
&= ~mask_to_clear
;
292 EXPORT_SYMBOL(bitmap_clear
);
295 * bitmap_find_next_zero_area_off - find a contiguous aligned zero area
296 * @map: The address to base the search on
297 * @size: The bitmap size in bits
298 * @start: The bitnumber to start searching at
299 * @nr: The number of zeroed bits we're looking for
300 * @align_mask: Alignment mask for zero area
301 * @align_offset: Alignment offset for zero area.
303 * The @align_mask should be one less than a power of 2; the effect is that
304 * the bit offset of all zero areas this function finds plus @align_offset
305 * is multiple of that power of 2.
307 unsigned long bitmap_find_next_zero_area_off(unsigned long *map
,
311 unsigned long align_mask
,
312 unsigned long align_offset
)
314 unsigned long index
, end
, i
;
316 index
= find_next_zero_bit(map
, size
, start
);
318 /* Align allocation */
319 index
= __ALIGN_MASK(index
+ align_offset
, align_mask
) - align_offset
;
324 i
= find_next_bit(map
, end
, index
);
331 EXPORT_SYMBOL(bitmap_find_next_zero_area_off
);
334 * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,
335 * second version by Paul Jackson, third by Joe Korty.
339 #define nbits_to_hold_value(val) fls(val)
340 #define BASEDEC 10 /* fancier cpuset lists input in decimal */
343 * __bitmap_parse - convert an ASCII hex string into a bitmap.
344 * @buf: pointer to buffer containing string.
345 * @buflen: buffer size in bytes. If string is smaller than this
346 * then it must be terminated with a \0.
347 * @is_user: location of buffer, 0 indicates kernel space
348 * @maskp: pointer to bitmap array that will contain result.
349 * @nmaskbits: size of bitmap, in bits.
351 * Commas group hex digits into chunks. Each chunk defines exactly 32
352 * bits of the resultant bitmask. No chunk may specify a value larger
353 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
354 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
355 * characters and for grouping errors such as "1,,5", ",44", "," and "".
356 * Leading and trailing whitespace accepted, but not embedded whitespace.
358 int __bitmap_parse(const char *buf
, unsigned int buflen
,
359 int is_user
, unsigned long *maskp
,
362 int c
, old_c
, totaldigits
, ndigits
, nchunks
, nbits
;
364 const char __user __force
*ubuf
= (const char __user __force
*)buf
;
366 bitmap_zero(maskp
, nmaskbits
);
368 nchunks
= nbits
= totaldigits
= c
= 0;
372 /* Get the next chunk of the bitmap */
376 if (__get_user(c
, ubuf
++))
386 * If the last character was a space and the current
387 * character isn't '\0', we've got embedded whitespace.
388 * This is a no-no, so throw an error.
390 if (totaldigits
&& c
&& isspace(old_c
))
393 /* A '\0' or a ',' signal the end of the chunk */
394 if (c
== '\0' || c
== ',')
401 * Make sure there are at least 4 free bits in 'chunk'.
402 * If not, this hexdigit will overflow 'chunk', so
405 if (chunk
& ~((1UL << (CHUNKSZ
- 4)) - 1))
408 chunk
= (chunk
<< 4) | hex_to_bin(c
);
409 ndigits
++; totaldigits
++;
413 if (nchunks
== 0 && chunk
== 0)
416 __bitmap_shift_left(maskp
, maskp
, CHUNKSZ
, nmaskbits
);
419 nbits
+= (nchunks
== 1) ? nbits_to_hold_value(chunk
) : CHUNKSZ
;
420 if (nbits
> nmaskbits
)
422 } while (buflen
&& c
== ',');
426 EXPORT_SYMBOL(__bitmap_parse
);
429 * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
431 * @ubuf: pointer to user buffer containing string.
432 * @ulen: buffer size in bytes. If string is smaller than this
433 * then it must be terminated with a \0.
434 * @maskp: pointer to bitmap array that will contain result.
435 * @nmaskbits: size of bitmap, in bits.
437 * Wrapper for __bitmap_parse(), providing it with user buffer.
439 * We cannot have this as an inline function in bitmap.h because it needs
440 * linux/uaccess.h to get the access_ok() declaration and this causes
441 * cyclic dependencies.
443 int bitmap_parse_user(const char __user
*ubuf
,
444 unsigned int ulen
, unsigned long *maskp
,
447 if (!access_ok(VERIFY_READ
, ubuf
, ulen
))
449 return __bitmap_parse((const char __force
*)ubuf
,
450 ulen
, 1, maskp
, nmaskbits
);
453 EXPORT_SYMBOL(bitmap_parse_user
);
456 * bitmap_print_to_pagebuf - convert bitmap to list or hex format ASCII string
457 * @list: indicates whether the bitmap must be list
458 * @buf: page aligned buffer into which string is placed
459 * @maskp: pointer to bitmap to convert
460 * @nmaskbits: size of bitmap, in bits
462 * Output format is a comma-separated list of decimal numbers and
463 * ranges if list is specified or hex digits grouped into comma-separated
464 * sets of 8 digits/set. Returns the number of characters written to buf.
466 int bitmap_print_to_pagebuf(bool list
, char *buf
, const unsigned long *maskp
,
469 ptrdiff_t len
= PTR_ALIGN(buf
+ PAGE_SIZE
- 1, PAGE_SIZE
) - buf
- 2;
473 n
= list
? scnprintf(buf
, len
, "%*pbl", nmaskbits
, maskp
) :
474 scnprintf(buf
, len
, "%*pb", nmaskbits
, maskp
);
480 EXPORT_SYMBOL(bitmap_print_to_pagebuf
);
483 * __bitmap_parselist - convert list format ASCII string to bitmap
484 * @buf: read nul-terminated user string from this buffer
485 * @buflen: buffer size in bytes. If string is smaller than this
486 * then it must be terminated with a \0.
487 * @is_user: location of buffer, 0 indicates kernel space
488 * @maskp: write resulting mask here
489 * @nmaskbits: number of bits in mask to be written
491 * Input format is a comma-separated list of decimal numbers and
492 * ranges. Consecutively set bits are shown as two hyphen-separated
493 * decimal numbers, the smallest and largest bit numbers set in
496 * Returns 0 on success, -errno on invalid input strings.
498 * %-EINVAL: second number in range smaller than first
499 * %-EINVAL: invalid character in string
500 * %-ERANGE: bit number specified too large for mask
502 static int __bitmap_parselist(const char *buf
, unsigned int buflen
,
503 int is_user
, unsigned long *maskp
,
507 int c
, old_c
, totaldigits
;
508 const char __user __force
*ubuf
= (const char __user __force
*)buf
;
509 int at_start
, in_range
;
512 bitmap_zero(maskp
, nmaskbits
);
518 /* Get the next cpu# or a range of cpu#'s */
522 if (__get_user(c
, ubuf
++))
531 * If the last character was a space and the current
532 * character isn't '\0', we've got embedded whitespace.
533 * This is a no-no, so throw an error.
535 if (totaldigits
&& c
&& isspace(old_c
))
538 /* A '\0' or a ',' signal the end of a cpu# or range */
539 if (c
== '\0' || c
== ',')
543 if (at_start
|| in_range
)
553 b
= b
* 10 + (c
- '0');
569 } while (buflen
&& c
== ',');
573 int bitmap_parselist(const char *bp
, unsigned long *maskp
, int nmaskbits
)
575 char *nl
= strchrnul(bp
, '\n');
578 return __bitmap_parselist(bp
, len
, 0, maskp
, nmaskbits
);
580 EXPORT_SYMBOL(bitmap_parselist
);
584 * bitmap_parselist_user()
586 * @ubuf: pointer to user buffer containing string.
587 * @ulen: buffer size in bytes. If string is smaller than this
588 * then it must be terminated with a \0.
589 * @maskp: pointer to bitmap array that will contain result.
590 * @nmaskbits: size of bitmap, in bits.
592 * Wrapper for bitmap_parselist(), providing it with user buffer.
594 * We cannot have this as an inline function in bitmap.h because it needs
595 * linux/uaccess.h to get the access_ok() declaration and this causes
596 * cyclic dependencies.
598 int bitmap_parselist_user(const char __user
*ubuf
,
599 unsigned int ulen
, unsigned long *maskp
,
602 if (!access_ok(VERIFY_READ
, ubuf
, ulen
))
604 return __bitmap_parselist((const char __force
*)ubuf
,
605 ulen
, 1, maskp
, nmaskbits
);
607 EXPORT_SYMBOL(bitmap_parselist_user
);
611 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
612 * @buf: pointer to a bitmap
613 * @pos: a bit position in @buf (0 <= @pos < @nbits)
614 * @nbits: number of valid bit positions in @buf
616 * Map the bit at position @pos in @buf (of length @nbits) to the
617 * ordinal of which set bit it is. If it is not set or if @pos
618 * is not a valid bit position, map to -1.
620 * If for example, just bits 4 through 7 are set in @buf, then @pos
621 * values 4 through 7 will get mapped to 0 through 3, respectively,
622 * and other @pos values will get mapped to -1. When @pos value 7
623 * gets mapped to (returns) @ord value 3 in this example, that means
624 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
626 * The bit positions 0 through @bits are valid positions in @buf.
628 static int bitmap_pos_to_ord(const unsigned long *buf
, unsigned int pos
, unsigned int nbits
)
630 if (pos
>= nbits
|| !test_bit(pos
, buf
))
633 return __bitmap_weight(buf
, pos
);
637 * bitmap_ord_to_pos - find position of n-th set bit in bitmap
638 * @buf: pointer to bitmap
639 * @ord: ordinal bit position (n-th set bit, n >= 0)
640 * @nbits: number of valid bit positions in @buf
642 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
643 * Value of @ord should be in range 0 <= @ord < weight(buf). If @ord
644 * >= weight(buf), returns @nbits.
646 * If for example, just bits 4 through 7 are set in @buf, then @ord
647 * values 0 through 3 will get mapped to 4 through 7, respectively,
648 * and all other @ord values returns @nbits. When @ord value 3
649 * gets mapped to (returns) @pos value 7 in this example, that means
650 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
652 * The bit positions 0 through @nbits-1 are valid positions in @buf.
654 unsigned int bitmap_ord_to_pos(const unsigned long *buf
, unsigned int ord
, unsigned int nbits
)
658 for (pos
= find_first_bit(buf
, nbits
);
660 pos
= find_next_bit(buf
, nbits
, pos
+ 1))
667 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
668 * @dst: remapped result
669 * @src: subset to be remapped
670 * @old: defines domain of map
671 * @new: defines range of map
672 * @nbits: number of bits in each of these bitmaps
674 * Let @old and @new define a mapping of bit positions, such that
675 * whatever position is held by the n-th set bit in @old is mapped
676 * to the n-th set bit in @new. In the more general case, allowing
677 * for the possibility that the weight 'w' of @new is less than the
678 * weight of @old, map the position of the n-th set bit in @old to
679 * the position of the m-th set bit in @new, where m == n % w.
681 * If either of the @old and @new bitmaps are empty, or if @src and
682 * @dst point to the same location, then this routine copies @src
685 * The positions of unset bits in @old are mapped to themselves
686 * (the identify map).
688 * Apply the above specified mapping to @src, placing the result in
689 * @dst, clearing any bits previously set in @dst.
691 * For example, lets say that @old has bits 4 through 7 set, and
692 * @new has bits 12 through 15 set. This defines the mapping of bit
693 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
694 * bit positions unchanged. So if say @src comes into this routine
695 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
698 void bitmap_remap(unsigned long *dst
, const unsigned long *src
,
699 const unsigned long *old
, const unsigned long *new,
702 unsigned int oldbit
, w
;
704 if (dst
== src
) /* following doesn't handle inplace remaps */
706 bitmap_zero(dst
, nbits
);
708 w
= bitmap_weight(new, nbits
);
709 for_each_set_bit(oldbit
, src
, nbits
) {
710 int n
= bitmap_pos_to_ord(old
, oldbit
, nbits
);
713 set_bit(oldbit
, dst
); /* identity map */
715 set_bit(bitmap_ord_to_pos(new, n
% w
, nbits
), dst
);
718 EXPORT_SYMBOL(bitmap_remap
);
721 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
722 * @oldbit: bit position to be mapped
723 * @old: defines domain of map
724 * @new: defines range of map
725 * @bits: number of bits in each of these bitmaps
727 * Let @old and @new define a mapping of bit positions, such that
728 * whatever position is held by the n-th set bit in @old is mapped
729 * to the n-th set bit in @new. In the more general case, allowing
730 * for the possibility that the weight 'w' of @new is less than the
731 * weight of @old, map the position of the n-th set bit in @old to
732 * the position of the m-th set bit in @new, where m == n % w.
734 * The positions of unset bits in @old are mapped to themselves
735 * (the identify map).
737 * Apply the above specified mapping to bit position @oldbit, returning
738 * the new bit position.
740 * For example, lets say that @old has bits 4 through 7 set, and
741 * @new has bits 12 through 15 set. This defines the mapping of bit
742 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
743 * bit positions unchanged. So if say @oldbit is 5, then this routine
746 int bitmap_bitremap(int oldbit
, const unsigned long *old
,
747 const unsigned long *new, int bits
)
749 int w
= bitmap_weight(new, bits
);
750 int n
= bitmap_pos_to_ord(old
, oldbit
, bits
);
754 return bitmap_ord_to_pos(new, n
% w
, bits
);
756 EXPORT_SYMBOL(bitmap_bitremap
);
759 * bitmap_onto - translate one bitmap relative to another
760 * @dst: resulting translated bitmap
761 * @orig: original untranslated bitmap
762 * @relmap: bitmap relative to which translated
763 * @bits: number of bits in each of these bitmaps
765 * Set the n-th bit of @dst iff there exists some m such that the
766 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
767 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
768 * (If you understood the previous sentence the first time your
769 * read it, you're overqualified for your current job.)
771 * In other words, @orig is mapped onto (surjectively) @dst,
772 * using the map { <n, m> | the n-th bit of @relmap is the
773 * m-th set bit of @relmap }.
775 * Any set bits in @orig above bit number W, where W is the
776 * weight of (number of set bits in) @relmap are mapped nowhere.
777 * In particular, if for all bits m set in @orig, m >= W, then
778 * @dst will end up empty. In situations where the possibility
779 * of such an empty result is not desired, one way to avoid it is
780 * to use the bitmap_fold() operator, below, to first fold the
781 * @orig bitmap over itself so that all its set bits x are in the
782 * range 0 <= x < W. The bitmap_fold() operator does this by
783 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
785 * Example [1] for bitmap_onto():
786 * Let's say @relmap has bits 30-39 set, and @orig has bits
787 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,
788 * @dst will have bits 31, 33, 35, 37 and 39 set.
790 * When bit 0 is set in @orig, it means turn on the bit in
791 * @dst corresponding to whatever is the first bit (if any)
792 * that is turned on in @relmap. Since bit 0 was off in the
793 * above example, we leave off that bit (bit 30) in @dst.
795 * When bit 1 is set in @orig (as in the above example), it
796 * means turn on the bit in @dst corresponding to whatever
797 * is the second bit that is turned on in @relmap. The second
798 * bit in @relmap that was turned on in the above example was
799 * bit 31, so we turned on bit 31 in @dst.
801 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
802 * because they were the 4th, 6th, 8th and 10th set bits
803 * set in @relmap, and the 4th, 6th, 8th and 10th bits of
804 * @orig (i.e. bits 3, 5, 7 and 9) were also set.
806 * When bit 11 is set in @orig, it means turn on the bit in
807 * @dst corresponding to whatever is the twelfth bit that is
808 * turned on in @relmap. In the above example, there were
809 * only ten bits turned on in @relmap (30..39), so that bit
810 * 11 was set in @orig had no affect on @dst.
812 * Example [2] for bitmap_fold() + bitmap_onto():
813 * Let's say @relmap has these ten bits set:
814 * 40 41 42 43 45 48 53 61 74 95
815 * (for the curious, that's 40 plus the first ten terms of the
816 * Fibonacci sequence.)
818 * Further lets say we use the following code, invoking
819 * bitmap_fold() then bitmap_onto, as suggested above to
820 * avoid the possibility of an empty @dst result:
822 * unsigned long *tmp; // a temporary bitmap's bits
824 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
825 * bitmap_onto(dst, tmp, relmap, bits);
827 * Then this table shows what various values of @dst would be, for
828 * various @orig's. I list the zero-based positions of each set bit.
829 * The tmp column shows the intermediate result, as computed by
830 * using bitmap_fold() to fold the @orig bitmap modulo ten
831 * (the weight of @relmap).
838 * 1 3 5 7 1 3 5 7 41 43 48 61
839 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45
840 * 0 9 18 27 0 9 8 7 40 61 74 95
842 * 0 11 22 33 0 1 2 3 40 41 42 43
843 * 0 12 24 36 0 2 4 6 40 42 45 53
844 * 78 102 211 1 2 8 41 42 74 (*)
846 * (*) For these marked lines, if we hadn't first done bitmap_fold()
847 * into tmp, then the @dst result would have been empty.
849 * If either of @orig or @relmap is empty (no set bits), then @dst
850 * will be returned empty.
852 * If (as explained above) the only set bits in @orig are in positions
853 * m where m >= W, (where W is the weight of @relmap) then @dst will
854 * once again be returned empty.
856 * All bits in @dst not set by the above rule are cleared.
858 void bitmap_onto(unsigned long *dst
, const unsigned long *orig
,
859 const unsigned long *relmap
, unsigned int bits
)
861 unsigned int n
, m
; /* same meaning as in above comment */
863 if (dst
== orig
) /* following doesn't handle inplace mappings */
865 bitmap_zero(dst
, bits
);
868 * The following code is a more efficient, but less
869 * obvious, equivalent to the loop:
870 * for (m = 0; m < bitmap_weight(relmap, bits); m++) {
871 * n = bitmap_ord_to_pos(orig, m, bits);
872 * if (test_bit(m, orig))
878 for_each_set_bit(n
, relmap
, bits
) {
879 /* m == bitmap_pos_to_ord(relmap, n, bits) */
880 if (test_bit(m
, orig
))
885 EXPORT_SYMBOL(bitmap_onto
);
888 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
889 * @dst: resulting smaller bitmap
890 * @orig: original larger bitmap
891 * @sz: specified size
892 * @nbits: number of bits in each of these bitmaps
894 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
895 * Clear all other bits in @dst. See further the comment and
896 * Example [2] for bitmap_onto() for why and how to use this.
898 void bitmap_fold(unsigned long *dst
, const unsigned long *orig
,
899 unsigned int sz
, unsigned int nbits
)
903 if (dst
== orig
) /* following doesn't handle inplace mappings */
905 bitmap_zero(dst
, nbits
);
907 for_each_set_bit(oldbit
, orig
, nbits
)
908 set_bit(oldbit
% sz
, dst
);
910 EXPORT_SYMBOL(bitmap_fold
);
913 * Common code for bitmap_*_region() routines.
914 * bitmap: array of unsigned longs corresponding to the bitmap
915 * pos: the beginning of the region
916 * order: region size (log base 2 of number of bits)
917 * reg_op: operation(s) to perform on that region of bitmap
919 * Can set, verify and/or release a region of bits in a bitmap,
920 * depending on which combination of REG_OP_* flag bits is set.
922 * A region of a bitmap is a sequence of bits in the bitmap, of
923 * some size '1 << order' (a power of two), aligned to that same
924 * '1 << order' power of two.
926 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
927 * Returns 0 in all other cases and reg_ops.
931 REG_OP_ISFREE
, /* true if region is all zero bits */
932 REG_OP_ALLOC
, /* set all bits in region */
933 REG_OP_RELEASE
, /* clear all bits in region */
936 static int __reg_op(unsigned long *bitmap
, unsigned int pos
, int order
, int reg_op
)
938 int nbits_reg
; /* number of bits in region */
939 int index
; /* index first long of region in bitmap */
940 int offset
; /* bit offset region in bitmap[index] */
941 int nlongs_reg
; /* num longs spanned by region in bitmap */
942 int nbitsinlong
; /* num bits of region in each spanned long */
943 unsigned long mask
; /* bitmask for one long of region */
944 int i
; /* scans bitmap by longs */
945 int ret
= 0; /* return value */
948 * Either nlongs_reg == 1 (for small orders that fit in one long)
949 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
951 nbits_reg
= 1 << order
;
952 index
= pos
/ BITS_PER_LONG
;
953 offset
= pos
- (index
* BITS_PER_LONG
);
954 nlongs_reg
= BITS_TO_LONGS(nbits_reg
);
955 nbitsinlong
= min(nbits_reg
, BITS_PER_LONG
);
958 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
959 * overflows if nbitsinlong == BITS_PER_LONG.
961 mask
= (1UL << (nbitsinlong
- 1));
967 for (i
= 0; i
< nlongs_reg
; i
++) {
968 if (bitmap
[index
+ i
] & mask
)
971 ret
= 1; /* all bits in region free (zero) */
975 for (i
= 0; i
< nlongs_reg
; i
++)
976 bitmap
[index
+ i
] |= mask
;
980 for (i
= 0; i
< nlongs_reg
; i
++)
981 bitmap
[index
+ i
] &= ~mask
;
989 * bitmap_find_free_region - find a contiguous aligned mem region
990 * @bitmap: array of unsigned longs corresponding to the bitmap
991 * @bits: number of bits in the bitmap
992 * @order: region size (log base 2 of number of bits) to find
994 * Find a region of free (zero) bits in a @bitmap of @bits bits and
995 * allocate them (set them to one). Only consider regions of length
996 * a power (@order) of two, aligned to that power of two, which
997 * makes the search algorithm much faster.
999 * Return the bit offset in bitmap of the allocated region,
1000 * or -errno on failure.
1002 int bitmap_find_free_region(unsigned long *bitmap
, unsigned int bits
, int order
)
1004 unsigned int pos
, end
; /* scans bitmap by regions of size order */
1006 for (pos
= 0 ; (end
= pos
+ (1U << order
)) <= bits
; pos
= end
) {
1007 if (!__reg_op(bitmap
, pos
, order
, REG_OP_ISFREE
))
1009 __reg_op(bitmap
, pos
, order
, REG_OP_ALLOC
);
1014 EXPORT_SYMBOL(bitmap_find_free_region
);
1017 * bitmap_release_region - release allocated bitmap region
1018 * @bitmap: array of unsigned longs corresponding to the bitmap
1019 * @pos: beginning of bit region to release
1020 * @order: region size (log base 2 of number of bits) to release
1022 * This is the complement to __bitmap_find_free_region() and releases
1023 * the found region (by clearing it in the bitmap).
1027 void bitmap_release_region(unsigned long *bitmap
, unsigned int pos
, int order
)
1029 __reg_op(bitmap
, pos
, order
, REG_OP_RELEASE
);
1031 EXPORT_SYMBOL(bitmap_release_region
);
1034 * bitmap_allocate_region - allocate bitmap region
1035 * @bitmap: array of unsigned longs corresponding to the bitmap
1036 * @pos: beginning of bit region to allocate
1037 * @order: region size (log base 2 of number of bits) to allocate
1039 * Allocate (set bits in) a specified region of a bitmap.
1041 * Return 0 on success, or %-EBUSY if specified region wasn't
1042 * free (not all bits were zero).
1044 int bitmap_allocate_region(unsigned long *bitmap
, unsigned int pos
, int order
)
1046 if (!__reg_op(bitmap
, pos
, order
, REG_OP_ISFREE
))
1048 return __reg_op(bitmap
, pos
, order
, REG_OP_ALLOC
);
1050 EXPORT_SYMBOL(bitmap_allocate_region
);
1053 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1054 * @dst: destination buffer
1055 * @src: bitmap to copy
1056 * @nbits: number of bits in the bitmap
1058 * Require nbits % BITS_PER_LONG == 0.
1061 void bitmap_copy_le(unsigned long *dst
, const unsigned long *src
, unsigned int nbits
)
1065 for (i
= 0; i
< nbits
/BITS_PER_LONG
; i
++) {
1066 if (BITS_PER_LONG
== 64)
1067 dst
[i
] = cpu_to_le64(src
[i
]);
1069 dst
[i
] = cpu_to_le32(src
[i
]);
1072 EXPORT_SYMBOL(bitmap_copy_le
);