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 <asm/uaccess.h>
18 * bitmaps provide an array of bits, implemented using an an
19 * array of unsigned longs. The number of valid bits in a
20 * given bitmap does _not_ need to be an exact multiple of
23 * The possible unused bits in the last, partially used word
24 * of a bitmap are 'don't care'. The implementation makes
25 * no particular effort to keep them zero. It ensures that
26 * their value will not affect the results of any operation.
27 * The bitmap operations that return Boolean (bitmap_empty,
28 * for example) or scalar (bitmap_weight, for example) results
29 * carefully filter out these unused bits from impacting their
32 * These operations actually hold to a slightly stronger rule:
33 * if you don't input any bitmaps to these ops that have some
34 * unused bits set, then they won't output any set unused bits
37 * The byte ordering of bitmaps is more natural on little
38 * endian architectures. See the big-endian headers
39 * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
40 * for the best explanations of this ordering.
43 int __bitmap_empty(const unsigned long *bitmap
, unsigned int bits
)
45 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
46 for (k
= 0; k
< lim
; ++k
)
50 if (bits
% BITS_PER_LONG
)
51 if (bitmap
[k
] & BITMAP_LAST_WORD_MASK(bits
))
56 EXPORT_SYMBOL(__bitmap_empty
);
58 int __bitmap_full(const unsigned long *bitmap
, unsigned int bits
)
60 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
61 for (k
= 0; k
< lim
; ++k
)
65 if (bits
% BITS_PER_LONG
)
66 if (~bitmap
[k
] & BITMAP_LAST_WORD_MASK(bits
))
71 EXPORT_SYMBOL(__bitmap_full
);
73 int __bitmap_equal(const unsigned long *bitmap1
,
74 const unsigned long *bitmap2
, unsigned int bits
)
76 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
77 for (k
= 0; k
< lim
; ++k
)
78 if (bitmap1
[k
] != bitmap2
[k
])
81 if (bits
% BITS_PER_LONG
)
82 if ((bitmap1
[k
] ^ bitmap2
[k
]) & BITMAP_LAST_WORD_MASK(bits
))
87 EXPORT_SYMBOL(__bitmap_equal
);
89 void __bitmap_complement(unsigned long *dst
, const unsigned long *src
, unsigned int bits
)
91 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
92 for (k
= 0; k
< lim
; ++k
)
95 if (bits
% BITS_PER_LONG
)
98 EXPORT_SYMBOL(__bitmap_complement
);
101 * __bitmap_shift_right - logical right shift of the bits in a bitmap
102 * @dst : destination bitmap
103 * @src : source bitmap
104 * @shift : shift by this many bits
105 * @bits : bitmap size, in bits
107 * Shifting right (dividing) means moving bits in the MS -> LS bit
108 * direction. Zeros are fed into the vacated MS positions and the
109 * LS bits shifted off the bottom are lost.
111 void __bitmap_shift_right(unsigned long *dst
,
112 const unsigned long *src
, int shift
, int bits
)
114 int k
, lim
= BITS_TO_LONGS(bits
), left
= bits
% BITS_PER_LONG
;
115 int off
= shift
/BITS_PER_LONG
, rem
= shift
% BITS_PER_LONG
;
116 unsigned long mask
= (1UL << left
) - 1;
117 for (k
= 0; off
+ k
< lim
; ++k
) {
118 unsigned long upper
, lower
;
121 * If shift is not word aligned, take lower rem bits of
122 * word above and make them the top rem bits of result.
124 if (!rem
|| off
+ k
+ 1 >= lim
)
127 upper
= src
[off
+ k
+ 1];
128 if (off
+ k
+ 1 == lim
- 1 && left
)
131 lower
= src
[off
+ k
];
132 if (left
&& off
+ k
== lim
- 1)
134 dst
[k
] = upper
<< (BITS_PER_LONG
- rem
) | lower
>> rem
;
135 if (left
&& k
== lim
- 1)
139 memset(&dst
[lim
- off
], 0, off
*sizeof(unsigned long));
141 EXPORT_SYMBOL(__bitmap_shift_right
);
145 * __bitmap_shift_left - logical left shift of the bits in a bitmap
146 * @dst : destination bitmap
147 * @src : source bitmap
148 * @shift : shift by this many bits
149 * @bits : bitmap size, in bits
151 * Shifting left (multiplying) means moving bits in the LS -> MS
152 * direction. Zeros are fed into the vacated LS bit positions
153 * and those MS bits shifted off the top are lost.
156 void __bitmap_shift_left(unsigned long *dst
,
157 const unsigned long *src
, int shift
, int bits
)
159 int k
, lim
= BITS_TO_LONGS(bits
), left
= bits
% BITS_PER_LONG
;
160 int off
= shift
/BITS_PER_LONG
, rem
= shift
% BITS_PER_LONG
;
161 for (k
= lim
- off
- 1; k
>= 0; --k
) {
162 unsigned long upper
, lower
;
165 * If shift is not word aligned, take upper rem bits of
166 * word below and make them the bottom rem bits of result.
173 if (left
&& k
== lim
- 1)
174 upper
&= (1UL << left
) - 1;
175 dst
[k
+ off
] = lower
>> (BITS_PER_LONG
- rem
) | upper
<< rem
;
176 if (left
&& k
+ off
== lim
- 1)
177 dst
[k
+ off
] &= (1UL << left
) - 1;
180 memset(dst
, 0, off
*sizeof(unsigned long));
182 EXPORT_SYMBOL(__bitmap_shift_left
);
184 int __bitmap_and(unsigned long *dst
, const unsigned long *bitmap1
,
185 const unsigned long *bitmap2
, unsigned int bits
)
188 unsigned int nr
= BITS_TO_LONGS(bits
);
189 unsigned long result
= 0;
191 for (k
= 0; k
< nr
; k
++)
192 result
|= (dst
[k
] = bitmap1
[k
] & bitmap2
[k
]);
195 EXPORT_SYMBOL(__bitmap_and
);
197 void __bitmap_or(unsigned long *dst
, const unsigned long *bitmap1
,
198 const unsigned long *bitmap2
, unsigned int bits
)
201 unsigned int nr
= BITS_TO_LONGS(bits
);
203 for (k
= 0; k
< nr
; k
++)
204 dst
[k
] = bitmap1
[k
] | bitmap2
[k
];
206 EXPORT_SYMBOL(__bitmap_or
);
208 void __bitmap_xor(unsigned long *dst
, const unsigned long *bitmap1
,
209 const unsigned long *bitmap2
, unsigned int bits
)
212 unsigned int nr
= BITS_TO_LONGS(bits
);
214 for (k
= 0; k
< nr
; k
++)
215 dst
[k
] = bitmap1
[k
] ^ bitmap2
[k
];
217 EXPORT_SYMBOL(__bitmap_xor
);
219 int __bitmap_andnot(unsigned long *dst
, const unsigned long *bitmap1
,
220 const unsigned long *bitmap2
, unsigned int bits
)
223 unsigned int nr
= BITS_TO_LONGS(bits
);
224 unsigned long result
= 0;
226 for (k
= 0; k
< nr
; k
++)
227 result
|= (dst
[k
] = bitmap1
[k
] & ~bitmap2
[k
]);
230 EXPORT_SYMBOL(__bitmap_andnot
);
232 int __bitmap_intersects(const unsigned long *bitmap1
,
233 const unsigned long *bitmap2
, unsigned int bits
)
235 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
236 for (k
= 0; k
< lim
; ++k
)
237 if (bitmap1
[k
] & bitmap2
[k
])
240 if (bits
% BITS_PER_LONG
)
241 if ((bitmap1
[k
] & bitmap2
[k
]) & BITMAP_LAST_WORD_MASK(bits
))
245 EXPORT_SYMBOL(__bitmap_intersects
);
247 int __bitmap_subset(const unsigned long *bitmap1
,
248 const unsigned long *bitmap2
, unsigned int bits
)
250 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
251 for (k
= 0; k
< lim
; ++k
)
252 if (bitmap1
[k
] & ~bitmap2
[k
])
255 if (bits
% BITS_PER_LONG
)
256 if ((bitmap1
[k
] & ~bitmap2
[k
]) & BITMAP_LAST_WORD_MASK(bits
))
260 EXPORT_SYMBOL(__bitmap_subset
);
262 int __bitmap_weight(const unsigned long *bitmap
, unsigned int bits
)
264 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
267 for (k
= 0; k
< lim
; k
++)
268 w
+= hweight_long(bitmap
[k
]);
270 if (bits
% BITS_PER_LONG
)
271 w
+= hweight_long(bitmap
[k
] & BITMAP_LAST_WORD_MASK(bits
));
275 EXPORT_SYMBOL(__bitmap_weight
);
277 void bitmap_set(unsigned long *map
, unsigned int start
, int len
)
279 unsigned long *p
= map
+ BIT_WORD(start
);
280 const unsigned int size
= start
+ len
;
281 int bits_to_set
= BITS_PER_LONG
- (start
% BITS_PER_LONG
);
282 unsigned long mask_to_set
= BITMAP_FIRST_WORD_MASK(start
);
284 while (len
- bits_to_set
>= 0) {
287 bits_to_set
= BITS_PER_LONG
;
292 mask_to_set
&= BITMAP_LAST_WORD_MASK(size
);
296 EXPORT_SYMBOL(bitmap_set
);
298 void bitmap_clear(unsigned long *map
, unsigned int start
, int len
)
300 unsigned long *p
= map
+ BIT_WORD(start
);
301 const unsigned int size
= start
+ len
;
302 int bits_to_clear
= BITS_PER_LONG
- (start
% BITS_PER_LONG
);
303 unsigned long mask_to_clear
= BITMAP_FIRST_WORD_MASK(start
);
305 while (len
- bits_to_clear
>= 0) {
306 *p
&= ~mask_to_clear
;
307 len
-= bits_to_clear
;
308 bits_to_clear
= BITS_PER_LONG
;
309 mask_to_clear
= ~0UL;
313 mask_to_clear
&= BITMAP_LAST_WORD_MASK(size
);
314 *p
&= ~mask_to_clear
;
317 EXPORT_SYMBOL(bitmap_clear
);
320 * bitmap_find_next_zero_area - find a contiguous aligned zero area
321 * @map: The address to base the search on
322 * @size: The bitmap size in bits
323 * @start: The bitnumber to start searching at
324 * @nr: The number of zeroed bits we're looking for
325 * @align_mask: Alignment mask for zero area
327 * The @align_mask should be one less than a power of 2; the effect is that
328 * the bit offset of all zero areas this function finds is multiples of that
329 * power of 2. A @align_mask of 0 means no alignment is required.
331 unsigned long bitmap_find_next_zero_area(unsigned long *map
,
335 unsigned long align_mask
)
337 unsigned long index
, end
, i
;
339 index
= find_next_zero_bit(map
, size
, start
);
341 /* Align allocation */
342 index
= __ALIGN_MASK(index
, align_mask
);
347 i
= find_next_bit(map
, end
, index
);
354 EXPORT_SYMBOL(bitmap_find_next_zero_area
);
357 * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,
358 * second version by Paul Jackson, third by Joe Korty.
362 #define nbits_to_hold_value(val) fls(val)
363 #define BASEDEC 10 /* fancier cpuset lists input in decimal */
366 * bitmap_scnprintf - convert bitmap to an ASCII hex string.
367 * @buf: byte buffer into which string is placed
368 * @buflen: reserved size of @buf, in bytes
369 * @maskp: pointer to bitmap to convert
370 * @nmaskbits: size of bitmap, in bits
372 * Exactly @nmaskbits bits are displayed. Hex digits are grouped into
373 * comma-separated sets of eight digits per set. Returns the number of
374 * characters which were written to *buf, excluding the trailing \0.
376 int bitmap_scnprintf(char *buf
, unsigned int buflen
,
377 const unsigned long *maskp
, int nmaskbits
)
379 int i
, word
, bit
, len
= 0;
381 const char *sep
= "";
385 chunksz
= nmaskbits
& (CHUNKSZ
- 1);
389 i
= ALIGN(nmaskbits
, CHUNKSZ
) - CHUNKSZ
;
390 for (; i
>= 0; i
-= CHUNKSZ
) {
391 chunkmask
= ((1ULL << chunksz
) - 1);
392 word
= i
/ BITS_PER_LONG
;
393 bit
= i
% BITS_PER_LONG
;
394 val
= (maskp
[word
] >> bit
) & chunkmask
;
395 len
+= scnprintf(buf
+len
, buflen
-len
, "%s%0*lx", sep
,
402 EXPORT_SYMBOL(bitmap_scnprintf
);
405 * __bitmap_parse - convert an ASCII hex string into a bitmap.
406 * @buf: pointer to buffer containing string.
407 * @buflen: buffer size in bytes. If string is smaller than this
408 * then it must be terminated with a \0.
409 * @is_user: location of buffer, 0 indicates kernel space
410 * @maskp: pointer to bitmap array that will contain result.
411 * @nmaskbits: size of bitmap, in bits.
413 * Commas group hex digits into chunks. Each chunk defines exactly 32
414 * bits of the resultant bitmask. No chunk may specify a value larger
415 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
416 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
417 * characters and for grouping errors such as "1,,5", ",44", "," and "".
418 * Leading and trailing whitespace accepted, but not embedded whitespace.
420 int __bitmap_parse(const char *buf
, unsigned int buflen
,
421 int is_user
, unsigned long *maskp
,
424 int c
, old_c
, totaldigits
, ndigits
, nchunks
, nbits
;
426 const char __user __force
*ubuf
= (const char __user __force
*)buf
;
428 bitmap_zero(maskp
, nmaskbits
);
430 nchunks
= nbits
= totaldigits
= c
= 0;
434 /* Get the next chunk of the bitmap */
438 if (__get_user(c
, ubuf
++))
448 * If the last character was a space and the current
449 * character isn't '\0', we've got embedded whitespace.
450 * This is a no-no, so throw an error.
452 if (totaldigits
&& c
&& isspace(old_c
))
455 /* A '\0' or a ',' signal the end of the chunk */
456 if (c
== '\0' || c
== ',')
463 * Make sure there are at least 4 free bits in 'chunk'.
464 * If not, this hexdigit will overflow 'chunk', so
467 if (chunk
& ~((1UL << (CHUNKSZ
- 4)) - 1))
470 chunk
= (chunk
<< 4) | hex_to_bin(c
);
471 ndigits
++; totaldigits
++;
475 if (nchunks
== 0 && chunk
== 0)
478 __bitmap_shift_left(maskp
, maskp
, CHUNKSZ
, nmaskbits
);
481 nbits
+= (nchunks
== 1) ? nbits_to_hold_value(chunk
) : CHUNKSZ
;
482 if (nbits
> nmaskbits
)
484 } while (buflen
&& c
== ',');
488 EXPORT_SYMBOL(__bitmap_parse
);
491 * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
493 * @ubuf: pointer to user buffer containing string.
494 * @ulen: buffer size in bytes. If string is smaller than this
495 * then it must be terminated with a \0.
496 * @maskp: pointer to bitmap array that will contain result.
497 * @nmaskbits: size of bitmap, in bits.
499 * Wrapper for __bitmap_parse(), providing it with user buffer.
501 * We cannot have this as an inline function in bitmap.h because it needs
502 * linux/uaccess.h to get the access_ok() declaration and this causes
503 * cyclic dependencies.
505 int bitmap_parse_user(const char __user
*ubuf
,
506 unsigned int ulen
, unsigned long *maskp
,
509 if (!access_ok(VERIFY_READ
, ubuf
, ulen
))
511 return __bitmap_parse((const char __force
*)ubuf
,
512 ulen
, 1, maskp
, nmaskbits
);
515 EXPORT_SYMBOL(bitmap_parse_user
);
518 * bscnl_emit(buf, buflen, rbot, rtop, bp)
520 * Helper routine for bitmap_scnlistprintf(). Write decimal number
521 * or range to buf, suppressing output past buf+buflen, with optional
522 * comma-prefix. Return len of what was written to *buf, excluding the
525 static inline int bscnl_emit(char *buf
, int buflen
, int rbot
, int rtop
, int len
)
528 len
+= scnprintf(buf
+ len
, buflen
- len
, ",");
530 len
+= scnprintf(buf
+ len
, buflen
- len
, "%d", rbot
);
532 len
+= scnprintf(buf
+ len
, buflen
- len
, "%d-%d", rbot
, rtop
);
537 * bitmap_scnlistprintf - convert bitmap to list format ASCII string
538 * @buf: byte buffer into which string is placed
539 * @buflen: reserved size of @buf, in bytes
540 * @maskp: pointer to bitmap to convert
541 * @nmaskbits: size of bitmap, in bits
543 * Output format is a comma-separated list of decimal numbers and
544 * ranges. Consecutively set bits are shown as two hyphen-separated
545 * decimal numbers, the smallest and largest bit numbers set in
546 * the range. Output format is compatible with the format
547 * accepted as input by bitmap_parselist().
549 * The return value is the number of characters which were written to *buf
550 * excluding the trailing '\0', as per ISO C99's scnprintf.
552 int bitmap_scnlistprintf(char *buf
, unsigned int buflen
,
553 const unsigned long *maskp
, int nmaskbits
)
556 /* current bit is 'cur', most recently seen range is [rbot, rtop] */
563 rbot
= cur
= find_first_bit(maskp
, nmaskbits
);
564 while (cur
< nmaskbits
) {
566 cur
= find_next_bit(maskp
, nmaskbits
, cur
+1);
567 if (cur
>= nmaskbits
|| cur
> rtop
+ 1) {
568 len
= bscnl_emit(buf
, buflen
, rbot
, rtop
, len
);
574 EXPORT_SYMBOL(bitmap_scnlistprintf
);
577 * __bitmap_parselist - convert list format ASCII string to bitmap
578 * @buf: read nul-terminated user string from this buffer
579 * @buflen: buffer size in bytes. If string is smaller than this
580 * then it must be terminated with a \0.
581 * @is_user: location of buffer, 0 indicates kernel space
582 * @maskp: write resulting mask here
583 * @nmaskbits: number of bits in mask to be written
585 * Input format is a comma-separated list of decimal numbers and
586 * ranges. Consecutively set bits are shown as two hyphen-separated
587 * decimal numbers, the smallest and largest bit numbers set in
590 * Returns 0 on success, -errno on invalid input strings.
592 * %-EINVAL: second number in range smaller than first
593 * %-EINVAL: invalid character in string
594 * %-ERANGE: bit number specified too large for mask
596 static int __bitmap_parselist(const char *buf
, unsigned int buflen
,
597 int is_user
, unsigned long *maskp
,
601 int c
, old_c
, totaldigits
;
602 const char __user __force
*ubuf
= (const char __user __force
*)buf
;
603 int exp_digit
, in_range
;
606 bitmap_zero(maskp
, nmaskbits
);
612 /* Get the next cpu# or a range of cpu#'s */
616 if (__get_user(c
, ubuf
++))
625 * If the last character was a space and the current
626 * character isn't '\0', we've got embedded whitespace.
627 * This is a no-no, so throw an error.
629 if (totaldigits
&& c
&& isspace(old_c
))
632 /* A '\0' or a ',' signal the end of a cpu# or range */
633 if (c
== '\0' || c
== ',')
637 if (exp_digit
|| in_range
)
648 b
= b
* 10 + (c
- '0');
662 } while (buflen
&& c
== ',');
666 int bitmap_parselist(const char *bp
, unsigned long *maskp
, int nmaskbits
)
668 char *nl
= strchr(bp
, '\n');
676 return __bitmap_parselist(bp
, len
, 0, maskp
, nmaskbits
);
678 EXPORT_SYMBOL(bitmap_parselist
);
682 * bitmap_parselist_user()
684 * @ubuf: pointer to user buffer containing string.
685 * @ulen: buffer size in bytes. If string is smaller than this
686 * then it must be terminated with a \0.
687 * @maskp: pointer to bitmap array that will contain result.
688 * @nmaskbits: size of bitmap, in bits.
690 * Wrapper for bitmap_parselist(), providing it with user buffer.
692 * We cannot have this as an inline function in bitmap.h because it needs
693 * linux/uaccess.h to get the access_ok() declaration and this causes
694 * cyclic dependencies.
696 int bitmap_parselist_user(const char __user
*ubuf
,
697 unsigned int ulen
, unsigned long *maskp
,
700 if (!access_ok(VERIFY_READ
, ubuf
, ulen
))
702 return __bitmap_parselist((const char __force
*)ubuf
,
703 ulen
, 1, maskp
, nmaskbits
);
705 EXPORT_SYMBOL(bitmap_parselist_user
);
709 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
710 * @buf: pointer to a bitmap
711 * @pos: a bit position in @buf (0 <= @pos < @bits)
712 * @bits: number of valid bit positions in @buf
714 * Map the bit at position @pos in @buf (of length @bits) to the
715 * ordinal of which set bit it is. If it is not set or if @pos
716 * is not a valid bit position, map to -1.
718 * If for example, just bits 4 through 7 are set in @buf, then @pos
719 * values 4 through 7 will get mapped to 0 through 3, respectively,
720 * and other @pos values will get mapped to 0. When @pos value 7
721 * gets mapped to (returns) @ord value 3 in this example, that means
722 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
724 * The bit positions 0 through @bits are valid positions in @buf.
726 static int bitmap_pos_to_ord(const unsigned long *buf
, int pos
, int bits
)
730 if (pos
< 0 || pos
>= bits
|| !test_bit(pos
, buf
))
733 i
= find_first_bit(buf
, bits
);
736 i
= find_next_bit(buf
, bits
, i
+ 1);
745 * bitmap_ord_to_pos - find position of n-th set bit in bitmap
746 * @buf: pointer to bitmap
747 * @ord: ordinal bit position (n-th set bit, n >= 0)
748 * @bits: number of valid bit positions in @buf
750 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
751 * Value of @ord should be in range 0 <= @ord < weight(buf), else
752 * results are undefined.
754 * If for example, just bits 4 through 7 are set in @buf, then @ord
755 * values 0 through 3 will get mapped to 4 through 7, respectively,
756 * and all other @ord values return undefined values. When @ord value 3
757 * gets mapped to (returns) @pos value 7 in this example, that means
758 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
760 * The bit positions 0 through @bits are valid positions in @buf.
762 int bitmap_ord_to_pos(const unsigned long *buf
, int ord
, int bits
)
766 if (ord
>= 0 && ord
< bits
) {
769 for (i
= find_first_bit(buf
, bits
);
771 i
= find_next_bit(buf
, bits
, i
+ 1))
773 if (i
< bits
&& ord
== 0)
781 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
782 * @dst: remapped result
783 * @src: subset to be remapped
784 * @old: defines domain of map
785 * @new: defines range of map
786 * @bits: number of bits in each of these bitmaps
788 * Let @old and @new define a mapping of bit positions, such that
789 * whatever position is held by the n-th set bit in @old is mapped
790 * to the n-th set bit in @new. In the more general case, allowing
791 * for the possibility that the weight 'w' of @new is less than the
792 * weight of @old, map the position of the n-th set bit in @old to
793 * the position of the m-th set bit in @new, where m == n % w.
795 * If either of the @old and @new bitmaps are empty, or if @src and
796 * @dst point to the same location, then this routine copies @src
799 * The positions of unset bits in @old are mapped to themselves
800 * (the identify map).
802 * Apply the above specified mapping to @src, placing the result in
803 * @dst, clearing any bits previously set in @dst.
805 * For example, lets say that @old has bits 4 through 7 set, and
806 * @new has bits 12 through 15 set. This defines the mapping of bit
807 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
808 * bit positions unchanged. So if say @src comes into this routine
809 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
812 void bitmap_remap(unsigned long *dst
, const unsigned long *src
,
813 const unsigned long *old
, const unsigned long *new,
818 if (dst
== src
) /* following doesn't handle inplace remaps */
820 bitmap_zero(dst
, bits
);
822 w
= bitmap_weight(new, bits
);
823 for_each_set_bit(oldbit
, src
, bits
) {
824 int n
= bitmap_pos_to_ord(old
, oldbit
, bits
);
827 set_bit(oldbit
, dst
); /* identity map */
829 set_bit(bitmap_ord_to_pos(new, n
% w
, bits
), dst
);
832 EXPORT_SYMBOL(bitmap_remap
);
835 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
836 * @oldbit: bit position to be mapped
837 * @old: defines domain of map
838 * @new: defines range of map
839 * @bits: number of bits in each of these bitmaps
841 * Let @old and @new define a mapping of bit positions, such that
842 * whatever position is held by the n-th set bit in @old is mapped
843 * to the n-th set bit in @new. In the more general case, allowing
844 * for the possibility that the weight 'w' of @new is less than the
845 * weight of @old, map the position of the n-th set bit in @old to
846 * the position of the m-th set bit in @new, where m == n % w.
848 * The positions of unset bits in @old are mapped to themselves
849 * (the identify map).
851 * Apply the above specified mapping to bit position @oldbit, returning
852 * the new bit position.
854 * For example, lets say that @old has bits 4 through 7 set, and
855 * @new has bits 12 through 15 set. This defines the mapping of bit
856 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
857 * bit positions unchanged. So if say @oldbit is 5, then this routine
860 int bitmap_bitremap(int oldbit
, const unsigned long *old
,
861 const unsigned long *new, int bits
)
863 int w
= bitmap_weight(new, bits
);
864 int n
= bitmap_pos_to_ord(old
, oldbit
, bits
);
868 return bitmap_ord_to_pos(new, n
% w
, bits
);
870 EXPORT_SYMBOL(bitmap_bitremap
);
873 * bitmap_onto - translate one bitmap relative to another
874 * @dst: resulting translated bitmap
875 * @orig: original untranslated bitmap
876 * @relmap: bitmap relative to which translated
877 * @bits: number of bits in each of these bitmaps
879 * Set the n-th bit of @dst iff there exists some m such that the
880 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
881 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
882 * (If you understood the previous sentence the first time your
883 * read it, you're overqualified for your current job.)
885 * In other words, @orig is mapped onto (surjectively) @dst,
886 * using the the map { <n, m> | the n-th bit of @relmap is the
887 * m-th set bit of @relmap }.
889 * Any set bits in @orig above bit number W, where W is the
890 * weight of (number of set bits in) @relmap are mapped nowhere.
891 * In particular, if for all bits m set in @orig, m >= W, then
892 * @dst will end up empty. In situations where the possibility
893 * of such an empty result is not desired, one way to avoid it is
894 * to use the bitmap_fold() operator, below, to first fold the
895 * @orig bitmap over itself so that all its set bits x are in the
896 * range 0 <= x < W. The bitmap_fold() operator does this by
897 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
899 * Example [1] for bitmap_onto():
900 * Let's say @relmap has bits 30-39 set, and @orig has bits
901 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,
902 * @dst will have bits 31, 33, 35, 37 and 39 set.
904 * When bit 0 is set in @orig, it means turn on the bit in
905 * @dst corresponding to whatever is the first bit (if any)
906 * that is turned on in @relmap. Since bit 0 was off in the
907 * above example, we leave off that bit (bit 30) in @dst.
909 * When bit 1 is set in @orig (as in the above example), it
910 * means turn on the bit in @dst corresponding to whatever
911 * is the second bit that is turned on in @relmap. The second
912 * bit in @relmap that was turned on in the above example was
913 * bit 31, so we turned on bit 31 in @dst.
915 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
916 * because they were the 4th, 6th, 8th and 10th set bits
917 * set in @relmap, and the 4th, 6th, 8th and 10th bits of
918 * @orig (i.e. bits 3, 5, 7 and 9) were also set.
920 * When bit 11 is set in @orig, it means turn on the bit in
921 * @dst corresponding to whatever is the twelfth bit that is
922 * turned on in @relmap. In the above example, there were
923 * only ten bits turned on in @relmap (30..39), so that bit
924 * 11 was set in @orig had no affect on @dst.
926 * Example [2] for bitmap_fold() + bitmap_onto():
927 * Let's say @relmap has these ten bits set:
928 * 40 41 42 43 45 48 53 61 74 95
929 * (for the curious, that's 40 plus the first ten terms of the
930 * Fibonacci sequence.)
932 * Further lets say we use the following code, invoking
933 * bitmap_fold() then bitmap_onto, as suggested above to
934 * avoid the possitility of an empty @dst result:
936 * unsigned long *tmp; // a temporary bitmap's bits
938 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
939 * bitmap_onto(dst, tmp, relmap, bits);
941 * Then this table shows what various values of @dst would be, for
942 * various @orig's. I list the zero-based positions of each set bit.
943 * The tmp column shows the intermediate result, as computed by
944 * using bitmap_fold() to fold the @orig bitmap modulo ten
945 * (the weight of @relmap).
952 * 1 3 5 7 1 3 5 7 41 43 48 61
953 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45
954 * 0 9 18 27 0 9 8 7 40 61 74 95
956 * 0 11 22 33 0 1 2 3 40 41 42 43
957 * 0 12 24 36 0 2 4 6 40 42 45 53
958 * 78 102 211 1 2 8 41 42 74 (*)
960 * (*) For these marked lines, if we hadn't first done bitmap_fold()
961 * into tmp, then the @dst result would have been empty.
963 * If either of @orig or @relmap is empty (no set bits), then @dst
964 * will be returned empty.
966 * If (as explained above) the only set bits in @orig are in positions
967 * m where m >= W, (where W is the weight of @relmap) then @dst will
968 * once again be returned empty.
970 * All bits in @dst not set by the above rule are cleared.
972 void bitmap_onto(unsigned long *dst
, const unsigned long *orig
,
973 const unsigned long *relmap
, int bits
)
975 int n
, m
; /* same meaning as in above comment */
977 if (dst
== orig
) /* following doesn't handle inplace mappings */
979 bitmap_zero(dst
, bits
);
982 * The following code is a more efficient, but less
983 * obvious, equivalent to the loop:
984 * for (m = 0; m < bitmap_weight(relmap, bits); m++) {
985 * n = bitmap_ord_to_pos(orig, m, bits);
986 * if (test_bit(m, orig))
992 for_each_set_bit(n
, relmap
, bits
) {
993 /* m == bitmap_pos_to_ord(relmap, n, bits) */
994 if (test_bit(m
, orig
))
999 EXPORT_SYMBOL(bitmap_onto
);
1002 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
1003 * @dst: resulting smaller bitmap
1004 * @orig: original larger bitmap
1005 * @sz: specified size
1006 * @bits: number of bits in each of these bitmaps
1008 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
1009 * Clear all other bits in @dst. See further the comment and
1010 * Example [2] for bitmap_onto() for why and how to use this.
1012 void bitmap_fold(unsigned long *dst
, const unsigned long *orig
,
1017 if (dst
== orig
) /* following doesn't handle inplace mappings */
1019 bitmap_zero(dst
, bits
);
1021 for_each_set_bit(oldbit
, orig
, bits
)
1022 set_bit(oldbit
% sz
, dst
);
1024 EXPORT_SYMBOL(bitmap_fold
);
1027 * Common code for bitmap_*_region() routines.
1028 * bitmap: array of unsigned longs corresponding to the bitmap
1029 * pos: the beginning of the region
1030 * order: region size (log base 2 of number of bits)
1031 * reg_op: operation(s) to perform on that region of bitmap
1033 * Can set, verify and/or release a region of bits in a bitmap,
1034 * depending on which combination of REG_OP_* flag bits is set.
1036 * A region of a bitmap is a sequence of bits in the bitmap, of
1037 * some size '1 << order' (a power of two), aligned to that same
1038 * '1 << order' power of two.
1040 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
1041 * Returns 0 in all other cases and reg_ops.
1045 REG_OP_ISFREE
, /* true if region is all zero bits */
1046 REG_OP_ALLOC
, /* set all bits in region */
1047 REG_OP_RELEASE
, /* clear all bits in region */
1050 static int __reg_op(unsigned long *bitmap
, int pos
, int order
, int reg_op
)
1052 int nbits_reg
; /* number of bits in region */
1053 int index
; /* index first long of region in bitmap */
1054 int offset
; /* bit offset region in bitmap[index] */
1055 int nlongs_reg
; /* num longs spanned by region in bitmap */
1056 int nbitsinlong
; /* num bits of region in each spanned long */
1057 unsigned long mask
; /* bitmask for one long of region */
1058 int i
; /* scans bitmap by longs */
1059 int ret
= 0; /* return value */
1062 * Either nlongs_reg == 1 (for small orders that fit in one long)
1063 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
1065 nbits_reg
= 1 << order
;
1066 index
= pos
/ BITS_PER_LONG
;
1067 offset
= pos
- (index
* BITS_PER_LONG
);
1068 nlongs_reg
= BITS_TO_LONGS(nbits_reg
);
1069 nbitsinlong
= min(nbits_reg
, BITS_PER_LONG
);
1072 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
1073 * overflows if nbitsinlong == BITS_PER_LONG.
1075 mask
= (1UL << (nbitsinlong
- 1));
1081 for (i
= 0; i
< nlongs_reg
; i
++) {
1082 if (bitmap
[index
+ i
] & mask
)
1085 ret
= 1; /* all bits in region free (zero) */
1089 for (i
= 0; i
< nlongs_reg
; i
++)
1090 bitmap
[index
+ i
] |= mask
;
1093 case REG_OP_RELEASE
:
1094 for (i
= 0; i
< nlongs_reg
; i
++)
1095 bitmap
[index
+ i
] &= ~mask
;
1103 * bitmap_find_free_region - find a contiguous aligned mem region
1104 * @bitmap: array of unsigned longs corresponding to the bitmap
1105 * @bits: number of bits in the bitmap
1106 * @order: region size (log base 2 of number of bits) to find
1108 * Find a region of free (zero) bits in a @bitmap of @bits bits and
1109 * allocate them (set them to one). Only consider regions of length
1110 * a power (@order) of two, aligned to that power of two, which
1111 * makes the search algorithm much faster.
1113 * Return the bit offset in bitmap of the allocated region,
1114 * or -errno on failure.
1116 int bitmap_find_free_region(unsigned long *bitmap
, int bits
, int order
)
1118 int pos
, end
; /* scans bitmap by regions of size order */
1120 for (pos
= 0 ; (end
= pos
+ (1 << order
)) <= bits
; pos
= end
) {
1121 if (!__reg_op(bitmap
, pos
, order
, REG_OP_ISFREE
))
1123 __reg_op(bitmap
, pos
, order
, REG_OP_ALLOC
);
1128 EXPORT_SYMBOL(bitmap_find_free_region
);
1131 * bitmap_release_region - release allocated bitmap region
1132 * @bitmap: array of unsigned longs corresponding to the bitmap
1133 * @pos: beginning of bit region to release
1134 * @order: region size (log base 2 of number of bits) to release
1136 * This is the complement to __bitmap_find_free_region() and releases
1137 * the found region (by clearing it in the bitmap).
1141 void bitmap_release_region(unsigned long *bitmap
, int pos
, int order
)
1143 __reg_op(bitmap
, pos
, order
, REG_OP_RELEASE
);
1145 EXPORT_SYMBOL(bitmap_release_region
);
1148 * bitmap_allocate_region - allocate bitmap region
1149 * @bitmap: array of unsigned longs corresponding to the bitmap
1150 * @pos: beginning of bit region to allocate
1151 * @order: region size (log base 2 of number of bits) to allocate
1153 * Allocate (set bits in) a specified region of a bitmap.
1155 * Return 0 on success, or %-EBUSY if specified region wasn't
1156 * free (not all bits were zero).
1158 int bitmap_allocate_region(unsigned long *bitmap
, int pos
, int order
)
1160 if (!__reg_op(bitmap
, pos
, order
, REG_OP_ISFREE
))
1162 __reg_op(bitmap
, pos
, order
, REG_OP_ALLOC
);
1165 EXPORT_SYMBOL(bitmap_allocate_region
);
1168 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1169 * @dst: destination buffer
1170 * @src: bitmap to copy
1171 * @nbits: number of bits in the bitmap
1173 * Require nbits % BITS_PER_LONG == 0.
1175 void bitmap_copy_le(void *dst
, const unsigned long *src
, int nbits
)
1177 unsigned long *d
= dst
;
1180 for (i
= 0; i
< nbits
/BITS_PER_LONG
; i
++) {
1181 if (BITS_PER_LONG
== 64)
1182 d
[i
] = cpu_to_le64(src
[i
]);
1184 d
[i
] = cpu_to_le32(src
[i
]);
1187 EXPORT_SYMBOL(bitmap_copy_le
);