/*

* lib/bitmap.c

* Helper functions for bitmap.h.

*

* This source code is licensed under the GNU General Public License,

* Version 2. See the file COPYING for more details.

*/

#include <linux/module.h>

#include <linux/ctype.h>

#include <linux/errno.h>

#include <linux/bitmap.h>

#include <linux/bitops.h>

#include <asm/uaccess.h>

/*

* bitmaps provide an array of bits, implemented using an an

* array of unsigned longs. The number of valid bits in a

* given bitmap does _not_ need to be an exact multiple of

* BITS_PER_LONG.

*

* The possible unused bits in the last, partially used word

* of a bitmap are 'don't care'. The implementation makes

* no particular effort to keep them zero. It ensures that

* their value will not affect the results of any operation.

* The bitmap operations that return Boolean (bitmap_empty,

* for example) or scalar (bitmap_weight, for example) results

* carefully filter out these unused bits from impacting their

* results.

*

* These operations actually hold to a slightly stronger rule:

* if you don't input any bitmaps to these ops that have some

* unused bits set, then they won't output any set unused bits

* in output bitmaps.

*

* The byte ordering of bitmaps is more natural on little

* endian architectures. See the big-endian headers

* include/asm-ppc64/bitops.h and include/asm-s390/bitops.h

* for the best explanations of this ordering.

*/

int __bitmap_empty(const unsigned long *bitmap, int bits)

{

int k, lim = bits/BITS_PER_LONG;

for (k = 0; k < lim; ++k)

if (bitmap[k])

return 0;

if (bits % BITS_PER_LONG)

if (bitmap[k] & BITMAP_LAST_WORD_MASK(bits))

return 0;

return 1;

}

EXPORT_SYMBOL(__bitmap_empty);

int __bitmap_full(const unsigned long *bitmap, int bits)

{

int k, lim = bits/BITS_PER_LONG;

for (k = 0; k < lim; ++k)

if (~bitmap[k])

return 0;

if (bits % BITS_PER_LONG)

if (~bitmap[k] & BITMAP_LAST_WORD_MASK(bits))

return 0;

return 1;

}

EXPORT_SYMBOL(__bitmap_full);

int __bitmap_equal(const unsigned long *bitmap1,

const unsigned long *bitmap2, int bits)

{

int k, lim = bits/BITS_PER_LONG;

for (k = 0; k < lim; ++k)

if (bitmap1[k] != bitmap2[k])

return 0;

if (bits % BITS_PER_LONG)

if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))

return 0;

return 1;

}

EXPORT_SYMBOL(__bitmap_equal);

void __bitmap_complement(unsigned long *dst, const unsigned long *src, int bits)

{

int k, lim = bits/BITS_PER_LONG;

for (k = 0; k < lim; ++k)

dst[k] = ~src[k];

if (bits % BITS_PER_LONG)

dst[k] = ~src[k] & BITMAP_LAST_WORD_MASK(bits);

}

EXPORT_SYMBOL(__bitmap_complement);

/**

* __bitmap_shift_right - logical right shift of the bits in a bitmap

* @dst : destination bitmap

* @src : source bitmap

* @shift : shift by this many bits

* @bits : bitmap size, in bits

*

* Shifting right (dividing) means moving bits in the MS -> LS bit

* direction. Zeros are fed into the vacated MS positions and the

* LS bits shifted off the bottom are lost.

*/

void __bitmap_shift_right(unsigned long *dst,

const unsigned long *src, int shift, int bits)

{

int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;

int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;

unsigned long mask = (1UL << left) - 1;

for (k = 0; off + k < lim; ++k) {

unsigned long upper, lower;

/*

* If shift is not word aligned, take lower rem bits of

* word above and make them the top rem bits of result.

*/

if (!rem || off + k + 1 >= lim)

upper = 0;

else {

upper = src[off + k + 1];

if (off + k + 1 == lim - 1 && left)

upper &= mask;

}

lower = src[off + k];

if (left && off + k == lim - 1)

lower &= mask;

dst[k] = upper << (BITS_PER_LONG - rem) | lower >> rem;

if (left && k == lim - 1)

dst[k] &= mask;

}

if (off)

memset(&dst[lim - off], 0, off*sizeof(unsigned long));

}

EXPORT_SYMBOL(__bitmap_shift_right);

/**

* __bitmap_shift_left - logical left shift of the bits in a bitmap

* @dst : destination bitmap

* @src : source bitmap

* @shift : shift by this many bits

* @bits : bitmap size, in bits

*

* Shifting left (multiplying) means moving bits in the LS -> MS

* direction. Zeros are fed into the vacated LS bit positions

* and those MS bits shifted off the top are lost.

*/

void __bitmap_shift_left(unsigned long *dst,

const unsigned long *src, int shift, int bits)

{

int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;

int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;

for (k = lim - off - 1; k >= 0; --k) {

unsigned long upper, lower;

/*

* If shift is not word aligned, take upper rem bits of

* word below and make them the bottom rem bits of result.

*/

if (rem && k > 0)

lower = src[k - 1];

else

lower = 0;

upper = src[k];

if (left && k == lim - 1)

upper &= (1UL << left) - 1;

dst[k + off] = lower >> (BITS_PER_LONG - rem) | upper << rem;

if (left && k + off == lim - 1)

dst[k + off] &= (1UL << left) - 1;

}

if (off)

memset(dst, 0, off*sizeof(unsigned long));

}

EXPORT_SYMBOL(__bitmap_shift_left);

int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,

const unsigned long *bitmap2, int bits)

{

int k;

int nr = BITS_TO_LONGS(bits);

unsigned long result = 0;

for (k = 0; k < nr; k++)

result |= (dst[k] = bitmap1[k] & bitmap2[k]);

return result != 0;

}

EXPORT_SYMBOL(__bitmap_and);

void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,

const unsigned long *bitmap2, int bits)

{

int k;

int nr = BITS_TO_LONGS(bits);

for (k = 0; k < nr; k++)

dst[k] = bitmap1[k] | bitmap2[k];

}

EXPORT_SYMBOL(__bitmap_or);

void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,

const unsigned long *bitmap2, int bits)

{

int k;

int nr = BITS_TO_LONGS(bits);

for (k = 0; k < nr; k++)

dst[k] = bitmap1[k] ^ bitmap2[k];

}

EXPORT_SYMBOL(__bitmap_xor);

int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,

const unsigned long *bitmap2, int bits)

{

int k;

int nr = BITS_TO_LONGS(bits);

unsigned long result = 0;

for (k = 0; k < nr; k++)

result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);

return result != 0;

}

EXPORT_SYMBOL(__bitmap_andnot);

int __bitmap_intersects(const unsigned long *bitmap1,

const unsigned long *bitmap2, int bits)

{

int k, lim = bits/BITS_PER_LONG;

for (k = 0; k < lim; ++k)

if (bitmap1[k] & bitmap2[k])

return 1;

if (bits % BITS_PER_LONG)

if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))

return 1;

return 0;

}

EXPORT_SYMBOL(__bitmap_intersects);

int __bitmap_subset(const unsigned long *bitmap1,

const unsigned long *bitmap2, int bits)

{

int k, lim = bits/BITS_PER_LONG;

for (k = 0; k < lim; ++k)

if (bitmap1[k] & ~bitmap2[k])

return 0;

if (bits % BITS_PER_LONG)

if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))

return 0;

return 1;

}

EXPORT_SYMBOL(__bitmap_subset);

int __bitmap_weight(const unsigned long *bitmap, int bits)

{

int k, w = 0, lim = bits/BITS_PER_LONG;

for (k = 0; k < lim; k++)

w += hweight_long(bitmap[k]);

if (bits % BITS_PER_LONG)

w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));

return w;

}

EXPORT_SYMBOL(__bitmap_weight);

void bitmap_set(unsigned long *map, int start, int nr)

{

unsigned long *p = map + BIT_WORD(start);

const int size = start + nr;

int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);

unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);

while (nr - bits_to_set >= 0) {

*p |= mask_to_set;

nr -= bits_to_set;

bits_to_set = BITS_PER_LONG;

mask_to_set = ~0UL;

p++;

}

if (nr) {

mask_to_set &= BITMAP_LAST_WORD_MASK(size);

*p |= mask_to_set;

}

}

EXPORT_SYMBOL(bitmap_set);

void bitmap_clear(unsigned long *map, int start, int nr)

{

unsigned long *p = map + BIT_WORD(start);

const int size = start + nr;

int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);

unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);

while (nr - bits_to_clear >= 0) {

*p &= ~mask_to_clear;

nr -= bits_to_clear;

bits_to_clear = BITS_PER_LONG;

mask_to_clear = ~0UL;

p++;

}

if (nr) {

mask_to_clear &= BITMAP_LAST_WORD_MASK(size);

*p &= ~mask_to_clear;

}

}

EXPORT_SYMBOL(bitmap_clear);

/*

* bitmap_find_next_zero_area - find a contiguous aligned zero area

* @map: The address to base the search on

* @size: The bitmap size in bits

* @start: The bitnumber to start searching at

* @nr: The number of zeroed bits we're looking for

* @align_mask: Alignment mask for zero area

*

* The @align_mask should be one less than a power of 2; the effect is that

* the bit offset of all zero areas this function finds is multiples of that

* power of 2. A @align_mask of 0 means no alignment is required.

*/

unsigned long bitmap_find_next_zero_area(unsigned long *map,

unsigned long size,

unsigned long start,

unsigned int nr,

unsigned long align_mask)

{

unsigned long index, end, i;

again:

index = find_next_zero_bit(map, size, start);

/* Align allocation */

index = __ALIGN_MASK(index, align_mask);

end = index + nr;

if (end > size)

return end;

i = find_next_bit(map, end, index);

if (i < end) {

start = i + 1;

goto again;

}

return index;

}

EXPORT_SYMBOL(bitmap_find_next_zero_area);

/*

* Bitmap printing & parsing functions: first version by Bill Irwin,

* second version by Paul Jackson, third by Joe Korty.

*/

#define CHUNKSZ 32

#define nbits_to_hold_value(val) fls(val)

#define BASEDEC 10 /* fancier cpuset lists input in decimal */

/**

* bitmap_scnprintf - convert bitmap to an ASCII hex string.

* @buf: byte buffer into which string is placed

* @buflen: reserved size of @buf, in bytes

* @maskp: pointer to bitmap to convert

* @nmaskbits: size of bitmap, in bits

*

* Exactly @nmaskbits bits are displayed. Hex digits are grouped into

* comma-separated sets of eight digits per set.

*/

int bitmap_scnprintf(char *buf, unsigned int buflen,

const unsigned long *maskp, int nmaskbits)

{

int i, word, bit, len = 0;

unsigned long val;

const char *sep = "";

int chunksz;

u32 chunkmask;

chunksz = nmaskbits & (CHUNKSZ - 1);

if (chunksz == 0)

chunksz = CHUNKSZ;

i = ALIGN(nmaskbits, CHUNKSZ) - CHUNKSZ;

for (; i >= 0; i -= CHUNKSZ) {

chunkmask = ((1ULL << chunksz) - 1);

word = i / BITS_PER_LONG;

bit = i % BITS_PER_LONG;

val = (maskp[word] >> bit) & chunkmask;

len += scnprintf(buf+len, buflen-len, "%s%0*lx", sep,

(chunksz+3)/4, val);

chunksz = CHUNKSZ;

sep = ",";

}

return len;

}

EXPORT_SYMBOL(bitmap_scnprintf);

/**

* __bitmap_parse - convert an ASCII hex string into a bitmap.

* @buf: pointer to buffer containing string.

* @buflen: buffer size in bytes. If string is smaller than this

* then it must be terminated with a \0.

* @is_user: location of buffer, 0 indicates kernel space

* @maskp: pointer to bitmap array that will contain result.

* @nmaskbits: size of bitmap, in bits.

*

* Commas group hex digits into chunks. Each chunk defines exactly 32

* bits of the resultant bitmask. No chunk may specify a value larger

* than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value

* then leading 0-bits are prepended. %-EINVAL is returned for illegal

* characters and for grouping errors such as "1,,5", ",44", "," and "".

* Leading and trailing whitespace accepted, but not embedded whitespace.

*/

int __bitmap_parse(const char *buf, unsigned int buflen,

int is_user, unsigned long *maskp,

int nmaskbits)

{

int c, old_c, totaldigits, ndigits, nchunks, nbits;

u32 chunk;

const char __user *ubuf = buf;

bitmap_zero(maskp, nmaskbits);

nchunks = nbits = totaldigits = c = 0;

do {

chunk = ndigits = 0;

/* Get the next chunk of the bitmap */

while (buflen) {

old_c = c;

if (is_user) {

if (__get_user(c, ubuf++))

return -EFAULT;

}

else

c = *buf++;

buflen--;

if (isspace(c))

continue;

/*

* If the last character was a space and the current

* character isn't '\0', we've got embedded whitespace.

* This is a no-no, so throw an error.

*/

if (totaldigits && c && isspace(old_c))

return -EINVAL;

/* A '\0' or a ',' signal the end of the chunk */

if (c == '\0' || c == ',')

break;

if (!isxdigit(c))

return -EINVAL;

/*

* Make sure there are at least 4 free bits in 'chunk'.

* If not, this hexdigit will overflow 'chunk', so

* throw an error.

*/

if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))

return -EOVERFLOW;

chunk = (chunk << 4) | hex_to_bin(c);

ndigits++; totaldigits++;

}

if (ndigits == 0)

return -EINVAL;

if (nchunks == 0 && chunk == 0)

continue;

__bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);

*maskp |= chunk;

nchunks++;

nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;

if (nbits > nmaskbits)

return -EOVERFLOW;

} while (buflen && c == ',');

return 0;

}

EXPORT_SYMBOL(__bitmap_parse);

/**

* bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap

*

* @ubuf: pointer to user buffer containing string.

* @ulen: buffer size in bytes. If string is smaller than this

* then it must be terminated with a \0.

* @maskp: pointer to bitmap array that will contain result.

* @nmaskbits: size of bitmap, in bits.

*

* Wrapper for __bitmap_parse(), providing it with user buffer.

*

* We cannot have this as an inline function in bitmap.h because it needs

* linux/uaccess.h to get the access_ok() declaration and this causes

* cyclic dependencies.

*/

int bitmap_parse_user(const char __user *ubuf,

unsigned int ulen, unsigned long *maskp,

int nmaskbits)

{

if (!access_ok(VERIFY_READ, ubuf, ulen))

return -EFAULT;

return __bitmap_parse((const char *)ubuf, ulen, 1, maskp, nmaskbits);

}

EXPORT_SYMBOL(bitmap_parse_user);

/*

* bscnl_emit(buf, buflen, rbot, rtop, bp)

*

* Helper routine for bitmap_scnlistprintf(). Write decimal number

* or range to buf, suppressing output past buf+buflen, with optional

* comma-prefix. Return len of what would be written to buf, if it

* all fit.

*/

static inline int bscnl_emit(char *buf, int buflen, int rbot, int rtop, int len)

{

if (len > 0)

len += scnprintf(buf + len, buflen - len, ",");

if (rbot == rtop)

len += scnprintf(buf + len, buflen - len, "%d", rbot);

else

len += scnprintf(buf + len, buflen - len, "%d-%d", rbot, rtop);

return len;

}

/**

* bitmap_scnlistprintf - convert bitmap to list format ASCII string

* @buf: byte buffer into which string is placed

* @buflen: reserved size of @buf, in bytes

* @maskp: pointer to bitmap to convert

* @nmaskbits: size of bitmap, in bits

*

* Output format is a comma-separated list of decimal numbers and

* ranges. Consecutively set bits are shown as two hyphen-separated

* decimal numbers, the smallest and largest bit numbers set in

* the range. Output format is compatible with the format

* accepted as input by bitmap_parselist().

*

* The return value is the number of characters which would be

* generated for the given input, excluding the trailing '\0', as

* per ISO C99.

*/

int bitmap_scnlistprintf(char *buf, unsigned int buflen,

const unsigned long *maskp, int nmaskbits)

{

int len = 0;

/* current bit is 'cur', most recently seen range is [rbot, rtop] */

int cur, rbot, rtop;

if (buflen == 0)

return 0;

buf[0] = 0;

rbot = cur = find_first_bit(maskp, nmaskbits);

while (cur < nmaskbits) {

rtop = cur;

cur = find_next_bit(maskp, nmaskbits, cur+1);

if (cur >= nmaskbits || cur > rtop + 1) {

len = bscnl_emit(buf, buflen, rbot, rtop, len);

rbot = cur;

}

}

return len;

}

EXPORT_SYMBOL(bitmap_scnlistprintf);

/**

* __bitmap_parselist - convert list format ASCII string to bitmap

* @buf: read nul-terminated user string from this buffer

* @buflen: buffer size in bytes. If string is smaller than this

* then it must be terminated with a \0.

* @is_user: location of buffer, 0 indicates kernel space

* @maskp: write resulting mask here

* @nmaskbits: number of bits in mask to be written

*

* Input format is a comma-separated list of decimal numbers and

* ranges. Consecutively set bits are shown as two hyphen-separated

* decimal numbers, the smallest and largest bit numbers set in

* the range.

*

* Returns 0 on success, -errno on invalid input strings.

* Error values:

* %-EINVAL: second number in range smaller than first

* %-EINVAL: invalid character in string

* %-ERANGE: bit number specified too large for mask

*/

static int __bitmap_parselist(const char *buf, unsigned int buflen,

int is_user, unsigned long *maskp,

int nmaskbits)

{

unsigned a, b;

int c, old_c, totaldigits;

const char __user *ubuf = buf;

int exp_digit, in_range;

totaldigits = c = 0;

bitmap_zero(maskp, nmaskbits);

do {

exp_digit = 1;

in_range = 0;

a = b = 0;

/* Get the next cpu# or a range of cpu#'s */

while (buflen) {

old_c = c;

if (is_user) {

if (__get_user(c, ubuf++))

return -EFAULT;

} else

c = *buf++;

buflen--;

if (isspace(c))

continue;

/*

* If the last character was a space and the current

* character isn't '\0', we've got embedded whitespace.

* This is a no-no, so throw an error.

*/

if (totaldigits && c && isspace(old_c))

return -EINVAL;

/* A '\0' or a ',' signal the end of a cpu# or range */

if (c == '\0' || c == ',')

break;

if (c == '-') {

if (exp_digit || in_range)

return -EINVAL;

b = 0;

in_range = 1;

exp_digit = 1;

continue;

}

if (!isdigit(c))

return -EINVAL;

b = b * 10 + (c - '0');

if (!in_range)

a = b;

exp_digit = 0;

totaldigits++;

}

if (!(a <= b))

return -EINVAL;

if (b >= nmaskbits)

return -ERANGE;

while (a <= b) {

set_bit(a, maskp);

a++;

}

} while (buflen && c == ',');

return 0;

}

int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)

{

char *nl = strchr(bp, '\n');

int len;

if (nl)

len = nl - bp;

else

len = strlen(bp);

return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);

}

EXPORT_SYMBOL(bitmap_parselist);

/**

* bitmap_parselist_user()

*

* @ubuf: pointer to user buffer containing string.

* @ulen: buffer size in bytes. If string is smaller than this

* then it must be terminated with a \0.

* @maskp: pointer to bitmap array that will contain result.

* @nmaskbits: size of bitmap, in bits.

*

* Wrapper for bitmap_parselist(), providing it with user buffer.

*

* We cannot have this as an inline function in bitmap.h because it needs

* linux/uaccess.h to get the access_ok() declaration and this causes

* cyclic dependencies.

*/

int bitmap_parselist_user(const char __user *ubuf,

unsigned int ulen, unsigned long *maskp,

int nmaskbits)

{

if (!access_ok(VERIFY_READ, ubuf, ulen))

return -EFAULT;

return __bitmap_parselist((const char *)ubuf,

ulen, 1, maskp, nmaskbits);

}

EXPORT_SYMBOL(bitmap_parselist_user);

/**

* bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap

* @buf: pointer to a bitmap

* @pos: a bit position in @buf (0 <= @pos < @bits)

* @bits: number of valid bit positions in @buf

*

* Map the bit at position @pos in @buf (of length @bits) to the

* ordinal of which set bit it is. If it is not set or if @pos

* is not a valid bit position, map to -1.

*

* If for example, just bits 4 through 7 are set in @buf, then @pos

* values 4 through 7 will get mapped to 0 through 3, respectively,

* and other @pos values will get mapped to 0. When @pos value 7

* gets mapped to (returns) @ord value 3 in this example, that means

* that bit 7 is the 3rd (starting with 0th) set bit in @buf.

*

* The bit positions 0 through @bits are valid positions in @buf.

*/

static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits)

{

int i, ord;

if (pos < 0 || pos >= bits || !test_bit(pos, buf))

return -1;

i = find_first_bit(buf, bits);

ord = 0;

while (i < pos) {

i = find_next_bit(buf, bits, i + 1);

ord++;

}

BUG_ON(i != pos);

return ord;

}

/**

* bitmap_ord_to_pos - find position of n-th set bit in bitmap

* @buf: pointer to bitmap

* @ord: ordinal bit position (n-th set bit, n >= 0)

* @bits: number of valid bit positions in @buf

*

* Map the ordinal offset of bit @ord in @buf to its position in @buf.

* Value of @ord should be in range 0 <= @ord < weight(buf), else

* results are undefined.

*

* If for example, just bits 4 through 7 are set in @buf, then @ord

* values 0 through 3 will get mapped to 4 through 7, respectively,

* and all other @ord values return undefined values. When @ord value 3

* gets mapped to (returns) @pos value 7 in this example, that means

* that the 3rd set bit (starting with 0th) is at position 7 in @buf.

*

* The bit positions 0 through @bits are valid positions in @buf.

*/

int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits)

{

int pos = 0;

if (ord >= 0 && ord < bits) {

int i;

for (i = find_first_bit(buf, bits);

i < bits && ord > 0;

i = find_next_bit(buf, bits, i + 1))

ord--;

if (i < bits && ord == 0)

pos = i;

}

return pos;

}

/**

* bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap

* @dst: remapped result

* @src: subset to be remapped

* @old: defines domain of map

* @new: defines range of map

* @bits: number of bits in each of these bitmaps

*

* Let @old and @new define a mapping of bit positions, such that

* whatever position is held by the n-th set bit in @old is mapped

* to the n-th set bit in @new. In the more general case, allowing

* for the possibility that the weight 'w' of @new is less than the

* weight of @old, map the position of the n-th set bit in @old to

* the position of the m-th set bit in @new, where m == n % w.

*

* If either of the @old and @new bitmaps are empty, or if @src and

* @dst point to the same location, then this routine copies @src

* to @dst.

*

* The positions of unset bits in @old are mapped to themselves

* (the identify map).

*

* Apply the above specified mapping to @src, placing the result in

* @dst, clearing any bits previously set in @dst.

*

* For example, lets say that @old has bits 4 through 7 set, and

* @new has bits 12 through 15 set. This defines the mapping of bit

* position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other

* bit positions unchanged. So if say @src comes into this routine

* with bits 1, 5 and 7 set, then @dst should leave with bits 1,

* 13 and 15 set.

*/

void bitmap_remap(unsigned long *dst, const unsigned long *src,

const unsigned long *old, const unsigned long *new,

int bits)

{

int oldbit, w;

if (dst == src) /* following doesn't handle inplace remaps */

return;

bitmap_zero(dst, bits);

w = bitmap_weight(new, bits);

for_each_set_bit(oldbit, src, bits) {

int n = bitmap_pos_to_ord(old, oldbit, bits);

if (n < 0 || w == 0)

set_bit(oldbit, dst); /* identity map */

else

set_bit(bitmap_ord_to_pos(new, n % w, bits), dst);

}

}

EXPORT_SYMBOL(bitmap_remap);

/**

* bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit

* @oldbit: bit position to be mapped

* @old: defines domain of map

* @new: defines range of map

* @bits: number of bits in each of these bitmaps

*

* Let @old and @new define a mapping of bit positions, such that

* whatever position is held by the n-th set bit in @old is mapped

* to the n-th set bit in @new. In the more general case, allowing

* for the possibility that the weight 'w' of @new is less than the

* weight of @old, map the position of the n-th set bit in @old to

* the position of the m-th set bit in @new, where m == n % w.

*

* The positions of unset bits in @old are mapped to themselves

* (the identify map).

*

* Apply the above specified mapping to bit position @oldbit, returning

* the new bit position.

*

* For example, lets say that @old has bits 4 through 7 set, and

* @new has bits 12 through 15 set. This defines the mapping of bit

* position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other

* bit positions unchanged. So if say @oldbit is 5, then this routine

* returns 13.

*/

int bitmap_bitremap(int oldbit, const unsigned long *old,

const unsigned long *new, int bits)

{

int w = bitmap_weight(new, bits);

int n = bitmap_pos_to_ord(old, oldbit, bits);

if (n < 0 || w == 0)

return oldbit;

else

return bitmap_ord_to_pos(new, n % w, bits);

}

EXPORT_SYMBOL(bitmap_bitremap);

/**

* bitmap_onto - translate one bitmap relative to another

* @dst: resulting translated bitmap

* @orig: original untranslated bitmap

* @relmap: bitmap relative to which translated

* @bits: number of bits in each of these bitmaps

*

* Set the n-th bit of @dst iff there exists some m such that the

* n-th bit of @relmap is set, the m-th bit of @orig is set, and

* the n-th bit of @relmap is also the m-th _set_ bit of @relmap.

* (If you understood the previous sentence the first time your

* read it, you're overqualified for your current job.)

*

* In other words, @orig is mapped onto (surjectively) @dst,

* using the the map { <n, m> | the n-th bit of @relmap is the

* m-th set bit of @relmap }.

*

* Any set bits in @orig above bit number W, where W is the

* weight of (number of set bits in) @relmap are mapped nowhere.

* In particular, if for all bits m set in @orig, m >= W, then

* @dst will end up empty. In situations where the possibility

* of such an empty result is not desired, one way to avoid it is

* to use the bitmap_fold() operator, below, to first fold the

* @orig bitmap over itself so that all its set bits x are in the

* range 0 <= x < W. The bitmap_fold() operator does this by

* setting the bit (m % W) in @dst, for each bit (m) set in @orig.

*

* Example [1] for bitmap_onto():

* Let's say @relmap has bits 30-39 set, and @orig has bits

* 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,

* @dst will have bits 31, 33, 35, 37 and 39 set.

*

* When bit 0 is set in @orig, it means turn on the bit in

* @dst corresponding to whatever is the first bit (if any)

* that is turned on in @relmap. Since bit 0 was off in the

* above example, we leave off that bit (bit 30) in @dst.

*

* When bit 1 is set in @orig (as in the above example), it

* means turn on the bit in @dst corresponding to whatever

* is the second bit that is turned on in @relmap. The second

* bit in @relmap that was turned on in the above example was

* bit 31, so we turned on bit 31 in @dst.

*

* Similarly, we turned on bits 33, 35, 37 and 39 in @dst,

* because they were the 4th, 6th, 8th and 10th set bits

* set in @relmap, and the 4th, 6th, 8th and 10th bits of

* @orig (i.e. bits 3, 5, 7 and 9) were also set.

*

* When bit 11 is set in @orig, it means turn on the bit in

* @dst corresponding to whatever is the twelfth bit that is

* turned on in @relmap. In the above example, there were

* only ten bits turned on in @relmap (30..39), so that bit

* 11 was set in @orig had no affect on @dst.

*

* Example [2] for bitmap_fold() + bitmap_onto():

* Let's say @relmap has these ten bits set:

* 40 41 42 43 45 48 53 61 74 95

* (for the curious, that's 40 plus the first ten terms of the

* Fibonacci sequence.)

*

* Further lets say we use the following code, invoking

* bitmap_fold() then bitmap_onto, as suggested above to

* avoid the possitility of an empty @dst result:

*

* unsigned long *tmp; // a temporary bitmap's bits

*

* bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);

* bitmap_onto(dst, tmp, relmap, bits);

*

* Then this table shows what various values of @dst would be, for

* various @orig's. I list the zero-based positions of each set bit.

* The tmp column shows the intermediate result, as computed by

* using bitmap_fold() to fold the @orig bitmap modulo ten

* (the weight of @relmap).

*

* @orig tmp @dst

* 0 0 40

* 1 1 41

* 9 9 95

* 10 0 40 (*)

* 1 3 5 7 1 3 5 7 41 43 48 61

* 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45

* 0 9 18 27 0 9 8 7 40 61 74 95

* 0 10 20 30 0 40

* 0 11 22 33 0 1 2 3 40 41 42 43

* 0 12 24 36 0 2 4 6 40 42 45 53

* 78 102 211 1 2 8 41 42 74 (*)

*

* (*) For these marked lines, if we hadn't first done bitmap_fold()

* into tmp, then the @dst result would have been empty.

*

* If either of @orig or @relmap is empty (no set bits), then @dst

* will be returned empty.

*

* If (as explained above) the only set bits in @orig are in positions

* m where m >= W, (where W is the weight of @relmap) then @dst will

* once again be returned empty.

*

* All bits in @dst not set by the above rule are cleared.

*/

void bitmap_onto(unsigned long *dst, const unsigned long *orig,

const unsigned long *relmap, int bits)

{

int n, m; /* same meaning as in above comment */

if (dst == orig) /* following doesn't handle inplace mappings */

return;

bitmap_zero(dst, bits);

/*

* The following code is a more efficient, but less

* obvious, equivalent to the loop:

* for (m = 0; m < bitmap_weight(relmap, bits); m++) {

* n = bitmap_ord_to_pos(orig, m, bits);

* if (test_bit(m, orig))

* set_bit(n, dst);

* }

*/

m = 0;

for_each_set_bit(n, relmap, bits) {

/* m == bitmap_pos_to_ord(relmap, n, bits) */

if (test_bit(m, orig))

set_bit(n, dst);

m++;

}

}

EXPORT_SYMBOL(bitmap_onto);

/**

* bitmap_fold - fold larger bitmap into smaller, modulo specified size

* @dst: resulting smaller bitmap

* @orig: original larger bitmap

* @sz: specified size