/*
* 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
* @nbits - 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
* @nbits - 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);
void __bitmap_and(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_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);
void __bitmap_andnot(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_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);
#if BITS_PER_LONG == 32
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 += hweight32(bitmap[k]);
if (bits % BITS_PER_LONG)
w += hweight32(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
return w;
}
#else
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 += hweight64(bitmap[k]);
if (bits % BITS_PER_LONG)
w += hweight64(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
return w;
}
#endif
EXPORT_SYMBOL(__bitmap_weight);
/*
* 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 unhex(c) (isdigit(c) ? (c - '0') : (toupper(c) - 'A' + 10))
#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 in user space containing string.
* @buflen: 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.
*
* 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 __user *ubuf, unsigned int ubuflen,
unsigned long *maskp, int nmaskbits)
{
int c, old_c, totaldigits, ndigits, nchunks, nbits;
u32 chunk;
bitmap_zero(maskp, nmaskbits);
nchunks = nbits = totaldigits = c = 0;
do {
chunk = ndigits = 0;
/* Get the next chunk of the bitmap */
while (ubuflen) {
old_c = c;
if (get_user(c, ubuf++))
return -EFAULT;
ubuflen--;
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) | unhex(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 (ubuflen && c == ',');
return 0;
}
EXPORT_SYMBOL(bitmap_parse);
/*
* 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;
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
* @mask: 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:
* -EINVAL: second number in range smaller than first
* -EINVAL: invalid character in string
* -ERANGE: bit number specified too large for mask
*/
int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
{
unsigned a, b;
bitmap_zero(maskp, nmaskbits);
do {
if (!isdigit(*bp))
return -EINVAL;
b = a = simple_strtoul(bp, (char **)&bp, BASEDEC);
if (*bp == '-') {
bp++;
if (!isdigit(*bp))
return -EINVAL;
b = simple_strtoul(bp, (char **)&bp, BASEDEC);
}
if (!(a <= b))
return -EINVAL;
if (b >= nmaskbits)
return -ERANGE;
while (a <= b) {
set_bit(a, maskp);
a++;
}
if (*bp == ',')
bp++;
} while (*bp != '\0' && *bp != '\n');
return 0;
}
EXPORT_SYMBOL(bitmap_parselist);
/*
* bitmap_pos_to_ord(buf, pos, bits)
* @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(buf, ord, bits)
* @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.
*/
static 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 (oldbit = find_first_bit(src, bits);
oldbit < bits;
oldbit = find_next_bit(src, bits, oldbit + 1)) {
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_find_free_region - find a contiguous aligned mem region
* @bitmap: an array of unsigned longs corresponding to the bitmap
* @bits: number of bits in the bitmap
* @order: region size to find (size is actually 1<<order)
*
* Find a sequence of free (zero) bits in a bitmap and allocate
* them (set them to one). Only consider sequences of length a
* power ('order') of two, aligned to that power of two, which
* makes the search algorithm much faster.
*
* Return the bit offset in bitmap of the allocated sequence,
* or -errno on failure.
*/
int bitmap_find_free_region(unsigned long *bitmap, int bits, int order)
{
int nbits; /* number of bits in region */
int nlongs; /* num longs spanned by region in bitmap */
int nbitsinlong; /* num bits of region in each spanned long */
unsigned long mask; /* bitmask of bits [0 .. nbitsinlong-1] */
int i; /* scans bitmap by longs */
nbits = 1 << order;
nlongs = (nbits + (BITS_PER_LONG - 1)) / BITS_PER_LONG;
nbitsinlong = nbits;
if (nbitsinlong > BITS_PER_LONG)
nbitsinlong = BITS_PER_LONG;
/* make a mask of the order */
mask = (1UL << (nbitsinlong - 1));
mask += mask - 1;
/* run up the bitmap nbitsinlong at a time */
for (i = 0; i < bits; i += nbitsinlong) {
int index = i / BITS_PER_LONG;
int offset = i - (index * BITS_PER_LONG);
int j, space = 1;
/* find space in the bitmap */
for (j = 0; j < nlongs; j++)
if ((bitmap[index + j] & (mask << offset))) {
space = 0;
break;
}
/* keep looking */
if (unlikely(!space))
continue;
for (j = 0; j < nlongs; j++)
/* set region in bitmap */
bitmap[index + j] |= (mask << offset);
return i;
}
return -ENOMEM;
}
EXPORT_SYMBOL(bitmap_find_free_region);
/**
* bitmap_release_region - release allocated bitmap region
* @bitmap: a pointer to the bitmap
* @pos: the beginning of the region
* @order: the order of the bits to release (number is 1<<order)
*
* This is the complement to __bitmap_find_free_region and releases
* the found region (by clearing it in the bitmap).
*/
void bitmap_release_region(unsigned long *bitmap, int pos, int order)
{
int nbits; /* number of bits in region */
int nlongs; /* num longs spanned by region in bitmap */
int index; /* index first long of region in bitmap */
int offset; /* bit offset region in bitmap[index] */
int nbitsinlong; /* num bits of region in each spanned long */
unsigned long mask; /* bitmask of bits [0 .. nbitsinlong-1] */
int i; /* scans bitmap by longs */
nbits = 1 << order;
nlongs = (nbits + (BITS_PER_LONG - 1)) / BITS_PER_LONG;
index = pos / BITS_PER_LONG;
offset = pos - (index * BITS_PER_LONG);
nbitsinlong = nbits;
if (nbitsinlong > BITS_PER_LONG)
nbitsinlong = BITS_PER_LONG;
mask = (1UL << (nbitsinlong - 1));
mask += mask - 1;
for (i = 0; i < nlongs; i++)
bitmap[index + i] &= ~(mask << offset);
}
EXPORT_SYMBOL(bitmap_release_region);
/**
* bitmap_allocate_region - allocate bitmap region
* @bitmap: a pointer to the bitmap
* @pos: the beginning of the region
* @order: the order of the bits to allocate (number is 1<<order)
*
* Allocate (set bits in) a specified region of a bitmap.
* Return 0 on success, or -EBUSY if specified region wasn't
* free (not all bits were zero).
*/
int bitmap_allocate_region(unsigned long *bitmap, int pos, int order)
{
int nbits; /* number of bits in region */
int nlongs; /* num longs spanned by region in bitmap */
int index; /* index first long of region in bitmap */
int offset; /* bit offset region in bitmap[index] */
int nbitsinlong; /* num bits of region in each spanned long */
unsigned long mask; /* bitmask of bits [0 .. nbitsinlong-1] */
int i; /* scans bitmap by longs */
nbits = 1 << order;
nlongs = (nbits + (BITS_PER_LONG - 1)) / BITS_PER_LONG;
index = pos / BITS_PER_LONG;
offset = pos - (index * BITS_PER_LONG);
nbitsinlong = nbits;
if (nbitsinlong > BITS_PER_LONG)
nbitsinlong = BITS_PER_LONG;
mask = (1UL << (nbitsinlong - 1));
mask += mask - 1;
for (i = 0; i < nlongs; i++)
if (bitmap[index + i] & (mask << offset))
return -EBUSY;
for (i = 0; i < nlongs; i++)
bitmap[index + i] |= (mask << offset);
return 0;
}
EXPORT_SYMBOL(bitmap_allocate_region);
