linux/lib/bitmap.c
Paul Jackson 3cf64b933c [PATCH] bitmap: region restructuring
Restructure the bitmap_*_region() operations, to avoid code duplication.

Also reduces binary text size by about 100 bytes (ia64 arch).  The original
Bottomley bitmap_*_region patch added about 1000 bytes of compiled kernel text
(ia64).  The Mundt multiword extension added another 600 bytes, and this
restructuring patch gets back about 100 bytes.

But the real motivation was the reduced amount of duplicated code.

Tested by Paul Mundt using <= BITS_PER_LONG as well as power of
2 aligned multiword spanning allocations.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-24 07:33:20 -08:00

819 lines
23 KiB
C

/*
* 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);
/*
* Common code for bitmap_*_region() routines.
* bitmap: array of unsigned longs corresponding to the bitmap
* pos: the beginning of the region
* order: region size (log base 2 of number of bits)
* reg_op: operation(s) to perform on that region of bitmap
*
* Can set, verify and/or release a region of bits in a bitmap,
* depending on which combination of REG_OP_* flag bits is set.
*
* A region of a bitmap is a sequence of bits in the bitmap, of
* some size '1 << order' (a power of two), aligned to that same
* '1 << order' power of two.
*
* Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
* Returns 0 in all other cases and reg_ops.
*/
enum {
REG_OP_ISFREE, /* true if region is all zero bits */
REG_OP_ALLOC, /* set all bits in region */
REG_OP_RELEASE, /* clear all bits in region */
};
static int __reg_op(unsigned long *bitmap, int pos, int order, int reg_op)
{
int nbits_reg; /* number of bits in region */
int index; /* index first long of region in bitmap */
int offset; /* bit offset region in bitmap[index] */
int nlongs_reg; /* num longs spanned by region in bitmap */
int nbitsinlong; /* num bits of region in each spanned long */
unsigned long mask; /* bitmask for one long of region */
int i; /* scans bitmap by longs */
int ret = 0; /* return value */
/*
* Either nlongs_reg == 1 (for small orders that fit in one long)
* or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
*/
nbits_reg = 1 << order;
index = pos / BITS_PER_LONG;
offset = pos - (index * BITS_PER_LONG);
nlongs_reg = BITS_TO_LONGS(nbits_reg);
nbitsinlong = min(nbits_reg, BITS_PER_LONG);
/*
* Can't do "mask = (1UL << nbitsinlong) - 1", as that
* overflows if nbitsinlong == BITS_PER_LONG.
*/
mask = (1UL << (nbitsinlong - 1));
mask += mask - 1;
mask <<= offset;
switch (reg_op) {
case REG_OP_ISFREE:
for (i = 0; i < nlongs_reg; i++) {
if (bitmap[index + i] & mask)
goto done;
}
ret = 1; /* all bits in region free (zero) */
break;
case REG_OP_ALLOC:
for (i = 0; i < nlongs_reg; i++)
bitmap[index + i] |= mask;
break;
case REG_OP_RELEASE:
for (i = 0; i < nlongs_reg; i++)
bitmap[index + i] &= ~mask;
break;
}
done:
return ret;
}
/**
* bitmap_find_free_region - find a contiguous aligned mem region
* @bitmap: array of unsigned longs corresponding to the bitmap
* @bits: number of bits in the bitmap
* @order: region size (log base 2 of number of bits) to find
*
* Find a region of free (zero) bits in a @bitmap of @bits bits and
* allocate them (set them to one). Only consider regions 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 region,
* or -errno on failure.
*/
int bitmap_find_free_region(unsigned long *bitmap, int bits, int order)
{
int pos; /* scans bitmap by regions of size order */
for (pos = 0; pos < bits; pos += (1 << order))
if (__reg_op(bitmap, pos, order, REG_OP_ISFREE))
break;
if (pos == bits)
return -ENOMEM;
__reg_op(bitmap, pos, order, REG_OP_ALLOC);
return pos;
}
EXPORT_SYMBOL(bitmap_find_free_region);
/**
* bitmap_release_region - release allocated bitmap region
* @bitmap: array of unsigned longs corresponding to the bitmap
* @pos: beginning of bit region to release
* @order: region size (log base 2 of number of bits) to release
*
* This is the complement to __bitmap_find_free_region and releases
* the found region (by clearing it in the bitmap).
*
* No return value.
*/
void bitmap_release_region(unsigned long *bitmap, int pos, int order)
{
__reg_op(bitmap, pos, order, REG_OP_RELEASE);
}
EXPORT_SYMBOL(bitmap_release_region);
/**
* bitmap_allocate_region - allocate bitmap region
* @bitmap: array of unsigned longs corresponding to the bitmap
* @pos: beginning of bit region to allocate
* @order: region size (log base 2 of number of bits) to allocate
*
* 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)
{
if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
return -EBUSY;
__reg_op(bitmap, pos, order, REG_OP_ALLOC);
return 0;
}
EXPORT_SYMBOL(bitmap_allocate_region);