0,0 → 1,848 |
/* |
* lib/bitmap.c |
* Helper functions for bitmap.h. |
* |
* Tlhis source code is licensed under the GNU General Public License, |
* Version 2. See the file COPYING for more details. |
*/ |
#include <syscall.h> |
#include <linux/export.h> |
//#include <linux/thread_info.h> |
#include <linux/ctype.h> |
#include <linux/errno.h> |
#include <linux/bitmap.h> |
#include <linux/bitops.h> |
#include <linux/bug.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 Nadia Yvette Chambers, |
* 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_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 |
* @bits: number of bits in each of these bitmaps |
* |
* For each bit oldbit in @orig, set bit oldbit mod @sz in @dst. |
* Clear all other bits in @dst. See further the comment and |
* Example [2] for bitmap_onto() for why and how to use this. |
*/ |
void bitmap_fold(unsigned long *dst, const unsigned long *orig, |
int sz, int bits) |
{ |
int oldbit; |
|
if (dst == orig) /* following doesn't handle inplace mappings */ |
return; |
bitmap_zero(dst, bits); |
|
for_each_set_bit(oldbit, orig, bits) |
set_bit(oldbit % sz, dst); |
} |
EXPORT_SYMBOL(bitmap_fold); |
|
/* |
* 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, end; /* scans bitmap by regions of size order */ |
|
for (pos = 0 ; (end = pos + (1 << order)) <= bits; pos = end) { |
if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE)) |
continue; |
__reg_op(bitmap, pos, order, REG_OP_ALLOC); |
return pos; |
} |
return -ENOMEM; |
} |
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); |
|
/** |
* bitmap_copy_le - copy a bitmap, putting the bits into little-endian order. |
* @dst: destination buffer |
* @src: bitmap to copy |
* @nbits: number of bits in the bitmap |
* |
* Require nbits % BITS_PER_LONG == 0. |
*/ |
void bitmap_copy_le(void *dst, const unsigned long *src, int nbits) |
{ |
unsigned long *d = dst; |
int i; |
|
for (i = 0; i < nbits/BITS_PER_LONG; i++) { |
if (BITS_PER_LONG == 64) |
d[i] = cpu_to_le64(src[i]); |
else |
d[i] = cpu_to_le32(src[i]); |
} |
} |
EXPORT_SYMBOL(bitmap_copy_le); |