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lib: add bitmap_find_next_zero_area_off() 

This commit adds a bitmap_find_next_zero_area_off() function which
works like bitmap_find_next_zero_area() function expect it allows an
offset to be specified when alignment is checked.  This lets caller
request a bit such that its number plus the offset is aligned
according to the mask.

Change-Id: Ib0593cf578ed69ba4c51b1e102a1f8ea1aeb93e8
Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Larry Bassel <lbassel@codeaurora.org>
(cherry picked from commit 5f2929128ae4db1a6577748c72437f102ed400a5)
This commit is contained in:
Michal Nazarewicz 2010-12-15 21:34:22 +01:00 committed by Stephen Boyd
parent c47ea09155
commit ad9f4504bc
2 changed files with 31 additions and 15 deletions
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24
include/linux/bitmap.h
View File

@ -45,6 +45,7 @@
* bitmap_set(dst, pos, nbits) Set specified bit area
* bitmap_clear(dst, pos, nbits) Clear specified bit area
* bitmap_find_next_zero_area(buf, len, pos, n, mask) Find bit free area
* bitmap_find_next_zero_area_off(buf, len, pos, n, mask) as above
* bitmap_shift_right(dst, src, n, nbits) *dst = *src >> n
* bitmap_shift_left(dst, src, n, nbits) *dst = *src << n
* bitmap_remap(dst, src, old, new, nbits) *dst = map(old, new)(src)
@ -114,11 +115,24 @@ extern int __bitmap_weight(const unsigned long *bitmap, int bits);
extern void bitmap_set(unsigned long *map, int i, int len);
extern void bitmap_clear(unsigned long *map, int start, int nr);
extern unsigned long bitmap_find_next_zero_area(unsigned long *map,
unsigned long size,
unsigned long start,
unsigned int nr,
unsigned long align_mask);
extern unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
unsigned long size,
unsigned long start,
unsigned int nr,
unsigned long align_mask,
unsigned long align_offset);
static inline unsigned long
bitmap_find_next_zero_area(unsigned long *map,
unsigned long size,
unsigned long start,
unsigned int nr,
unsigned long align_mask)
{
return bitmap_find_next_zero_area_off(map, size, start, nr,
align_mask, 0);
}
extern int bitmap_scnprintf(char *buf, unsigned int len,
const unsigned long *src, int nbits);

22
lib/bitmap.c
View File

@ -315,30 +315,32 @@ void bitmap_clear(unsigned long *map, int start, int nr)
}
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
* @align_offset: Alignment offset 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.
* the bit offset of all zero areas this function finds plus @align_offset
* is multiple of that power of 2.
*/
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 bitmap_find_next_zero_area_off(unsigned long *map,
unsigned long size,
unsigned long start,
unsigned int nr,
unsigned long align_mask,
unsigned long align_offset)
{
unsigned long index, end, i;
again:
index = find_next_zero_bit(map, size, start);
/* Align allocation */
index = __ALIGN_MASK(index, align_mask);
index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset;
end = index + nr;
if (end > size)
@ -350,7 +352,7 @@ again:
}
return index;
}
EXPORT_SYMBOL(bitmap_find_next_zero_area);
EXPORT_SYMBOL(bitmap_find_next_zero_area_off);
/*
* Bitmap printing & parsing functions: first version by Bill Irwin,