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lib: add bitmap_find_next_zero_area_off()

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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_set(dst, pos, nbits) Set specified bit area
* bitmap_clear(dst, pos, nbits) Clear 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(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_right(dst, src, n, nbits) *dst = *src >> n
* bitmap_shift_left(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) * 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_set(unsigned long *map, int i, int len);
extern void bitmap_clear(unsigned long *map, int start, int nr); 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, extern unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
unsigned long start, unsigned long size,
unsigned int nr, unsigned long start,
unsigned long align_mask); 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, extern int bitmap_scnprintf(char *buf, unsigned int len,
const unsigned long *src, int nbits); 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); EXPORT_SYMBOL(bitmap_clear);
/* /**
* bitmap_find_next_zero_area - find a contiguous aligned zero area * bitmap_find_next_zero_area - find a contiguous aligned zero area
* @map: The address to base the search on * @map: The address to base the search on
* @size: The bitmap size in bits * @size: The bitmap size in bits
* @start: The bitnumber to start searching at * @start: The bitnumber to start searching at
* @nr: The number of zeroed bits we're looking for * @nr: The number of zeroed bits we're looking for
* @align_mask: Alignment mask for zero area * @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 @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 * the bit offset of all zero areas this function finds plus @align_offset
* power of 2. A @align_mask of 0 means no alignment is required. * is multiple of that power of 2.
*/ */
unsigned long bitmap_find_next_zero_area(unsigned long *map, unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
unsigned long size, unsigned long size,
unsigned long start, unsigned long start,
unsigned int nr, unsigned int nr,
unsigned long align_mask) unsigned long align_mask,
unsigned long align_offset)
{ {
unsigned long index, end, i; unsigned long index, end, i;
again: again:
index = find_next_zero_bit(map, size, start); index = find_next_zero_bit(map, size, start);
/* Align allocation */ /* Align allocation */
index = __ALIGN_MASK(index, align_mask); index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset;
end = index + nr; end = index + nr;
if (end > size) if (end > size)
@@ -350,7 +352,7 @@ again:
} }
return index; 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, * Bitmap printing & parsing functions: first version by Bill Irwin,