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hbitmap: add next_zero function

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The function searches for next zero bit.
Also add interface for BdrvDirtyBitmap and unit test.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 20171012135313.227864-2-vsementsov@virtuozzo.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
This commit is contained in:
Vladimir Sementsov-Ogievskiy
2017-10-12 16:53:09 +03:00
committed by Jeff Cody
parent 411ad78115
commit 56207df55e
5 changed files with 114 additions and 0 deletions
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39
util/hbitmap.c
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@ -188,6 +188,45 @@ void hbitmap_iter_init(HBitmapIter *hbi, const HBitmap *hb, uint64_t first)
}
}
int64_t hbitmap_next_zero(const HBitmap *hb, uint64_t start)
{
size_t pos = (start >> hb->granularity) >> BITS_PER_LEVEL;
unsigned long *last_lev = hb->levels[HBITMAP_LEVELS - 1];
uint64_t sz = hb->sizes[HBITMAP_LEVELS - 1];
unsigned long cur = last_lev[pos];
unsigned start_bit_offset =
(start >> hb->granularity) & (BITS_PER_LONG - 1);
int64_t res;
cur |= (1UL << start_bit_offset) - 1;
assert((start >> hb->granularity) < hb->size);
if (cur == (unsigned long)-1) {
do {
pos++;
} while (pos < sz && last_lev[pos] == (unsigned long)-1);
if (pos >= sz) {
return -1;
}
cur = last_lev[pos];
}
res = (pos << BITS_PER_LEVEL) + ctol(cur);
if (res >= hb->size) {
return -1;
}
res = res << hb->granularity;
if (res < start) {
assert(((start - res) >> hb->granularity) == 0);
return start;
}
return res;
}
bool hbitmap_empty(const HBitmap *hb)
{
return hb->count == 0;