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bitmap: introduce bitmap_count_one()

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Count how many bits set in the bitmap.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
This commit is contained in:
Peter Xu 2017-08-30 16:31:59 +08:00 committed by Juan Quintela
parent ab089e058e
commit fc7deeea26
2 changed files with 25 additions and 0 deletions
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10
include/qemu/bitmap.h
View File

@ -82,6 +82,7 @@ int slow_bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
const unsigned long *bitmap2, long bits);
int slow_bitmap_intersects(const unsigned long *bitmap1,
const unsigned long *bitmap2, long bits);
long slow_bitmap_count_one(const unsigned long *bitmap, long nbits);
static inline unsigned long *bitmap_try_new(long nbits)
{
@ -216,6 +217,15 @@ static inline int bitmap_intersects(const unsigned long *src1,
}
}
static inline long bitmap_count_one(const unsigned long *bitmap, long nbits)
{
if (small_nbits(nbits)) {
return ctpopl(*bitmap & BITMAP_LAST_WORD_MASK(nbits));
} else {
return slow_bitmap_count_one(bitmap, nbits);
}
}
void bitmap_set(unsigned long *map, long i, long len);
void bitmap_set_atomic(unsigned long *map, long i, long len);
void bitmap_clear(unsigned long *map, long start, long nr);

15
util/bitmap.c
View File

@ -355,3 +355,18 @@ int slow_bitmap_intersects(const unsigned long *bitmap1,
}
return 0;
}
long slow_bitmap_count_one(const unsigned long *bitmap, long nbits)
{
long k, lim = nbits / BITS_PER_LONG, result = 0;
for (k = 0; k < lim; k++) {
result += ctpopl(bitmap[k]);
}
if (nbits % BITS_PER_LONG) {
result += ctpopl(bitmap[k] & BITMAP_LAST_WORD_MASK(nbits));
}
return result;
}