[PATCH v2 08/26] ewah: implement `bitmap_is_empty()`
- From
Taylor Blau <me@ttaylorr.com>
- Date
- Dec 14, 2023, 22:23 UTC
- Message-ID
- <595b3b698615cd341cef49623523c0d3ea1b6802.1702592604.git.me@ttaylorr.com>
- In-Reply-To
- <cover.1702592603.git.me@ttaylorr.com>
In a future commit, we will want to check whether or not a bitmap has any bits set in any of its words. The best way to do this (prior to the existence of this patch) is to call `bitmap_popcount()` and check whether the result is non-zero.
But this is semi-wasteful, since we do not need to know the exact number of bits set, only whether or not there is at least one of them.
Implement a new helper function to check just that.
Suggested-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Taylor Blau <me@ttaylorr.com> --- ewah/bitmap.c | 9 +++++++++ ewah/ewok.h | 1 + 2 files changed, 10 insertions(+)
diff --git a/ewah/bitmap.c b/ewah/bitmap.c index 7b525b1ecd..ac7e0af622 100644 --- a/ewah/bitmap.c +++ b/ewah/bitmap.c @@ -169,6 +169,15 @@ size_t bitmap_popcount(struct bitmap *self) return count; } +int bitmap_is_empty(struct bitmap *self) +{ + size_t i; + for (i = 0; i < self->word_alloc; i++) + if (self->words[i]) + return 0; + return 1; +} + int bitmap_equals(struct bitmap *self, struct bitmap *other) { struct bitmap *big, *small; diff --git a/ewah/ewok.h b/ewah/ewok.h index 7eb8b9b630..c11d76c6f3 100644 --- a/ewah/ewok.h +++ b/ewah/ewok.h @@ -189,5 +189,6 @@ void bitmap_or_ewah(struct bitmap *self, struct ewah_bitmap *other); void bitmap_or(struct bitmap *self, const struct bitmap *other); size_t bitmap_popcount(struct bitmap *self); +int bitmap_is_empty(struct bitmap *self); #endif
-- 2.43.0.102.ga31d690331.dirty