ewah: implement `bitmap_is_empty()`
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> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Taylor Blau committed
Dec 14, 2023 at 17:23 UTC
e5d48bf38bc0e1f44f4daa7c8e0f75cd9296d020
2 files changed
+10
ewah/bitmap.c
+9
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;
ewah/ewok.h
+1
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