[v4,17/24] ewah: implement `ewah_bitmap_popcount()`

Commit Message

Taylor Blau May 23, 2024, 9:27 p.m. UTC

Some of the pseudo-merge test helpers (which will be introduced in the
following commit) will want to indicate the total number of commits in
or objects reachable from a pseudo-merge.

Implement a popcount() function that operates on EWAH bitmaps to quickly
determine how many bits are set in each of the respective bitmaps.

Signed-off-by: Taylor Blau <[e-mail]>
---
 ewah/bitmap.c | 14 ++++++++++++++
 ewah/ewok.h   |  1 +
 2 files changed, 15 insertions(+)

Patch

diff --git a/ewah/bitmap.c b/ewah/bitmap.c
index d352fec54ce..dc2ca190f12 100644
--- a/ewah/bitmap.c
+++ b/ewah/bitmap.c
@@ -212,6 +212,20 @@  size_t bitmap_popcount(struct bitmap *self)
 	return count;
 }
 
+size_t ewah_bitmap_popcount(struct ewah_bitmap *self)
+{
+	struct ewah_iterator it;
+	eword_t word;
+	size_t count = 0;
+
+	ewah_iterator_init(&it, self);
+
+	while (ewah_iterator_next(&word, &it))
+		count += ewah_bit_popcount64(word);
+
+	return count;
+}
+
 int bitmap_is_empty(struct bitmap *self)
 {
 	size_t i;
diff --git a/ewah/ewok.h b/ewah/ewok.h
index 2b6c4ac499c..7074a6347b7 100644
--- a/ewah/ewok.h
+++ b/ewah/ewok.h
@@ -195,6 +195,7 @@  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);
+size_t ewah_bitmap_popcount(struct ewah_bitmap *self);
 int bitmap_is_empty(struct bitmap *self);
 
 #endif