[PATCH v2 13/24] bitmap: add bitmap_diff_nonzero()

[Taylor Blau <me@xxxxxxxxxxxx>]

From: Derrick Stolee <dstolee@xxxxxxxxxxxxx>

The bitmap_diff_nonzero() checks if the 'self' bitmap contains any bits
that are not on in the 'other' bitmap.

Also, delete the declaration of bitmap_is_subset() as it is not used or
implemented.

Signed-off-by: Derrick Stolee <dstolee@xxxxxxxxxxxxx>
Signed-off-by: Taylor Blau <me@xxxxxxxxxxxx>
---
 ewah/bitmap.c | 24 ++++++++++++++++++++++++
 ewah/ewok.h   |  2 +-
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/ewah/bitmap.c b/ewah/bitmap.c
index eb7e2539be..e2ebeac0e5 100644
--- a/ewah/bitmap.c
+++ b/ewah/bitmap.c
@@ -200,6 +200,30 @@ int bitmap_equals(struct bitmap *self, struct bitmap *other)
 	return 1;
 }
 
+int bitmap_diff_nonzero(struct bitmap *self, struct bitmap *other)
+{
+	struct bitmap *small;
+	size_t i;
+
+	if (self->word_alloc < other->word_alloc) {
+		small = self;
+	} else {
+		small = other;
+
+		for (i = other->word_alloc; i < self->word_alloc; i++) {
+			if (self->words[i] != 0)
+				return 1;
+		}
+	}
+
+	for (i = 0; i < small->word_alloc; i++) {
+		if ((self->words[i] & ~other->words[i]))
+			return 1;
+	}
+
+	return 0;
+}
+
 void bitmap_reset(struct bitmap *bitmap)
 {
 	memset(bitmap->words, 0x0, bitmap->word_alloc * sizeof(eword_t));
diff --git a/ewah/ewok.h b/ewah/ewok.h
index 1fc555e672..156c71d06d 100644
--- a/ewah/ewok.h
+++ b/ewah/ewok.h
@@ -180,7 +180,7 @@ int bitmap_get(struct bitmap *self, size_t pos);
 void bitmap_reset(struct bitmap *self);
 void bitmap_free(struct bitmap *self);
 int bitmap_equals(struct bitmap *self, struct bitmap *other);
-int bitmap_is_subset(struct bitmap *self, struct bitmap *super);
+int bitmap_diff_nonzero(struct bitmap *self, struct bitmap *other);
 
 struct ewah_bitmap * bitmap_to_ewah(struct bitmap *bitmap);
 struct bitmap *ewah_to_bitmap(struct ewah_bitmap *ewah);
-- 
2.29.2.312.gabc4d358d8