[v2,09/24] ewah: add bitmap_dup() function

Commit Message

Taylor Blau Nov. 17, 2020, 9:47 p.m. UTC

From: Jeff King <[e-mail]>

There's no easy way to make a copy of a bitmap. Obviously a caller can
iterate over the bits and set them one by one in a new bitmap, but we
can go much faster by copying whole words with memcpy().

Signed-off-by: Jeff King <[e-mail]>
Signed-off-by: Taylor Blau <[e-mail]>
---
 ewah/bitmap.c | 7 +++++++
 ewah/ewok.h   | 1 +
 2 files changed, 8 insertions(+)

Patch

diff --git a/ewah/bitmap.c b/ewah/bitmap.c
index c3f8e7242b..eb7e2539be 100644
--- a/ewah/bitmap.c
+++ b/ewah/bitmap.c
@@ -35,6 +35,13 @@  struct bitmap *bitmap_new(void)
 	return bitmap_word_alloc(32);
 }
 
+struct bitmap *bitmap_dup(const struct bitmap *src)
+{
+	struct bitmap *dst = bitmap_word_alloc(src->word_alloc);
+	COPY_ARRAY(dst->words, src->words, src->word_alloc);
+	return dst;
+}
+
 static void bitmap_grow(struct bitmap *self, size_t word_alloc)
 {
 	if (word_alloc > self->word_alloc) {
diff --git a/ewah/ewok.h b/ewah/ewok.h
index 011852bef1..1fc555e672 100644
--- a/ewah/ewok.h
+++ b/ewah/ewok.h
@@ -173,6 +173,7 @@  struct bitmap {
 
 struct bitmap *bitmap_new(void);
 struct bitmap *bitmap_word_alloc(size_t word_alloc);
+struct bitmap *bitmap_dup(const struct bitmap *src);
 void bitmap_set(struct bitmap *self, size_t pos);
 void bitmap_unset(struct bitmap *self, size_t pos);
 int bitmap_get(struct bitmap *self, size_t pos);