ewah: add bitmap_dup() function

peff · gitster · commit ccae08e822d7 · 2020-12-08T14:48:16.000-08:00
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 &lt;peff@peff.net&gt;
Signed-off-by: Taylor Blau &lt;me@ttaylorr.com&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
diff --git 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)
 {
 	size_t old_size = self->word_alloc;
diff --git 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);

Original file line number	Diff line number	Diff line change
`@@ -35,6 +35,13 @@ struct bitmap *bitmap_new(void)`
`35`	`35`	`return bitmap_word_alloc(32);`
`36`	`36`	`}`
`37`	`37`
	`38`	`+struct bitmap bitmap_dup(const struct bitmap src)`
	`39`	`+{`
	`40`	`+ struct bitmap *dst = bitmap_word_alloc(src->word_alloc);`
	`41`	`+ COPY_ARRAY(dst->words, src->words, src->word_alloc);`
	`42`	`+ return dst;`
	`43`	`+}`
	`44`	`+`
`38`	`45`	`static void bitmap_grow(struct bitmap *self, size_t word_alloc)`
`39`	`46`	`{`
`40`	`47`	`size_t old_size = self->word_alloc;`