[Qemu-devel] [RFC 04/29] bitmap: introduce bitmap_invert()

[Peter Xu]

It is used to invert the whole bitmap.

Signed-off-by: Peter Xu <address@hidden>
---
 include/qemu/bitmap.h | 10 ++++++++++
 util/bitmap.c         | 13 +++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/include/qemu/bitmap.h b/include/qemu/bitmap.h
index c318da1..460d899 100644
--- a/include/qemu/bitmap.h
+++ b/include/qemu/bitmap.h
@@ -82,6 +82,7 @@ int slow_bitmap_andnot(unsigned long *dst, const unsigned 
long *bitmap1,
                        const unsigned long *bitmap2, long bits);
 int slow_bitmap_intersects(const unsigned long *bitmap1,
                            const unsigned long *bitmap2, long bits);
+void slow_bitmap_invert(unsigned long *bitmap, long nbits);
 
 static inline unsigned long *bitmap_try_new(long nbits)
 {
@@ -216,6 +217,15 @@ static inline int bitmap_intersects(const unsigned long 
*src1,
     }
 }
 
+static inline void bitmap_invert(unsigned long *bitmap, long nbits)
+{
+    if (small_nbits(nbits)) {
+        *bitmap ^= BITMAP_LAST_WORD_MASK(nbits);
+    } else {
+        slow_bitmap_invert(bitmap, nbits);
+    }
+}
+
 void bitmap_set(unsigned long *map, long i, long len);
 void bitmap_set_atomic(unsigned long *map, long i, long len);
 void bitmap_clear(unsigned long *map, long start, long nr);
diff --git a/util/bitmap.c b/util/bitmap.c
index efced9a..9b7408c 100644
--- a/util/bitmap.c
+++ b/util/bitmap.c
@@ -355,3 +355,16 @@ int slow_bitmap_intersects(const unsigned long *bitmap1,
     }
     return 0;
 }
+
+void slow_bitmap_invert(unsigned long *bitmap, long nbits)
+{
+    long k, lim = nbits/BITS_PER_LONG;
+
+    for (k = 0; k < lim; k++) {
+        bitmap[k] ^= ULONG_MAX;
+    }
+
+    if (nbits % BITS_PER_LONG) {
+        bitmap[k] ^= BITMAP_LAST_WORD_MASK(nbits);
+    }
+}
-- 
2.7.4