[libvirt] [PATCH 1/3] util: Add a helper to check if all bits of a bitmap are clear

[Osier Yang]

---
 src/libvirt_private.syms |  1 +
 src/util/virbitmap.c     | 30 ++++++++++++++++++++++++++++++
 src/util/virbitmap.h     |  3 +++
 3 files changed, 34 insertions(+)

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 96eea0a..35ac957 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1048,6 +1048,7 @@ virBitmapEqual;
 virBitmapFormat;
 virBitmapFree;
 virBitmapGetBit;
+virBitmapIsAllClear;
 virBitmapIsAllSet;
 virBitmapNew;
 virBitmapNewCopy;
diff --git a/src/util/virbitmap.c b/src/util/virbitmap.c
index 21509ac..99a8572 100644
--- a/src/util/virbitmap.c
+++ b/src/util/virbitmap.c
@@ -591,6 +591,36 @@ bool virBitmapIsAllSet(virBitmapPtr bitmap)
 }
 
 /**
+ * virBitmapIsAllClear:
+ * @bitmap: the bitmap to check
+ *
+ * check if all bits in @bitmap are clear
+ */
+bool virBitmapIsAllClear(virBitmapPtr bitmap)
+{
+    int i;
+    int unusedBits;
+    size_t sz;
+
+    unusedBits = bitmap->map_len * VIR_BITMAP_BITS_PER_UNIT - bitmap->max_bit;
+
+    sz = bitmap->map_len;
+    if (unusedBits > 0)
+        sz--;
+
+    for (i = 0; i < sz; i++)
+        if (bitmap->map[i] != 0)
+            return false;
+
+    if (unusedBits > 0) {
+        if ((bitmap->map[sz] & ((1UL << (VIR_BITMAP_BITS_PER_UNIT - unusedBits)) - 1)))
+            return false;
+    }
+
+    return true;
+}
+
+/**
  * virBitmapNextSetBit:
  * @bitmap: the bitmap
  * @pos: the position after which to search for a set bit
diff --git a/src/util/virbitmap.h b/src/util/virbitmap.h
index 044c7a6..b682523 100644
--- a/src/util/virbitmap.h
+++ b/src/util/virbitmap.h
@@ -100,6 +100,9 @@ void virBitmapClearAll(virBitmapPtr bitmap)
 bool virBitmapIsAllSet(virBitmapPtr bitmap)
     ATTRIBUTE_NONNULL(1);
 
+bool virBitmapIsAllClear(virBitmapPtr bitmap)
+    ATTRIBUTE_NONNULL(1);
+
 ssize_t virBitmapNextSetBit(virBitmapPtr bitmap, ssize_t pos)
     ATTRIBUTE_NONNULL(1);
 
-- 
1.8.1.4