Re: [libvirt] [PATCH 1/3] util: Add a helper to check if all bits of a bitmap are clear
On 04/02/2013 01:42 AM, Osier Yang wrote:
---
src/libvirt_private.syms | 1 +
src/util/virbitmap.c | 30 ++++++++++++++++++++++++++++++
src/util/virbitmap.h | 3 +++
3 files changed, 34 insertions(+)
Since there already is a "virBitmapIsAllSet()" - why isn't it used? I
see callers which do "if (virBitmapIsAllSet(...)" and "if
(!virBitmapIsAllSet(...)".
If you're going to have a AllClear(), then why not change those !
callers to use AllClear()...
I only wonder about the last comparison - it's the "-1" logic that
throws me off especially since the IsAllSet() code is doing a comparison.
It also stands to reason that tests/virbitmaptest.c could add new tests
to ensure you did get the logic right.
John
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);