Re: [libvirt] [PATCH V2 1/3] Add function to find and set next available bit
On 02/01/2013 02:57 PM, Stefan Berger wrote:
Add function to find the next available bit in the bitmap and set
it.
Signed-off-by: Stefan Berger <stefanb(a)linux.vnet.ibm.com>
---
src/libvirt_private.syms | 1 +
src/util/virbitmap.c | 34 ++++++++++++++++++++++++++++++++++
src/util/virbitmap.h | 3 +++
3 files changed, 38 insertions(+)
Index: libvirt/src/util/virbitmap.c
===================================================================
--- libvirt.orig/src/util/virbitmap.c
+++ libvirt/src/util/virbitmap.c
@@ -642,3 +642,37 @@ virBitmapCountBits(virBitmapPtr bitmap)
return ret;
}
@@ -106,4 +106,7 @@ ssize_t virBitmapNextSetBit(virBitmapPtr
size_t virBitmapCountBits(virBitmapPtr bitmap)
ATTRIBUTE_NONNULL(1);
+size_t virBitmapSetNextBit(virBitmapPtr bitmap, ssize_t pos)
+ ATTRIBUTE_NONNULL(1);
With this patch, we'd have:
virBitmapNextSetBit() - find without modifying
virBitmapSetNextBit() - find and modify
that feels a bit confusing (without reading the description, which one
do you want?). Also, your implementation is slow (testing one bit at a
time is slower than using tricks like ffsl). I'd rather see a
virBitmapNextClearBit() with same semantics of virBitmapNextSetBit at
iterating through the bitmap using ffsl() optimizations, then have
callers explicitly set the returned bit, instead of providing a
find-and-set function.
And our testsuite should be updated to cover this new function.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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