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Re: [Xen-devel] [PATCH] tools/libxl new bitmap functions



Hey Konrad,

On 4/2/2015 1:34 PM, Konrad Rzeszutek Wilk wrote:
On Thu, Apr 02, 2015 at 11:38:16AM -0600, Linda Jacobson wrote:
From: Linda <lindaj@xxxxxxxx>

Added bitmap functions for union intersection and difference betweenn two 
bitmaps

Signed-off-by: Linda <lindaj@xxxxxxxx>
---
  tools/libxl/libxl_utils.c | 115 ++++++++++++++++++++++++++++++++++++++++++++++
  tools/libxl/libxl_utils.h |  10 ++++
  2 files changed, 125 insertions(+)

diff --git a/tools/libxl/libxl_utils.c b/tools/libxl/libxl_utils.c
index 9053b27..c390ddc 100644
--- a/tools/libxl/libxl_utils.c
+++ b/tools/libxl/libxl_utils.c
@@ -699,6 +699,121 @@ int libxl_bitmap_count_set(const libxl_bitmap *bitmap)
return nr_set_bits;
  }
+int libxl_bitmap_union(libxl_ctx *ctx, libxl_bitmap *union_bitmap,
You have an extra space at the end..
+libxl_bitmap *bitmap1, libxl_bitmap *bitmap2)
And this should really start at the same line length as 'libxl_ctx'

Ditto for the rest of the functions.
+{
+    int size;
+    int rc;
+
+    GC_INIT(ctx);
+
+// if bitmaps aren't the same size, union should be size of larger bit map
The comments are in:

  /* Comment here. */


+    size = (bitmap1->size > bitmap2->size) ? bitmap1->size : bitmap2->size;
There might be an 'max' macro somwhere in the code that you could use
for this?
Any guesses on where I might find the max macro. When I grep max, all I find are definitions of constants that are the
max of something.

Thanks.

Linda

+
+    libxl_bitmap_init(union_bitmap);
+    rc = libxl_bitmap_alloc(ctx, union_bitmap, size);
+    if (rc)
+    {
+        // Following the coding standards here.
+       //First goto I've written in decades.
Hehe.

No need to add the braces, you can just do:

        if (rc)
                goto out;

+        goto out;
+    }
+
+    for (int bit = 0; bit < (size * 8); bit++)
Please move the 'int bit' to the start of the function.

+    {
+        // libxl_bitmap_test returns 0 if past end of bitmap
+        // if the bit is set in either bitmap, set it in their union
I would change that comment to be:

/* NB. libxl_bitmap_test returns 0 if past the end of bitmap. */

+        if (libxl_bitmap_test(bitmap1, bit))
+        {
+            libxl_bitmap_set(union_bitmap, bit);
+        }
+        else if (libxl_bitmap_test(bitmap2, bit))
+        {
+            libxl_bitmap_set(union_bitmap, bit);
+        }
You can ditch the braces.

+    }
+
+out:
+    GC_FREE;
+    return rc;
+}
+
+int libxl_bitmap_intersection (libxl_ctx *ctx, libxl_bitmap
There is space :                ^ - which should not be there.

+*intersection_bitmap, libxl_bitmap *bitmap1, libxl_bitmap *bitmap2)
+{
+    int size;
+    int rc;
+
+    GC_INIT(ctx);
+
+// if bitmaps aren't same size, intersection should be size of
+// smaller bit map
I believe the comments I've above apply to the code below as well.

+    size = (bitmap1->size > bitmap2->size) ? bitmap2->size : bitmap1->size;
+
+    libxl_bitmap_init(intersection_bitmap);
+    rc = libxl_bitmap_alloc(ctx, intersection_bitmap, size);
+    if (rc)
+    {
+        goto out;
+    }
+
+    for (int bit = 0; bit < (size * 8); bit++)
+    {
+        // libxl_bitmap_test returns 0 if past end of bitmap
+        // if the bit is set in both bitmaps, set it in their intersection
+        if (libxl_bitmap_test (bitmap1, bit) &&
+                libxl_bitmap_test (bitmap2, bit) )
You have an extra space at the end there. Don't think you need that
in libxl code (thought you do for libxc). Yeah, two different
styleguides!

+        {
+            libxl_bitmap_set (intersection_bitmap, bit);
+        }
+    }
+
+out:
+    GC_FREE;
+    return rc;
+}
+int libxl_bitmap_difference(libxl_ctx *ctx, libxl_bitmap *difference_bitmap,
+libxl_bitmap *bitmap1, libxl_bitmap *bitmap2)
+{
+    int size;
+    int rc;
+
+    GC_INIT(ctx);
+
+// if bitmaps aren't the same size, difference should be size of larger
+    size = (bitmap1->size > bitmap2->size) ? bitmap1->size : bitmap2->size;
+
+    libxl_bitmap_init(difference_bitmap);
+    rc = libxl_bitmap_alloc(ctx, difference_bitmap, size);
+    if (rc)
+    {
+        goto out;
+    }
+
+    for (int bit = 0; bit < (size * 8); bit++)
+    {
+        /* libxl_bitmap_test returns 0 if past end of bitmap
+         if the bit is set in one bitmap and not the other, set it in
+their difference
+        NOTE:  if one bit map is larger, this will result in all bits
+being set past the size of the smaller bitmap;  if this is not
+        the desired behavior, please let me know
That would make this a bit strange. Perhaps demand that they
must be the same size? If they are not then just return an error?
+        */
+
+        if (libxl_bitmap_test (bitmap1, bit)
You have an extra space at the end there.      ^
+               && (!libxl_bitmap_test (bitmap2, bit)) )
+        {
+            libxl_bitmap_set (difference_bitmap, bit);
+        }
+    }
+
+out:
+    GC_FREE;
+    return rc;
+}
+
+
+
/* NB. caller is responsible for freeing the memory */
  char *libxl_bitmap_to_hex_string(libxl_ctx *ctx, const libxl_bitmap *bitmap)
diff --git a/tools/libxl/libxl_utils.h b/tools/libxl/libxl_utils.h
index acacdd9..521e4bb 100644
--- a/tools/libxl/libxl_utils.h
+++ b/tools/libxl/libxl_utils.h
@@ -91,6 +91,16 @@ void libxl_bitmap_set(libxl_bitmap *bitmap, int bit);
  void libxl_bitmap_reset(libxl_bitmap *bitmap, int bit);
  int libxl_bitmap_count_set(const libxl_bitmap *cpumap);
  char *libxl_bitmap_to_hex_string(libxl_ctx *ctx, const libxl_bitmap *cpumap);
+/*
+   union, intersection and difference functions for
+       two bitmaps
+*/
+int libxl_bitmap_union(libxl_ctx *ctx, libxl_bitmap *new_bitmap, libxl_bitmap 
*bitmap1, libxl_bitmap *bitmap2);
+
+int libxl_bitmap_intersection(libxl_ctx *ctx, libxl_bitmap *new_bitmap, 
libxl_bitmap *bitmap1, libxl_bitmap *bitmap2);
+
+int libxl_bitmap_difference(libxl_ctx *ctx, libxl_bitmap *new_bitmap, 
libxl_bitmap *bitmap1, libxl_bitmap *bitmap2);
+
  static inline void libxl_bitmap_set_any(libxl_bitmap *bitmap)
  {
      memset(bitmap->map, -1, bitmap->size);
--
1.9.1


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