[Qemu-block] [PATCH 15/21] bitmap: add bitmap_count_between() function

[Vladimir Sementsov-Ogievskiy]

Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
Reviewed-by: Pavel Butsykin <address@hidden>
---
 include/qemu/bitmap.h |  4 ++++
 util/bitmap.c         | 27 +++++++++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/include/qemu/bitmap.h b/include/qemu/bitmap.h
index 63ea2d0..3bfc33e 100644
--- a/include/qemu/bitmap.h
+++ b/include/qemu/bitmap.h
@@ -216,6 +216,10 @@ static inline int bitmap_intersects(const unsigned long 
*src1,
     }
 }
 
+unsigned long bitmap_count_between(const unsigned long *src,
+                                   unsigned long start,
+                                   unsigned long end);
+
 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 43ed011..e5aaa1c 100644
--- a/util/bitmap.c
+++ b/util/bitmap.c
@@ -336,3 +336,30 @@ int slow_bitmap_intersects(const unsigned long *bitmap1,
     }
     return 0;
 }
+
+unsigned long bitmap_count_between(const unsigned long *src,
+                                   unsigned long start,
+                                   unsigned long end)
+{
+    unsigned long first = start / BITS_PER_LONG;
+    unsigned long lim = end / BITS_PER_LONG;
+    unsigned long sum, i;
+
+    assert(start < end);
+
+    sum = ctpopl(src[first] & BITMAP_FIRST_WORD_MASK(start));
+
+    for (i = first + 1; i < lim; ++i) {
+        sum += ctpopl(src[i]);
+    }
+
+    if (end % BITS_PER_LONG) {
+        if (first == lim) {
+            sum -= ctpopl(src[first] & BITMAP_FIRST_WORD_MASK(end));
+        } else {
+            sum += ctpopl(src[i] & BITMAP_LAST_WORD_MASK(end));
+        }
+    }
+
+    return sum;
+}
-- 
1.8.3.1