[Qemu-devel] [PATCH v15 2/5] lib/xbitmap: add xb_find_next_bit() and xb_zero()

[Wei Wang]

xb_find_next_bit() is used to find the next "1" or "0" bit in the
given range. xb_zero() is used to zero the given range of bits.

Signed-off-by: Wei Wang <address@hidden>
Cc: Andrew Morton <address@hidden>
Cc: Matthew Wilcox <address@hidden>
Cc: Michal Hocko <address@hidden>
Cc: Michael S. Tsirkin <address@hidden>
---
 include/linux/xbitmap.h |  3 +++
 lib/xbitmap.c           | 39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/include/linux/xbitmap.h b/include/linux/xbitmap.h
index 25b05ff..0061f7a 100644
--- a/include/linux/xbitmap.h
+++ b/include/linux/xbitmap.h
@@ -38,6 +38,9 @@ static inline void xb_init(struct xb *xb)
 int xb_set_bit(struct xb *xb, unsigned long bit);
 bool xb_test_bit(struct xb *xb, unsigned long bit);
 void xb_clear_bit(struct xb *xb, unsigned long bit);
+void xb_zero(struct xb *xb, unsigned long start, unsigned long end);
+unsigned long xb_find_next_bit(struct xb *xb, unsigned long start,
+                              unsigned long end, bool set);
 
 /* Check if the xb tree is empty */
 static inline bool xb_is_empty(const struct xb *xb)
diff --git a/lib/xbitmap.c b/lib/xbitmap.c
index 8c55296..b9e2a0c 100644
--- a/lib/xbitmap.c
+++ b/lib/xbitmap.c
@@ -174,3 +174,42 @@ void xb_preload(gfp_t gfp)
        }
 }
 EXPORT_SYMBOL(xb_preload);
+
+/**
+ *  xb_zero - zero a range of bits in the xbitmap
+ *  @xb: the xbitmap that the bits reside in
+ *  @start: the start of the range, inclusive
+ *  @end: the end of the range, inclusive
+ */
+void xb_zero(struct xb *xb, unsigned long start, unsigned long end)
+{
+       unsigned long i;
+
+       for (i = start; i <= end; i++)
+               xb_clear_bit(xb, i);
+}
+EXPORT_SYMBOL(xb_zero);
+
+/**
+ * xb_find_next_bit - find next 1 or 0 in the give range of bits
+ * @xb: the xbitmap that the bits reside in
+ * @start: the start of the range, inclusive
+ * @end: the end of the range, inclusive
+ * @set: the polarity (1 or 0) of the next bit to find
+ *
+ * Return the index of the found bit in the xbitmap. If the returned index
+ * exceeds @end, it indicates that no such bit is found in the given range.
+ */
+unsigned long xb_find_next_bit(struct xb *xb, unsigned long start,
+                              unsigned long end, bool set)
+{
+       unsigned long i;
+
+       for (i = start; i <= end; i++) {
+               if (xb_test_bit(xb, i) == set)
+                       break;
+       }
+
+       return i;
+}
+EXPORT_SYMBOL(xb_find_next_bit);
-- 
2.7.4