Use the new variadic-macro.h library to implement macro
INITIALIZE_BITMAP(nbits, ...), which can be used for compile time bitmap
initialization in the form
static DECLARE_BITMAP(bm, 100) = INITIALIZE_BITMAP(100, 7, 9, 66, 98);
The macro uses the BUILD_BUG_ON_ZERO mechanism to ensure a compile-time
error if an argument is out of range.
Signed-off-by: Marek Behún <ka...@kernel.org>
---
include/linux/bitmap.h | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 70a932470b2d..a9e74d3420bf 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -8,6 +8,7 @@
#include <linux/bitops.h>
#include <linux/string.h>
#include <linux/kernel.h>
+#include <linux/variadic-macro.h>
/*
* bitmaps provide bit arrays that consume one or more unsigned
@@ -114,6 +115,29 @@
* contain all bit positions from 0 to 'bits' - 1.
*/
+/**
+ * DOC: initialize bitmap
+ * The INITIALIZE_BITMAP(bits, args...) macro expands to a designated
+ * initializer for bitmap of length 'bits', setting each bit specified
+ * in 'args...'.
+ */
+#define _BIT_MEMBER(bit) ((bit) / BITS_PER_LONG)
+#define _VERIFY_BIT(bit, nbits)
\
+ BUILD_BUG_ON_ZERO((bit) < 0 || (bit) >= (nbits))
+#define _INIT_BITMAP_MEMBER_VALUE(bit, member_bit) \
+ | (_BIT_MEMBER(bit) == _BIT_MEMBER(member_bit) \
+ ? BIT((bit) % BITS_PER_LONG) \
+ : 0)
+#define _INIT_BITMAP_MEMBER(bit, nbits, ...) \
+ [_VERIFY_BIT((bit), (nbits)) + _BIT_MEMBER(bit)] = \
+ (0 EXPAND_FOR_EACH(_INIT_BITMAP_MEMBER_VALUE, \
+ (bit), ##__VA_ARGS__)),
+#define INITIALIZE_BITMAP(nbits, ...) \
+ { \
+ EXPAND_FOR_EACH_PASS_ARGS(_INIT_BITMAP_MEMBER, (nbits), \
+ ##__VA_ARGS__) \
+ }
+
/*
* Allocation and deallocation of bitmap.
* Provided in lib/bitmap.c to avoid circular dependency.
--
2.26.2
