[PATCH net-next v3 09/18] include: bitmap: add macro for bitmap initialization
From: Marek Behún <kabel@kernel.org>
Date: 2021-04-06 22:12:07
Subsystem:
bitmap api, the rest · Maintainers:
Yury Norov, Linus Torvalds
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 <kabel@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