[PATCH v3] bitfield.h: add FIELD_MAX() and field_max()
From: Alex Elder <hidden>
Date: 2020-03-11 02:42:49
Also in:
lkml
Subsystem:
bitmap api, the rest · Maintainers:
Yury Norov, Linus Torvalds
Define FIELD_MAX(), which supplies the maximum value that can be represented by a field value. Define field_max() as well, to go along with the lower-case forms of the field mask functions. Signed-off-by: Alex Elder <redacted> Acked-by: Jakub Kicinski <kuba@kernel.org> --- v3: Rebased on latest netdev-next/master. David, please take this into net-next as soon as possible. When the IPA code was merged the other day this prerequisite patch was not included, and as a result the IPA driver fails to build. Thank you. See: https://lkml.org/lkml/2020/3/10/1839 -Alex include/linux/bitfield.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h
index 4bbb5f1c8b5b..48ea093ff04c 100644
--- a/include/linux/bitfield.h
+++ b/include/linux/bitfield.h@@ -55,6 +55,19 @@ (1ULL << __bf_shf(_mask))); \ }) +/** + * FIELD_MAX() - produce the maximum value representable by a field + * @_mask: shifted mask defining the field's length and position + * + * FIELD_MAX() returns the maximum value that can be held in the field + * specified by @_mask. + */ +#define FIELD_MAX(_mask) \ + ({ \ + __BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_MAX: "); \ + (typeof(_mask))((_mask) >> __bf_shf(_mask)); \ + }) + /** * FIELD_FIT() - check if value fits in the field * @_mask: shifted mask defining the field's length and position
@@ -110,6 +123,7 @@ static __always_inline u64 field_mask(u64 field) { return field / field_multiplier(field); } +#define field_max(field) ((typeof(field))field_mask(field)) #define ____MAKE_OP(type,base,to,from) \ static __always_inline __##type type##_encode_bits(base v, base field) \ { \
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2.20.1