[PATCH v2 01/17] bitfield.h: add FIELD_MAX() and field_max()
From: Alex Elder <hidden>
Date: 2019-05-31 03:54:00
Also in:
linux-arm-kernel, linux-arm-msm, linux-devicetree, 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> --- include/linux/bitfield.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h
index 3f1ef4450a7c..cf4f06774520 100644
--- a/include/linux/bitfield.h
+++ b/include/linux/bitfield.h@@ -63,6 +63,19 @@ (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
@@ -118,6 +131,7 @@ 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) \ { \
--
2.20.1