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bitfield.h: add FIELD_MAX() and field_max()

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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 <elder@linaro.org>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alex Elder 2020-03-12 11:44:27 -05:00 committed by David S. Miller
parent 82a9822b26
commit e31a50162f
1 changed files with 14 additions and 0 deletions
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14
include/linux/bitfield.h
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@ -55,6 +55,19 @@
(1ULL << __bf_shf(_mask))); \ (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 * FIELD_FIT() - check if value fits in the field
* @_mask: shifted mask defining the field's length and position * @_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); return field / field_multiplier(field);
} }
#define field_max(field) ((typeof(field))field_mask(field))
#define ____MAKE_OP(type,base,to,from) \ #define ____MAKE_OP(type,base,to,from) \
static __always_inline __##type type##_encode_bits(base v, base field) \ static __always_inline __##type type##_encode_bits(base v, base field) \
{ \ { \