From: Alex Elder Date: Thu, 12 Mar 2020 16:44:27 +0000 (-0500) Subject: bitfield.h: add FIELD_MAX() and field_max() X-Git-Tag: v5.7-rc1~146^2~180^2~1 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e31a50162feb352147d3fc87b9e036703c8f2636;p=thirdparty%2Fkernel%2Flinux.git bitfield.h: add FIELD_MAX() and field_max() 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 Acked-by: Jakub Kicinski Signed-off-by: David S. Miller --- diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h index 4bbb5f1c8b5b7..48ea093ff04cc 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) \ { \