From patchwork Mon May 4 12:45:20 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Sylwester Nawrocki/Kernel \\\(PLT\\\) /SRPOL/Staff Engineer/Samsung Electronics" X-Patchwork-Id: 245009 List-Id: U-Boot discussion From: s.nawrocki at samsung.com (Sylwester Nawrocki) Date: Mon, 4 May 2020 14:45:20 +0200 Subject: [PATCH v2 07/10] linux/bitfield.h: Add primitives for manipulating bitfields both in host- and fixed-endian In-Reply-To: <20200504124523.23484-1-s.nawrocki@samsung.com> References: <20200504124523.23484-1-s.nawrocki@samsung.com> Message-ID: <20200504124523.23484-8-s.nawrocki@samsung.com> From: Nicolas Saenz Julienne Imports Al Viro's original Linux commit 00b0c9b82663a, which contains an in depth explanation and two fixes from Johannes Berg: e7d4a95da86e0 "bitfield: fix *_encode_bits()", 37a3862e12382 "bitfield: add u8 helpers". Signed-off-by: Nicolas Saenz Julienne [s.nawrocki: added empty lines between functions and macros] Signed-off-by: Sylwester Nawrocki Reviewed-by: Bin Meng --- Changes since v1: - added empty lines between functions and macros. Changes since RFC: - new patch. --- include/linux/bitfield.h | 50 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h index 8b9d6ff..7acba4c 100644 --- a/include/linux/bitfield.h +++ b/include/linux/bitfield.h @@ -103,4 +103,54 @@ (typeof(_mask))(((_reg) & (_mask)) >> __bf_shf(_mask)); \ }) +extern void __compiletime_error("value doesn't fit into mask") +__field_overflow(void); +extern void __compiletime_error("bad bitfield mask") +__bad_mask(void); +static __always_inline u64 field_multiplier(u64 field) +{ + if ((field | (field - 1)) & ((field | (field - 1)) + 1)) + __bad_mask(); + return field & -field; +} +static __always_inline u64 field_mask(u64 field) +{ + return field / field_multiplier(field); +} + +#define ____MAKE_OP(type,base,to,from) \ +static __always_inline __##type type##_encode_bits(base v, base field) \ +{ \ + if (__builtin_constant_p(v) && (v & ~field_mask(field))) \ + __field_overflow(); \ + return to((v & field_mask(field)) * field_multiplier(field)); \ +} \ +static __always_inline __##type type##_replace_bits(__##type old, \ + base val, base field) \ +{ \ + return (old & ~to(field)) | type##_encode_bits(val, field); \ +} \ +static __always_inline void type##p_replace_bits(__##type *p, \ + base val, base field) \ +{ \ + *p = (*p & ~to(field)) | type##_encode_bits(val, field); \ +} \ +static __always_inline base type##_get_bits(__##type v, base field) \ +{ \ + return (from(v) & field)/field_multiplier(field); \ +} + +#define __MAKE_OP(size) \ + ____MAKE_OP(le##size,u##size,cpu_to_le##size,le##size##_to_cpu) \ + ____MAKE_OP(be##size,u##size,cpu_to_be##size,be##size##_to_cpu) \ + ____MAKE_OP(u##size,u##size,,) + +____MAKE_OP(u8,u8,,) +__MAKE_OP(16) +__MAKE_OP(32) +__MAKE_OP(64) + +#undef __MAKE_OP +#undef ____MAKE_OP + #endif