Re: [RFC][PATCH] Add primitives for manipulating bitfields both in host- and fixed-endian.

Jakub Kicinski
2017-12-15T05:07:24Z

Looks great to me!

On Fri, 15 Dec 2017 02:33:43 +0000, Al Viro wrote:
> The following primitives are defined in linux/bitfield.h:
>
> * u32 le32_get_bits(__le32 val, u32 field) extracts the contents of the
> bitfield specified by @field in little-endian 32bit value @val and
> converts it to host-endian.
>
> * void le32p_replace_bits(__le32 *p, u32 v, u32 field) replaces
> the contents of the bitfield specified by @field in little-endian
> 32bit object pointet to by *p with the value of @v. New value is
> given in host-endian and stored as little-endian.
>
> * __le32 le32_replace_bits(__le32 old, u32 v, u32 field) is equivalent to
> ({__le32 tmp = old; le32p_replace_bits(&old, v, field); tmp;})
> In other words, instead of modifying an object in memory, it takes
> the initial value and returns the modified one.

the current macros take filed/mask as first param, not sure if it's
worth maintaining the order