Re: Help on bit operation

[Ben Rosenberg <scdlbx@gmail.com>]

On Fri, Aug 28, 2009 at 11:40 AM, Randi Botse<nightdecoder@gmail.com> wrote:
> Ben, after assign all bitfield struct member, how to pack them to be a
> 32bit integer value?
>
> DEC      BIN
> 43        101011        -> foo.a (6 bit)
> 11        1011            -> foo.b (4 bit)
> 120      01111000    -> foo.c (8 bit)
> 30        11110          -> foo.d (5 bit)
> 418      110100010  -> foo.e (9 bit)
>
> the bit pattern is : 10101110110111100011110110100010 or 2933800354 in
> decimal, is this possible?
>
> while with masking and shift i can pack them with:
> ((foo.a & 0x3f) << 26) | ((foo.b & 0xf) << 22) | ((foo,c & 0xff) <<
> 14) | ((foo.d & 0x1f) << 9) | (foo.e & 0x1ff)
>
>

The bitfield struct is already packed, you don't need to do anything
else. Just assign values to the different parts.

Ben
--
To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html