Re: Help on bit operation

[Uday Verma <uday.karan@gmail.com>]

If the sizes of your infos is fixed you can do something like this:

info5 = packet & 0x1FF;
info4 = (packet >> 9) & 0x1F;
.. and so on

note that I am masking out unwanted parts of the 32 bit packet using
an all 1s  bit pattern 0x1FF : 1 1111 1111, 0x1F : 1 1111.  in case of
info4, I first need to move the value 9 bits to the right so that 5
bits of info4 form the LSB.

You can form the packet similarly,

unsigned int packet = ((info1 & 0x3F) << 26) | ((info2 & 0xF) << 22) ...

HTH

packet is your single 32-bit integer which has all these infos encoded.

On Wed, Aug 26, 2009 at 6:02 PM, Randi Botse<nightdecoder@gmail.com> wrote:
> Hi, I'm beginner C programmer, i have a problem, i want to store some
> information in a integer, a integer will be 32 bit on my machine, i
> want to have as follow:
>
> 6 bit (information 1)   MSB
> 4 bit (information 2)
> 8 bit (information 3)
> 5 bit (information 4)
> 9 bit (information 5)   LSB
>
> For example i set the informations as follow (in decimal):
>
> information 1 = 43        or 101011
> information 2 = 11        or 1011
> information 3 = 120      or 1111000
> information 3 = 30        or 11110
> information 4 = 418      or 110100010
>
> if i join all informations i should get a 32 bit integer valued
> 2935782212 or 01010111011111100011110110100010, then my problem is how
> to retrieve these informations on bit operation? i want to know what's
> the value of information-2 or information-3, etc directly.  And, is
> there any good way to join these informations to be an 32 bit integer?
>
> at this time i convert the 32bit integer into binary string, process
> it's with array segment to get all informations then convert them to
> integer,
> to build the 32bit integer, i join all information value into binary
> string (yes, 32 bit of char ;p) join all of them then convert to
> integer.
>
> I know my way is sucks and too far away from COOL thing ;p,  i think
> there are cool way to do this!.
>
> Thanks before!
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-- 
Uday
http://soundc.de/
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