Re: [Discuss-gnuradio] splitting bits

[Eric Blossom]

On Thu, Jan 10, 2008 at 04:43:17PM -0500, Steven Clark wrote:
> Hey folks-
> 
> Let's say I have a stream of shorts whose values are one of [0,1,2,3] (in
> other words, the bottom 2 bits are active). I want to split these bits, so
> that:
> [2,3,3,1,0] -> [1,0,1,1,1,1,0,1,0,0], etc.
> 
> What block(s) can help me achieve this?


gr_packed_to_unpacked or gr_chunks_to_symbols are probably close to
what you're looking for.

Eric


/*!
 * \brief Convert a stream of packed bytes or shorts to stream of unpacked 
bytes or shorts.
 * \ingroup block
 *
 * input: stream of @I_TYPE@; output: stream of @O_TYPE@
 *
 * This is the inverse of gr_unpacked_to_packed_XX.
 *
 * The bits in the bytes or shorts input stream are grouped into chunks of 
 * \p bits_per_chunk bits and each resulting chunk is written right-
 * justified to the output stream of bytes or shorts.  
 * All b or 16 bits of the each input bytes or short are processed.  
 * The right thing is done if bits_per_chunk is not a power of two.
 *
 * The combination of gr_packed_to_unpacked_XX_ followed by
 * gr_chunks_to_symbols_Xf or gr_chunks_to_symbols_Xc handles the
 * general case of mapping from a stream of bytes or shorts into 
 * arbitrary float or complex symbols.
 *
 * \sa gr_packed_to_unpacked_bb, gr_unpacked_to_packed_bb,
 * \sa gr_packed_to_unpacked_ss, gr_unpacked_to_packed_ss,
 * \sa gr_chunks_to_symbols_bf, gr_chunks_to_symbols_bc.
 * \sa gr_chunks_to_symbols_sf, gr_chunks_to_symbols_sc.
 */