Pack K Bits: Difference between revisions

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[[Category:Block Docs]]
[[Category:Block Docs]]
[[Category:Stub Docs]]
Converts a stream of bytes with 1 bit in the LSB to a byte with K relevant bits.  It's the opposite of [[Unpack K Bits]]
Converts a stream of bytes with 1 bit in the LSB to a byte with K relevant bits.  It's the opposite of [[Unpack K Bits]]


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The next four bytes get combined to form binary 1000 which is 0x08. Note that even though one of the input bytes was 0x81, all that mattered was the least significant bit, which was a 1, the rest of the bits in that byte got discarded.
The next four bytes get combined to form binary 1000 which is 0x08. Note that even though one of the input bytes was 0x81, all that mattered was the least significant bit, which was a 1, the rest of the bits in that byte got discarded.
This is the template for the [[:Category:Block_Docs|"Page-per-block Docs"]].  This first section should describe what the block does and how to use it, using however many paragraphs necessary.  Note that the title of the wiki page should match the block's name in GRC, i.e. the one defined in the block's .grc file.  Look at the [[FFT]] Block for a good example.
As this is a basic template, it's also in the [[:Category:Stub_Docs|"Stub Docs category"]]. Please improve it.


== Parameters ==
== Parameters ==
(''R''): <span class="plainlinks">[https://wiki.gnuradio.org/index.php/GNURadioCompanion#Variable_Controls ''Run-time adjustable'']</span>
; K
 
: Number of bits to be packed.
; Param 1 (''R'')
: Description of parameter, provide any tips or recommended values.  Note that the name of the parameter above should match the param's label that shows up in grc (e.g. Sample Rate).
 
; Param 2
: blah blah blah


== Example Flowgraph ==
== Example Flowgraph ==
Insert description of flowgraph here, then show a screenshot of the flowgraph and the output if there is an interesting GUI.  Currently we have no standard method of uploading the actual flowgraph to the wiki or git repo, unfortunately.  The plan is to have an example flowgraph showing how the block might be used, for every block, and the flowgraphs will live in the git repo.
[[File:Fft-ex.png|700px]]
[[File:Fft-ex-output.png|700px]]


== Source Files ==
== Source Files ==


; C++ files
; C++ files
: [https://github.com/gnuradio/gnuradio/blob/master/gr-fft/lib/fft_vcc_fftw.cc Complex input]
: [https://github.com/gnuradio/gnuradio/blob/main/gr-blocks/lib/pack_k_bits_bb_impl.cc Byte implementation]
: [https://github.com/gnuradio/gnuradio/blob/master/gr-fft/lib/fft_vfc_fftw.cc Real input]
: [https://github.com/gnuradio/gnuradio/blob/main/gr-blocks/lib/pack_k_bits.cc Base class]
: [https://github.com/gnuradio/gnuradio/blob/master/gr-fft/lib/fft.cc Core algorithms]


; Header files
; Header files
: [https://github.com/gnuradio/gnuradio/blob/master/gr-fft/lib/fft_vcc_fftw.h Complex input]
: [https://github.com/gnuradio/gnuradio/blob/main/gr-blocks/lib/pack_k_bits_bb_impl.h]
: [https://github.com/gnuradio/gnuradio/blob/master/gr-fft/lib/fft_vfc_fftw.h Real input]


; Public header files
; Public header files
: [https://github.com/gnuradio/gnuradio/blob/master/gr-fft/include/gnuradio/fft/fft_vcc.h Complex input]
: [https://github.com/gnuradio/gnuradio/blob/main/gr-blocks/include/gnuradio/blocks/pack_k_bits_bb.h Byte implementation]
: [https://github.com/gnuradio/gnuradio/blob/master/gr-fft/include/gnuradio/fft/fft_vfc.h Real input ]
: [https://github.com/gnuradio/gnuradio/blob/main/gr-blocks/include/gnuradio/blocks/pack_k_bits.h Base class]


; Block definition
; Block definition
: [https://github.com/gnuradio/gnuradio/blob/master/gr-fft/grc/fft_fft_vxx.block.yml GRC yaml]
: [https://github.com/gnuradio/gnuradio/blob/main/gr-blocks/grc/blocks_pack_k_bits_bb.block.yml]

Latest revision as of 13:23, 25 April 2023

Converts a stream of bytes with 1 bit in the LSB to a byte with K relevant bits. It's the opposite of Unpack K Bits

In other words, it packs K unpacked bits (one bit per byte, since the byte is the smallest item size in GNU Radio) into a single packed byte containing K bits and 8 - K zeros.

This block takes in K bytes at a time, and uses the least significant bit to form a new byte.

Example:

K = 4

in = [0, 1, 0, 1, 0x81, 0x00, 0x00, 0x00]

out = [0x05, 0x08]

The first four bytes coming in get combined to form binary 0101 which is 0x05

The next four bytes get combined to form binary 1000 which is 0x08. Note that even though one of the input bytes was 0x81, all that mattered was the least significant bit, which was a 1, the rest of the bits in that byte got discarded.

Parameters

K
Number of bits to be packed.

Example Flowgraph

Source Files

C++ files
Byte implementation
Base class
Header files
[1]
Public header files
Byte implementation
Base class
Block definition
[2]
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