GNU Radio Manual and C++ API Reference  3.10.9.1
The Free & Open Software Radio Ecosystem
async_decoder.h
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1 /* -*- c++ -*- */
2 /*
3  * Copyright 2014 Free Software Foundation, Inc.
4  *
5  * This file is part of GNU Radio
6  *
7  * SPDX-License-Identifier: GPL-3.0-or-later
8  *
9  */
10 
11 #ifndef INCLUDED_FEC_ASYNC_DECODER_H
12 #define INCLUDED_FEC_ASYNC_DECODER_H
13 
14 #include <gnuradio/block.h>
15 #include <gnuradio/fec/api.h>
17 #include <memory>
18 
19 namespace gr {
20 namespace fec {
21 
22 /*!
23  * \brief Creates the decoder block for use in GNU Radio
24  * flowgraphs from a given FEC API object derived from the
25  * generic_decoder class.
26  * \ingroup error_coding_blk
27  *
28  * \details
29  *
30  * Decodes frames received as async messages over a message
31  * port. This decoder deployment expects messages of soft decision
32  * symbols in and can produce either packed, PDU messages (\p
33  * packed = True) or messages full of unpacked bits (\p packed =
34  * False).
35  *
36  * This decoder works off a full message as one frame or block to
37  * decode. The message length is used to calculate the frame
38  * length. To support this, the decoder variable used will have
39  * had its frame_size set. This block treats that initial
40  * frame_size value as the maximum transmission unit (MTU) and
41  * will not process frames larger than that after being decoded.
42  *
43  * The packed PDU form of this deployment is designed to work well
44  * with other PDU-based blocks to operate within the processing
45  * flow of data packets or frames.
46  *
47  * Due to differences in how data is packed and processed, this
48  * block also offers the ability to change the direction of how
49  * bits are packed. All inputs messages are one soft decision per
50  * item. By default, the \p rev_pack mode is set to True. Using
51  * this setup allows the async block to behave with PDUs in the
52  * same operation and format as the tagged stream decoders. That
53  * is, putting the same data into both the tagged stream decoder
54  * deployment and this with the default setting should produce the
55  * same data.
56  *
57  * Because the block handles data as a full frame per message,
58  * this decoder deployment cannot work with any decoders that
59  * require history. For example, the gr::fec::code::cc_decoder
60  * decoder in streaming mode requires an extra rate*(K-1) bits to
61  * complete the decoding, so it would have to wait for the next
62  * message to come in and finish processing. Therefore, the
63  * streaming mode of the CC decoder is not allowed. The other
64  * three modes will work with this deployment since the frame is
65  * self-contained for decoding.
66  */
67 class FEC_API async_decoder : virtual public block
68 {
69 public:
70  typedef std::shared_ptr<async_decoder> sptr;
71 
72  /*!
73  * Build the PDU-based FEC decoder block from an FECAPI decoder object.
74  *
75  * \param my_decoder An FECAPI decoder object child of the generic_decoder class.
76  * \param packed Sets output to packed bytes if true; otherwise, 1 bit per byte.
77  * \param rev_pack If packing bits, should they be reversed?
78  * \param mtu The Maximum Transmission Unit (MTU) of the output
79  * frame that the block will be able to
80  * process. Specified in bytes and defaults to 1500.
81  */
82  static sptr make(generic_decoder::sptr my_decoder,
83  bool packed = false,
84  bool rev_pack = true,
85  int mtu = 1500);
86 
87  int general_work(int noutput_items,
88  gr_vector_int& ninput_items,
89  gr_vector_const_void_star& input_items,
90  gr_vector_void_star& output_items) override = 0;
91 };
92 
93 } /* namespace fec */
94 } /* namespace gr */
95 
96 #endif /* INCLUDED_FEC_ASYNC_DECODER_H */
The abstract base class for all 'terminal' processing blocks.
Definition: gnuradio-runtime/include/gnuradio/block.h:63
Creates the decoder block for use in GNU Radio flowgraphs from a given FEC API object derived from th...
Definition: async_decoder.h:68
std::shared_ptr< async_decoder > sptr
Definition: async_decoder.h:70
int general_work(int noutput_items, gr_vector_int &ninput_items, gr_vector_const_void_star &input_items, gr_vector_void_star &output_items) override=0
compute output items from input items
static sptr make(generic_decoder::sptr my_decoder, bool packed=false, bool rev_pack=true, int mtu=1500)
std::shared_ptr< generic_decoder > sptr
Definition: generic_decoder.h:62
#define FEC_API
Definition: gr-fec/include/gnuradio/fec/api.h:18
GNU Radio logging wrapper.
Definition: basic_block.h:29
std::vector< const void * > gr_vector_const_void_star
Definition: types.h:28
std::vector< void * > gr_vector_void_star
Definition: types.h:27
std::vector< int > gr_vector_int
Definition: types.h:23