unpack_2bit_samples.h File Reference

Unpacks 2 bit samples samples may be packed in any of the following ways: 1) Into bytes [ item == byte ] 1a) Big endian ordering within the byte 1b) Little endian ordering within the byte 2) Into shorts [ item == short ] 2a) Big endian ordering of bytes, big endian within the byte 2b) Big endian ordering of bytes, little endian within the byte 2c) Little endian ordering of bytes, big endian within the byte 2d) Little endian ordering of bytes, little endian within the byte. More...

#include "gnss_block_interface.h"
#include <gnuradio/sync_interpolator.h>
#include <cstdint>
#include <vector>

Go to the source code of this file.

Classes
class	unpack_2bit_samples
	This class takes 2 bit samples that have been packed into bytes or shorts as input and generates a byte for each sample. It generates eight times as much data as is input (every two bits become 16 bits). More...

Typedefs
using	unpack_2bit_samples_sptr = gnss_shared_ptr<unpack_2bit_samples>

Functions
unpack_2bit_samples_sptr	make_unpack_2bit_samples (bool big_endian_bytes, size_t item_size, bool big_endian_items, bool reverse_interleaving=false)

Detailed Description

Unpacks 2 bit samples samples may be packed in any of the following ways: 1) Into bytes [ item == byte ] 1a) Big endian ordering within the byte 1b) Little endian ordering within the byte 2) Into shorts [ item == short ] 2a) Big endian ordering of bytes, big endian within the byte 2b) Big endian ordering of bytes, little endian within the byte 2c) Little endian ordering of bytes, big endian within the byte 2d) Little endian ordering of bytes, little endian within the byte.

Within a byte the two possibilities look like this: 7 6 5 4 3 2 1 0 : Bit number x_n,1 x_n,0 x_n+1,1 x_n+1,0 x_n+2,1 x_n+2,0 x_n+3,1 x_n+3,0 : Little endian x_n+3,1 x_n+3,0 x_n+2,1 x_n+2,0 x_n+1,0 x_n+1,0 x_n,1 x_n, 0 : Big Endian

For a short (uint16_t) the bytes are either transmitted as follows:

1 0 : Byte number Byte_n Byte_n+1 : Little endian Byte_n+1 Byte_n : Bit endian

The two bit values are assumed to have the following mapping:

x_1 x_0 Value 0 0 +1 0 1 +3 1 0 -3 1 1 -1

Letting x denote the two's complement interpretation of x_1 x_0, then:

Value = 2*x + 1

We want to output the data in the order:

Value_0, Value_1, Value_2, ..., Value_n, Value_n+1, Value_n+2, ...

Author

Cillian O'Driscoll cillian.odriscoll (at) gmail . com

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GNSS-SDR is a Global Navigation Satellite System software-defined receiver. This file is part of GNSS-SDR.

Copyright (C) 2010-2020 (see AUTHORS file for a list of contributors) SPDX-License-Identifier: GPL-3.0-or-later

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Definition in file unpack_2bit_samples.h.