mirror of
https://github.com/f4exb/sdrangel.git
synced 2024-11-14 12:22:00 -05:00
129 lines
4.7 KiB
C++
129 lines
4.7 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
|
|
// Copyright (C) 2020-2021 Jon Beniston, M7RCE <jon@beniston.com> //
|
|
// //
|
|
// This program is free software; you can redistribute it and/or modify //
|
|
// it under the terms of the GNU General Public License as published by //
|
|
// the Free Software Foundation as version 3 of the License, or //
|
|
// (at your option) any later version. //
|
|
// //
|
|
// This program is distributed in the hope that it will be useful, //
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of //
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
|
|
// GNU General Public License V3 for more details. //
|
|
// //
|
|
// You should have received a copy of the GNU General Public License //
|
|
// along with this program. If not, see <http://www.gnu.org/licenses/>. //
|
|
///////////////////////////////////////////////////////////////////////////////////
|
|
|
|
#ifndef INCLUDE_LFSR_H
|
|
#define INCLUDE_LFSR_H
|
|
|
|
#include <stdint.h>
|
|
|
|
#include "export.h"
|
|
|
|
// Linear feedback shift register that can be used for scrambling or generating
|
|
// PN (Pseudo Noise) random sequence.
|
|
class SDRBASE_API LFSR
|
|
{
|
|
public:
|
|
// Create and initialise LFSR with specified number of bits, polynomial and
|
|
// initial state (which must be non-zero, unless a multiplicative scrambler).
|
|
// The +1 is implicit in the polynomial so x^1 + 1 should be passed as 0x01
|
|
LFSR(uint32_t polynomial, uint32_t init_value = ~0U, int rand_bits = 1) :
|
|
m_rand_bits(rand_bits),
|
|
m_polynomial(polynomial),
|
|
m_init_value(init_value)
|
|
{
|
|
init();
|
|
}
|
|
|
|
// Initialise LFSR state
|
|
void init()
|
|
{
|
|
m_sr = m_init_value;
|
|
}
|
|
|
|
// Shift the LFSR one bit and return output of XOR
|
|
int shift();
|
|
|
|
// Multiplicative scramble a single bit using LFSR
|
|
int scramble(int bit_in);
|
|
|
|
// Multiplicative scramble of data using LFSR - LSB first
|
|
void scramble(uint8_t *data, int length);
|
|
// Descramble data using LFSR - LSB first
|
|
void descramble(uint8_t *data, int length);
|
|
|
|
// XOR data with rand_bits from LFSR generating pseudo noise (PN) sequence - LSB first
|
|
void randomize(uint8_t *data, int length);
|
|
// XOR data with rand_bits from LFSR generating pseudo noise (PN) sequence - MSB first
|
|
void randomizeMSB(const uint8_t *dataIn, uint8_t *dataOut, int length);
|
|
|
|
// Get current shift-register value
|
|
uint32_t getSR()
|
|
{
|
|
return m_sr;
|
|
}
|
|
|
|
// Set the polynomial
|
|
void setPolynomial(uint32_t polynomial)
|
|
{
|
|
m_polynomial = polynomial;
|
|
}
|
|
|
|
// Get the polynomial
|
|
uint32_t getPolynomial()
|
|
{
|
|
return m_polynomial;
|
|
}
|
|
|
|
private:
|
|
int m_rand_bits; // Which bits from the SR to use in randomize()
|
|
uint32_t m_polynomial; // Polynomial coefficients (+1 is implicit)
|
|
uint32_t m_init_value; // Value to initialise SR to when init() is called
|
|
uint32_t m_sr; // Shift register
|
|
};
|
|
|
|
// http://www.jrmiller.demon.co.uk/products/figs/man9k6.pdf
|
|
// In Matlab: comm.Scrambler(2, '1 + z^-12 + z^-17', 0)
|
|
// Call scramble()
|
|
class SDRBASE_API ScramblerG3RUG : public LFSR
|
|
{
|
|
public:
|
|
ScramblerG3RUG() : LFSR(0x10800, 0x0) {}
|
|
};
|
|
|
|
// https://public.ccsds.org/Pubs/131x0b3e1.pdf
|
|
// x^8+x^7+x^5+x^3+1
|
|
// In Matlab: comm.PNSequence('Polynomial', 'x^8+x^7+x^5+x^3+1', 'InitialConditions', [1 1 1 1 1 1 1 1])
|
|
// randomize() shifts to right, so polynomial below is reversed with x^8 implicit
|
|
// Call randomize()
|
|
class SDRBASE_API RandomizeCCSDS : public LFSR
|
|
{
|
|
public:
|
|
RandomizeCCSDS() : LFSR(0x95, 0xff, 1<<7) {}
|
|
};
|
|
|
|
// DVB-S
|
|
// https://www.etsi.org/deliver/etsi_en/300400_300499/300421/01.01.02_60/en_300421v010102p.pdf
|
|
// x^15+x^14+1
|
|
// In Matlab: comm.PNSequence('Polynomial', 'z^15+z^1+1', 'InitialConditions', [1 0 0 1 0 1 0 1 0 0 0 0 0 0 0], 'Mask', [0 0 0 0 0 0 0 0 0 0 0 0 0 1 1])
|
|
// Call randomizeMSB()
|
|
class SDRBASE_API RandomizeDVBS : public LFSR
|
|
{
|
|
public:
|
|
RandomizeDVBS() : LFSR(0x6000, 0x00a9, 0x6000) {}
|
|
};
|
|
|
|
// 802.15.4 GFSK PHY
|
|
// In Matlab: comm.PNSequence('Polynomial', [1 0 0 0 1 0 0 0 0 1], 'InitialConditions', [0 1 1 1 1 1 1 1 1], 'Mask', [1 0 0 0 0 0 0 0 0])
|
|
// Call randomize()
|
|
class SDRBASE_API Randomize_802_15_4_PN9 : public LFSR
|
|
{
|
|
public:
|
|
Randomize_802_15_4_PN9() : LFSR(0x108, 0x1fe, 1) {}
|
|
};
|
|
|
|
#endif
|