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sdrangel/plugins/channeltx/moddatv/dvb-s2/dvb2_scrambler.cpp

40 lines
1.8 KiB
C++

///////////////////////////////////////////////////////////////////////////////////////
// Copyright (C) 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/>. //
///////////////////////////////////////////////////////////////////////////////////////
#include "DVB2.h"
void DVB2::init_bb_randomiser(void)
{
int sr = 0x4A80;
for( int i = 0; i < FRAME_SIZE_NORMAL; i++ )
{
int b = ((sr)^(sr>>1))&1;
m_bb_randomise[i] = b;
sr >>= 1;
if( b ) sr |= 0x4000;
}
}
//
// Randomise the data bits
//
void DVB2::bb_randomise(void)
{
for( int i = 0; i < m_format[0].kbch; i++ )
{
m_frame[i] ^= m_bb_randomise[i];
}
}