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127 lines
3.6 KiB
C++
127 lines
3.6 KiB
C++
///////////////////////////////////////////////////////////////////////////////////////
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// Copyright (C) 2021 Jon Beniston, M7RCE <jon@beniston.com> //
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// //
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// This program is free software; you can redistribute it and/or modify //
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// it under the terms of the GNU General Public License as published by //
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// the Free Software Foundation as version 3 of the License, or //
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// (at your option) any later version. //
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// //
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// This program is distributed in the hope that it will be useful, //
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// but WITHOUT ANY WARRANTY; without even the implied warranty of //
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
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// GNU General Public License V3 for more details. //
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// //
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// You should have received a copy of the GNU General Public License //
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// along with this program. If not, see <http://www.gnu.org/licenses/>. //
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///////////////////////////////////////////////////////////////////////////////////////
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#include "DVBS2.h"
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int DVBS2::parity_chk( long a, long b)
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{
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int c = 0;
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a = a & b;
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for( int i = 0; i < 18; i++ )
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{
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if( a&(1L<<i)) c++;
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}
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return c&1;
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}
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//
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// This is not time sensitive and is only run at start up
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//
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void DVBS2::build_symbol_scrambler_table( void )
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{
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long x,y;
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int xa,xb,xc,ya,yb,yc;
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int rn,zna,znb;
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// Initialisation
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x = 0x00001;
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y = 0x3FFFF;
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for( int i = 0; i < FRAME_SIZE_NORMAL; i++ )
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{
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xa = parity_chk( x, 0x8050 );
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xb = parity_chk( x, 0x0081 );
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xc = x&1;
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x >>= 1;
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if( xb ) x |= 0x20000;
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ya = parity_chk( y, 0x04A1 );
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yb = parity_chk( y, 0xFF60 );
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yc = y&1;
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y >>= 1;
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if( ya ) y |= 0x20000;
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zna = xc ^ yc;
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znb = xa ^ yb;
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rn = (znb<<1) + zna;
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m_cscram[i] = rn;
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}
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}
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void DVBS2::pl_scramble_symbols( scmplx *fs, int len )
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{
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scmplx x;
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// Start at the end of the PL Header.
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for( int n = 0; n < len; n++ )
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{
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switch( m_cscram[n] )
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{
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case 0:
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// Do nothing
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break;
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case 1:
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x = fs[n];
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fs[n].re = -x.im;
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fs[n].im = x.re;
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break;
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case 2:
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fs[n].re = -fs[n].re;
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fs[n].im = -fs[n].im;
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break;
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case 03:
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x = fs[n];
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fs[n].re = x.im;
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fs[n].im = -x.re;
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break;
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}
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}
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}
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void DVBS2::pl_scramble_dummy_symbols( int len )
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{
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scmplx x;
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int p = 0;
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x = m_bpsk[0][0];
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for( int n = 90; n < len; n++ )
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{
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switch( m_cscram[p] )
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{
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case 0:
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// Do nothing
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m_pl_dummy[n].re = x.re;
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m_pl_dummy[n].im = x.im;
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break;
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case 1:
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m_pl_dummy[n].re = -x.im;
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m_pl_dummy[n].im = x.re;
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break;
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case 2:
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m_pl_dummy[n].re = -x.re;
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m_pl_dummy[n].im = -x.im;
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break;
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case 3:
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m_pl_dummy[n].re = x.im;
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m_pl_dummy[n].im = -x.re;
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break;
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}
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p++;
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}
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}
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