mirror of
https://github.com/SatDump/SatDump
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143 lines
No EOL
3.6 KiB
C++
143 lines
No EOL
3.6 KiB
C++
/* -*- c++ -*- */
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/*
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* Copyright 2018 Ron Economos.
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*
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* This 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; either version 3, or (at your option)
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* any later version.
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*
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* This software 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 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 software; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street,
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* Boston, MA 02110-1301, USA.
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*/
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/*
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* This file has been adapted from https://github.com/drmpeg/gr-dvbs2rx
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*/
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#include "bbframe_descramble.h"
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#include <algorithm>
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namespace dvbs2
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{
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BBFrameDescrambler::BBFrameDescrambler(dvbs2_framesize_t framesize, dvbs2_code_rate_t rate)
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{
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if (framesize == FECFRAME_NORMAL)
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{
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switch (rate)
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{
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case C1_4:
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kbch = 16008;
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break;
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case C1_3:
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kbch = 21408;
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break;
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case C2_5:
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kbch = 25728;
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break;
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case C1_2:
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kbch = 32208;
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break;
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case C3_5:
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kbch = 38688;
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break;
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case C2_3:
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kbch = 43040;
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break;
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case C3_4:
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kbch = 48408;
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break;
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case C4_5:
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kbch = 51648;
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break;
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case C5_6:
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kbch = 53840;
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break;
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case C8_9:
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kbch = 57472;
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break;
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case C9_10:
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kbch = 58192;
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break;
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default:
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kbch = 0;
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break;
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}
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}
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else if (framesize == FECFRAME_SHORT)
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{
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switch (rate)
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{
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case C1_4:
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kbch = 3072;
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break;
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case C1_3:
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kbch = 5232;
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break;
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case C2_5:
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kbch = 6312;
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break;
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case C1_2:
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kbch = 7032;
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break;
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case C3_5:
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kbch = 9552;
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break;
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case C2_3:
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kbch = 10632;
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break;
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case C3_4:
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kbch = 11712;
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break;
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case C4_5:
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kbch = 12432;
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break;
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case C5_6:
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kbch = 13152;
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break;
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case C8_9:
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kbch = 14232;
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break;
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default:
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kbch = 0;
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break;
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}
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}
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init();
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}
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BBFrameDescrambler::~BBFrameDescrambler()
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{
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}
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void BBFrameDescrambler::init()
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{
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std::fill(bb_derandomise, &bb_derandomise[FRAME_SIZE_NORMAL / 8], 0);
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int sr = 0x4A80;
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for (int i = 0; i < FRAME_SIZE_NORMAL; i++)
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{
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int b = ((sr) ^ (sr >> 1)) & 1;
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bb_derandomise[i / 8] = b << (7 - (i % 8)) | bb_derandomise[i / 8];
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sr >>= 1;
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if (b)
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sr |= 0x4000;
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}
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}
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int BBFrameDescrambler::work(uint8_t *frame)
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{
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for (int j = 0; j < (int)kbch / 8; ++j)
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frame[j] = frame[j] ^ bb_derandomise[j];
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return 0;
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}
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} |