77 lines
2.1 KiB
C++
77 lines
2.1 KiB
C++
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/*
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* Copyright (C) 2017 Jared Boone, ShareBrained Technology, Inc.
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* Copyright (C) 2019 Furrtek
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*
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* This file is part of PortaPack.
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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; either version 2, or (at your option)
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* 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 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; 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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#include "rfm69.hpp"
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#include "crc.hpp"
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#include "portapack_shared_memory.hpp"
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uint32_t RFM69::gen_frame(std::vector<uint8_t>& payload) {
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CRC<16> crc { 0x1021, 0x1D0F, 0xFFFF };
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std::vector<uint8_t> frame { };
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uint8_t byte_out = 0;
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// Preamble
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// Really is 0xAA but the RFM69 skips the very last bit (bug ?)
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// so the whole preamble is shifted right to simulate that
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frame.insert(frame.begin(), num_preamble_, 0x55);
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// Sync word
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frame.push_back(sync_word_ >> 8);
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frame.push_back(sync_word_ & 0xFF);
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// Payload length
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payload.insert(payload.begin(), payload.size());
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crc.process_bytes(payload.data(), payload.size());
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if (CRC_) {
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payload.push_back(crc.checksum() >> 8);
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payload.push_back(crc.checksum() & 0xFF);
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}
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// Manchester-encode payload
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if (manchester_) {
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for (auto byte : payload) {
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for (uint32_t b = 0; b < 8; b++) {
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byte_out <<= 2;
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if (byte & 0x80)
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byte_out |= 0b10;
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else
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byte_out |= 0b01;
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if ((b & 3) == 3)
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frame.push_back(byte_out);
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byte <<= 1;
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}
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}
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} else {
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frame.insert(frame.end(), payload.begin(), payload.end());
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}
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memcpy(shared_memory.bb_data.data, frame.data(), frame.size());
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// Copy for baseband
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return frame.size();
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}
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