mirror of
https://github.com/portapack-mayhem/mayhem-firmware.git
synced 2024-12-13 03:34:35 +00:00
106 lines
2.4 KiB
C++
106 lines
2.4 KiB
C++
/*
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* Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc.
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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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#ifndef __PACKET_BUILDER_H__
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#define __PACKET_BUILDER_H__
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#include <cstdint>
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#include <cstddef>
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#include <bitset>
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#include "bit_pattern.hpp"
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class PacketBuilder {
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public:
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void configure(
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const BitPattern preamble,
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const BitPattern unstuffing,
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size_t new_payload_length
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);
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template<typename PayloadHandler>
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void execute(
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const uint_fast8_t symbol,
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PayloadHandler payload_handler
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) {
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bit_history.add(symbol);
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switch(state) {
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case State::Preamble:
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if( found_preamble() ) {
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state = State::Payload;
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}
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break;
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case State::Payload:
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if( found_end_flag() || packet_truncated() ) {
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payload_handler(payload, bits_received);
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reset_state();
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} else {
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if( !found_stuffing_bit() ) {
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payload[bits_received++] = symbol;
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}
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}
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break;
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default:
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reset_state();
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break;
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}
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}
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private:
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enum State {
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Preamble,
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Payload,
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};
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bool packet_truncated() const {
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return bits_received > payload.size();
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}
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bool found_preamble() const {
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return bit_history.matches(preamble_pattern);
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}
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bool found_stuffing_bit() const {
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return bit_history.matches(unstuff_pattern);
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}
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bool found_end_flag() const {
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return bit_history.matches(end_flag_pattern);
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}
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BitHistory bit_history;
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BitPattern preamble_pattern { 0b01010101010101010101111110, 26, 1 };
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BitPattern unstuff_pattern { 0b111110, 6 };
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BitPattern end_flag_pattern { 0b01111110, 8 };
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size_t payload_length { 0 };
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size_t bits_received { 0 };
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State state { State::Preamble };
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std::bitset<256> payload;
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void reset_state();
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};
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#endif/*__PACKET_BUILDER_H__*/
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