mirror of
https://github.com/portapack-mayhem/mayhem-firmware.git
synced 2025-04-21 22:21:44 +00:00
125 lines
3.5 KiB
C++
125 lines
3.5 KiB
C++
/*
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* Copyright (C) 2015 Jared Boone, ShareBrained Technology, Inc.
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* Copyright (C) 2016 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 "pocsag.hpp"
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#include "baseband_api.hpp"
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#include "portapack.hpp"
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#include "portapack_persistent_memory.hpp"
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using namespace portapack;
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#include "string_format.hpp"
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#include "utility.hpp"
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namespace pocsag {
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std::string bitrate_str(BitRate bitrate) {
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switch (bitrate) {
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case BitRate::FSK512: return "512 ";
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case BitRate::FSK1200: return "1200";
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case BitRate::FSK2400: return "2400";
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default: return "????";
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}
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}
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std::string flag_str(PacketFlag packetflag) {
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switch (packetflag) {
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case PacketFlag::NORMAL: return "OK";
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case PacketFlag::IDLE: return "IDLE";
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case PacketFlag::TIMED_OUT: return "TIMED OUT";
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case PacketFlag::TOO_LONG: return "TOO LONG";
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default: return "";
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}
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}
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bool decode_batch(const POCSAGPacket& batch, POCSAGState * const state) {
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uint32_t codeword;
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char ascii_char;
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std::string output_text = "";
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state->out_type = EMPTY;
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// For each codeword...
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for (size_t i = 0; i < 16; i++) {
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codeword = batch[i];
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if (!(codeword & 0x80000000U)) {
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// Address codeword
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if (state->mode == STATE_CLEAR) {
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if (codeword != POCSAG_IDLE) {
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state->function = (codeword >> 11) & 3;
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state->address = (codeword >> 10) & 0x1FFFF8U; // 18 MSBs are transmitted
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state->mode = STATE_HAVE_ADDRESS;
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state->out_type = ADDRESS;
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state->ascii_idx = 0;
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state->ascii_data = 0;
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}
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} else {
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state->mode = STATE_CLEAR; // New address = new message
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}
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} else {
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// Message codeword
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if (state->mode == STATE_HAVE_ADDRESS) {
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// First message codeword: complete address
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state->address |= (i >> 1); // Add in the 3 LSBs (frame #)
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state->mode = STATE_GETTING_MSG;
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}
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state->out_type = MESSAGE;
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state->ascii_data |= ((codeword >> 11) & 0xFFFFF); // Get 20 message bits
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state->ascii_idx += 20;
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// Raw 20 bits to 7 bit reversed ASCII
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while (state->ascii_idx >= 7) {
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state->ascii_idx -= 7;
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ascii_char = ((state->ascii_data) >> (state->ascii_idx)) & 0x7F;
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// Bottom's up
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ascii_char = (ascii_char & 0xF0) >> 4 | (ascii_char & 0x0F) << 4; // 01234567 -> 45670123
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ascii_char = (ascii_char & 0xCC) >> 2 | (ascii_char & 0x33) << 2; // 45670123 -> 67452301
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ascii_char = (ascii_char & 0xAA) >> 2 | (ascii_char & 0x55); // 67452301 -> *7654321
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// Translate non-printable chars
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if ((ascii_char < 32) || (ascii_char > 126))
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output_text += "[" + to_string_dec_uint(ascii_char) + "]";
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else
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output_text += ascii_char;
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}
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state->ascii_data <<= 20; // Remaining bits are for next time...
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}
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}
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state->output = output_text;
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if (state->mode == STATE_HAVE_ADDRESS)
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state->mode = STATE_CLEAR;
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return true;
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}
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} /* namespace pocsag */
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