portapack-mayhem/firmware/application/protocols/lcr.cpp

/*
 * Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc.
 * Copyright (C) 2016 Furrtek
 *
 * This file is part of PortaPack.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street,
 * Boston, MA 02110-1301, USA.
 */

#include "lcr.hpp"
#include "string_format.hpp"

namespace lcr {

std::string generate_message(std::string rgsb, std::vector<std::string> litterals, size_t option_ec) {
    const std::string ec_lut[4] = {"A", "J", "N", "S"};  // Eclairage (Auto, Jour, Nuit)
    char eom[3] = {3, 0, 0};                             // EOM and space for checksum
    uint8_t i;
    std::string lcr_message{127, 127, 127, 127, 127, 127, 127, 5};  // 5/15 ? Modem sync and SOM
    char checksum = 0;

    // Pad litterals to 7 chars (not required ?)
    for (auto& litteral : litterals)
        while (litteral.length() < 7)
            litteral += ' ';

    // Compose LCR message
    lcr_message += rgsb;
    lcr_message += "PA ";

    i = 1;
    for (auto& litteral : litterals) {
        lcr_message += "AM=";
        lcr_message += to_string_dec_uint(i, 1);
        lcr_message += " AF=\"";
        lcr_message += litteral;
        lcr_message += "\" CL=0 ";
        i++;
    }

    lcr_message += "EC=";
    lcr_message += ec_lut[option_ec];
    lcr_message += " SAB=0";

    // Checksum
    i = 7;  // Skip modem sync
    while (lcr_message[i])
        checksum ^= lcr_message[i++];
    checksum ^= eom[0];  // EOM char
    checksum &= 0x7F;    // Trim
    eom[1] = checksum;

    lcr_message += eom;

    return lcr_message;
}

} /* namespace lcr */