R2D2

build_packet.js

const ESC = 0xAB;
const SOP = 0x8D;
const EOP = 0xD8;
const ESC_ESC = 0x23;
const ESC_SOP = 0x05;
const ESC_EOP = 0x50;

let seq = 0;

let buildPacket = (init, payload=[]) => {
    let packet = [SOP];
    let body = [];
    let packetEncoded = [];

    body.push(...init);
    body.push(seq);
    body.push(...payload);

    body.push(calculateChk(body));

    for (let i = 0 ; i < body.length ; i++) {
        if (body[i] == ESC) {
            packetEncoded.push(...[ESC, ESC_ESC]);
        }
        else if (body[i] == SOP) {
            packetEncoded.push(...[ESC, ESC_SOP]);
        }
        else if (body[i] == EOP) {
            packetEncoded.push(...[ESC, ESC_EOP]);
        }
        else {
            packetEncoded.push(body[i])
        }
    }

    packet.push(...packetEncoded);
    packet.push(EOP);
    seq++;

    return packet;
}