Torque OBD2 Parser in JS

data.csv

example.js

const toposort = require('toposort');
const math = require('mathjs');
const fs = require('fs');
const csv = require('csv');
const data = fs.readFileSync('./data.csv', 'utf8');

const formulas = [];
const parser = csv.parse(data, {
  trim: true,
  skip_empty_lines: true,
  columns: ['name','shortName', 'mode', 'equation', 'min', 'max', 'units', 'header'],
});

let record;
while (record = parser.read()) formulas.push(record);

const graph = formulas.reduce((acc, formula) => {
  const deps = formula.equation.match(/val\{.*?\}/g);
  if (deps) {
    acc.push(...deps.map(dep => [formula.name, dep.substr(4, dep.length - 5)]));
  } else {
    acc.push([formula.name]);
  }
  return acc;
}, []);

const processEquation = (equation) => {
  return String(equation)
    .replace(/signed\s*\(/ig, 'sign(')
    .replace(/</g, '<<')
    .replace(/val\s*\{(.*?)\}/g, (a, b) => `val("${b}")`)
    .replace(/\{\s*([a-zA-Z]{1,2})\s*:\s*(\d+)\s*\}/g, (a, b, c) => `bit(${b},${c})`);
}

const sortedFormulas = toposort(graph).reverse().map((name) => formulas.find(f => f.name === name)).filter(n => !!n);

const processFrame = (frame, formulas) => {
  const result = {};
  const val = (name) => result[name];
  const bit = (a, b) => {
    const bits = (a >> 0).toString(2).padEnd(8, '0');
    return Number(bits[b]);
  }
  formulas.forEach(({ name, equation }) => {
    const eq = processEquation(equation);
    try {
      result[name] = math.eval(eq, {
        ...frame,
        val,
        bit,
      });
    } catch (err) {
      result[name] = 0;
    }
  });
  return result;
}


// Example frame

const raw = 'FF F7 E7 FF BC 16 AE 43 08 00 00 00 0F CF 09 08 08 08 08 09 00 00 0A CE 30 CE 4A 00 00 78 00 00 15 B2 00 00 12 F4 00 00 08 40 00 00 06 D1 00 05 F7 06 09 00 03 00 00 00 00 03 E8';

const frame = raw.split(' ').reduce((acc, value, i) => {
  let key = String.fromCharCode(97 + i);
  if (i > 25) {
    key = String.fromCharCode(96 + Math.floor(i / 26)) + String.fromCharCode(97 + (i % 26));
  }
  acc[key.toUpperCase()] = parseInt(value, 16);
  acc[key.toLowerCase()] = parseInt(value, 16);
  return acc;
}, []);

console.log(processFrame(frame, sortedFormulas));