performance-check.js

'use strict';

/*
 * Fill the display with each character and determine how often the display
 * can be filled per second. At the same time, determine how often
 * setInterval(..., 1) times out per second.
 */
const Lcd = require('../lcd');
const lcd = new Lcd({rs: 23, e: 24, data: [17, 18, 22, 27], cols: 20, rows: 4});

let charCode = 0;
let timeouts = 0;
let time;
let iv;

const fillDisplay = _ => {
  lcd.print(new Array(20 * 4 + 1).join(String.fromCharCode(charCode)));
  charCode += 1;
};

const printResults = _ => {
  let seconds;
  let displayFillsPerSec;
  let timeoutsPerSec;

  time = process.hrtime(time);
  seconds = time[0] + time[1] / 1E9;

  displayFillsPerSec = Math.floor(256 / seconds);
  console.log(displayFillsPerSec + ' display fills per second');

  timeoutsPerSec = Math.floor(timeouts / seconds);
  console.log(timeoutsPerSec + ' timeouts per second');
};

lcd.on('ready',_ => {
  time = process.hrtime();
  iv = setInterval(_ => timeouts += 1, 1);
  fillDisplay();
});

lcd.on('printed', _ => {
  if (charCode < 256) {
    fillDisplay();
  } else {
    printResults();
    clearInterval(iv);
    lcd.close();
  }
});