dmitryweiner

[Solved] uConsole CM4: built-in keyboard dead, garbage USB descriptors (5/.3/,%) — root cause + software fix

TL;DR: If your uConsole keyboard doesn't work and lsusb shows the keyboard with a garbled name like 5/.3/,% and wMaxPacketSize 0, your mainboard USB hub chip is likely defective: bit 6 of every byte passing through its Transaction Translator is stuck at 0. The keyboard itself is fine. There is a software workaround (below) that forces the USB host port to Full Speed and bypasses the broken block entirely — my keyboard and trackball work perfectly now. The proper fix is a mainboard replacement (warranty).

Symptoms

dmitryweiner

JavaScript JIT Optimization Guide

A comprehensive guide to writing JavaScript code that's friendly to JIT (Just-In-Time) compilers like V8, SpiderMonkey, and JavaScriptCore.

Table of Contents

1. Type Consistency
2. Object Shape Stability
3. Function Optimization
4. Array Operations

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const obj = { // אוביקט
    a: 1, // שדה
};

function sum(arr /* פרמטר */) { // פונקציה
    let acc// משתנה
        = 0; // ערך המשתנה
    for(let i = 0; i < arr.length; i++) { // לולאה
        acc += arr[i];
    }

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package com.dmitryweiner.myapplication;

import androidx.appcompat.app.AppCompatActivity;

import android.os.AsyncTask;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.View;
import android.widget.Button;

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package com.example.myapplication;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import android.Manifest;
import android.content.pm.PackageManager;
import android.os.Bundle;