MRobertEvers

// TopicMatch.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <vector>
#include <string>
#include <iostream>

using namespace std;

MRobertEvers

Synchronization Objects

Mutexes, Semaphores, etc. are provided by the operating system as a means of synchronization. Their behavior is handled by the operating system.

Normally, on windows/freeRTOS, the scheduler will not context switch into a thread that is waiting on a synchronization object.

See here for windows https://docs.microsoft.com/en-us/windows/desktop/procthread/context-switches

MRobertEvers

https://stackoverflow.com/questions/40841882/automatically-access-git-submodules-via-ssh-or-https/44630028

MRobertEvers

# Decorators Differences
https://stackoverflow.com/questions/35572663/using-python-decorator-with-or-without-parentheses

MRobertEvers

Caching Effects In Arrays

https://stackoverflow.com/questions/9936132/why-does-the-order-of-the-loops-affect-performance-when-iterating-over-a-2d-arra

https://stackoverflow.com/questions/11413855/why-is-transposing-a-matrix-of-512x512-much-slower-than-transposing-a-matrix-of?noredirect=1&lq=1

Branch Prediction

https://stackoverflow.com/questions/11227809/why-is-it-faster-to-process-a-sorted-array-than-an-unsorted-array

MRobertEvers

Android Studio

What is Gradle

Gradle is a generic build system like Make (of course Gradle is more modern). It allows you to run scripts by using gradle.scripts or build.gradle. E.g.

dependencies{
    compile "Package..."
}

MRobertEvers

Pairing is the process of exchanging security information between two bluetooth devices so they can use an encrypted channel. Bonded means that the devices store a longer term key so that they need not reexchange security information. By that definition, a Bonded device is a paired device.

https://www.silabs.com/community/wireless/bluetooth/knowledge-base.entry.html/2017/05/16/understanding_thebl-sICq

http://blog.bluetooth.com/bluetooth-pairing-part-1-pairing-feature-exchange

https://stackoverflow.com/questions/36396456/bluetooth-difference-between-pairing-and-paging-bonding

MRobertEvers

Resources

JTAG explained

https://blog.senr.io/blog/jtag-explained

OpenOCD and JTAG

https://stackoverflow.com/questions/38033130/how-to-use-the-gdb-gnu-debugger-and-openocd-for-microcontroller-debugging-fr

MRobertEvers

ISRs in ESP32 FreeRTOS

As of 5/21/18 According the the ESP-IDF readthedocs here, ISRs must be placed in IRAM.

After some investigation, I found this to not be entirely true. I noticed that their UART driver did not have its ISR placed in IRAM and I set out to find out why they could get away with this.

Furthermore, the [SPI flash drivers] state that they disable all non-IRAM ISRs. I found that this is only true if the driver for some ISR is installed in a way that notifies the SPI drivers that the new driver is not IRAM.

See the following links for explanation ISRs in IRAM: IRAM ISRs and

MRobertEvers

Web Devolopment Notes

Notes on the Buzzword soup of web development.

JavaScript

1. JavaScript is single threaded in the web browser. *Web Workers provide a threading-like interface
2. Operates on event loop. https://developer.mozilla.org/en-US/docs/Web/JavaScript/EventLoop
3. What does the new operator do? https://stackoverflow.com/questions/6750880/how-does-the-new-operator-work-in-javascript

JavaScript Event Loop

https://www.youtube.com/watch?v=8aGhZQkoFbQ Javascript is basically a language interpreter with a stack and a heap. It is single threaded. Asynchronous programming is acheived by the libraries provided to it by the environment. E.g. setTimeout is offered by the web browser and accessible in Javascript. In that case, the Web Browser performs the input action after a given amount of time by placing the action into the Javascript event queue. When the main thread (read 'stack') is empty, the event loop places the callback onto Javascript's stack, and Javascript executes it.