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Upgrade LineageOS with Magisk

WARNING: tested only on my setup (LineageOS 18.1 on instantnoodle), other setups may break and brick the device!

Step-by-step instructions (for reinstalling patched boot.img for Magisk):

upgrade LineageOS to the latest by the standard way in Android GUI (download + install + reboot)
if using not the latest Magisk: wipe old (possibly hidden) Magisk app then install the up-to-date one from the official Magisk github repo
~~install (git clone) payload_dumper from GitHub (in Termux or in an SSH session on the Android device) for the 1st time, or update (git pull) later~~
~~the Android terminal session: wget the same LineageOS nightly image installed in step 1 from https://download.lineageos.org/~~

Event Loop

In computer science, the event loop, message dispatcher, message loop, message pump, or run loop is a programming construct that waits for and dispatches events or messages in a program.

It works by making a request to some internal or external "event provider" (that generally blocks the request until an event has arrived), and then it calls the relevant event handler ("dispatches the event").

The event-loop may be used in conjunction with a reactor, if the event provider follows the file interface, which can be selected or 'polled' (the Unix system call, not actual polling).

The event loop almost always operates asynchronously with the message originator.

For memory leaks

Build in CMake with these params:

CMAKE_CXX_FLAGS:STRING= -fsanitize=address  -fsanitize=leak -g
CMAKE_C_FLAGS:STRING=-fsanitize=address  -fsanitize=leak -g
CMAKE_EXE_LINKER_FLAGS:STRING=-fsanitize=address  -fsanitize=leak
CMAKE_MODULE_LINKER_FLAGS:STRING=-fsanitize=address  -fsanitize=leak

Which can be done with:

GCC compiler optimization for ARM-based systems

2017-03-03 fm4dd

The gcc compiler can optimize code by taking advantage of CPU specific features. Especially for ARM CPU's, this can have impact on application performance. ARM CPU's, even under the same architecture, could be implemented with different versions of floating point units (FPU). Utilizing full FPU potential improves performance of heavier operating systems such as full Linux distributions.

-mcpu, -march: Defining the CPU type and architecture

These flags can both be used to set the CPU type. Setting one or the other is sufficient.

The Go language for experienced programmers

Why use Go?

Like C, but with garbage collection, memory safety, and special mechanisms for concurrency
Pointers but no pointer arithmetic
No header files
Simple, clean syntax
Very fast native compilation (about as quick to edit code and restart as a dynamic language)
Easy-to-distribute executables

Generic makefile example for a C++ project

If you need a small makefile introduction/reference you can take a look at my notes https://www.mauriciopoppe.com/notes/os/bin/make/

Project structure

. project
├── Makefile
├── build

Receiving RTSP stream using FFMPEG and OpenCV

如果想要用OpenCV接收IPcam的串流來源，其中一種方法可以透過FFMPEG的Library實現。

首先電腦必須安裝FFMPEG

以下是Sample Code：

#include "stdafx.h"

Memory Optimization (Christer Ericson, GDC 2003)
http://realtimecollisiondetection.net/pubs/GDC03_Ericson_Memory_Optimization.ppt

Cache coherency primer (Fabian Giesen)
https://fgiesen.wordpress.com/2014/07/07/cache-coherency/

Code Clinic 2015: How to Write Code the Compiler Can Actually Optimize (Mike Acton)
http://gdcvault.com/play/1021866/Code-Clinic-2015-How-to

	#include <iostream>

	#include "borrow_checker.hpp"

	int main()
	{
	auto i = 42;

	// borrow `i` under name `ref`
	borrow_var(ref, i)

	/**
	* OpenCV video streaming over TCP/IP
	* Client: Receives video from server and display it
	* by Steve Tuenkam
	*/

	#include "opencv2/opencv.hpp"
	#include <sys/socket.h>
	#include <arpa/inet.h>
	#include <unistd.h>