8thString

Wednesday, October 01, 2025

QNX: Running a function at specific interval using timer interrupt

#include <iostream>
#include <csignal>
#include <ctime>
#include <cerrno>
#include <cstring>
#include <unistd.h>
#include <sys/time.h>
#include <time.h>
#include <stdio.h>

void timer_handler(int signo) { 
    struct timeval tv;
    gettimeofday(&tv, NULL);
    char buf[100];
    struct tm* nowtm;
    nowtm = localtime(&tv.tv_sec);
    strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", nowtm);
    printf("Timer expired at %s.%03ld\n", buf, tv.tv_usec / 1000);
}

int main() {
    timer_t timerid;
    struct sigevent sev;
    struct itimerspec its;
    struct sigaction sa;

    // Install the timer handler
    sa.sa_flags = 0;
    sa.sa_handler = timer_handler;
    sigemptyset(&sa.sa_mask);
    if (sigaction(SIGRTMIN, &sa, NULL) == -1) {
        std::cerr << "sigaction: " << errno << std::endl;
        return -1;
    }

    // Create the timer
    sev.sigev_notify = SIGEV_SIGNAL;
    sev.sigev_signo = SIGRTMIN;
    if (timer_create(CLOCK_REALTIME, &sev, &timerid) == -1) {
        std::cerr << "timer_create: " << errno << std::endl;
        return -1;
    }

    // Set the timer to expire every second
    its.it_value.tv_sec = 1;
    its.it_value.tv_nsec = 0;
    its.it_interval.tv_sec = 1;
    its.it_interval.tv_nsec = 0;
    if (timer_settime(timerid, 0, &its, NULL) == -1) {
        std::cerr << "timer_settime: " << errno << std::endl;
        return -1;
    }

    // Main loop
    while (true) {
        pause(); // Wait for signals
    }

    return 0;
}

Monday, September 29, 2025

CPP Quick Guide

Basics
Hello world
User input
While loop
If statement
For loop
Switch statement
Read file using ifstream
Write to a file using ofstream

Containers
Basic usage of std::list
Basic usage of std::map
Basic usage of std::vector
Data type conversion

Windows API with Exmaples
DeviceIoControl
FindFirstVolumeW
GetDiskFreeSpaceExW
GetLogicalDrives
GetLogicalDriveStrings

C++/WinRT
C++/WinRT Hello World

QNX
Using timer interrupt

Qt Cross-platform
Installing Qt Creator 9.0.1 on Windows 10
Qt console hello world
Qt Widget hello world
Qt Widget hello world code only

Keywords: C++, Qt, Programming, Tutorial

Sunday, September 21, 2025

Qt console hello world

This guide shows how a Qt console hello world looks like.

▣ Open Qt Creator and click on Create Project...

▣ Create Qt Console Application by following the section from @1 to @3.

▣ In Project Location window provide a project name, i.e., HelloWorldConsole

▣ In Define Build System select CMake

▣ In Translation File, take the default values

▣ In Kit Selection, select the toolchain kit to be used. Below shows only one which is MinGW 64-bit.

▣ In Project Management, take the default.

▣ In line 6, I have added an instruction to output Hello World in to the console. Also changed to return 0 to exit the application as event loop is not needed.

▣ Gist source code shown below for convenience

In Qt Creator 17.0.1/Qt 6.9.2, need to add QTextStream

▣ Running it using Qt Creator is well and good but we probably want to run it external to the IDE. To deploy the binary with all the dependencies, open the compiler environment used to build the application. In the case above we have used Qt 6.4.1 (MinGW 11.2.0 64-bit).

▣ Run the following command (change the paths as necessary)

cd \
md tmp
cd tmp
copy C:\Users\t\Documents\build-HelloWorldConsole-Desktop_Qt_6_4_1_MinGW_64_bit-Debug\HelloWorldConsole.exe
windeployqt HelloWorldConsole.exe

▣ The folder structure should look like this. It also shows a sample out from the application.

Keywords: CPP, Qt, Hello World

Wednesday, September 17, 2025

Several modules must be compiled when running VMware Workstation on Ubuntu

I have a machine with Ubuntu 24.04.2 with VMware Workstation working as expected. When I connected to the machine Ubuntu told me there were packages available that can be updated inlcuding the kernel. So, I did the update and rebooted the machine. Running VMware Workstation failed with "several modules must be compiled". The fix is quite easy, run the following to fix it.

$ sudo vmware-modconfig --console --install-all

Notes:
- VMWare Workstation: 17.6.3
- Host: Ubuntu 24.04.2 LTS

Friday, September 12, 2025

Hello world assembly on x86 Linux

Save code below as hello.asm

global _start

section .data
message: db 'hello, world!', 10

section .text
_start:
    mov     rax, 1          ; system call number should be stored in rax
    mov     rdi, 1          ; argument #1 in rdi, where to write (description)?
    mov     rsi, message    ; argument #2 in rsi, where does the string start?
    mov     rdx, 14         ; argument #3 in rdx, how many bytes to write?
    syscall                 ; this instruction invokes a system call

    mov     rax, 60         ; 'exit' syscall number
    xor     rdi, rdi
    syscall

Now assemble/build the file

nasm -felf64 hello.asm -o hello.o

Link to create executable

ld -o hello hello.o

Run it

u1@v1vm10:~$ ./hello 
hello, world!

Wednesday, September 10, 2025

Formatting code in Blogger

I have been using Github gists to share code and I have no plan of abandoning it. For smaller/one liners, I sometimes use div element with inline CSS.

I have been exploring formatting my code directly in Blogger but it is mostly hit and miss. I came accross highlight.js and I am impressed with the result.

Below is a quick guide how to format code using highlight.js:

Open blogger template
Before the <head> element, add the following
In the post itself, soround the code like:

Sunday, September 07, 2025

Test page for code formatting

netsh advfirewall firewall add rule name="RPC Endpoint Mapper" dir=in action=allow protocol=TCP localport=135

netsh advfirewall firewall add rule name="RPC Endpoint Mapper" dir=in action=allow protocol=TCP localport=135

Tags:
- Highlight.js
- hilite.me