Author Archives: Niall Cooling

About Niall Cooling

Co-Founder and Director of Feabhas since 1995.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.

Navigating Memory in C++: A Guide to Using std::uintptr_t for Address Handling

Posted on February 22, 2024 by Niall Cooling

In the modern landscape of embedded software development, efficiency and safety are paramount. As applications become more complex and demands on performance and security increase, developers turn to every tool in their arsenal to meet these challenges. Enter std::uintptr_t, a data type that, while not new, is sadly overlooked in most embedded codebases. This guide aims to introduce std::uintptr_t, showcasing its benefits and demonstrating how to use it effectively in your projects.

This article is written using C++ examples, but it […]

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Embedded Expertise: Beyond Fixed-Size Integers; Exploring Fast and Least Types

Posted on January 15, 2024 by Niall Cooling

The Challenge of Fixed-Size Integers Before C99

In embedded programming, before adopting the C99 standard (ISO/IEC 9899:1999), a significant challenge was ensuring the consistent sizing of key data objects. This complexity stemmed from the C standard’s (ISO/IEC 9899) non-committal stance on the size of an int. We knew:

A short is a minimum of 16-bits.
A long is a minimum of 32-bits.
An int is somewhere between a short and a long.

This flexibility boosted C’s portability, making it a favourite for various architectures, including […]

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Disassembling a Cortex-M raw binary file with Ghidra

Posted on December 20, 2022 by Niall Cooling

BlackHat Europe 2022

During the first week of December, I had the pleasure of attending a training course at BlackHat Europe 2022 titled Assessing and Exploiting Control Systems and IIoT run by Justin Searle.

Part of the course involved Assessing and Exploiting Embedded Firmware by reading on-chip Flash using OpenOCD. Unfortunately, we ran out of time to finish the last labs during the training (we ran 9 am-6 pm each day). So I decided to follow along with the very comprehensive notes […]

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Using final in C++ to improve performance

Posted on November 14, 2022 by Niall Cooling

Dynamic polymorphism (virtual functions) is central to Object-Oriented Programming (OOP). Used well, it provides hooks into an existing codebase where new functionality and behaviour can (relatively) easily be integrated into a proven, tested codebase.

Subtype inheritance can bring significant benefits, including easier integration, reduced regression test time and improved maintenance.

However, using virtual functions in C++ brings a runtime performance overhead. This overhead may appear inconsequential for individual calls, but in a non-trivial real-time embedded application, these overheads may build up and […]

Posted in C/C++ Programming, Design Issues | Tagged , , , , , | 12 Comments

Understanding Arm Cortex-M Intel-Hex (ihex) files

Posted on October 12, 2022 by Niall Cooling

Creating a flash image

The primary purpose of the ihex file in the embedded space is to create a file that is used to program/reprogram a target system. There are various file formats around, with the Intel Hex (ihex) format being among the most widely used.

The output of the linker stage of a build process is typically to generate a .elf file (Executable and Linkable Format). Many debuggers and programmers can work directly with the ELF file format. However, in many […]

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Working with Strings in Embedded C++

Posted on February 4, 2022 by Niall Cooling

In this post, by Embedded I’m generally referring to deeply embedded/bare-metal systems as opposed to Linux-based embedded systems.

Embedded systems and strings

Historically, the need for and thus the use of strings in embedded systems was fairly limited. However, this has changed with the advent of cheaper, full graphic displays and the growth of the ‘Internet of Things’ (IoT).

Many embedded systems sport full-colour graphics displays, supported by embedded-specific graphics libraries, including:

free open-source – e.g. LVGL
vendor-specific – e.g. TouchGFX from STMicroelectronics
fully specialised graphics […]

Posted in C/C++ Programming | Tagged , , , , , , | 11 Comments

TDD in C with Ceedling and WSL2 – performance issues

Posted on October 7, 2021 by Niall Cooling

Ceedling is still probably the best Test-Driven Development (TDD) environment for C programmers out there. But, as with many Free Open-Source Software ( FOSS ), tools getting it to work natively on a Windows environment involves the odd hoop-jumping exercise; either involving messing around with the likes of Cygwin or Mingw; or using a full Virtual Machine (VM) environment such as VirtualBox or VMware.

However, with the introduction of Windows-Subsystem-for-Linux (WSL) and the much-improved update to WSL2, running Linux centric FOSS […]

Posted in Build-systems, C/C++ Programming, Linux, Testing | Tagged , , , , , | 3 Comments

C++20 modules with GCC11

Posted on August 18, 2021 by Niall Cooling

Introduction

One of the headline changes of the C++20 standard is the inclusion of modules. Modules promise to significantly change the structure of C++ codebases and possibly signal headers’ ultimate demise (but probably not in my lifetime). It also opens the door to potentially have a unified build system and package manager, similar to Rust’s Cargo package manager; though I imaging standardising a unified build system would be one bloody battle.

Pre-C++20 builds

If you want to start a heated debate on any […]

Posted in C/C++ Programming | Tagged , | 12 Comments

Modern Embedded C++ – Deprecation of volatile

Posted on May 12, 2021 by Niall Cooling

Compiling the following, straightforward code:

volatile int x;

int main() {
x += 10;
}

https://godbolt.org/z/jq83vdvj5

Using g++ with the directive -std=c++17 builds without any warnings or errors. However, change the directive to -std=c++20, and the result is:

source>: In function ‘int main()’:
<source>:5:5: warning: compound assignment with ‘volatile’-qualified left operand is deprecated [-Wvolatile]
5 | x += 10;
| ~~^~~~~
Compiler returned: 0

The new C++ standard, C++20, has deprecated volatile! So, what […]

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GitHub Codespaces and online development

Posted on January 28, 2021 by Niall Cooling

In our previous posting, we discussed using VSCode’s Dev Container extension to allow running workspaces directly within a Docker container.

In December 2020, I was granted early access to a new feature developed by GitHub called Codespaces. Codespaces offers an online VSCode development environment, enabling you to develop entirely in the cloud.

The great news is that Codespaces uses the same core process, and file structure, as Dev Containers; meaning once we have our .devcontainer folder setup (if you are unfamiliar with […]

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