Category Archives: C/C++ Programming

CMake Part 2 – Release and Debug builds

Associate Instructor at Feabhas Ltd
An independent IT trainer Martin has over 40 years academic and commercial experience in open systems software engineering. He has worked with a range of technologies from real time process controllers, through compilers, to large scale parallel processing systems; and across multiple sectors including industrial systems, semi-conductor manufacturing, telecomms, banking, MoD, and government.
Martin Bond
Latest posts by Martin Bond (see all)

In my previous blog post CMake Part – The Dark Arts I discussed how to configure CMake to cross-compile to target hardware such as our STM32F407 Discovery board.

We looked at the minimum requirements to configure the CMake build generator for a cross-compilation project using a project definition file (CMakeLists.txt), a toolchain definition file (toolchain-STM32F407.cmake). The CMake commands used to generate and build the project are:

cmake -S . -B build -DCMAKE_TOOLCHAIN_FILE=toolchain-STM32F407.cmake
cmake –build build

In the real world, projects are never as simple […]

Posted in ARM, Build-systems, C/C++ Programming, Cortex, General, Toolchain | Tagged , | 3 Comments

CMake Part 1 – The Dark Arts

Associate Instructor at Feabhas Ltd
An independent IT trainer Martin has over 40 years academic and commercial experience in open systems software engineering. He has worked with a range of technologies from real time process controllers, through compilers, to large scale parallel processing systems; and across multiple sectors including industrial systems, semi-conductor manufacturing, telecomms, banking, MoD, and government.
Martin Bond
Latest posts by Martin Bond (see all)

In our previous post Why We Need Build Systems we examined the need for Build Systems in modern software development. In this post we will examine how to use CMake to mange the build process for a cross compilation project.

CMake can be described as a marmite application: you either love it or hate it. Here at Feabhas, we find ourselves falling in the latter category, despite the fact the CMake is widely used within the embedded and deeply embedded development […]

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Why We Need Build Systems

Associate Instructor at Feabhas Ltd
An independent IT trainer Martin has over 40 years academic and commercial experience in open systems software engineering. He has worked with a range of technologies from real time process controllers, through compilers, to large scale parallel processing systems; and across multiple sectors including industrial systems, semi-conductor manufacturing, telecomms, banking, MoD, and government.
Martin Bond
Latest posts by Martin Bond (see all)

Build systems were developed to simplify and automate running the compiler and linker and are an essential part of modern software development. This blog post is a precursor to future posts discussing our experiences refactoring the training projects to use the CMake build generator.

Using Build Systems

Build systems can be standalone command line applications such as  Make, Scons and Ninja; or part of an (Integrated Development Environment IDE) like Visual Studio , XCode or IAR Workbench.

Configuring build systems for a project […]

Posted in Build-systems, C/C++ Programming, Toolchain | 8 Comments

Modern Embedded C++ – Deprecation of volatile

Director at Feabhas Limited
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.

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

Director at Feabhas Limited
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.

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 […]

Posted in Agile, C/C++ Programming, General, Industry Analysis, Testing | Tagged , , , , , | Leave a comment

VSCode, Dev Containers and Docker: moving software development forward

Director at Feabhas Limited
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.

Long term readers of this blog will know our devotion to using container-based technology, especially Docker, to significantly improve software quality through repeatable builds.

In the Autumn/fall of 2020, Microsoft introduced a Visual Studio Code (VSCode) extension Remote – Containers. With one quick stroke, this extension allows you to open a VSCode project within a Docker container.

Getting started with Dev Containers and Docker

There are several different approaches to using Dev Containers. In this post, we shall cover three options:

Using an existing […]

Posted in Agile, C/C++ Programming, Testing | Tagged , , , , , , , | 1 Comment

Introduction to the ARM® Cortex®-M7 Cache – Part 3 Optimising software to use cache

Director at Feabhas Limited
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.

Caches – Why do we miss?
Cold Start

As stated, both data and instruction caches are required to be invalidated on system start. Therefore, the first load of any object (code or data) cannot be in cache (thus the cold start condition).

One available technique to help with cold-start conditions is the ability to pre-load data into the cache. The ARMv7-M instruction set adds the Preload Data (PLD) instruction. The PLD instruction signals to the memory system that data memory accesses from a […]

Posted in ARM, C/C++ Programming, CMSIS, Cortex, Design Issues | Tagged , | 2 Comments

TDD with Compiler Explorer

Director at Feabhas Limited
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.

Compiler Explorer (CE) has been around for several years now. When it first appeared on the scene, it immediately became an invaluable tool. Its ability to show generated assembler from given source code across many different compilers and ISAs (Instruction Set Architectures) is “mind-blowing”. We use it extensively when teaching as it allows you to clarify the effect your code can have on both performance and memory usage. 

However, rather than limiting itself to only showing generated assembler, recent developments include the […]

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Side effects and sequence points; why volatile matters

Director at Feabhas Limited
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.

Introduction

Most embedded programmers, and indeed anyone who has attended a Feabhas programming course, is familiar with using the volatile directive when accessing registers. But it is not always obvious the ‘whys and wherefores’ of the use of volatile.

In this article, we explore why using volatile works, but more importantly, why it is needed in the first place.

Peripheral register access

If we start with a simple, fictitious, example. Suppose we have a peripheral with the following register layout:

register
width
offset

control
byte
0x00

configuration
byte
0x01

data
byte
0x02

status
byte
0x03

with a base address of […]

Posted in ARM, C/C++ Programming, CMSIS, Cortex | Tagged , , , , | 2 Comments

Practice makes perfect, part 3 – Idiomatic kata

Technical Consultant at Feabhas Ltd
Glennan is an embedded systems and software engineer with over 20 years experience, mostly in high-integrity systems for the defence and aerospace industry.

He specialises in C++, UML, software modelling, Systems Engineering and process development.
Glennan Carnie

Previously, we looked at some of the foundational C++ code kata – that is, elements of C++ coding that are absolutely key to master if you’re going to be programming in C++.
Practice makes perfect, part 1 – Code kata
Practice makes perfect, part 2 – foundation kata

In this article I want to introduce what I call ‘idiomatic’ kata.  These exercises have a bit more latitude (and variation) in how they can be implemented.  In that respect they are closer to traditional […]

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