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Category Archives: Design Issues
Using final in C++ to improve performance
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.
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.
Latest posts by Niall Cooling (see all)
- Disassembling a Cortex-M raw binary file with Ghidra - December 20, 2022
- Using final in C++ to improve performance - November 14, 2022
- Understanding Arm Cortex-M Intel-Hex (ihex) files - October 12, 2022
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 C++, design patterns, final, interface, Modern C++, Polymorphism
12 Comments
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.
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.
Latest posts by Niall Cooling (see all)
- Disassembling a Cortex-M raw binary file with Ghidra - December 20, 2022
- Using final in C++ to improve performance - November 14, 2022
- Understanding Arm Cortex-M Intel-Hex (ihex) files - October 12, 2022
Part 1 Cache Basics
Part 2 Cache Replacement Policy
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 […]
Introduction to the ARM® Cortex®-M7 Cache – Part 2 Cache Replacement Policy
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.
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.
Latest posts by Niall Cooling (see all)
- Disassembling a Cortex-M raw binary file with Ghidra - December 20, 2022
- Using final in C++ to improve performance - November 14, 2022
- Understanding Arm Cortex-M Intel-Hex (ihex) files - October 12, 2022
Part 1 Cache Basics
Instruction Cache Replacement Policy
Starting with the simpler instruction cache case; when we encounter a cache miss the normal policy is to evict the current cache line and replace it with the new cache line. This is known as a read-allocate policy and is the default on all instruction caches.
Cold start (first read)
It should also be noted that on system power-up the initial state of the cache is unknown. On the ARMv7-M all caches are disabled at reset. […]
Introduction to the ARM® Cortex®-M7 Cache – Part 1 Cache Basics
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.
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.
Latest posts by Niall Cooling (see all)
- Disassembling a Cortex-M raw binary file with Ghidra - December 20, 2022
- Using final in C++ to improve performance - November 14, 2022
- Understanding Arm Cortex-M Intel-Hex (ihex) files - October 12, 2022
For many years, the majority of smaller microprocessor-based systems have typically not used caches. With the launch of the ARMv7 architectures, caches were supported in the ARMv7-A family (e.g. Cortex-A8, etc.) but not supported in the core design of the ARMv7-M micro-controllers such as the Cortex-M3 and Cortex-M4. However, when the Cortex-M7 was announced, it broke that mould by offering cache support for the smaller embedded micro-controller.
This series is broken down in three parts:
Basic principles of cache
Cache replacement policies
Optimising software […]
Posted in ARM, CMSIS, Cortex, Design Issues
Tagged cache, Cortex-M, cortex-m7, modified harvard, TCM
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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.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
Latest posts by Glennan Carnie (see all)
- Practice makes perfect, part 3 – Idiomatic kata - February 27, 2020
- Practice makes perfect, part 2– foundation kata - February 13, 2020
- Practice makes perfect, part 1 – Code kata - January 30, 2020
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 […]
Posted in C/C++ Programming, Design Issues, training
Tagged Code kata, exercises, Modern C++. C++11. C++14, training
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Practice makes perfect, part 2 – foundation 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.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
Latest posts by Glennan Carnie (see all)
- Practice makes perfect, part 3 – Idiomatic kata - February 27, 2020
- Practice makes perfect, part 2– foundation kata - February 13, 2020
- Practice makes perfect, part 1 – Code kata - January 30, 2020
In the previously article we looked at the need for repetitive practice – code kata. In this article I want to present some of my preferred foundational kata.
If you’re a beginner to C++ I recommend you fully internalize all these examples before having a look at the idiomatic kata.
If you’re a more experienced C++ programmer you may be looking at these kata and thinking “Jeez – these are so basic! Who couldn’t do this!”. Bear in mind though – we […]
Posted in C/C++ Programming, Design Issues, training
Tagged Code kata, exercises, Modern C++. C++11. C++14, training
1 Comment
Practice makes perfect, part 1 – Code 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.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
Latest posts by Glennan Carnie (see all)
- Practice makes perfect, part 3 – Idiomatic kata - February 27, 2020
- Practice makes perfect, part 2– foundation kata - February 13, 2020
- Practice makes perfect, part 1 – Code kata - January 30, 2020
Imagine you’re at a Jazz club, enjoying a smooth jazz quartet. It’s time for the sax player’s solo. All of a sudden, he stops the band, rifles in a bag a pulls out a book of music theory.
“What the?!” you think.
The saxophonist looks to the audience, “I’ve just got to look up the notes for E-flat minor. I can never remember them.”
It’s understandable you’re unlikely be too impressed with this particular musician.
If you’re a musician, a sportsperson, a dancer, martial […]
Posted in C/C++ Programming, Design Issues, training
Tagged C++, Code kata, exercises, Modern C++. C++11. C++14, practice
3 Comments
Celebrating 10 years – my top 10 blog articles
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.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
Latest posts by Glennan Carnie (see all)
- Practice makes perfect, part 3 – Idiomatic kata - February 27, 2020
- Practice makes perfect, part 2– foundation kata - February 13, 2020
- Practice makes perfect, part 1 – Code kata - January 30, 2020
It’s difficult to believe we’ve been writing articles for 10 years. In that time I’ve written over 90 technical articles on C, C++ and embedded system design.
To celebrate I’ve picked my ‘Top 10’ articles, with a little background into why I enjoyed writing them so much, or the story behind them.
So, sit back, cue up “At the Sign of the Swinging Cymbal“* and enjoy.
(* This really dates
Posted in C/C++ Programming, Design Issues, Testing, UML
Tagged arrays, casting, forwarding, Modern C++. C++11. C++14, move semantics, priority, Testing, unit test
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An Introduction to Docker for Embedded Developers – Part 1 Getting Started
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.
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.
Latest posts by Niall Cooling (see all)
- Disassembling a Cortex-M raw binary file with Ghidra - December 20, 2022
- Using final in C++ to improve performance - November 14, 2022
- Understanding Arm Cortex-M Intel-Hex (ihex) files - October 12, 2022
Docker is a relatively new technology, only appearing just over four years ago. The core building blocks have always been part of Unix; but the significant support, Linux containers (LCX), first appeared back in 2008.
Initially Docker was only supported on Linux, but more recently native support for OSX (my development OS of choice) and Windows (albeit Windows 10 Pro) suddenly opens up some interesting workflow choices.
The “What”
So, first, what is Docker? I’m always trying to find the right words here […]
Posted in Agile, Design Issues, Testing
6 Comments
Making things do stuff – Part 9
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.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
Latest posts by Glennan Carnie (see all)
- Practice makes perfect, part 3 – Idiomatic kata - February 27, 2020
- Practice makes perfect, part 2– foundation kata - February 13, 2020
- Practice makes perfect, part 1 – Code kata - January 30, 2020
As a final instalment in this series on hardware manipulation I thought I’d revisit read-only and write-only register types.
Using tag dispatch is not the only way to solve the read- or write-only Register problem. For completeness let’s explore two other alternatives – SFINAE and constexpr if.
For these examples I’m going to use a simplified version of our Register class. I’m ignoring the bit proxy class and using a reduced API. Once understood, the techniques below can be applied to these […]
Posted in C/C++ Programming, Design Issues
Tagged C++, C++0x, C++11, C++1y, constexpr-if, GPIO, hardware manipulation, Modern C++, SFINAE, tag dispatch, Templates
1 Comment