Archive for November 2021
Assembly Language is Number 8
Introduction
Tiobe regularly produces a list of the most popular programming languages and their recently published list has Assembly Language at number 8, moving up from number 16 last year. The top eight languages are:
The top spots are all well established and well used, C shows remarkable resilience and Java remains popular, in spite of Oracle. In the early days of the PC, all major applications and games were written in Assembly Language, but with the availability of high quality C compilers, this waned and application development switched to C and then other high level languages. Let’s look at why Assembly Language is having a bit of a renaissance.
Assembly Language is Accessible
In the early days, you needed to buy a macro assembler from the chip manufacturer or some other vendor, such as Microsoft’s MASM. Now, all the chip vendors add their Assembly Language support directly into the open source GNU Assembler and/or the LLVM Assembler. Both of these are excellent macro assemblers, run on any hardware, support cross compiling and best of all are completely free.
In my first job out of university, I did some Assembly Language programming on an Intel 80186 board and to debug it, I needed to use an in-circuit emulator (I2ICE) which was a big expensive piece of hardware that replaced the CPU with a debugging probe. Now, all the CPUs and boards have excellent debug probes and you can debug them using open source tools like GNU’s gdb.
Another big help are all the great books on Assembly Language that are available such as: “Raspberry Pi Assembly Language Programming”, “Programming with 64-Bit ARM Assembly Language” and “RP2040 Assembly Language Programming”.
Microcontrollers are Everywhere
The Arduino microcontroller has created a giant community of DIY electronics hobbyists. There is a huge proliferation of inexpensive microcontrollers. In the Arduino world, you program these in Arduino C, but often to get the performance you need, you need to drop down to Assembly Language. Similarly, the memory on these boards is limited, and Assembly Language is the only way to get use of every single bit available to you. With the newer microcontrollers like Raspberry’s RP2040 which are based on ARM 32-bit M-series CPUs, these are much more powerful and have more memory. However, with the extra power, people are attempting more ambitious projects, often involving machine learning applications or other compute intensive applications. Again, they hit the wall with C or MicroPython programming and have to delve into Assembly Language to solve their problems.
When people program these microcontrollers, they are connecting to all sorts of imaginative hardware devices, and they have to create their own libraries to interface to these and often the best way to do this is via Assembly Language.
Competition in the Phone App Market
The App markets for both iOS and Android have matured where as new versions come out, there are fewer changes. The competition between various Apps in a given category is intense and one key way for vendors to differentiate themselves from their competition is via improved performance. Beyond re-writing code to use more efficient algorithms, programmers are turning to hand-crafting the core routines of their Apps into Assembly Language.
Machine Learning
Machine Learning (ML) or AI is extremely compute intensive. There has been a proliferation of coprocessor boards for performing ML computations. All these coprocessors need to be programmed in their own native Assembly Language. Similarly, although you can program nVidia GPUs in CUDA C, to get the absolute most out of a board, you need to delve into the board’s native Assembly Language. Most of the ML libraries are built over top of older Linear Algebra mathematical libraries written in Fortran. As people take on harder and harder problems and need to get useful work done out of every CPU cycle, many routines are being re-written in Assembly Language.
Summary
Modern applications are usually written with a number of modules, each module written in the best programming language for the module’s function. Perhaps C for a back end process, JavaScript for a web page and then Assembly Language for important performance critical routines. I don’t think anyone is taking on large applications in 100% Assembly Language, but enough Assembly Language is making its way into applications to move it up the Tiobe index.
Assembly Language is a great way to learn about how computers work and you might want to take a look at one of my books on the subject.
RP2040 Assembly Language Programming
Introduction
My third book on ARM Assembly Language programming has recently started shipping from Apress/Springer, just in time for Christmas. This one is “RP2040 Assembly Language Programming” and goes into detail on how to program Raspberry’s RP2040 SoC. This chip is used in the Raspberry Pi Pico along with boards from several other manufacturers such as Seeed Studios, AdaFruit, Arduino and Pimoroni.
Flavours of ARM Assembly Language
ARM has ambitions to provide CPUs from the cheapest microcontrollers costing less than a dollar all the way up to supercomputers costing millions of dollars. Along the road to this, there are now three distinct flavours of ARM Assembly Language:
- A Series 32-bit
- M Series 32-bit
- 64-bit
Let’s look at each of these in turn.
A Series 32-bit
For A Series, each instruction is 32-bits in length and as the processors have evolved they added features to support virtual memory, advanced security and other features to support advanced operating systems like Linux, iOS and Android. This is the Assembly Language used in 32-bit phones, tablets and the Raspberry Pi OS. This is covered in my book “Raspberry Pi Assembly Language Programming”.
M Series 32-bit
The full A series instruction set didn’t work well in microcontroller environments. Using 32-bits for each instruction was considered wasteful as well as supporting all the features for advanced operating systems made the CPUs too expensive. To solve the memory problem, ARM introduced a mode to A series 32-bit where each instruction was 16-bits, this saved memory, but the processors were still too expensive. When ARM introduced their M series, or microcontroller processors, they made this 16-bit instruction format the native format and removed most of the advanced operating system features. The RP2040 SoC used in the Raspberry Pi Pico is one of these M Series CPUs using dual core ARM Cortex M0+ CPUs. This is the subject of my current book “RP2040 Assembly Language Programming”.
64-bit
Like Intel and AMD, ARM made the transition from 32-bit to 64-bit processors. As part of this they cleaned up the instruction set, added registers and created a third variant of ARM Assembly Language. iOS and Android are now fully 64-bit and you can run 64-bit versions of Linux on newer Raspberry Pis. The ARM 64-bit instruction set is the topic of my book: “Programming with 64-Bit ARM Assembly Language”.
ARM 64-bit CPUs can run the 32-bit instruction set, and then the M series instruction set is a subset of the A series 32-bit instruction set. Each one is a full featured rich instruction set and deserves a book of its own. If you want to learn all three, I recommend buying all three of my books.
More Than ARM CPUs
The RP2040 is a System on a Chip (SoC), it includes the two M-series ARM CPU cores; but, it also includes many built in hardware interfaces, memory and other components. RP2040 boards don’t need much beyond the RP2040 chip besides a method to interface other components.
“RP2040 Assembly Language Programming” includes coverage of how to use the various hardware registers to control the built-in hardware controllers, as well as the innovative Programmable I/O (PIO) hardware coprocessors. These PIO coprocessors have their own Assembly Language and are capable of some very sophisticated communications protocols, even VGA.
Where to Buy
“RP2040 Assembly Language Programming” is available from most booksellers including:
- Apress/Springer Publishing Directly
- Amazon.com
- Amazon.ca
- Amazon.co.uk
- Amazon.com.au
- Indigo Books
- Barnes & Noble
- Book Depository
Currently if you search for “RP2040” in books on any of these sites, my book comes up first.
Summary
The Raspberry Pi Pico and the RP2040 chip aren’t the first ARM M-series based microcontrollers, but with their release, suddenly the popularity and acceptance of ARM processors in the microcontroller space has exploded. The instruction set for ARM’s M-series processors is simple, clean and a great example of a RISC instruction set. Whether you are into more advanced microcontroller applications or learning Assembly Language for the first time, this is a great place to start.
Stephen Smith's Blog 