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24 March 2022

Low-level programming

An introduction to low-level programming

8 minutes reading

An introduction to low-level programming

A programming language could be described as a way of translating a programmer's intentions into machine code that can be understood by a processor. There is much information about high- and low-level programming languages available from various sources. How to tell them apart? 

Low-level programming languages allow for unambiguous and precise control over exactly what machine code will be the result of a compilation. In high-level languages, the algorithms select the instructions, often simplifying them and not allowing for their modification.

This article sheds some light on low-level programming and shows how this kind of programming differs from the high-level option. It also mentions the advantages and disadvantages of low-level programming, providing examples.

What is low-level programming?

Low-level programming is often described as machine-oriented. It is also close to computer peripherals and requires knowledge of the processor's instructions and orientation within the relationships of internal systems or related devices.

Low-level programming aims to guide a specific language compiler to use machine code instructions that will perform the tasks in the fastest and safest possible way, using the minimum amount of memory. It often uses the individual advantages of the core or system periphery to achieve this. 

Low-level programming vs. high-level programming

Both these terms are common but sometimes explanations are lacking, blurring the differences between them. The following brief descriptions should give a clear idea and facilitate an understanding of the topic. 

High-level programming is considered more developer-friendly as it is closer to the human language. Such programming often consists of English words, making them easier to read and write for a developer. Another advantage of high-level programming is the fact that it is machine-independent. This means high-level programming is portable, and can be run on different platforms. However, it does have to be translated into machine code to be executed by the computer. 

In other words, in high-level programming, the developer focuses on algorithms and data flows. It is more generic, universal, easier to maintain, but often at the expense of performance.

Low-level programming, as mentioned above, is more machine-friendly. It aims to control and modify the computer's hardware and sits close to the hardware on which the code is run. That makes low-level programming non-portable and dependent on the machine. However, it can be much faster and memory efficient compared to high-level languages. 

On the other hand, low-level programming requires knowledge of the system architecture and specific, dedicated solutions. Each processor or group of similar processors has specifically defined instruction sets established by the processor manufacturer. This is one of the reasons why low-level programming is more demanding than high-level programming – the programmer has to know and understand the hardware’s design and capabilities. 

It is worth mentioning low-level programming drawbacks and advantages to be aware of possible inconveniences.

Advantages and disadvantages of low-level programming 

The main advantages of low-level programming are better control both over the code and the device’s resources.

  • Better control over the code, and the possibility for programmers to optimize the program – more experienced developers can take advantage of low-level programming and write more efficient programs with better data flow management. 
  • Programs run more efficiently, even if there is limited memory and storage – this makes low-level programming perfect for embedded systems, for example. 

What are the disadvantages of low-level languages? In general – their complexity. 

  • Non portability – as mentioned before, low-level code works on a dedicated device (i.e. it is machine-dependent), the opposite to high-level languages. 
  • Writing low-level code requires the programmer to have good knowledge of the hardware being used – there are no libraries, the code has to be written anew each time. 

At this point, it is worth mentioning that an assembly language is definitely easier to understand and modify, but it stays machine-dependent. 

When does a programming language support low-level programming?

A language that supports low-level programming allows for controlling the size of the variables (we can use this feature to minimize resource use). What is also important is that it gives additional tips to the compiler for choosing better optimization strategies and allows for allocating resources on demand.

Machine code and assembly code are basic examples of solutions that support low-level programming. 

Machine code sets off tasks executed by the processor, and does not require translation before the run. However, the fact that it is written in binary (i.e. it consists only of 0s and 1s) makes it difficult to write, understand and debug. 

Instructions in machine code can be divided into opcode and operand. Opcode marks operations that should be executed. The instruction from the opcode is specified in addressing mode, which also determines the operand interpretation. Operand is about the value(s) connected with opcode. For example, opcode determines the data storage instruction, and operand has the information stating where this data is to be stored. 

Assembly code is a direct reflection of machine code. It enables developers to write machine code with its assembly equivalents – mnemonics. Mnemonics are English abbreviations of operations initially described binarily. However, there is no one list of mnemonics – each different processor has its own assembly language. 

When would you use low-level programming?

Low-level programming is necessary in cases where there is a need to write a program that depends on predefined hardware. Low-level programming is used to manipulate the hardware directly, give access to special processor instructions, or to address critical problems of optimization. Typical applications are device drivers, fast calculation libraries, and operating system kernels. 

They are also characterized by a minimal memory footprint and high speed. For that reason, low-level languages are used to write programs for microcontrollers to maximize their power, and at the same time, minimize memory storage. More extended servers/computers have their own dedicated controller devices.

Conclusion 

Currently, many sources focus on high-level programming, and low-level programming can seem a little sidelined. However, there is no reason for this to be so. Low-level programming allows a programmer to adapt the processor to specific needs and requirements, offering the best performance with minimum memory. It is also the best choice for managing and maintaining device drivers, libraries for fast calculations, and operating system kernels.

Daniel

Daniel Jędrzejczyk

Senior Software Engineer
Karolina

Karolina Rusinowicz

Content writer