ARM cortex processors primarily use the ARM assembly language and C/C++ for programming. The ARM assembly language is specific to ARM architecture and provides low-level control of the processor. C/C++ are highly portable languages that allow developers to write efficient and optimized code for ARM cores. Additionally, other higher-level languages like Python, Java, and Rust can also be used on ARM cortex CPUs through cross-compilation.
ARM Assembly Language
The ARM assembly language is the native low-level programming language designed specifically for ARM processor architecture. Unlike high-level languages like C/C++, assembly language provides direct access to the CPU registers, condition codes, and instructions. It allows developers precise control over the processor at the expense of being more complex and requiring deeper knowledge of the hardware.
ARM assembly code consists of mnemonic instruction codes like ADD, MOV, BNE etc that map to the underlying processor opcodes. The syntax follows the general structure: MNEMONIC {cond} {S} operands
Where {cond} is an optional condition code, {S} denotes whether the instruction updates status flags, and operands specify registers or immediate values.
For example, a simple ARM instruction to add two registers: ADD R0, R1, R2
This adds the values in register R1 and R2 and stores the result in R0. The benefits of coding in assembly language include:
- Direct hardware access for best performance
- Precise control over memory and registers
- Ability to optimize code at instruction level
- No overhead from high-level abstractions
- Can leverage processor-specific features
ARM assembly is used widely in embedded systems programming, OS kernels, device drivers, and other performance critical applications. It is essential for achieving the best possible efficiency on ARM CPUs.
C and C++ Languages
The C and C++ programming languages are ubiquitous in ARM cortex application development, especially user-space applications. C offers a good balance between high-level code portability and low-level hardware control. C++ builds on C by providing object-oriented features for better code organization.
Key reasons for using C/C++ on ARM cortex include:
- C/C++ compilers are available for every ARM platform
- Allows access to low-level system functions
- Suitable for performance intensive tasks
- Can directly access hardware and ARM core features
- Supports inline ARM assembly code
- Standard libraries work across ARM chips
- Produces highly optimized machine code
- C++ provides object-oriented, generic, and metaprogramming features
For example, embedded operating systems like FreeRTOS and embedded Linux are written predominantly in C. ARM CPU vendor provided HAL and driver libraries use C/C++ interfaces. The Android OS stack also relies heavily on C/C++ code.
With C/C++, developers can craft high-performance ARM applications while retaining portability across devices. The combination of assembly and C/C++ gives complete control over ARM cortex hardware capabilities.
Python
Python has emerged as a popular high-level language for ARM cortex devices and supports many ARM boards like Raspberry Pi, BeagleBone etc. It provides an interactive interpreter, object-oriented features, vast standard libraries and is easy to learn.
Python code runs on ARM by cross-compiling the interpreter and libraries for the target architecture. CPython, MicroPython, CircuitPython are some efforts that enable efficient Python execution on resource-constrained ARM cores.
Key advantages of Python on ARM include:
- Rapid development through interpreted scripting
- Extensive libraries for common tasks
- Simpler syntax compared to C/C++
- Dynamically typed language
- REPL provides instant feedback during coding
- Large ecosystem of ARM support with MicroPython etc
Python is a great choice for ARM applications like:
- Automation scripts
- IoT firmware
- Machine learning
- Web applications
- Rapid prototyping
- Education and learning
The combination of Python and C modules can allow optimizing performance critical sections while retaining Python’s productivity advantages.
Java
Java is a popular object-oriented language that also sees significant use on ARM cortex devices. Java code gets compiled to platform-independent bytecode which then runs on a Java Virtual Machine optimized for each architecture.
Advantages of using Java on ARM include:
- Object-oriented programming model
- Automated memory management with garbage collection
- Vast standard libraries and APIs
- Write once, run anywhere portability
- Large ecosystem of tools and IDEs
- Supports just-in-time compilation for improved performance
Java enables ARM developers to reuse code across projects and abstract away hardware details. Android apps are primarily written in Java and run on ARM-based mobile devices. Other uses include:
- Enterprise backend applications
- Network servers
- Big data processing
- Desktop apps and utilities
- Raspberry Pi home automation
The Java Class Library and tooling make it a productive language for ARM applications requiring portability, code reuse and maintainability.
Rust
Rust is a modern systems programming language that balances low-level control, performance and high-level ergonomics. It prevents entire classes of bugs through its ownership and borrowing rules for memory management.
Key aspects of Rust on ARM Cortex include:
- Zero-cost abstractions without runtime overhead
- Provides low-level control like C
- Safe concurrency through ownership system
- Trait-based generics
- Pattern matching and expression-based syntax
- Great for performance critical tasks
- Supports embedded ARM development
Rust is used to build ARM applications like:
- Bare-metal embedded firmware
- Device drivers
- High-performance servers and cloud services
- Cryptography, security and blockchain
- Networking stacks
- CLI and productivity tools
Rust gives ARM developers the performance of C/C++ without giving up high-level ergonomics and safety. It prevents entire classes of memory bugs and corruption issues.
Conclusion
ARM cortex processors have a flexible and robust software ecosystem spanning multiple languages. Developers can choose ARM assembly for ultimate control, C/C++ for the right balance of power and portability, or languages like Python, Java and Rust for higher-level application development. The vibrant ARM software landscape enables building full-stack applications from low-level firmware up to user interfaces and cloud services.
