How can you optimize C/C++ code for embedded systems with limited resources?

1 Choose the right compiler and flags

The first step to optimize C/C++ code for embedded systems is to choose the right compiler and flags for your target platform. Different compilers may have different features, optimizations, and compatibility with your hardware and software. You should also use the appropriate flags to enable or disable certain optimizations, such as loop unrolling, function inlining, or dead code elimination. You can use tools like GCC, Clang, or IAR to compile your C/C++ code for embedded systems.

2 Use static and const keywords

The second step to optimize C/C++ code for embedded systems is to use the static and const keywords whenever possible. The static keyword can reduce the scope of variables and functions, and prevent unnecessary relocations and initializations. The const keyword can indicate that a variable or a function parameter is not modified, and allow the compiler to perform constant folding and propagation. Using static and const keywords can also improve the readability and maintainability of your code.

3 Avoid dynamic memory allocation

The third step to optimize C/C++ code for embedded systems is to avoid dynamic memory allocation, such as using malloc, new, or free. Dynamic memory allocation can cause memory fragmentation, overhead, and unpredictability, which can affect the performance and stability of your embedded system. Instead, you should use static or stack memory allocation, and allocate memory at compile time or at the beginning of your program. You can also use memory pools or custom allocators to manage your memory more efficiently.

4 Use bitwise operations and bit fields

The fourth step to optimize C/C++ code for embedded systems is to use bitwise operations and bit fields to manipulate individual bits or groups of bits. Bitwise operations and bit fields can save memory and improve speed, especially when dealing with low-level hardware or communication protocols. For example, you can use bitwise operations to set, clear, or toggle bits in a register, or use bit fields to pack multiple flags or values into a single byte or word.

5 Use inline functions and macros

The fifth step to optimize C/C++ code for embedded systems is to use inline functions and macros to replace small and frequently used functions or expressions. Inline functions and macros can eliminate the function call overhead and improve the execution speed, especially in time-critical sections of your code. However, you should be careful not to abuse inline functions and macros, as they can also increase the code size and reduce the readability and portability of your code.

6 Test and measure your code

The final step to optimize C/C++ code for embedded systems is to test and measure your code using various tools and methods. You should not rely on intuition or assumptions, but rather use empirical data and evidence to evaluate the impact of your optimizations. You can use tools like profilers, debuggers, or simulators to measure the memory usage, execution time, or energy consumption of your code. You can also use benchmarks, unit tests, or code reviews to ensure the correctness and quality of your code.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?