Скачать или смотреть Optimize String Handling in ARM Cortex Using boost::string_view

Discover how to efficiently utilize `boost::string_view` for string literals in ARM Cortex projects while optimizing compiler performance.
---
This video is based on the question https://stackoverflow.com/q/76202201/ asked by the user 'DanielR' ( https://stackoverflow.com/u/21853212/ ) and on the answer https://stackoverflow.com/a/76202955/ provided by the user 'Jarod42' ( https://stackoverflow.com/u/2684539/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: String literal, getting compiler to compute length for string_view constructor

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Optimize String Handling in ARM Cortex Using boost::string_view

When working on embedded systems like the ARM Cortex, optimizing every cycle is crucial for performance. A common challenge developers face is when they need to manage string literals efficiently. In this blog, we'll explore how to utilize boost::string_view effectively, ensuring that your compiler computes the string length at compile time rather than at runtime, thus saving precious cycles.

The Problem

In many projects using ARM Cortex processors, strings are often utilized in functions, such as:

[[See Video to Reveal this Text or Code Snippet]]

Here, the function UART_WriteStr() is designed to take a boost::string_view as an argument. While string_view is highly beneficial because it avoids unnecessary string allocations, it typically computes the length of the string by searching for a null terminator. This behavior introduces inefficiencies that can be detrimental in a cycle-sensitive environment.

The Challenge

Since the ARM compiler being used does not support C++17 features, you might find it inconvenient to create string views directly from string literals without incurring a runtime overhead. When trying different methods to infer the string length at compile time, you may run into the limitation of regular function overloads. This raises the question: How can you overload the UART_WriteStr() function to work with string literals while also ensuring its string length is computed at compile-time?

The Solution

Template Overloading

The optimal solution involves using template specialization which allows us to pass the string literals with their lengths determined at compile time. Here’s how you can implement it:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Solution

Template Function: The UART_WriteStr function template takes a constant reference to an array of characters. The size of the array is automatically deduced by the compiler.

Compile-time Length: The template parameter N corresponds to the length of the string, allowing you to create a boost::string_view with a known length at compile time. This eliminates the need for a runtime calculation of the string length via a loop.

Handling Null Terminators: The N - 1 ensures that the resulting string_view does not include the null terminator, which is crucial for accurate representation.

Advantages of the Mapping

Performance: By calculating the length at compile time, this method leverages the compiler's efficiency, reducing execution time for UART communications.

Code Simplicity: It allows direct usage of string literals without additional functions or constructs, keeping your code clean and intuitive.

Conclusion

By employing this template method for your UART_WriteStr() function, you can efficiently optimize how you handle string literals in your ARM Cortex projects. Not only does it maintain the performance needs for resource-constrained environments, but it also enhances code readability and reduces potential runtime errors related to string handling.

Feel free to incorporate this technique into your projects whenever you're dealing with string literals, and experience the performance benefits it brings!