https://github.com/aj528/mmemmove

memmove() written in ARM Cortex-M Assembly
https://github.com/aj528/mmemmove

arm assembly c cortex-m embedded memmove

Last synced: 5 days ago
JSON representation

memmove() written in ARM Cortex-M Assembly

• Host: GitHub
• URL: https://github.com/aj528/mmemmove
• Owner: AJ528
• License: gpl-3.0
• Created: 2025-01-13T02:27:36.000Z (about 1 month ago)
• Default Branch: main
• Last Pushed: 2025-02-08T23:09:13.000Z (6 days ago)
• Last Synced: 2025-02-09T00:18:45.060Z (6 days ago)
• Topics: arm, assembly, c, cortex-m, embedded, memmove
• Language: C
• Homepage:
• Size: 603 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

README

        
# mmemmove

`memmove()` written in ARM Cortex-M Assembly. Designed for ARMv7-M architecture (Cortex M3, M4, and M7).

### Status 

Does everything I need it to. Will fix bugs as I come across them.

### How to use this in an embedded project

1. Copy `mmemmove.s` from the src folder into your project

2. Add a function declaration for `memmove_()` somewhere in your project. The function declaration should look something like `extern void* memmove_(void *destination, const void *source, size_t num);`.

3. Use `memmove_()` just like you would the normal `memmove()` function.

4. Done!

### How to measure the size of this project

1. copy these files into an embedded project.

2. compile the project.

3. measure the size of the `mmemmove.o` object file using `size -A`.

4. the total size is found from summing all relevant sections together.

### Details

Compiles down to under 350 bytes on `arm-none-eabi-gcc`. memmove is about 120 lines of code (per David A. Wheeler's `SLOCCount`).

In my testing, `memmove_()` is always faster than my standard `memmove()`. Sometimes it's only a few cycles faster, other times it is more than 7x faster.

This repo is designed to run on an STM32WLxx microcontroller with semihosting. It uses the cycle counter of the Cortex-M4 microcontroller to profile the functions during testing.

Note: the environment this repo was developed in is only important to know if you want to test the `memmove_()` function like I did. If you just want to use it, follow the instructions in [How to use this in an embedded project](#how-to-use-this-in-an-embedded-project).

I also included testing using Greatest from https://github.com/silentbicycle/greatest. There's a number of tests that compare `memmove_()` against the standard `memmove()`.