mmemmove

memmove() written in ARM Cortex-M Assembly. Designed for Cortex M4 and M0+ cores. Probably works on other ARMv6-M and ARMv7-M architectures.

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 common/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 230 bytes on arm-none-eabi-gcc. memmove is about 130 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 7x faster.

This repo is designed to run on an STM32WLxx microcontroller. 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.

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().