How to compile the ST to a lib and then call it from Rust

[jiguorui]

I have some old codes in ST for a PLC platfrom. If I want to compile the codes into a library or something like that, how do I call it from Rust.

[ghaith]

Hello @jiguorui sorry for the late reply.
So if you have your PLC code in flat files, you can compile them with the compiler using something similar to the the gcc or rustc command lines. plc -c file.st -o file.o which will give you an object file that you can use in another application. You can also create libraries by using plc --shared file.st -o file.so Make sure to read our documentation at https://plc-lang.github.io/rusty
To use your library from rust, you need to declare the functions you need as extern C functions. We use the C calling conventions on our generated code. In rust you will need to declare such functions as unsafe similar to what you would do with C functions (check the ffi guide from rust).
Some general things to remember about the PLC libs we generate is there is no heap allocation, instead PROGRAM and global variables are available globally. You can access any symbol that is defined as global. Programs and Function blocks are functions that are backed by a struct. To call a function block, you first need to create the struct and pass it as a pointer parameter. If you need to access the instance of a program you can use <program_name>_instance.
We have more documentation regarding writing libraries for PLC here: https://plc-lang.github.io/rusty/libraries/api_lib_guide.html but you can also use this information the other way around. This explains the structure of a PLC program compiled with rusty

If you have more specific questions feel free to ask here :)

[jiguorui]

Thank you for such a detailed and useful response. I will make some attempts and share here