Passing C enum to function and read in TypeScript
First of all I am not a trained software developper, so please forgive me if I am missing some basics. I am trying to build a wrapper around a dynamic library to IEC 61850 communication.
On the the exposed functions of that library is
On the the exposed functions of that library is
IedConnection_connect(..., IedClientError error, ...) , where IedClientError is a enum with 23 entries.
To be able to use the library I need to
1. create the enumeration in TypeScript and change it to a type array? to be able to pass it down
2. but then I also need to read the changed error again in TypeScript
I am not sure how enumerations are coded and how to decode those in TypeScript again and I was hoping one of you can help me out 🙂
BR,
Jakobmarvinh.•18d ago
There is a good page about enums in the TS documentation https://www.typescriptlang.org/docs/handbook/enums.html
Leokuma•18d ago
They are just numbers
You need to find the enum declaration in the header file (something like
IedClientError.h) and see what value is assigned to each enum option. If they are not assigned anything, by default they are assigned a number starting from 0. So if you want to use the first enum option, you pass 0Jakob•18d ago
How would+
This means that I could do something like this?
let error = 0;
lib.symbols.IedConnection_connect(... , error, ...);
console.log(error)
This gives me a Segmentation fault (core dumped) error. I think the enum has to be instantiated as an ArrayBuffer, but do not know how to read that buffer correctly.
Leokuma•18d ago
That should work, without an ArrayBuffer
Are you declaring the enum as
i32?
IedConnection_connect: {parameters: [..., "i32", ...]}
ooh sorry I just reread OP
the function will change the value of the error you pass?Jakob•18d ago
Yes exactly that
Leokuma•18d ago
I'm stupid
Jakob•18d ago
It does work like so for me. But I am not sure if this is the propper way of doing it:
const error = new Uint8Array(1);
lib.symbols.IedConnection_connect(conn, error, host, port);
The result is then error[0]
And I declare the variable as buffer in the symbols object
Leokuma•18d ago
That's correct
Jakob•18d ago
Thank you for the fast response 😄
Leokuma•18d ago
BTW, to make sure the function is actually writing to the buffer, I suggest you fill up the buffer with something before calling it, just to see if it goes back to zero
If it doesn't change, I think we'll have to create a pointer to a buffer or something
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