Read and Write Traits not implemented

[tolgadot]

Implementing these traits would take no effort as far I can see (since there are already functions called read and write which is all that is needed) but allow the ftdi struct to be directly used in useful structures like BufReader or BufWriter etc.

Is there a specific reason why this is not implemented?

[newAM]

Is there a specific reason why this is not implemented?

It has been a while since I wrote this, I think the reason was that the libft2xx error type does not cleanly convert into std::io::Error.

Happy to accept a pull-request if you want to implement it!

[newAM]

I would still like to keep the existing methods though, the libft2xx errror codes are useful when asking for support from the vendor.

[tolgadot]

I see, that makes sense. For now in my application I am working with

struct Wrapper {
    ftdi: Ftdi,
}

impl std::io::Read for Wrapper {
    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
        self.ftdi
            .read(buf)
            .map_err(|e| std::io::Error::new(std::io::ErrorKind::Other, e))
    }
}

as a quick work-around.

What do you think about a solution where From<std::io::Error> is properly implemented for FtStatus where we try to match the error types as much as possible, with the un-matchable ones propagated like above? I am not very experienced with library error handling much either unfortunately.

[tolgadot]

Also turns out I was wrong, for Write one also needs to provide a flush function. Do you know how this is supposed to behave in this case?

[newAM]

Also turns out I was wrong, for Write one also needs to provide a flush function. Do you know how this is supposed to behave in this case?

The libftd2xx documentation does not mention how write behaves internally, if I recall correctly.
If write flushes itself then std::io::Write::flush can be empty, if write does not flush itself then it probably cannot be adapted to std::io::Write.

[newAM]

Just to make sure you have seen it, there is another crate that uses the open source libftdi driver which has std::io traits out of the box: https://crates.io/crates/ftdi
I would only recommend libftd2xx instead of libftdi if you need to target Windows platforms.

[tolgadot]

Yes I need to support Windows as well as Linux unfortunately :)

(by the way @newAM do you know if it is possible to statically compile this library from Linux for a Windows target? cargo build --target x86_64-pc-windows-msvc --features static fails because could not find native static library ftd2xx)

[tolgadot]

In my wrapper type I have indeed left the flush empty:

    fn flush(&mut self) -> std::io::Result<()> {
        Ok(())
    }

This has been working without an issue so far.

[newAM]

do you know if it is possible to statically compile this library from Linux for a Windows target?

I think this is a bug, I took a look and cross-compiling for Windows from Linux uses \ path separators when it should probably use /.

Working on it here: ftdi-rs/libftd2xx-ffi#57

[newAM]

Yup, that was the problem (for that specific error), good find! Will get a release of libftd2xx-ffi out shortly.

[newAM]

For linking I found this guide from bevy: https://bevy-cheatbook.github.io/setup/cross/linux-windows.html

Worked for me after that.