rust example

cargo.toml

[package]
name = "serialapi"
version = "0.1.0"
authors = ["ifukazoo <ifukazoo@gmail.com>"]
edition = "2018"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
libc = "*"
serialport = "*"
lazy_static = "*"

[lib]
crate-type = ["cdylib"]

lib.rs

#[macro_use]
extern crate lazy_static;
extern crate libc;
extern crate serialport;

use std::string::FromUtf8Error;
use std::sync::mpsc::channel;
use std::sync::mpsc::Receiver;
use std::sync::mpsc::Sender;
use std::sync::mpsc::TryRecvError;
use std::sync::Mutex;
use std::thread;
use std::time;

enum Cmd {
    Quit,
    Start,
    End,
}

struct Channels {
    tx: Mutex<Sender<Cmd>>,
    rx: Mutex<Receiver<Cmd>>,
}

lazy_static! {
    static ref CHANNELS: Channels = {
        let (tx, rx) = channel();
        let tx = Mutex::new(tx);
        let rx = Mutex::new(rx);
        Channels { tx, rx }
    };
    static ref RECEIVED: Mutex<Vec<u8>> = Mutex::new(Vec::new());
}
#[no_mangle]
pub fn finish() -> bool {
    let tx = CHANNELS.tx.lock().unwrap();
    match tx.send(Cmd::Quit) {
        Ok(()) => true,
        Err(e) => {
            eprintln!("{}", e);
            false
        }
    }
}
#[no_mangle]
pub fn start() -> bool {
    let tx = CHANNELS.tx.lock().unwrap();
    match tx.send(Cmd::Start) {
        Ok(()) => true,
        Err(e) => {
            eprintln!("{}", e);
            false
        }
    }
}
#[no_mangle]
pub fn end() -> bool {
    let tx = CHANNELS.tx.lock().unwrap();
    match tx.send(Cmd::End) {
        Ok(()) => true,
        Err(e) => {
            eprintln!("{}", e);
            false
        }
    }
}
#[no_mangle]
pub fn get_data(buf: *mut libc::c_void, buflen: usize, get_len: *mut usize) {
    let mut received = RECEIVED.lock().unwrap();
    let min = std::cmp::min(buflen, received.len());
    let dst = received.as_ptr();
    let dst = dst as *const libc::c_void;
    unsafe {
        libc::memcpy(buf, dst, min);
        *get_len = min;
    }
    received.truncate(0);
}


#[no_mangle]
pub fn initialize(portname: *const libc::c_char) -> bool {
    let port_name = match get_str(portname) {
        Ok(p) => p,
        Err(e) => {
            eprintln!("{}", e);
            return false;
        }
    };
    let port_name = std::ffi::OsString::from(port_name);
    let settings = serialport_settings();
    let mut port = match serialport::open_with_settings(&port_name, &settings) {
        Ok(p) => p,
        Err(e) => {
            eprintln!("{}", e);
            return false;
        }
    };

    thread::spawn(move || loop {
        // 開始 or 終了 を待つ
        let rx = CHANNELS.rx.lock().unwrap();
        let from_api = rx.recv().unwrap();
        match from_api {
            Cmd::End => continue,
            Cmd::Quit => return,

            // 開始コマンド送信
            Cmd::Start => {
                let sendcmd = String::from("start");
                let sendcmd = sendcmd.as_bytes();
                port.write_all(sendcmd).unwrap();

                // 受信のループ
                loop {
                    // APIコマンドのチェック
                    let from_api = rx.try_recv();
                    match from_api {
                        // APIコマンド受信
                        Ok(cmd) => match cmd {
                            Cmd::Start => continue,
                            Cmd::Quit => return,

                            // 終了コマンド送信
                            Cmd::End => {
                                let sendcmd = String::from("end");
                                let sendcmd = sendcmd.as_bytes();
                                port.write_all(sendcmd).unwrap();
                                // 受信のループを抜ける
                                break;
                            }
                        },
                        // APIコマンド受信していない
                        Err(e) => match e {
                            TryRecvError::Disconnected => return,
                            TryRecvError::Empty => {
                                // シリアルポート受信
                                let mut arr: [u8; 1024] = [0; 1024];
                                match port.read(&mut arr) {
                                    // 受信した
                                    Ok(size) => {
                                        let slice = &arr[0..size];
                                        let mut buf = slice.to_vec();
                                        // 受信バッファへ追加
                                        let mut gbuf = RECEIVED.lock().unwrap();
                                        gbuf.append(&mut buf);
                                    }
                                    // 受信してない
                                    Err(_) => continue,
                                };
                            }
                        },
                    }
                }
            }
        };
    });
    true
}

fn serialport_settings() -> serialport::SerialPortSettings {
    serialport::SerialPortSettings {
        baud_rate: 115200,
        data_bits: serialport::DataBits::Eight,
        flow_control: serialport::FlowControl::None,
        parity: serialport::Parity::None,
        stop_bits: serialport::StopBits::One,
        timeout: time::Duration::from_millis(1),
    }
}

fn get_str(p: *const libc::c_char) -> Result<String, FromUtf8Error> {
    let mut buf: Vec<u8> = Vec::new();
    unsafe {
        let len = libc::strlen(p);
        buf.reserve(len);
        let src = p as *const libc::c_void;
        let dst = buf.as_mut_ptr() as *mut libc::c_void;
        libc::memcpy(dst, src, len);
        buf.set_len(len);
    }
    let s = String::from_utf8(buf)?;
    Ok(s)
}

#[cfg(test)]
mod tests {
    #[test]
    fn it_works() {
        assert_eq!(2 + 2, 4);
    }
}