Factor out line reading into ::read_line()

This function handles the per-buffer waiting time.
This commit is contained in:
Leonora Tindall 2019-12-28 09:04:52 -08:00
parent 8891b8b6bf
commit 33f7fbcf21
Signed by: nora
GPG Key ID: 7A8B52EC67E09AAF
1 changed files with 54 additions and 23 deletions

View File

@ -2,7 +2,8 @@
// to communicate with an external device, any operation could discover a disconnection
// from the RN2903 serial link, so everything which does such communication will return
// a `Result<T, rn2903::Error>`.
#[macro_use] extern crate quick_error;
#[macro_use]
extern crate quick_error;
use std::io;
quick_error! {
@ -41,12 +42,12 @@ type Result<T> = std::result::Result<T, Error>;
// exports all the configuration information needed to configure a serial port to
// communicate correctly with an RN2903.
use serialport::prelude::*;
use std::io::prelude::*;
use core::convert::AsRef;
use std::ffi::OsStr;
use std::thread;
use core::time::Duration;
use serialport::prelude::*;
use std::ffi::OsStr;
use std::io::prelude::*;
use std::thread;
/// Returns a `serialport::SerialPortSettings` corresponding to the default settings of
/// an RNB2903. Use this to configure your serial port.
@ -61,7 +62,7 @@ pub fn serial_config() -> SerialPortSettings {
flow_control: FlowControl::None,
parity: Parity::None,
stop_bits: StopBits::One,
timeout: Duration::new(1, 0)
timeout: Duration::new(1, 0),
}
}
@ -70,6 +71,12 @@ pub fn serial_config() -> SerialPortSettings {
// wrapper struct's `::new()` function checks the output of the `sys get ver` command,
// which is well-specified.
// In order to turn the raw bytes into a String for display, this helper function comes
// in handy. It also removes the trailing crlf.
fn bytes_to_string(bytes: &[u8]) -> String {
(&*String::from_utf8_lossy(bytes).trim_end()).into()
}
/// A handle to a serial link connected to a RN2903 module.
///
/// This library guarantees safety regardless of the state of the RN2903.
@ -86,18 +93,13 @@ impl Rn2903 {
}
/// Open a new connection to a module over the given serial connection.
pub fn new(mut port: Box<dyn SerialPort>) -> Result<Self> {
let mut buf = [0; 35];
port.write_all(b"sys get ver\x0D\x0A")?;
port.flush()?;
thread::sleep(Duration::from_millis(12));
port.read(&mut buf)?;
if &buf[0..6] != b"RN2903" {
Err(Error::WrongDevice((&*String::from_utf8_lossy(&buf)).into()))
pub fn new(port: Box<dyn SerialPort>) -> Result<Self> {
let mut new = Self { port };
let version = new.system_version()?;
if &version[0..6] != "RN2903" {
Err(Error::WrongDevice(version))
} else {
Ok(Self {
port
})
Ok(new)
}
}
@ -105,12 +107,41 @@ impl Rn2903 {
///
/// Returns a `String` like `RN2903 1.0.3 Aug 8 2017 15:11:09`
pub fn system_version(&mut self) -> Result<String> {
let mut buf = [0; 35];
self.port.write_all(b"sys get ver\x0D\x0A")?;
self.port.flush()?;
thread::sleep(Duration::from_millis(12));
Ok(bytes_to_string(&self.read_line()?))
}
/// Read bytes from the device until a CRLF is encountered, then returns the bytes
/// read, including the CRLF.
// This operation waits 12ms between each 32-byte read because the LoStick has
// the hiccups.
fn read_line(&mut self) -> Result<Vec<u8>> {
let mut vec = Vec::with_capacity(32);
loop {
let mut buf = [0; 32];
self.port.read(&mut buf)?;
Ok((&*String::from_utf8_lossy(&buf).trim_end()).into())
vec.extend_from_slice(&buf);
// Check if crlf was added to the buffer.
let mut found_lf = false;
let mut found_crlf = false;
for byte in vec.iter().rev() {
if found_lf {
if *byte == b'\x0D' {
found_crlf = true;
break;
}
} else {
found_lf = *byte == b'\x0A';
}
}
if found_crlf {
break;
} else {
thread::sleep(Duration::from_millis(12));
}
}
Ok(vec)
}
}