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// Copyright 2022 The Pigweed Authors
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
/* eslint-env browser */
import { BehaviorSubject, Observable, Subject, Subscription } from 'rxjs';
import DeviceTransport from './device_transport';
import type {
SerialPort,
Serial,
SerialOptions,
Navigator,
SerialPortFilter,
} from '../types/serial';
const DEFAULT_SERIAL_OPTIONS: SerialOptions & { baudRate: number } = {
// Some versions of chrome use `baudrate` (linux)
baudrate: 115200,
// Some versions use `baudRate` (chromebook)
baudRate: 115200,
databits: 8,
parity: 'none',
stopbits: 1,
};
interface PortReadConnection {
chunks: Observable<Uint8Array>;
errors: Observable<Error>;
}
interface PortConnection extends PortReadConnection {
sendChunk: (chunk: Uint8Array) => Promise<void>;
}
export class DeviceLostError extends Error {
override message = 'The device has been lost';
}
export class DeviceLockedError extends Error {
override message =
"The device's port is locked. Try unplugging it" +
' and plugging it back in.';
}
/**
* WebSerialTransport sends and receives UInt8Arrays to and
* from a serial device connected over USB.
*/
export class WebSerialTransport implements DeviceTransport {
chunks = new Subject<Uint8Array>();
errors = new Subject<Error>();
connected = new BehaviorSubject<boolean>(false);
private portConnections: Map<SerialPort, PortConnection> = new Map();
private activePortConnectionConnection: PortConnection | undefined;
private rxSubscriptions: Subscription[] = [];
private writer: WritableStreamDefaultWriter<Uint8Array> | undefined;
private abortController: AbortController | undefined;
constructor(
private serial: Serial = (navigator as unknown as Navigator).serial,
private filters: SerialPortFilter[] = [],
private serialOptions = DEFAULT_SERIAL_OPTIONS,
) {}
/**
* Send a UInt8Array chunk of data to the connected device.
* @param {Uint8Array} chunk The chunk to send
*/
async sendChunk(chunk: Uint8Array): Promise<void> {
if (this.activePortConnectionConnection) {
return this.activePortConnectionConnection.sendChunk(chunk);
}
throw new Error('Device not connected');
}
/**
* Attempt to open a connection to a device. This includes
* asking the user to select a serial port and should only
* be called in response to user interaction.
*/
async connect(): Promise<void> {
const port = await this.serial.requestPort({ filters: this.filters });
await this.connectPort(port);
}
async disconnect() {
for (const subscription of this.rxSubscriptions) {
subscription.unsubscribe();
}
this.rxSubscriptions = [];
this.activePortConnectionConnection = undefined;
this.portConnections.clear();
this.abortController?.abort();
try {
await this.writer?.close();
} catch (err) {
this.errors.next(err as Error);
}
this.connected.next(false);
}
/**
* Connect to a given SerialPort. This involves no user interaction.
* and can be called whenever a port is available.
*/
async connectPort(port: SerialPort): Promise<void> {
this.activePortConnectionConnection =
this.portConnections.get(port) ?? (await this.connectNewPort(port));
this.connected.next(true);
this.rxSubscriptions.push(
this.activePortConnectionConnection.chunks.subscribe(
(chunk: any) => {
this.chunks.next(chunk);
},
(err: any) => {
throw new Error(`Chunks observable had an unexpected error ${err}`);
},
() => {
this.connected.next(false);
this.portConnections.delete(port);
// Don't complete the chunks observable because then it would not
// be able to forward any future chunks.
},
),
);
this.rxSubscriptions.push(
this.activePortConnectionConnection.errors.subscribe((error: any) => {
this.errors.next(error);
if (error instanceof DeviceLostError) {
// The device has been lost
this.connected.next(false);
}
}),
);
}
private async connectNewPort(port: SerialPort): Promise<PortConnection> {
await port.open(this.serialOptions);
const writer = port.writable.getWriter();
this.writer = writer;
async function sendChunk(chunk: Uint8Array) {
await writer.ready;
await writer.write(chunk);
}
const { chunks, errors } = this.getChunks(port);
const connection: PortConnection = { sendChunk, chunks, errors };
this.portConnections.set(port, connection);
return connection;
}
private getChunks(port: SerialPort): PortReadConnection {
const chunks = new Subject<Uint8Array>();
const errors = new Subject<Error>();
const abortController = new AbortController();
this.abortController = abortController;
async function read() {
if (!port.readable) {
throw new DeviceLostError();
}
if (port.readable.locked) {
throw new DeviceLockedError();
}
await port.readable.pipeTo(
new WritableStream({
write: (chunk) => {
chunks.next(chunk);
},
close: () => {
chunks.complete();
errors.complete();
},
}),
{ signal: abortController.signal },
);
}
function connect() {
read().catch((err) => {
// Don't error the chunks observable since that stops it from
// reading any more packets, and we often want to continue
// despite an error. Instead, push errors to the 'errors'
// observable.
errors.next(err);
});
}
connect();
return { chunks, errors };
}
}
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