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BrowserSerial.ts
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BrowserSerial.ts
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// notes:
// done doesnt seem to ever be true?
// want to be able to specify pipelines of decoders
// ie linedecoder or just standard decoder
const defaultSerialOptions: SerialOptions = {
baudRate: 115200,
dataBits: 8,
stopBits: 1,
parity: "none",
bufferSize: 255,
flowControl: "none",
};
const defaultSerialFilters: SerialPortRequestOptions = {};
export class BrowserSerial {
serialOptions: SerialOptions;
serialFilters: SerialPortRequestOptions;
port: SerialPort | null;
EOF: string;
encoder: TextEncoderStream;
decoder: TextDecoderStream;
lineTransformer: TransformStream;
writeToStream: WritableStream;
readFromStream: ReadableStream;
reader: ReadableStreamDefaultReader | null;
readTransformers: Array<TextDecoderStream | TransformStream>;
constructor(
serialOptions?: SerialOptions,
serialFilters?: SerialPortRequestOptions
) {
this.serialOptions = { ...defaultSerialOptions, ...serialOptions };
this.serialFilters = { ...defaultSerialFilters, ...serialFilters };
this.EOF = "\n";
this.port = null;
this.encoder = new TextEncoderStream();
this.decoder = new TextDecoderStream("utf-8");
this.lineTransformer = new TransformStream(new LineBreakTransformer());
// port reads from encoder.readable, i write to encoder.writable
this.writeToStream = this.encoder.writable;
// port writes to decoder.writable, i read from decoder.readable
this.readTransformers = [this.decoder];
this.readFromStream = this.decoder.readable;
if (this.EOF === "\n") {
this.readTransformers.push(this.lineTransformer);
this.readFromStream = this.lineTransformer.readable;
}
this.reader = null;
}
async connect(): Promise<void> {
this.port = this.serialFilters
? await navigator.serial.requestPort(this.serialFilters)
: await navigator.serial.requestPort();
await this.port.open(this.serialOptions);
// connect the port stream to the in and out stream
const pipeReducer = (
accumulator: ReadableStream,
currentValue: TextDecoderStream | TransformStream
) => accumulator.pipeThrough(currentValue);
this.readTransformers.reduce(pipeReducer, this.port.readable); //.pipeTo(writable)
this.encoder.readable.pipeTo(this.port.writable);
}
async disconnect(): Promise<void> {
if (this.reader) {
// cancel the reader
await this.reader.cancel();
// await this.inDone.catch(() => {});
this.reader = null;
// this.inDone = null;
}
if (this.writeToStream) {
// cancel the writer
await this.writeToStream.getWriter().close();
// await this.outDone;
this.writeToStream = null;
// this.outDone = null;
}
// close the port
await this.port.close();
this.port = null;
}
async write(cmd: string): Promise<void> {
// spawn a new writer and lock to writeToStream
const writer = this.writeToStream.getWriter();
// write command and unlock
writer.write(cmd + this.EOF);
writer.releaseLock();
}
async readLoop(
callable: (value: string, done: boolean) => boolean
): Promise<void> {
// while we can read from the port
while (this.port.readable) {
// lock the reader to the port stream loop
this.reader = this.readFromStream.getReader();
try {
while (true) {
// await for values from the reader
let { done, value } = await this.reader.read();
// if no more values, break
// FYI done seems to always return false...
done = callable(value, done);
console.log(done);
if (done === true) {
console.log("breaking");
break;
}
}
} catch (e) {
console.log("ERROR, ", e);
} finally {
console.log("unlocking reader");
console.log("before unlock");
this.reader.releaseLock();
console.log("after unlock");
this.reader = null;
console.log(this.reader);
}
}
}
// assumes that the stream reads line by line
async readUntilLine(
until: string,
reader: ReadableStreamDefaultReader,
callable: (value: string, done: boolean) => void
): Promise<void> {
try {
while (true) {
// await for values from the reader
let { done, value } = await reader.read();
// if no more values, break
// FYI done seems to always return false...
callable(value, done);
if (value === until) {
console.log("breaking");
break;
}
}
} catch (e) {
console.log("ERROR, ", e);
} finally {
reader.releaseLock();
}
}
// assumes that the stream reads line by line
async readUntil(
until: string,
callable: (value: string, done: boolean) => void
): Promise<void> {
// while we can read from the port
while (this.port.readable) {
this.reader = this.readFromStream.getReader();
try {
while (true) {
// await for values from the reader
let { done, value } = await this.reader.read();
// if no more values, break
// FYI done seems to always return false...
callable(value, done);
if (value === until) {
console.log("breaking");
break;
}
}
} catch (e) {
console.log("ERROR, ", e);
} finally {
console.log("unlocking reader");
console.log("before unlock");
this.reader.releaseLock();
console.log("after unlock");
this.reader = null;
console.log(this.reader);
}
}
}
readAllChunks(readableStream: ReadableStream) {
const reader = readableStream.getReader();
var chunks: string = "";
return pump();
async function pump(): Promise<any> {
const { value, done } = await reader.read();
if (done) {
return chunks;
}
chunks += value;
return pump();
}
}
async *readGenerator(): AsyncGenerator<
{ value: any; done: boolean },
void,
unknown
> {
while (this.port.readable) {
this.reader = this.readFromStream.getReader();
try {
while (true) {
const { value, done } = await this.reader.read();
yield { value, done };
if (done === true) {
console.log("breaking!");
break;
}
}
} catch (e) {
console.log("ERROR, ", e);
} finally {
console.log("unlocking reader");
this.reader.releaseLock();
}
}
}
getReader(): ReadableStreamDefaultReader | void {
if (this.port.readable) {
return this.readFromStream.getReader();
}
}
// test out the generator
async *readLineGenerator(): AsyncGenerator<
{ value: any; done: boolean },
void,
unknown
> {
while (this.port.readable) {
this.reader = this.readFromStream.getReader();
try {
while (true) {
const { value, done } = await this.reader.read();
yield { value, done };
if (done === true) {
console.log("breaking!");
break;
}
}
} catch (e) {
console.log("ERROR, ", e);
} finally {
console.log("unlocking reader");
this.reader.releaseLock();
}
}
}
}
class LineBreakTransformer {
container: string;
constructor() {
this.container = "";
}
transform(chunk: string, controller: TransformStreamDefaultController) {
this.container += chunk;
const lines = this.container.split("\r\n");
let pop = lines.pop();
this.container = "";
if (pop) {
this.container = pop;
}
lines.forEach((line) => controller.enqueue(line));
}
flush(controller: TransformStreamDefaultController) {
controller.enqueue(this.container);
}
}