Only getting 1 byte in readAsync

[fishcharlie]

The following code only prints 1 to the console a bunch of times.

import * as rtljs from "rtljs";
import * as fs from "fs";

const DEFAULT_RATE = 3_000_000;
const DEFAULT_FREQ = 1090 * rtljs.mhz; // 1090 MHz
const ASYNC_BUF_NUMBER = 12;
const DATA_LEN = 16 * 16384; // 256k

const device = rtljs.open(0);

device.setTunerGainMode(1);
device.setTunerGain(50);
device.setAGCMode(0);
device.setCenterFreq(DEFAULT_FREQ);
device.setSampleRate(DEFAULT_RATE);
device.resetBuffer();

fs.writeFileSync("data.bin", Buffer.alloc(0));
device.readAsync((data) => {
	console.log(data.length);
	fs.appendFileSync("data.bin", Buffer.from(data));
}, ASYNC_BUF_NUMBER, DATA_LEN);

However, the following code prints 262144 to the console a bunch of times.

import * as rtljs from "rtljs";
import * as fs from "fs";

const DEFAULT_RATE = 3_000_000;
const DEFAULT_FREQ = 1090 * rtljs.mhz; // 1090 MHz
const ASYNC_BUF_NUMBER = 12;
const DATA_LEN = 16 * 16384; // 256k

const device = rtljs.open(0);

device.setTunerGainMode(1);
device.setTunerGain(50);
device.setAGCMode(0);
device.setCenterFreq(DEFAULT_FREQ);
device.setSampleRate(DEFAULT_RATE);
device.resetBuffer();

fs.writeFileSync("data.bin", Buffer.alloc(0));

while (true) {
	const data = device.readSync(DATA_LEN);
	fs.appendFileSync("data.bin", Buffer.from(data));
	console.log(data.length);
}

Why would readSync give me the data length I want, whereas readAsync does not?

[Arkanic]

Sorry mate - readAsync is really broken at the moment, and I sort of entirely forgot about it
ffi-napi, which is what the library uses to interact with librtlsdr, really doesn't like the way that librtlsdr uses a callback to a c function for readAsync to work, and I haven't figured out a way to get it working yet.

I might take a look at it sometime soon but from past attempts and my minimal experience I haven't had the best of luck, for now it might be best to readSync repeatedly either in a seperate thread on the nodejs side, or just in small enough sizes that it doesn't interfere with the main thread.

Sorry about the hassle, I can understand the frustration but I simply don't have the answers right now.

Best regards

[fishcharlie]

@Arkanic Got it. Just concerned that I'll miss data from the device if I do the sync version. But maybe that isn't as big of a concern.

[Arkanic]

That is actually a valid concern I haven't thought about, again i'll take a look at some point but for now it remains unresolved.

[Arkanic]

update: ffi-napi seems to have been abandoned entirely, last release to npm was 3 years ago, and it doesn't build on modern versions of node anymore - which was the whole point of this library
might be time for a rewrite, i'll go hunting for a good way to interface and potentially remake

[Arkanic]

Just reworked the entire backend with a new library, it works on the latest version of node now
Everything is working except readasync/cancelasync - which i know is what you wanted, but i've had some trouble with the readAsync function blocking the entire nodejs process regardless of whether or not readAsync is on a seperate thread or not :(
I'll play around a bit more but i'm not too sure of which angle to tackle it from at the moment, just know that the code as a whole is just a little bit closer to actually doing the job it is supposed to do....

cheers