72 lines
2.3 KiB
Markdown
72 lines
2.3 KiB
Markdown
# ax25.js — AX.25 + HDLC utilities (TypeScript)
|
||
|
||
This repository provides low-level utilities for AX.25 frame construction/parsing and HDLC framing used in amateur radio applications. It's intentionally small and focused on framing, FCS and control-field helpers.
|
||
|
||
## Highlights
|
||
|
||
- `Address` – create and parse callsigns, produce 7-byte AX.25 address fields.
|
||
- `Frame` – `InformationFrame`, `SupervisoryFrame`, `UnnumberedFrame` and `Frame.fromBytes()` parsing.
|
||
- Control builders: `buildIControl`, `buildSControl`, `buildUControl` (and extended 2‑byte builders).
|
||
- Encoders: `encodeFrame`, convenience `encodeAx25` / alias `encodeAX25`.
|
||
- HDLC: `encodeHDLC`, `escapeBuffer`, `unescapeBuffer`, `computeFcs` / `crc16Ccitt`, `verifyAndStripFcs`.
|
||
- Convenience stream helpers: `toHDLC`, `toWire`, `toWireStream`.
|
||
- `FX25` class: detection heuristics; full FEC decoding (Reed–Solomon) is a TODO.
|
||
|
||
## Install & tests
|
||
|
||
```bash
|
||
npm install
|
||
npm test
|
||
```
|
||
|
||
## Examples
|
||
|
||
Note: during development you can import directly from `src/*`. When published, import from the package entrypoint.
|
||
|
||
### Address
|
||
|
||
```ts
|
||
import { Address } from './src/address';
|
||
|
||
const a = Address.fromString('N0CALL-0');
|
||
console.log(a.toString()); // N0CALL-0
|
||
```
|
||
|
||
### Build an AX.25 UI payload and HDLC-wrap it
|
||
|
||
```ts
|
||
import { Address } from './src/address';
|
||
import { UnnumberedFrame, encodeFrame, encodeAX25, toHDLC } from './src/frame';
|
||
|
||
const src = Address.fromString('SRC-1');
|
||
const dst = Address.fromString('DST-0');
|
||
const info = new TextEncoder().encode('payload');
|
||
|
||
// quick builder
|
||
const ax = encodeAX25(dst, src, info, { ui: true });
|
||
|
||
// or construct Frame and HDLC-wrap
|
||
const f = new UnnumberedFrame(src, dst, 0x03, 'UI', 0, info);
|
||
const hdlc = toHDLC(f); // includes FCS, escapes and flags
|
||
```
|
||
|
||
### Parsing
|
||
|
||
```ts
|
||
import { Frame } from './src/frame';
|
||
|
||
const frame = Frame.fromBytes(ax);
|
||
console.log(frame.toString());
|
||
```
|
||
|
||
## HDLC & FCS
|
||
|
||
- `computeFcs(payload)` — CRC-16-CCITT with AX.25/X.25 inversion semantics.
|
||
- `encodeHDLC(payload, { includeFcs: true })` — wraps payload with 0x7E flags, appends FCS and escapes special bytes.
|
||
- `verifyAndStripFcs(buf)` — validates and strips a little-endian 2-byte FCS from a buffer.
|
||
|
||
## Testing and style
|
||
|
||
- Tests live in `test/` and are run with Vitest. They follow `describe('Class.method', ...)` naming.
|
||
- Keep tests targeted and add coverage for new behavior.
|