matterbridge-bthome/dist/BTHomeDecoder.js

Matterbridge BTHome plugin

import { BTHOME_SPEC } from './BTHomeSpec.js';
export function decodeBTHome(buf) {
    const info = buf.readUInt8(0);
    const version = (info >> 5) & 0b00000111;
    const encrypted = Boolean(info & 0b00000001);
    const trigger = Boolean(info & 0b00000100);
    const readings = {};
    const unknown = [];
    let offset = 1;
    const ids = [];
    while (offset < buf.length) {
        const id = buf.readUInt8(offset++);
        ids.push(id);
        const spec = BTHOME_SPEC[id];
        if (!spec) {
            unknown.push(`0x${id.toString(16)} → 0x${buf.slice(offset - 1).toString('hex')}`);
            break;
        }
        let value;
        if (spec.parser) {
            value = spec.parser(buf, offset);
            if (spec.bytes != null) {
                offset += spec.bytes;
            }
            else {
                const len = buf.readUInt8(offset);
                offset += 1 + len;
            }
        }
        else {
            if (spec.bytes == null) {
                throw new Error(`BTHome spec for ${spec.name} is missing 'bytes'`);
            }
            const bytes = spec.bytes;
            const factor = spec.factor ?? 1;
            const raw = spec.signed ? buf.readIntLE(offset, bytes) : buf.readUIntLE(offset, bytes);
            value = parseFloat((raw * factor).toFixed(Math.log10(1 / factor)));
            offset += bytes;
        }
        const count = ids.filter((existingId) => existingId === id).length;
        let name = spec.name;
        if (count > 1) {
            name = spec.name + `:${count}`;
            if (spec.name in readings) {
                readings[spec.name + ':1'] = readings[spec.name];
                delete readings[spec.name];
            }
        }
        readings[name] = value;
    }
    return { version, encrypted, trigger, readings, unknown };
}