102 lines
3.1 KiB
JavaScript
102 lines
3.1 KiB
JavaScript
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'use strict';
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/**
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* The slice of OSC 1.0 AbleSet speaks — messages and bundles with int32,
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* float32, string, blob, true/false/nil — encoded and decoded with Buffer
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* alone, so the module needs nothing outside Node.
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*/
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function pad4(n) {
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return (n + 3) & ~3;
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}
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function encodeString(s) {
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const raw = Buffer.from(String(s), 'utf8');
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const out = Buffer.alloc(pad4(raw.length + 1));
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raw.copy(out);
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return out;
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}
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/**
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* One message. Arguments are typed by their JS value: integers are int32,
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* other numbers float32, booleans T/F, null nil, everything else a string.
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*/
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function encodeMessage(address, args = []) {
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let tags = ',';
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const parts = [];
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for (const a of args) {
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if (a === null || a === undefined) {
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tags += 'N';
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} else if (typeof a === 'boolean') {
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tags += a ? 'T' : 'F';
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} else if (typeof a === 'number' && Number.isInteger(a)) {
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tags += 'i';
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const b = Buffer.alloc(4);
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b.writeInt32BE(a);
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parts.push(b);
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} else if (typeof a === 'number') {
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tags += 'f';
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const b = Buffer.alloc(4);
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b.writeFloatBE(a);
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parts.push(b);
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} else {
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tags += 's';
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parts.push(encodeString(a));
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}
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}
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return Buffer.concat([encodeString(address), encodeString(tags), ...parts]);
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}
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function readString(buf, at) {
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let end = at;
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while (end < buf.length && buf[end] !== 0) end += 1;
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if (end >= buf.length) throw new Error('unterminated OSC string');
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return { value: buf.toString('utf8', at, end), next: pad4(end + 1) };
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}
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function decodeMessage(buf, out) {
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const addr = readString(buf, 0);
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let at = addr.next;
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const args = [];
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if (at < buf.length && buf[at] === 0x2c) {
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const tagStr = readString(buf, at);
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at = tagStr.next;
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for (const t of tagStr.value.slice(1)) {
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switch (t) {
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case 'i': args.push(buf.readInt32BE(at)); at += 4; break;
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case 'f': args.push(buf.readFloatBE(at)); at += 4; break;
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case 'd': args.push(buf.readDoubleBE(at)); at += 8; break;
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case 'h': args.push(Number(buf.readBigInt64BE(at))); at += 8; break;
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case 's': case 'S': { const s = readString(buf, at); args.push(s.value); at = s.next; break; }
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case 'b': { const n = buf.readInt32BE(at); args.push(buf.subarray(at + 4, at + 4 + n)); at = pad4(at + 4 + n); break; }
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case 'T': args.push(true); break;
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case 'F': args.push(false); break;
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case 'N': args.push(null); break;
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case 'I': args.push(Infinity); break;
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case 't': at += 8; break;
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default: throw new Error(`unsupported OSC type tag "${t}"`);
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}
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}
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}
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out.push({ address: addr.value, args });
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}
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/** Every message in a packet, bundles flattened, in order. */
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function decodePacket(buf, out = []) {
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if (buf.length >= 16 && buf.toString('ascii', 0, 8) === '#bundle\0') {
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let at = 16; // "#bundle\0" + 8-byte timetag
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while (at + 4 <= buf.length) {
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const n = buf.readInt32BE(at);
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at += 4;
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if (n <= 0 || at + n > buf.length) break;
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decodePacket(buf.subarray(at, at + n), out);
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at += n;
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}
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return out;
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}
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decodeMessage(buf, out);
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return out;
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}
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module.exports = { encodeMessage, decodePacket };
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