initial commit

src/decoders/index.ts

@@ -0,0 +1,5 @@
+import RTTrPHeader from './rttrp';
+
+export const Decoders = {
+  RTTrPHeader,
+};

src/decoders/rttrp.ts

@@ -0,0 +1,48 @@
+import { RTTrPHeader } from '../models';
+
+export default (bytes: Uint8Array): RTTrPHeader => {
+  if (bytes.length < 18) {
+    throw new Error('RTTrP Header must be at least 18 bytes long');
+  }
+
+  const view = new DataView(bytes.buffer, bytes.byteOffset, bytes.byteLength);
+
+  let dataOffset = 0;
+
+  let isLittleEndian = false;
+  const intHeader = view.getUint16(dataOffset, isLittleEndian);
+  dataOffset += 2;
+  const fltHeader = view.getUint16(dataOffset, isLittleEndian);
+  dataOffset += 2;
+  if (intHeader === 0x4154) {
+    isLittleEndian = false;
+  }
+  const version = view.getUint16(dataOffset, isLittleEndian);
+  dataOffset += 2;
+  if (version !== 0x0002) {
+    throw new Error('Only version 2 of the RTTrP header is currently supported');
+  }
+  const pID = view.getUint32(dataOffset, isLittleEndian);
+  dataOffset += 4;
+
+  const pForm = view.getUint8(dataOffset);
+  dataOffset += 1;
+  const pktSize = view.getUint16(dataOffset, isLittleEndian);
+  dataOffset += 2;
+  const context = view.getUint32(dataOffset, isLittleEndian);
+  dataOffset += 4;
+  const numMods = view.getUint8(dataOffset);
+  dataOffset += 1;
+  const data = bytes.slice(dataOffset);
+  return {
+    intHeader,
+    fltHeader,
+    version,
+    pID,
+    pForm,
+    pktSize,
+    context,
+    numMods,
+    data,
+  };
+};