Add WAVE demuxer

src/wave/riff-reader.ts

@@ -0,0 +1,40 @@
+import { Reader } from '../reader';
+
+export class RiffReader {
+	pos = 0;
+	littleEndian = true;
+
+	constructor(public reader: Reader) {}
+
+	readBytes(length: number) {
+		const { view, offset } = this.reader.getViewAndOffset(this.pos, this.pos + length);
+		this.pos += length;
+
+		return new Uint8Array(view.buffer, offset, length);
+	}
+
+	readU16() {
+		const { view, offset } = this.reader.getViewAndOffset(this.pos, this.pos + 2);
+		this.pos += 2;
+
+		return view.getUint16(offset, this.littleEndian);
+	}
+
+	readU32() {
+		const { view, offset } = this.reader.getViewAndOffset(this.pos, this.pos + 4);
+		this.pos += 4;
+
+		return view.getUint32(offset, this.littleEndian);
+	}
+
+	readAscii(length: number) {
+		const { view, offset } = this.reader.getViewAndOffset(this.pos, this.pos + length);
+		this.pos += length;
+
+		let str = '';
+		for (let i = 0; i < length; i++) {
+			str += String.fromCharCode(view.getUint8(offset + i));
+		}
+		return str;
+	}
+}