Move RiffWriter into separate file

src/wave/riff-writer.ts

@@ -0,0 +1,22 @@
+import { Writer } from '../writer';
+
+export class RiffWriter {
+	private helper = new Uint8Array(8);
+	private helperView = new DataView(this.helper.buffer);
+
+	constructor(private writer: Writer) {}
+
+	writeU32(value: number) {
+		this.helperView.setUint32(0, value, true);
+		this.writer.write(this.helper.subarray(0, 4));
+	}
+
+	writeU16(value: number) {
+		this.helperView.setUint16(0, value, true);
+		this.writer.write(this.helper.subarray(0, 2));
+	}
+
+	writeAscii(text: string) {
+		this.writer.write(new TextEncoder().encode(text));
+	}
+}