Consolidate util.js

Author: dy

apply.js

@@ -49,8 +49,4 @@ export { default as dpss } from './dpss.js'
 export { default as ultraspherical } from './ultraspherical.js'
 
 // Utilities
-export { default as generate } from './generate.js'
-export { default as apply } from './apply.js'
-export { default as enbw } from './enbw.js'
-export { default as scallopLoss } from './scallopLoss.js'
-export { default as cola } from './cola.js'
+export { generate, apply, enbw, scallopLoss, cola } from './util.js'

cola.js

@@ -39,11 +39,7 @@
     "./taylor": "./taylor.js",
     "./dpss": "./dpss.js",
     "./ultraspherical": "./ultraspherical.js",
-    "./generate": "./generate.js",
-    "./apply": "./apply.js",
-    "./enbw": "./enbw.js",
-    "./scallopLoss": "./scallopLoss.js",
-    "./cola": "./cola.js"
+    "./util": "./util.js"
   },
   "types": "./index.d.ts",
   "typesVersions": { "*": { "*": ["./index.d.ts"] } },

enbw.js

@@ -0,0 +1,42 @@
+import { cos, sin, sqrt, abs, PI } from './_util.js'
+
+/** Generate a full window as Float64Array. */
+export function generate (fn, N, ...params) {
+	let w = new Float64Array(N)
+	for (let i = 0; i < N; i++) w[i] = fn(i, N, ...params)
+	return w
+}
+
+/** Apply window to a signal in-place. */
+export function apply (signal, fn, ...params) {
+	for (let i = 0, N = signal.length; i < N; i++) signal[i] *= fn(i, N, ...params)
+	return signal
+}
+
+/** Equivalent noise bandwidth in frequency bins. Rectangular = 1.0, Hann ≈ 1.5. */
+export function enbw (fn, N, ...params) {
+	let s = 0, s2 = 0
+	for (let i = 0; i < N; i++) { let v = fn(i, N, ...params); s += v; s2 += v * v }
+	return N * s2 / (s * s)
+}
+
+/** Worst-case amplitude error in dB when a tone falls between DFT bins. */
+export function scallopLoss (fn, N, ...params) {
+	let s = 0, re = 0, im = 0
+	for (let i = 0; i < N; i++) { let v = fn(i, N, ...params); s += v; re += v * cos(PI * i / N); im -= v * sin(PI * i / N) }
+	return s === 0 ? Infinity : -20 * Math.log10(sqrt(re * re + im * im) / abs(s))
+}
+
+/** COLA deviation. Returns max relative deviation from constant overlap-add sum; 0 = perfect. */
+export function cola (fn, N, hop, ...params) {
+	let win = generate(fn, N, ...params)
+	let sums = new Float64Array(hop)
+	for (let t = 0; t < hop; t++) for (let k = t; k < N; k += hop) sums[t] += win[k]
+	let mean = 0
+	for (let t = 0; t < hop; t++) mean += sums[t]
+	mean /= hop
+	if (mean === 0) return Infinity
+	let maxDev = 0
+	for (let t = 0; t < hop; t++) { let d = abs(sums[t] - mean) / mean; if (d > maxDev) maxDev = d }
+	return maxDev
+}