From 43fcc0679a7abb53e6a33270407e22b8ebcaf3c5 Mon Sep 17 00:00:00 2001
From: George Satellite <lunaerxs@gmail.com>
Date: Thu, 5 Oct 2023 14:32:29 +0300
Subject: [PATCH] apps/docs: math/decibels

---
 apps/docs/src/utils/math/decibels.test.ts | 23 +++++++++++++++++++++++
 apps/docs/src/utils/math/decibels.ts      |  8 ++++++++
 2 files changed, 31 insertions(+)
 create mode 100644 apps/docs/src/utils/math/decibels.test.ts
 create mode 100644 apps/docs/src/utils/math/decibels.ts

diff --git a/apps/docs/src/utils/math/decibels.test.ts b/apps/docs/src/utils/math/decibels.test.ts
new file mode 100644
index 0000000..426cac9
--- /dev/null
+++ b/apps/docs/src/utils/math/decibels.test.ts
@@ -0,0 +1,23 @@
+import {describe, expect, it} from 'vitest';
+import {gainToDecibels, dbMin} from './decibels';
+
+describe('gainToDecibels', () => {
+  it('should convert gain to decibels correctly', () => {
+    expect(gainToDecibels(10)).toBeCloseTo(20.0);
+    expect(gainToDecibels(2)).toBeCloseTo(6.02);
+    expect(gainToDecibels(1)).toBeCloseTo(0);
+    expect(gainToDecibels(0.5)).toBeCloseTo(-6.02);
+    expect(gainToDecibels(0.25)).toBeCloseTo(-12.04);
+    expect(gainToDecibels(0.125)).toBeCloseTo(-18.06);
+    expect(gainToDecibels(0.01)).toBeCloseTo(-40);
+    expect(gainToDecibels(0.001)).toBeCloseTo(-60);
+  });
+
+  it(`should return ${dbMin} for extremely low values`, () => {
+    expect(gainToDecibels(1e-10)).toBeCloseTo(dbMin);
+    expect(gainToDecibels(1e-20)).toBeCloseTo(dbMin);
+    expect(gainToDecibels(1e-30)).toBeCloseTo(dbMin);
+    expect(gainToDecibels(1e-40)).toBeCloseTo(dbMin);
+    expect(gainToDecibels(0)).toBeCloseTo(dbMin);
+  });
+});
diff --git a/apps/docs/src/utils/math/decibels.ts b/apps/docs/src/utils/math/decibels.ts
new file mode 100644
index 0000000..fb123b5
--- /dev/null
+++ b/apps/docs/src/utils/math/decibels.ts
@@ -0,0 +1,8 @@
+export const dbMin = -96;
+
+export const gainToDecibels = (gain: number): number => {
+  let res = 20 * Math.log10(gain);
+  res = Number.isFinite(res) ? res : dbMin;
+  res = Math.max(res, dbMin);
+  return res;
+};