Add methods to pack and unpack two numbers from another

src/algorithms/index.js

@@ -1 +1,2 @@
-export * from './sort/index.js'
+export * from './sort/index.js'
+export * from './packnumber.js'

src/algorithms/packnumber.js

@@ -0,0 +1,42 @@
+/**
+ * Packs two numbers into a single number.
+ * 
+ * #### Note
+ * This operation is should be analogous to packing two 32 bit
+ * numbers into a 64 bit number in the high and low bits.Due
+ * to language limitations, the high bits of this implementation
+ * can only be up to 2 ^ 20, otherwise the output will be garbled
+ * nonsense.
+ * 
+ * @param {number} low 
+ * @param {number} high
+ * @returns 
+ */
+export function packInto64Int(low, high) {
+
+  // We cant use bit manipulation as javascript has a 32 bit limit on
+  // manipulating "integers"
+  return (high * 2 ** 32) + low
+}
+
+/**
+ * Unpacks two numbers from a single number.
+ * 
+ * #### Note
+ * This operation is should be analogous to unpacking two 32 bit
+ * numbers from 64 bit number in the high and low bits.Due
+ * to language limitations, the number passed into this function
+ * can only be up to 2 ^ 53, otherwise the output will be garbled
+ * nonsense.
+ * 
+ * @param {number} value 
+ */
+export function unpackFrom64Int(value) {
+
+  // We cant use bit manipulation as javascript has a 32 bit limit on
+  // manipulating "integers"
+  const low = value % 2 ** 32
+  const high = Math.floor(value / 2 ** 32)
+
+  return [low, high]
+}

src/algorithms/tests/packNumbers.test.js

@@ -0,0 +1,46 @@
+import { test, describe } from "node:test";
+import { deepStrictEqual, strictEqual } from "node:assert";
+import { packInto64Int, unpackFrom64Int } from "../packnumber.js";
+
+describe("Testing pack and unpacking numbers", () => {
+  test('Testing packing number.', () => {
+    const num1 = packInto64Int(0, 0)
+    const num2 = packInto64Int(1, 0)
+    const num3 = packInto64Int(3, 0)
+    const num4 = packInto64Int(0, 1)
+    const num5 = packInto64Int(1, 1)
+    const num6 = packInto64Int(4, 1)
+    const num7 = packInto64Int(0, 3)
+    const num8 = packInto64Int(2, 3)
+
+    strictEqual(num1, 0)
+    strictEqual(num2, 1)
+    strictEqual(num3, 3)
+    strictEqual(num4, 4294967296)
+    strictEqual(num5, 4294967297)
+    strictEqual(num6, 4294967300)
+    strictEqual(num7, 12884901888)
+    strictEqual(num8, 12884901890)
+  })
+
+  test('Testing unpacking number.', () => {
+    const num1 = unpackFrom64Int(0)
+    const num2 = unpackFrom64Int(1)
+    const num3 = unpackFrom64Int(3)
+    const num4 = unpackFrom64Int(4294967296)
+    const num5 = unpackFrom64Int(4294967297)
+    const num6 = unpackFrom64Int(4294967300)
+    const num7 = unpackFrom64Int(12884901888)
+    const num8 = unpackFrom64Int(12884901890)
+
+    deepStrictEqual(num1, [0, 0])
+    deepStrictEqual(num2, [1, 0])
+    deepStrictEqual(num3, [3, 0])
+    deepStrictEqual(num4, [0, 1])
+    deepStrictEqual(num5, [1, 1])
+    deepStrictEqual(num6, [4, 1])
+    deepStrictEqual(num7, [0, 3])
+    deepStrictEqual(num8, [2, 3])
+
+  })
+})