Utils: Optimize hex buffer conversion functions

lib/utils.ts

@@ -413,19 +413,85 @@ export function formatSQLArray(arr: unknown[], args?: unknown[]) {
 	return [...'?'.repeat(arr.length)].join(', ');
 }
 
-export function bufFromHex(hex: string) {
-	const buf = new Uint8Array(Math.ceil(hex.length / 2));
-	bufWriteHex(buf, hex);
+/**
+ * Nibble lookup table to convert ASCII character codes to their hexadecimal values (0-15).
+ * Invalid characters are marked with 0xFF.
+ */
+const nibbleLookup = (() => {
+	const lookup = new Uint8Array(256);
+	for (let i = 0; i < 256; i++) {
+		lookup[i] = 0xFF; // Mark as invalid by default
+	}
+	'0123456789abcdef'.split('').forEach((char, index) => {
+		lookup[char.charCodeAt(0)] = index;
+	});
+	'0123456789ABCDEF'.split('').forEach((char, index) => {
+		lookup[char.charCodeAt(0)] = index;
+	});
+	return lookup;
+})();
+
+/**
+ * Byte-to-hex lookup table for efficient conversion from bytes to hexadecimal strings.
+ */
+const byteToHexTable = (() => {
+	const table = new Array<string>(256);
+	for (let i = 0; i < 256; i++) {
+		table[i] = (i < 16 ? '0' : '') + i.toString(16);
+	}
+	return table;
+})();
+
+export function bufFromHex(hex: string): Uint8Array {
+	const len = hex.length;
+	const buf = new Uint8Array(Math.ceil(len / 2));
+	let j = 0;
+
+	for (let i = 0; i < len; i += 2) {
+		const hiChar = hex.charCodeAt(i);
+		const loChar = i + 1 < len ? hex.charCodeAt(i + 1) : 0x30; // '0' if no character
+		const hi = nibbleLookup[hiChar];
+		const lo = nibbleLookup[loChar];
+
+		if (hi === 0xFF || lo === 0xFF) {
+			throw new Error(
+				`Invalid hex character encountered: '${hex[i]}' or '${hex[i + 1] || '0'}'`
+			);
+		}
+
+		buf[j++] = (hi << 4) | lo;
+	}
+
 	return buf;
 }
-export function bufWriteHex(buf: Uint8Array, hex: string, offset = 0) {
-	const size = Math.ceil(hex.length / 2);
-	for (let i = 0; i < size; i++) {
-		buf[offset + i] = parseInt(hex.slice(i * 2, i * 2 + 2).padEnd(2, '0'), 16);
+
+export function bufWriteHex(buf: Uint8Array, hex: string, offset = 0): void {
+	const len = hex.length;
+	let j = offset;
+
+	for (let i = 0; i < len; i += 2) {
+		const hiChar = hex.charCodeAt(i);
+		const loChar = i + 1 < len ? hex.charCodeAt(i + 1) : 0x30; // '0' if no character
+		const hi = nibbleLookup[hiChar];
+		const lo = nibbleLookup[loChar];
+
+		if (hi === 0xFF || lo === 0xFF) {
+			throw new Error(
+				`Invalid hex character encountered: '${hex[i]}' or '${hex[i + 1] || '0'}'`
+			);
+		}
+
+		buf[j++] = (hi << 4) | lo;
 	}
 }
-export function bufReadHex(buf: Uint8Array, start = 0, end?: number) {
-	return [...buf.slice(start, end)].map(val => val.toString(16).padStart(2, '0')).join('');
+
+export function bufReadHex(buf: Uint8Array, start = 0, end?: number): string {
+	if (end === undefined) end = buf.length;
+	let out = '';
+	for (let i = start; i < end; i++) {
+		out += byteToHexTable[buf[i]];
+	}
+	return out;
 }
 
 export class Multiset<T> extends Map<T, number> {