From b8a78a7f6a9b25dd6abea02ceb2e751bc543a716 Mon Sep 17 00:00:00 2001
From: Brandon Liu <bdon@bdon.org>
Date: Sat, 10 Dec 2022 18:36:04 +0800
Subject: [PATCH] js: avoid use of BigInt operations for older safari browsers
 [#103]

---
 js/index.ts        | 28 +++++++++++++++++-----------
 js/test/v3.test.ts | 11 +++++++++++
 2 files changed, 28 insertions(+), 11 deletions(-)

diff --git a/js/index.ts b/js/index.ts
index 00ccb86..57d2181 100644
--- a/js/index.ts
+++ b/js/index.ts
@@ -330,6 +330,12 @@ export class FetchSource implements Source {
 	}
 }
 
+export function getUint64(v: DataView, offset: number): number {
+	const wh = v.getUint32(offset + 4, true);
+	const wl = v.getUint32(offset + 0, true);
+	return wh * Math.pow(2, 32) + wl;
+}
+
 export function bytesToHeader(bytes: ArrayBuffer, etag?: string): Header {
 	const v = new DataView(bytes);
 	const spec_version = v.getUint8(7);
@@ -341,17 +347,17 @@ export function bytesToHeader(bytes: ArrayBuffer, etag?: string): Header {
 
 	return {
 		specVersion: spec_version,
-		rootDirectoryOffset: Number(v.getBigUint64(8, true)),
-		rootDirectoryLength: Number(v.getBigUint64(16, true)),
-		jsonMetadataOffset: Number(v.getBigUint64(24, true)),
-		jsonMetadataLength: Number(v.getBigUint64(32, true)),
-		leafDirectoryOffset: Number(v.getBigUint64(40, true)),
-		leafDirectoryLength: Number(v.getBigUint64(48, true)),
-		tileDataOffset: Number(v.getBigUint64(56, true)),
-		tileDataLength: Number(v.getBigUint64(64, true)),
-		numAddressedTiles: Number(v.getBigUint64(72, true)),
-		numTileEntries: Number(v.getBigUint64(80, true)),
-		numTileContents: Number(v.getBigUint64(88, true)),
+		rootDirectoryOffset: getUint64(v, 8),
+		rootDirectoryLength: getUint64(v, 16),
+		jsonMetadataOffset: getUint64(v, 24),
+		jsonMetadataLength: getUint64(v, 32),
+		leafDirectoryOffset: getUint64(v, 40),
+		leafDirectoryLength: getUint64(v, 48),
+		tileDataOffset: getUint64(v, 56),
+		tileDataLength: getUint64(v, 64),
+		numAddressedTiles: getUint64(v, 72),
+		numTileEntries: getUint64(v, 80),
+		numTileContents: getUint64(v, 88),
 		clustered: v.getUint8(96) === 1,
 		internalCompression: v.getUint8(97),
 		tileCompression: v.getUint8(98),
diff --git a/js/test/v3.test.ts b/js/test/v3.test.ts
index e148acb..369afee 100644
--- a/js/test/v3.test.ts
+++ b/js/test/v3.test.ts
@@ -14,6 +14,7 @@ import {
 	RangeResponse,
 	EtagMismatch,
 	PMTiles,
+	getUint64,
 } from "../index";
 
 test("varint", () => {
@@ -171,6 +172,16 @@ test("cache getHeader", async () => {
 	assert.strictEqual(header.maxLat, 1);
 });
 
+test("getUint64", async () => {
+	const view = new DataView(new ArrayBuffer(8));
+	view.setBigUint64(0, 0n, true);
+	assert.strictEqual(getUint64(view, 0), 0);
+	view.setBigUint64(0, 1n, true);
+	assert.strictEqual(getUint64(view, 0), 1);
+	view.setBigUint64(0, 9007199254740991n, true);
+	assert.strictEqual(getUint64(view, 0), 9007199254740991);
+});
+
 test("cache check against empty", async () => {
 	const source = new TestNodeFileSource("test/data/empty.pmtiles", "1");
 	const cache = new SharedPromiseCache();