From 9af6d262fe60e5eba6556e210e6cde8bf850d8d2 Mon Sep 17 00:00:00 2001
From: Alexey Andreev <konsoletyper@gmail.com>
Date: Fri, 18 Aug 2023 17:54:52 +0200
Subject: [PATCH] classlib: properly implement ByteOrder.nativeOrder

---
 .../teavm/classlib/java/nio/TByteOrder.java   | 23 ++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/classlib/src/main/java/org/teavm/classlib/java/nio/TByteOrder.java b/classlib/src/main/java/org/teavm/classlib/java/nio/TByteOrder.java
index 90058eb29..79ef0e5b4 100644
--- a/classlib/src/main/java/org/teavm/classlib/java/nio/TByteOrder.java
+++ b/classlib/src/main/java/org/teavm/classlib/java/nio/TByteOrder.java
@@ -15,9 +15,16 @@
  */
 package org.teavm.classlib.java.nio;
 
+import org.teavm.classlib.PlatformDetector;
+import org.teavm.interop.Address;
+import org.teavm.jso.typedarrays.ArrayBuffer;
+import org.teavm.jso.typedarrays.Int16Array;
+import org.teavm.jso.typedarrays.Int8Array;
+
 public final class TByteOrder {
     public static final TByteOrder BIG_ENDIAN = new TByteOrder("BIG_ENDIAN");
     public static final TByteOrder LITTLE_ENDIAN = new TByteOrder("LITTLE_ENDIAN");
+    private static TByteOrder nativeOrder;
     private String name;
 
     private TByteOrder(String name) {
@@ -25,7 +32,21 @@ public final class TByteOrder {
     }
 
     public static TByteOrder nativeOrder() {
-        return BIG_ENDIAN;
+        if (nativeOrder == null) {
+            if (PlatformDetector.isJavaScript()) {
+                var buffer = ArrayBuffer.create(2);
+                var shortArray = Int16Array.create(buffer);
+                shortArray.set(0, (short) 1);
+                var byteArray = Int8Array.create(buffer);
+                nativeOrder = byteArray.get(0) == 0 ? BIG_ENDIAN : LITTLE_ENDIAN;
+            } else {
+                var array = new short[1];
+                array[0] = 1;
+                var firstByte = Address.ofData(array).getByte();
+                nativeOrder = firstByte == 0 ? BIG_ENDIAN : LITTLE_ENDIAN;
+            }
+        }
+        return nativeOrder;
     }
 
     @Override