remove reverse in ByteFunctionHelpers

java/vector/src/main/java/org/apache/arrow/vector/util/ByteFunctionHelpers.java

@@ -39,7 +39,7 @@ private ByteFunctionHelpers() {}
    * @param right  Right ArrowBuf for comparison
    * @param rStart start offset in the buffer
    * @param rEnd   end offset in the buffer
-   * @return 1 if left input is greater, -1 if left input is smaller, 0 otherwise
+   * @return 1 if equals, 0 otherwise
    */
   public static final int equal(final ArrowBuf left, int lStart, int lEnd, final ArrowBuf right, int rStart, int rEnd) {
     if (BoundsChecking.BOUNDS_CHECKING_ENABLED) {
@@ -138,7 +138,7 @@ private static int memcmp(
       long leftLong = PlatformDependent.getLong(lPos);
       long rightLong = PlatformDependent.getLong(rPos);
       if (leftLong != rightLong) {
-        return unsignedLongCompare(Long.reverseBytes(leftLong), Long.reverseBytes(rightLong));
+        return unsignedLongCompare(leftLong, rightLong);
       }
       lPos += 8;
       rPos += 8;
@@ -149,7 +149,7 @@ private static int memcmp(
       int leftInt = PlatformDependent.getInt(lPos);
       int rightInt = PlatformDependent.getInt(rPos);
       if (leftInt != rightInt) {
-        return unsignedIntCompare(Integer.reverseBytes(leftInt), Integer.reverseBytes(rightInt));
+        return unsignedIntCompare(leftInt, rightInt);
       }
       lPos += 4;
       rPos += 4;

java/vector/src/test/java/org/apache/arrow/vector/util/TestByteFunctionHelpers.java

@@ -0,0 +1,92 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.arrow.vector.util;
+
+import static org.junit.Assert.assertEquals;
+
+import org.apache.arrow.memory.BufferAllocator;
+import org.apache.arrow.memory.RootAllocator;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import io.netty.buffer.ArrowBuf;
+
+public class TestByteFunctionHelpers {
+
+  private BufferAllocator allocator;
+
+  private static final int SIZE = 100;
+
+  @Before
+  public void init() {
+    allocator = new RootAllocator(Long.MAX_VALUE);
+
+  }
+
+  @After
+  public void terminate() throws Exception {
+    allocator.close();
+  }
+
+  @Test
+  public void testEquals() {
+    ArrowBuf buffer1 = allocator.buffer(SIZE);
+    ArrowBuf buffer2 = allocator.buffer(SIZE);
+
+    for (int i = 0; i < SIZE; i++) {
+      buffer1.setByte(i, i);
+      buffer2.setByte(i, i);
+    }
+
+    assertEquals(1, ByteFunctionHelpers.equal(buffer1, 0, SIZE - 1,
+        buffer2, 0, SIZE - 1));
+
+    buffer1.setByte(50, 10);
+
+    assertEquals(0, ByteFunctionHelpers.equal(buffer1, 0, SIZE - 1,
+        buffer2, 0, SIZE - 1));
+
+    buffer1.close();
+    buffer2.close();
+
+  }
+
+  @Test
+  public void testCompare() {
+    ArrowBuf buffer1 = allocator.buffer(SIZE);
+    ArrowBuf buffer2 = allocator.buffer(SIZE);
+
+    for (int i = 0; i < SIZE; i++) {
+      buffer1.setByte(i, i);
+      buffer2.setByte(i, i);
+    }
+
+    assertEquals(0, ByteFunctionHelpers.compare(buffer1, 0, SIZE - 1,
+        buffer2, 0, SIZE - 1));
+
+    buffer1.setByte(50, 10);
+
+    assertEquals(-1, ByteFunctionHelpers.compare(buffer1, 0, SIZE - 1,
+        buffer2, 0, SIZE - 1));
+
+    buffer1.close();
+    buffer2.close();
+
+  }
+}