Add ByteUtils for byte utility functions
Bug: 254155029
Test: atest NetworkStaticLibTests
Change-Id: I996ead6f23698313828e844672de5917efdfce69
diff --git a/staticlibs/framework/com/android/net/module/util/ByteUtils.java b/staticlibs/framework/com/android/net/module/util/ByteUtils.java
new file mode 100644
index 0000000..3324975
--- /dev/null
+++ b/staticlibs/framework/com/android/net/module/util/ByteUtils.java
@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed 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 com.android.net.module.util;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+
+/**
+ * Byte utility functions.
+ * @hide
+ */
+public class ByteUtils {
+ /**
+ * Returns the index of the first appearance of the value {@code target} in {@code array}.
+ *
+ * @param array an array of {@code byte} values, possibly empty
+ * @param target a primitive {@code byte} value
+ * @return the least index {@code i} for which {@code array[i] == target}, or {@code -1} if no
+ * such index exists.
+ */
+ public static int indexOf(@NonNull byte[] array, @Nullable byte target) {
+ return indexOf(array, target, 0, array.length);
+ }
+
+ private static int indexOf(byte[] array, byte target, int start, int end) {
+ for (int i = start; i < end; i++) {
+ if (array[i] == target) {
+ return i;
+ }
+ }
+ return -1;
+ }
+
+ /**
+ * Returns the values from each provided array combined into a single array. For example, {@code
+ * concat(new byte[] {a, b}, new byte[] {}, new byte[] {c}} returns the array {@code {a, b, c}}.
+ *
+ * @param arrays zero or more {@code byte} arrays
+ * @return a single array containing all the values from the source arrays, in order
+ */
+ public static byte[] concat(@NonNull byte[]... arrays) {
+ int length = 0;
+ for (byte[] array : arrays) {
+ length += array.length;
+ }
+ byte[] result = new byte[length];
+ int pos = 0;
+ for (byte[] array : arrays) {
+ System.arraycopy(array, 0, result, pos, array.length);
+ pos += array.length;
+ }
+ return result;
+ }
+}
diff --git a/staticlibs/tests/unit/src/com/android/net/module/util/ByteUtilsTests.kt b/staticlibs/tests/unit/src/com/android/net/module/util/ByteUtilsTests.kt
new file mode 100644
index 0000000..e58adad
--- /dev/null
+++ b/staticlibs/tests/unit/src/com/android/net/module/util/ByteUtilsTests.kt
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed 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 com.android.net.module.util
+
+import com.android.net.module.util.ByteUtils.indexOf
+import com.android.net.module.util.ByteUtils.concat
+import org.junit.Test
+import kotlin.test.assertContentEquals
+import kotlin.test.assertEquals
+import kotlin.test.assertNotSame
+
+class ByteUtilsTests {
+ private val EMPTY = byteArrayOf()
+ private val ARRAY1 = byteArrayOf(1)
+ private val ARRAY234 = byteArrayOf(2, 3, 4)
+
+ @Test
+ fun testIndexOf() {
+ assertEquals(-1, indexOf(EMPTY, 1))
+ assertEquals(-1, indexOf(ARRAY1, 2))
+ assertEquals(-1, indexOf(ARRAY234, 1))
+ assertEquals(0, indexOf(byteArrayOf(-1), -1))
+ assertEquals(0, indexOf(ARRAY234, 2))
+ assertEquals(1, indexOf(ARRAY234, 3))
+ assertEquals(2, indexOf(ARRAY234, 4))
+ assertEquals(1, indexOf(byteArrayOf(2, 3, 2, 3), 3))
+ }
+
+ @Test
+ fun testConcat() {
+ assertContentEquals(EMPTY, concat())
+ assertContentEquals(EMPTY, concat(EMPTY))
+ assertContentEquals(EMPTY, concat(EMPTY, EMPTY, EMPTY))
+ assertContentEquals(ARRAY1, concat(ARRAY1))
+ assertNotSame(ARRAY1, concat(ARRAY1))
+ assertContentEquals(ARRAY1, concat(EMPTY, ARRAY1, EMPTY))
+ assertContentEquals(byteArrayOf(1, 1, 1), concat(ARRAY1, ARRAY1, ARRAY1))
+ assertContentEquals(byteArrayOf(1, 2, 3, 4), concat(ARRAY1, ARRAY234))
+ }
+}
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