1 files changed, 59 insertions, 0 deletions
diff --git a/LoopbackApp/app/src/main/java/org/drrickorang/loopback/Utilities.java b/LoopbackApp/app/src/main/java/org/drrickorang/loopback/Utilities.java
new file mode 100644
index 0000000..2d74b29
--- /dev/null
+++ b/LoopbackApp/app/src/main/java/org/drrickorang/loopback/Utilities.java
@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2015 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 org.drrickorang.loopback;
+
+
+/**
+ * This class contains functions that can be reused in different classes.
+ */
+
+public class Utilities {
+
+
+    /** Multiply the input array with a hanning window. */
+    public static double[] hanningWindow(double[] samples) {
+        int length = samples.length;
+        final double alpha = 0.5;
+        final double beta = 0.5;
+        double coefficient;
+        for (int i = 0; i < length; i++) {
+            coefficient = (Constant.TWO_PI * i) / (length - 1);
+            samples[i] *= alpha - beta * Math.cos(coefficient);
+        }
+
+        return samples;
+    }
+
+
+    /** Round up to the nearest power of 2. */
+    public static int roundup(int size)
+    {
+        // Integer.numberOfLeadingZeros() returns 32 for zero input
+        if (size == 0) {
+            size = 1;
+        }
+
+        int lz = Integer.numberOfLeadingZeros(size);
+        int rounded = 0x80000000 >>> lz;
+        // 0x800000001 and higher are actually rounded _down_ to prevent overflow
+        if (size > rounded && lz > 0) {
+            rounded <<= 1;
+        }
+        return rounded;
+    }
+
+}