| /* |
| * Copyright (C) 2010 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. |
| */ |
| |
| #include "Window.h" |
| |
| #include <stdlib.h> |
| #include <math.h> |
| |
| void Window::windowCreate(int size) { |
| if (mWindowWeights && (mWindowSize < size)) { |
| delete [] mWindowWeights; |
| mWindowWeights = NULL; |
| mWindowSize = 0; |
| } |
| if (!mWindowWeights) { |
| mWindowWeights = new float[size]; |
| } |
| if (mWindowSize != size) { |
| double arg = M_PI * 2.0 / size; |
| mWindowSize = size; |
| for (int i = 0; i < size; ++i) { |
| mWindowWeights[i] = 0.5 - (0.5 * cos((i + 0.5) * arg)); |
| } |
| } |
| } |
| |
| void Window::windowCleanup() { |
| mWindowSize = 0; |
| delete [] mWindowWeights; |
| mWindowWeights = NULL; |
| } |
| |
| /* Multiply the signal in data by the window weights. Place the |
| resulting mWindowSize floating-point values in output. If preemp |
| is != 0.0, apply a 1st-order preemphasis filter, and assume that |
| there are mWindowSize+1 samples available in data. */ |
| void Window::window(short* data, float* output, float preemp) { |
| if (preemp == 0.0) { |
| for (int i = 0; i < mWindowSize; ++i) |
| output[i] = data[i] * mWindowWeights[i]; |
| } else { |
| for (int i = 0; i < mWindowSize; ++i) |
| output[i] = (data[i+1] - (preemp * data[i])) * mWindowWeights[i]; |
| } |
| } |
| |