1/*
2 * Copyright (C) 2011 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17
18package android.filterfw.core;
19
20import android.filterfw.core.Frame;
21
22/**
23 * @hide
24 */
25public class NativeBuffer {
26
27    // These are set by the native layer
28    private long mDataPointer = 0;
29    private int mSize = 0;
30
31    private Frame mAttachedFrame;
32
33    private boolean mOwnsData = false;
34    private int mRefCount = 1;
35
36    public NativeBuffer() {
37    }
38
39    public NativeBuffer(int count) {
40        allocate(count * getElementSize());
41        mOwnsData = true;
42    }
43
44    public NativeBuffer mutableCopy() {
45        NativeBuffer result = null;
46        try {
47            Class myClass = getClass();
48            result = (NativeBuffer)myClass.newInstance();
49        } catch (Exception e) {
50            throw new RuntimeException("Unable to allocate a copy of " + getClass() + "! Make " +
51                                       "sure the class has a default constructor!");
52        }
53        if (mSize > 0 && !nativeCopyTo(result)) {
54            throw new RuntimeException("Failed to copy NativeBuffer to mutable instance!");
55        }
56        return result;
57    }
58
59    public int size() {
60        return mSize;
61    }
62
63    public int count() {
64        return (mDataPointer != 0) ? mSize / getElementSize() : 0;
65    }
66
67    public int getElementSize() {
68        return 1;
69    }
70
71    public NativeBuffer retain() {
72        if (mAttachedFrame != null) {
73            mAttachedFrame.retain();
74        } else if (mOwnsData) {
75            ++mRefCount;
76        }
77        return this;
78    }
79
80    public NativeBuffer release() {
81        // Decrement refcount
82        boolean doDealloc = false;
83        if (mAttachedFrame != null) {
84            doDealloc = (mAttachedFrame.release() == null);
85        } else if (mOwnsData) {
86            --mRefCount;
87            doDealloc = (mRefCount == 0);
88        }
89
90        // Deallocate if necessary
91        if (doDealloc) {
92            deallocate(mOwnsData);
93            return null;
94        } else {
95            return this;
96        }
97    }
98
99    public boolean isReadOnly() {
100        return (mAttachedFrame != null) ? mAttachedFrame.isReadOnly() : false;
101    }
102
103    static {
104        System.loadLibrary("filterfw");
105    }
106
107    void attachToFrame(Frame frame) {
108        // We do not auto-retain. We expect the user to call retain() if they want to hold on to
109        // the frame.
110        mAttachedFrame = frame;
111    }
112
113    protected void assertReadable() {
114        if (mDataPointer == 0 || mSize == 0
115        || (mAttachedFrame != null && !mAttachedFrame.hasNativeAllocation())) {
116            throw new NullPointerException("Attempting to read from null data frame!");
117        }
118    }
119
120    protected void assertWritable() {
121        if (isReadOnly()) {
122            throw new RuntimeException("Attempting to modify read-only native (structured) data!");
123        }
124    }
125
126    private native boolean allocate(int size);
127    private native boolean deallocate(boolean ownsData);
128    private native boolean nativeCopyTo(NativeBuffer buffer);
129}
130