1/*
2 * Copyright (C) 2008 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#ifndef android_nio_utils_DEFINED
18#define android_nio_utils_DEFINED
19
20#include <android_runtime/AndroidRuntime.h>
21
22namespace android {
23
24/**
25 * Given an nio.Buffer, return a pointer to it, beginning at its current
26 * position. The returned pointer is only valid for the current JNI stack-frame.
27 * For performance, it does not create any global references, so the getPointer
28 * (and releasePointer if array is returned non-null) must be done in the
29 * same JNI stack-frame.
30 *
31 * @param env   The current JNI env
32 * @param buffer    The nio.Buffer object
33 * @param array     REQUIRED. Output. If on return it is set to non-null, then
34 *                  nio_releasePointer must be called with the array
35 *                  and the returned pointer when the caller is through with it.
36 *                  If on return it is set to null, do not call
37 *                  nio_releasePointer.
38 * @return The pointer to the memory in the buffer object
39 */
40void* nio_getPointer(JNIEnv *env, jobject buffer, jarray *array);
41
42/**
43 * Call this if android_nio_getPointer returned non-null in its array parameter.
44 * Pass that array and the returned pointer when you are done accessing the
45 * pointer. If called (i.e. array is non-null), it must be called in the same
46 * JNI stack-frame as getPointer
47 *
48 * @param env   The current JNI env
49 * @param buffer    The array returned from android_nio_getPointer (!= null)
50 * @param pointer   The pointer returned by android_nio_getPointer
51 * @param commit    JNI_FALSE if the pointer was just read, and JNI_TRUE if
52 *                  the pointer was written to.
53 */
54void nio_releasePointer(JNIEnv *env, jarray array, void *pointer,
55                                jboolean commit);
56
57class AutoBufferPointer {
58public:
59    AutoBufferPointer(JNIEnv* env, jobject nioBuffer, jboolean commit);
60    ~AutoBufferPointer();
61
62    void* pointer() const { return fPointer; }
63
64private:
65    JNIEnv* fEnv;
66    void*   fPointer;
67    jarray  fArray;
68    jint    fRemaining;
69    jboolean fCommit;
70};
71
72}   /* namespace android */
73
74#endif
75