core/jni/android_nio_utils.cpp

/*
 * Copyright (C) 2008 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 "android_nio_utils.h"

#include "core_jni_helpers.h"

void* android::nio_getPointer(JNIEnv *_env, jobject buffer, jarray *array) {
    assert(array);

    jint position;
    jint limit;
    jint elementSizeShift;
    jlong pointer = jniGetNioBufferFields(_env, buffer, &position, &limit, &elementSizeShift);
    if (pointer != 0L) {
        pointer += position << elementSizeShift;
        return reinterpret_cast<void*>(pointer);
    }

    jint offset = jniGetNioBufferBaseArrayOffset(_env, buffer);
    *array = jniGetNioBufferBaseArray(_env, buffer);
    void * data = _env->GetPrimitiveArrayCritical(*array, (jboolean *) 0);
    return reinterpret_cast<void*>(reinterpret_cast<char*>(data) + offset);
}


void android::nio_releasePointer(JNIEnv *_env, jarray array, void *data,
                                jboolean commit) {
    _env->ReleasePrimitiveArrayCritical(array, data,
                                        commit ? 0 : JNI_ABORT);
}

///////////////////////////////////////////////////////////////////////////////

android::AutoBufferPointer::AutoBufferPointer(JNIEnv* env, jobject nioBuffer,
                                              jboolean commit) {
    fEnv = env;
    fCommit = commit;
    fPointer = android::nio_getPointer(env, nioBuffer, &fArray);
}

android::AutoBufferPointer::~AutoBufferPointer() {
    if (NULL != fArray) {
        android::nio_releasePointer(fEnv, fArray, fPointer, fCommit);
    }
}