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      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 #include "android_nio_utils.h"
     18 
     19 #include "core_jni_helpers.h"
     20 
     21 struct NioJNIData {
     22     jclass nioAccessClass;
     23 
     24     jmethodID getBasePointerID;
     25     jmethodID getBaseArrayID;
     26     jmethodID getBaseArrayOffsetID;
     27 };
     28 
     29 static NioJNIData gNioJNI;
     30 
     31 void* android::nio_getPointer(JNIEnv *_env, jobject buffer, jarray *array) {
     32     assert(array);
     33 
     34     jlong pointer;
     35     jint offset;
     36     void *data;
     37 
     38     pointer = _env->CallStaticLongMethod(gNioJNI.nioAccessClass,
     39                                          gNioJNI.getBasePointerID, buffer);
     40     if (pointer != 0L) {
     41         *array = NULL;
     42         return reinterpret_cast<void *>(pointer);
     43     }
     44 
     45     *array = (jarray) _env->CallStaticObjectMethod(gNioJNI.nioAccessClass,
     46                                                gNioJNI.getBaseArrayID, buffer);
     47     offset = _env->CallStaticIntMethod(gNioJNI.nioAccessClass,
     48                                        gNioJNI.getBaseArrayOffsetID, buffer);
     49     data = _env->GetPrimitiveArrayCritical(*array, (jboolean *) 0);
     50 
     51     return (void *) ((char *) data + offset);
     52 }
     53 
     54 
     55 void android::nio_releasePointer(JNIEnv *_env, jarray array, void *data,
     56                                 jboolean commit) {
     57     _env->ReleasePrimitiveArrayCritical(array, data,
     58                                         commit ? 0 : JNI_ABORT);
     59 }
     60 
     61 ///////////////////////////////////////////////////////////////////////////////
     62 
     63 android::AutoBufferPointer::AutoBufferPointer(JNIEnv* env, jobject nioBuffer,
     64                                               jboolean commit) {
     65     fEnv = env;
     66     fCommit = commit;
     67     fPointer = android::nio_getPointer(env, nioBuffer, &fArray);
     68 }
     69 
     70 android::AutoBufferPointer::~AutoBufferPointer() {
     71     if (NULL != fArray) {
     72         android::nio_releasePointer(fEnv, fArray, fPointer, fCommit);
     73     }
     74 }
     75 
     76 ///////////////////////////////////////////////////////////////////////////////
     77 
     78 namespace android {
     79 
     80 int register_android_nio_utils(JNIEnv* env) {
     81     jclass localClass = FindClassOrDie(env, "java/nio/NIOAccess");
     82     gNioJNI.getBasePointerID = GetStaticMethodIDOrDie(env, localClass, "getBasePointer",
     83                                                       "(Ljava/nio/Buffer;)J");
     84     gNioJNI.getBaseArrayID = GetStaticMethodIDOrDie(env, localClass, "getBaseArray",
     85                                                     "(Ljava/nio/Buffer;)Ljava/lang/Object;");
     86     gNioJNI.getBaseArrayOffsetID = GetStaticMethodIDOrDie(env, localClass, "getBaseArrayOffset",
     87                                                           "(Ljava/nio/Buffer;)I");
     88 
     89     // now record a permanent version of the class ID
     90     gNioJNI.nioAccessClass = MakeGlobalRefOrDie(env, localClass);
     91 
     92     return 0;
     93 }
     94 
     95 }
     96