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
19struct NioJNIData {
20    jclass nioAccessClass;
21
22    jmethodID getBasePointerID;
23    jmethodID getBaseArrayID;
24    jmethodID getBaseArrayOffsetID;
25};
26
27static NioJNIData gNioJNI;
28
29void* android::nio_getPointer(JNIEnv *_env, jobject buffer, jarray *array) {
30    assert(array);
31
32    jlong pointer;
33    jint offset;
34    void *data;
35
36    pointer = _env->CallStaticLongMethod(gNioJNI.nioAccessClass,
37                                         gNioJNI.getBasePointerID, buffer);
38    if (pointer != 0L) {
39        *array = NULL;
40        return (void *) (jint) pointer;
41    }
42
43    *array = (jarray) _env->CallStaticObjectMethod(gNioJNI.nioAccessClass,
44                                               gNioJNI.getBaseArrayID, buffer);
45    offset = _env->CallStaticIntMethod(gNioJNI.nioAccessClass,
46                                       gNioJNI.getBaseArrayOffsetID, buffer);
47    data = _env->GetPrimitiveArrayCritical(*array, (jboolean *) 0);
48
49    return (void *) ((char *) data + offset);
50}
51
52
53void android::nio_releasePointer(JNIEnv *_env, jarray array, void *data,
54                                jboolean commit) {
55    _env->ReleasePrimitiveArrayCritical(array, data,
56                                        commit ? 0 : JNI_ABORT);
57}
58
59///////////////////////////////////////////////////////////////////////////////
60
61android::AutoBufferPointer::AutoBufferPointer(JNIEnv* env, jobject nioBuffer,
62                                              jboolean commit) {
63    fEnv = env;
64    fCommit = commit;
65    fPointer = android::nio_getPointer(env, nioBuffer, &fArray);
66}
67
68android::AutoBufferPointer::~AutoBufferPointer() {
69    if (NULL != fArray) {
70        android::nio_releasePointer(fEnv, fArray, fPointer, fCommit);
71    }
72}
73
74///////////////////////////////////////////////////////////////////////////////
75
76static jclass findClass(JNIEnv* env, const char name[]) {
77    jclass c = env->FindClass(name);
78    LOG_FATAL_IF(!c, "Unable to find class %s", name);
79    return c;
80}
81
82static jmethodID findStaticMethod(JNIEnv* env, jclass c, const char method[],
83                                  const char params[]) {
84    jmethodID m = env->GetStaticMethodID(c, method, params);
85    LOG_FATAL_IF(!m, "Unable to find method %s", method);
86    return m;
87}
88
89static jfieldID getFieldID(JNIEnv* env, jclass c, const char name[],
90                           const char type[]) {
91    jfieldID f = env->GetFieldID(c, name, type);
92    LOG_FATAL_IF(!f, "Unable to find field %s", name);
93    return f;
94}
95
96namespace android {
97
98int register_android_nio_utils(JNIEnv* env) {
99    jclass localClass = findClass(env, "java/nio/NIOAccess");
100    gNioJNI.getBasePointerID = findStaticMethod(env, localClass,
101                                    "getBasePointer", "(Ljava/nio/Buffer;)J");
102    gNioJNI.getBaseArrayID = findStaticMethod(env, localClass,
103                    "getBaseArray", "(Ljava/nio/Buffer;)Ljava/lang/Object;");
104    gNioJNI.getBaseArrayOffsetID = findStaticMethod(env, localClass,
105                                "getBaseArrayOffset", "(Ljava/nio/Buffer;)I");
106
107    // now record a permanent version of the class ID
108    gNioJNI.nioAccessClass = (jclass) env->NewGlobalRef(localClass);
109
110    return 0;
111}
112
113}
114