Simple NN API code sample

Change-Id: I49acd9fd09cf72303a1bd4b67ecaf29de032d043

nn_sample/.gitignore

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+*.iml
+.gradle
+/local.properties
+/.idea/workspace.xml
+/.idea/libraries
+.DS_Store
+/build
+/captures
+.externalNativeBuild

nn_sample/README.md

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+Android Neural Networks API Sample
+======
+Android Neural Networks API (NN API) Sample demonstrates basic usages of NN API with a simple model that consists of three operations: two additions and a multiplication.
+
+The sums created by the additions are the inputs to the multiplication. In essence, we are creating a graph that computes: (tensor0 + tensor1) * (tensor2 + tensor3).
+
+tensor0 ---+
+           +--- ADD ---> intermediateOutput0 ---+
+tensor1 ---+                                    |
+                                                +--- MUL---> output
+tensor2 ---+                                    |
+           +--- ADD ---> intermediateOutput1 ---+
+tensor3 ---+
+
+Two of the four tensors, tensor0 and tensor2 being added are constants, defined in the model. They represent the weights that would have been learned during a training process, loaded from model_data.bin.
+
+The other two tensors, tensor1 and tensor3 will be inputs to the model. Their values will be provided when we execute the model. These values can change from execution to execution.
+
+Besides the two input tensors, an optional fused activation function can also be defined for ADD and MUL. In this example, we'll simply set it to NONE.
+
+The model then has 8 operands:
+- 2 tensors that are inputs to the model. These are fed to the two ADD operations.
+- 2 constant tensors that are the other two inputs to the ADD operations.
+- 1 fuse activation operand reused for the ADD operations and the MUL operation.
+- 2 intermediate tensors, representing outputs of the ADD operations and inputs to the MUL operation.
+- 1 model output.
+
+Pre-requisites
+--------------
+- Android Studio 3.0+.
+- NDK r16+.
+- Android API 27+.
+
+Getting Started
+---------------
+1. [Download Android Studio](http://developer.android.com/sdk/index.html)
+1. Launch Android Studio.
+1. Open the sample directory.
+1. Click *Tools/Android/Sync Project with Gradle Files*.
+1. Click *Run/Run 'app'*.
+
+Screenshots
+-----------
+![screenshot](screenshot.png)
+
+Support
+-------
+If you've found an error in these samples, please [file an issue](https://github.com/googlesamples/android-ndk/issues/new).
+
+Patches are encouraged, and may be submitted by [forking this project](https://github.com/googlesamples/android-ndk/fork) and
+submitting a pull request through GitHub. Please see [CONTRIBUTING.md](../CONTRIBUTING.md) for more details.
+
+- [Stack Overflow](http://stackoverflow.com/questions/tagged/android-ndk)
+- [Google+ Community](https://plus.google.com/communities/105153134372062985968)
+- [Android Tools Feedbacks](http://tools.android.com/feedback)
+
+License
+-------
+Copyright 2017 Google, Inc.
+
+Licensed to the Apache Software Foundation (ASF) under one or more contributor
+license agreements.  See the NOTICE file distributed with this work for
+additional information regarding copyright ownership.  The ASF licenses this
+file to you 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.

nn_sample/app/.gitignore

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+/build

nn_sample/app/build.gradle

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+apply plugin: 'com.android.application'
+
+android {
+    compileSdkVersion 27
+    defaultConfig {
+        applicationId "com.example.android.nnapidemo"
+        minSdkVersion 27
+        targetSdkVersion 27
+        versionCode 1
+        versionName "1.0"
+        ndk.abiFilters 'armeabi-v7a', 'arm64-v8a', 'x86', 'x86_64'
+        externalNativeBuild {
+            cmake {
+                cppFlags "-std=c++14"
+            }
+        }
+    }
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+        }
+    }
+    externalNativeBuild {
+        cmake {
+            path "src/main/cpp/CMakeLists.txt"
+        }
+    }
+    aaptOptions {
+        noCompress 'bin'
+    }
+
+}
+
+dependencies {
+    implementation fileTree(dir: 'libs', include: ['*.jar'])
+    implementation 'com.android.support.constraint:constraint-layout:1.0.2'
+}

nn_sample/app/proguard-rules.pro

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+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

nn_sample/app/src/main/AndroidManifest.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.example.android.nnapidemo">
+
+    <application
+        android:allowBackup="true"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:roundIcon="@mipmap/ic_launcher_round"
+        android:supportsRtl="true"
+        android:theme="@style/AppTheme">
+        <activity android:name=".MainActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
+
+</manifest>

nn_sample/app/src/main/cpp/CMakeLists.txt

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+cmake_minimum_required(VERSION 3.4.1)
+
+add_library(nn_sample
+            SHARED
+            nn_sample.cpp
+            simple_model.cpp)
+
+target_link_libraries(nn_sample
+
+                      # Link with libneuralnetworks.so for NN API
+                      neuralnetworks
+                      android
+                      log)

nn_sample/app/src/main/cpp/nn_sample.cpp

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+/**
+ * Copyright 2017 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 <jni.h>
+#include <string>
+#include <iomanip>
+#include <sstream>
+#include <fcntl.h>
+
+#include <android/asset_manager_jni.h>
+#include <android/log.h>
+#include <android/sharedmem.h>
+#include <sys/mman.h>
+
+#include "simple_model.h"
+
+extern "C"
+JNIEXPORT jlong
+JNICALL
+Java_com_example_android_nnapidemo_MainActivity_initModel(
+        JNIEnv *env,
+        jobject /* this */,
+        jobject _assetManager,
+        jstring _assetName) {
+    // Get the file descriptor of the the model data file.
+    AAssetManager *assetManager = AAssetManager_fromJava(env, _assetManager);
+    const char *assetName = env->GetStringUTFChars(_assetName, NULL);
+    AAsset *asset = AAssetManager_open(assetManager, assetName, AASSET_MODE_BUFFER);
+    if(asset == nullptr) {
+        __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, "Failed to open the asset.");
+        return 0;
+    }
+    env->ReleaseStringUTFChars(_assetName, assetName);
+    off_t offset, length;
+    int fd = AAsset_openFileDescriptor(asset, &offset, &length);
+    AAsset_close(asset);
+    if (fd < 0) {
+        __android_log_print(ANDROID_LOG_ERROR, LOG_TAG,
+                            "Failed to open the model_data file descriptor.");
+        return 0;
+    }
+    SimpleModel* nn_model = new SimpleModel(length, PROT_READ, fd, offset);
+    if (!nn_model->CreateCompiledModel()) {
+        __android_log_print(ANDROID_LOG_ERROR, LOG_TAG,
+                            "Failed to prepare the model.");
+        return 0;
+    }
+
+    return (jlong)(uintptr_t)nn_model;
+}
+
+extern "C"
+JNIEXPORT jfloat
+JNICALL
+Java_com_example_android_nnapidemo_MainActivity_startCompute(
+        JNIEnv *env,
+        jobject /* this */,
+        jlong _nnModel,
+        jfloat inputValue1,
+        jfloat inputValue2) {
+    SimpleModel* nn_model = (SimpleModel*) _nnModel;
+    float result = 0.0f;
+    nn_model->Compute(inputValue1, inputValue2, &result);
+    return result;
+}
+
+extern "C"
+JNIEXPORT void
+JNICALL
+Java_com_example_android_nnapidemo_MainActivity_destroyModel(
+        JNIEnv *env,
+        jobject /* this */,
+        jlong _nnModel) {
+    SimpleModel* nn_model = (SimpleModel*) _nnModel;
+    delete(nn_model);
+}