Adding the glue logic (and an activity for testing) to run the C++ sound

engine on Android. Note that this particular patchset disables the Java-based
synthesis, so probably shouldn't be committed as-is to mainline.

android/.externalToolBuilders/NDK Builder.launch

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<launchConfiguration type="org.eclipse.ui.externaltools.ProgramBuilderLaunchConfigurationType">
+<stringAttribute key="org.eclipse.debug.core.ATTR_REFRESH_SCOPE" value="${working_set:&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot;?&gt;&#10;&lt;resources&gt;&#10;&lt;item path=&quot;/MusicSynthesizer/libs&quot; type=&quot;2&quot;/&gt;&#10;&lt;/resources&gt;}"/>
+<booleanAttribute key="org.eclipse.debug.ui.ATTR_LAUNCH_IN_BACKGROUND" value="false"/>
+<stringAttribute key="org.eclipse.ui.externaltools.ATTR_BUILD_SCOPE" value="${working_set:&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot;?&gt;&#10;&lt;resources&gt;&#10;&lt;item path=&quot;/MusicSynthesizer/jni&quot; type=&quot;2&quot;/&gt;&#10;&lt;/resources&gt;}"/>
+<stringAttribute key="org.eclipse.ui.externaltools.ATTR_LOCATION" value="${system_property:user.home}/install/android-ndk-r7b/ndk-build"/>
+<stringAttribute key="org.eclipse.ui.externaltools.ATTR_RUN_BUILD_KINDS" value="full,incremental,auto,"/>
+<booleanAttribute key="org.eclipse.ui.externaltools.ATTR_TRIGGERS_CONFIGURED" value="true"/>
+<stringAttribute key="org.eclipse.ui.externaltools.ATTR_WORKING_DIRECTORY" value="${project_loc}"/>
+</launchConfiguration>

android/jni/Android.mk

@@ -0,0 +1,18 @@
+LOCAL_PATH := $(call my-dir)/../../cpp/src
+
+include $(CLEAR_VARS)
+LOCAL_MODULE := synth
+LOCAL_CPP_EXTENSION := .cc
+LOCAL_SRC_FILES := dx7note.cc \
+                   env.cc \
+                   fm_core.cc \
+                   fm_op_kernel.cc \
+                   freqlut.cc \
+                   resofilter.cc \
+                   ringbuffer.cc \
+                   sawtooth.cc \
+                   sin.cc \
+                   synth_unit.cc
+
+include $(BUILD_SHARED_LIBRARY)
+

android/jni/Application.mk

@@ -0,0 +1 @@
+APP_STL := stlport_static

android/project.properties

@@ -0,0 +1,14 @@
+# This file is automatically generated by Android Tools.
+# Do not modify this file -- YOUR CHANGES WILL BE ERASED!
+#
+# This file must be checked in Version Control Systems.
+#
+# To customize properties used by the Ant build system edit
+# "ant.properties", and override values to adapt the script to your
+# project structure.
+#
+# To enable ProGuard to shrink and obfuscate your code, uncomment this (available properties: sdk.dir, user.home):
+#proguard.config=${sdk.dir}/tools/proguard/proguard-android.txt:proguard-project.txt
+
+# Project target.
+target=android-15

android/src/com/google/synthesizer/android/AndroidGlue.java

@@ -0,0 +1,14 @@
+package com.google.synthesizer.android;
+
+
+public class AndroidGlue {
+
+  public native void start();
+  public native void setPlayState(boolean isPlaying);
+  public native void sendMidi(byte[] midiData);
+
+  static {
+    System.loadLibrary("synth");
+  }
+}
+

android/src/com/google/synthesizer/android/ui/PianoActivity2.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2012 Google Inc.
+ * 
+ * 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.
+ */
+
+package com.google.synthesizer.android.ui;
+
+import android.app.Activity;
+import android.os.Bundle;
+import android.widget.Spinner;
+
+import com.google.synthesizer.R;
+import com.google.synthesizer.android.AndroidGlue;
+import com.google.synthesizer.android.widgets.knob.KnobView;
+import com.google.synthesizer.android.widgets.piano.PianoView;
+
+/**
+ * Activity for simply playing the piano.
+ * This version is hacked up to send MIDI to the C++ engine. This needs to
+ * be refactored to make it cleaner.
+ */
+public class PianoActivity2 extends Activity {
+  @Override
+  public void onCreate(Bundle savedInstanceState) {
+    super.onCreate(savedInstanceState);
+    setContentView(R.layout.piano);
+
+    piano_ = (PianoView)findViewById(R.id.piano);
+    volumeKnob_ = (KnobView)findViewById(R.id.volumeKnob);
+    presetSpinner_ = (Spinner)findViewById(R.id.presetSpinner);
+    // TODO: wire these up (preset spinner should send patch selection)
+
+    androidGlue_ = new AndroidGlue();
+    androidGlue_.start();
+
+    piano_.bindTo(androidGlue_);
+  }
+
+  @Override
+  protected void onPause() {
+    androidGlue_.setPlayState(false);
+    super.onPause();
+  }
+
+  @Override
+  protected void onResume() {
+    androidGlue_.setPlayState(true);
+    super.onResume();
+  }
+
+  private AndroidGlue androidGlue_;
+  private PianoView piano_;
+  private KnobView volumeKnob_;
+  private Spinner presetSpinner_;
+}

cpp/src/android_glue.cc

@@ -0,0 +1,145 @@
+#include <assert.h>
+#include <stddef.h>
+#include <jni.h>
+#include <SLES/OpenSLES.h>
+#include <SLES/OpenSLES_Android.h>
+
+#include <android/log.h>
+#define LOGI(...) __android_log_print(ANDROID_LOG_INFO, "synth", __VA_ARGS__)
+
+#include "synth.h"
+#include "freqlut.h"
+#include "sin.h"
+#include "synth_unit.h"
+
+RingBuffer *ring_buffer;
+SynthUnit *synth_unit;
+
+const int N_BUFFERS = 2;
+const int BUFFER_SIZE = 64;
+
+int16_t buffer[BUFFER_SIZE * N_BUFFERS];
+int cur_buffer = 0;
+int count = 0;
+
+// engine interfaces
+static SLObjectItf engineObject = NULL;
+static SLEngineItf engineEngine;
+
+// output mix interfaces
+static SLObjectItf outputMixObject = NULL;
+
+// buffer queue player interfaces
+static SLObjectItf bqPlayerObject = NULL;
+static SLPlayItf bq_player_play;
+static SLVolumeItf bq_player_volume;
+static SLAndroidSimpleBufferQueueItf bq_player_buffer_queue;
+static SLBufferQueueItf buffer_queue_itf;
+
+extern "C" void BqPlayerCallback(SLAndroidSimpleBufferQueueItf queueItf,
+    void *data) {
+  if (count >= 1000) return;
+  int16_t *buf_ptr = buffer + BUFFER_SIZE * cur_buffer;
+  synth_unit->GetSamples(BUFFER_SIZE, buf_ptr);
+  SLresult result = (*queueItf)->Enqueue(bq_player_buffer_queue,
+      buf_ptr, BUFFER_SIZE * 2);
+  assert(SL_RESULT_SUCCESS == result);
+  cur_buffer = (cur_buffer + 1) % N_BUFFERS;
+}
+
+extern "C" JNIEXPORT jint JNICALL
+Java_com_google_synthesizer_android_AndroidGlue_hello(JNIEnv *env,
+    jobject thiz) {
+  LOGI("here %d!", 42);
+  return 42;
+}
+
+void CreateEngine() {
+  SLresult result;
+  result = slCreateEngine(&engineObject, 0, NULL, 0, NULL, NULL);
+  assert(SL_RESULT_SUCCESS == result);
+
+  result = (*engineObject)->Realize(engineObject, SL_BOOLEAN_FALSE);
+  assert(SL_RESULT_SUCCESS == result);
+
+  result = (*engineObject)->GetInterface(engineObject, SL_IID_ENGINE,
+      &engineEngine);
+  assert(SL_RESULT_SUCCESS == result);
+
+  result = (*engineEngine)->CreateOutputMix(engineEngine, &outputMixObject,
+      0, NULL, NULL);
+  assert(SL_RESULT_SUCCESS == result);
+  result = (*outputMixObject)->Realize(outputMixObject, SL_BOOLEAN_FALSE);
+  assert(SL_RESULT_SUCCESS == result);
+}
+
+extern "C" JNIEXPORT void JNICALL
+Java_com_google_synthesizer_android_AndroidGlue_start(JNIEnv *env,
+    jobject thiz) {
+  CreateEngine();
+  SLDataLocator_AndroidSimpleBufferQueue loc_bufq =
+    {SL_DATALOCATOR_ANDROIDSIMPLEBUFFERQUEUE, N_BUFFERS};
+  SLDataFormat_PCM format_pcm = {
+    SL_DATAFORMAT_PCM, 1, SL_SAMPLINGRATE_48,
+    SL_PCMSAMPLEFORMAT_FIXED_16, SL_PCMSAMPLEFORMAT_FIXED_16,
+    SL_SPEAKER_FRONT_CENTER, SL_BYTEORDER_LITTLEENDIAN
+      // TODO: compute real endianness
+  };
+  SLDataSource audio_src = {&loc_bufq, &format_pcm};
+  SLDataLocator_OutputMix loc_outmix = {SL_DATALOCATOR_OUTPUTMIX,
+    outputMixObject};
+  SLDataSink audio_sink = {&loc_outmix, NULL};
+  const SLInterfaceID ids[2] = {SL_IID_BUFFERQUEUE, SL_IID_VOLUME};
+  const SLboolean req[2] = {SL_BOOLEAN_TRUE, SL_BOOLEAN_TRUE};
+  SLresult result;
+  result = (*engineEngine)->CreateAudioPlayer(engineEngine, &bqPlayerObject,
+      &audio_src, &audio_sink, 2, ids, req);
+  assert(SL_RESULT_SUCCESS == result);
+  result = (*bqPlayerObject)->Realize(bqPlayerObject, SL_BOOLEAN_FALSE);
+  assert(SL_RESULT_SUCCESS == result);
+  result = (*bqPlayerObject)->GetInterface(bqPlayerObject, SL_IID_PLAY,
+      &bq_player_play);
+  assert(SL_RESULT_SUCCESS == result);
+  result = (*bqPlayerObject)->GetInterface(bqPlayerObject, SL_IID_BUFFERQUEUE,
+      &bq_player_buffer_queue);
+  assert(SL_RESULT_SUCCESS == result);
+
+  result = (*bqPlayerObject)->GetInterface(bqPlayerObject, SL_IID_VOLUME,
+      &bq_player_volume);
+  assert(SL_RESULT_SUCCESS == result);
+  result = (*bq_player_buffer_queue)->RegisterCallback(bq_player_buffer_queue,
+      &BqPlayerCallback, NULL);
+  assert(SL_RESULT_SUCCESS == result);
+
+  double sample_rate = 48000.0;
+  Freqlut::init(sample_rate);
+  Sin::init();
+  ring_buffer = new RingBuffer();
+  synth_unit = new SynthUnit(ring_buffer);
+  for (int i = 0; i < N_BUFFERS - 1; ++i) {
+    BqPlayerCallback(bq_player_buffer_queue, NULL);
+  }
+
+  result = (*bq_player_play)->SetPlayState(bq_player_play,
+      SL_PLAYSTATE_PLAYING);
+  assert(SL_RESULT_SUCCESS == result);
+}
+
+extern "C" JNIEXPORT void JNICALL
+Java_com_google_synthesizer_android_AndroidGlue_sendMidi(JNIEnv *env,
+    jobject thiz, jbyteArray jb) {
+  uint8_t *data = (uint8_t *)env->GetByteArrayElements(jb, NULL);
+  if (data != NULL) {
+    ring_buffer->Write(data, env->GetArrayLength(jb));
+    env->ReleaseByteArrayElements(jb, (jbyte *)data, JNI_ABORT);
+  }
+}
+
+extern "C" JNIEXPORT void JNICALL
+Java_com_google_synthesizer_android_AndroidGlue_setPlayState(JNIEnv *env,
+    jobject thiz, jboolean isPlaying) {
+  SLresult result = (*bq_player_play)->SetPlayState(bq_player_play,
+      isPlaying ? SL_PLAYSTATE_PLAYING : SL_PLAYSTATE_PAUSED);
+  assert(SL_RESULT_SUCCESS == result);
+}
+

cpp/src/synth.h

@@ -29,14 +29,15 @@
 #define SynthMemoryBarrier() OSMemoryBarrier()
 #elif defined(__GNUC__)
 #if (__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 1)
-#define SynthMemoryBarrier __sync_synchronize()
-#else
-#warning Memory barrier is not enabled
+#define SynthMemoryBarrier() __sync_synchronize()
 #endif
-#warning Memory barrier is not enabled
 #endif
 
 // #undef SynthMemoryBarrier()
-// #define SynthMemoryBarrier()
+
+#ifndef SynthMemoryBarrier
+#warning Memory barrier is not enabled
+#define SynthMemoryBarrier()
+#endif
 
 #endif  // __SYNTH_H

cpp/src/synth_unit.cc

@@ -39,6 +39,7 @@ SynthUnit::SynthUnit(RingBuffer *ring_buffer) {
   input_buffer_index_ = 0;
   std::memcpy(patch_data_, epiano, sizeof(epiano));
   current_patch_ = 0;
+  current_note_ = 0;
 }
 
 // Transfer as many bytes as possible from ring buffer to input buffer.