android: Implement emulator audio playback

Former-commit-id: 5d0daee9e7616212aa184e31be360b0110b4c054

AndroidApp/app/src/main/java/com/mrmichel/rustboyadvance/EmulatorBindings.java

@@ -45,6 +45,13 @@ public class EmulatorBindings {
      */
     public static native void runFrame(long ctx, int[] frame_buffer);
 
+    /**
+     * Collect pending audio samples
+     * @param ctx
+     * @return sample buffer
+     */
+    public static native short[] collectAudioSamples(long ctx);
+
     /**
      * @param ctx
      * @return The loaded ROM title

AndroidApp/app/src/main/java/com/mrmichel/rustboyadvance/PcmStream.java

@@ -1,12 +0,0 @@
-package com.mrmichel.rustboyadvance;
-
-import java.io.IOException;
-import java.io.InputStream;
-
-public class AudioStream extends InputStream {
-
-    @Override
-    public int read(byte[] b) throws IOException {
-        return super.read(b);
-    }
-}

AndroidApp/app/src/main/java/com/mrmichel/rustdroid_emu/core/AudioThread.java

@@ -0,0 +1,47 @@
+package com.mrmichel.rustdroid_emu.core;
+
+import android.media.AudioTrack;
+
+public class AudioThread extends Thread {
+
+    AudioTrack audioTrack;
+    Emulator emulator;
+    boolean enabled;
+    boolean stopping;
+
+    public AudioThread(AudioTrack audioTrack, Emulator emulator) {
+        super();
+        this.audioTrack = audioTrack;
+        this.emulator = emulator;
+        this.enabled = true;
+        this.stopping = false;
+    }
+
+    public void setStopping(boolean stopping) {
+        this.stopping = stopping;
+    }
+
+    public void setEnabled(boolean enabled) {
+        this.enabled = enabled;
+    }
+
+    public boolean isStopping() {
+        return stopping;
+    }
+
+    public boolean isEnabled() {
+        return enabled;
+    }
+
+    @Override
+    public void run() {
+        super.run();
+
+        while (!stopping) {
+            if (enabled) {
+                short[] samples = emulator.collectAudioSamples();
+                audioTrack.write(samples, 0, samples.length);
+            }
+        }
+    }
+}

AndroidApp/app/src/main/java/com/mrmichel/rustdroid_emu/core/Emulator.java

@@ -1,7 +1,5 @@
 package com.mrmichel.rustdroid_emu.core;
 
-import android.graphics.Bitmap;
-
 import com.mrmichel.rustboyadvance.EmulatorBindings;
 
 public class Emulator {
@@ -32,8 +30,12 @@ public class Emulator {
     }
 
     public synchronized void runFrame() {
-        EmulatorBindings.setKeyState(this.ctx, this.keypad.getKeyState());
+        EmulatorBindings.setKeyState(ctx, keypad.getKeyState());
-        EmulatorBindings.runFrame(this.ctx, this.frameBuffer);
+        EmulatorBindings.runFrame(ctx, frameBuffer);
+    }
+
+    public synchronized short[] collectAudioSamples() {
+        return EmulatorBindings.collectAudioSamples(ctx);
     }
 
     public synchronized void setKeyState(int keyState) {

AndroidApp/app/src/main/java/com/mrmichel/rustdroid_emu/core/Snapshot.java

@@ -2,7 +2,6 @@ package com.mrmichel.rustdroid_emu.core;
 
 import android.graphics.Bitmap;
 
-import java.io.ByteArrayOutputStream;
 import java.io.File;
 
 public class Snapshot {

AndroidApp/app/src/main/java/com/mrmichel/rustdroid_emu/core/SnapshotManager.java

@@ -9,13 +9,10 @@ import android.graphics.Bitmap;
 import android.graphics.BitmapFactory;
 import android.util.Log;
 
-import java.io.BufferedInputStream;
-import java.io.BufferedReader;
 import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
-import java.io.InputStreamReader;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 import java.sql.Timestamp;

AndroidApp/app/src/main/java/com/mrmichel/rustdroid_emu/ui/EmulatorActivity.java

@@ -1,10 +1,13 @@
 package com.mrmichel.rustdroid_emu.ui;
 
-import android.app.Activity;
 import android.content.DialogInterface;
 import android.content.Intent;
 import android.graphics.Bitmap;
+import android.media.AudioFormat;
+import android.media.AudioManager;
+import android.media.AudioTrack;
 import android.net.Uri;
+import android.os.Build;
 import android.os.Bundle;
 
 import androidx.annotation.NonNull;
@@ -13,9 +16,7 @@ import androidx.appcompat.app.AlertDialog;
 import androidx.appcompat.app.AppCompatActivity;
 
 import android.util.Log;
-import android.view.ContextMenu;
 import android.view.Menu;
-import android.view.MenuInflater;
 import android.view.MenuItem;
 import android.view.MotionEvent;
 import android.view.View;
@@ -25,10 +26,10 @@ import android.widget.Switch;
 import android.widget.Toast;
 
 import com.mrmichel.rustboyadvance.EmulatorBindings;
+import com.mrmichel.rustdroid_emu.core.AudioThread;
 import com.mrmichel.rustdroid_emu.core.Emulator;
 import com.mrmichel.rustdroid_emu.core.Keypad;
 import com.mrmichel.rustdroid_emu.R;
-import com.mrmichel.rustdroid_emu.core.Snapshot;
 import com.mrmichel.rustdroid_emu.core.SnapshotManager;
 import com.mrmichel.rustdroid_emu.ui.snapshots.ChosenSnapshot;
 import com.mrmichel.rustdroid_emu.ui.snapshots.SnapshotActivity;
@@ -39,13 +40,18 @@ import java.io.InputStream;
 public class EmulatorActivity extends AppCompatActivity implements View.OnClickListener, View.OnTouchListener {
 
     private static final String TAG = "EmulatorActivty";
+
     private static final int LOAD_ROM_REQUESTCODE = 123;
     private static final int LOAD_SNAPSHOT_REQUESTCODE = 124;
 
+    private static int SAMPLE_RATE_HZ = 44100;
+
     private byte[] bios;
     private Emulator emulator = null;
     private EmulationRunnable runnable;
     private Thread emulationThread;
+    private AudioThread audioThread;
+    private AudioTrack audioTrack;
     private byte[] on_resume_saved_state = null;
     private ImageView screen;
     private boolean turboMode = false;
@@ -169,6 +175,16 @@ public class EmulatorActivity extends AppCompatActivity implements View.OnClickL
             }
             emulationThread = null;
         }
+        if (audioThread != null) {
+            audioThread.setStopping(true);
+            try {
+                audioThread.join();
+            } catch (InterruptedException e) {
+                Log.e(TAG, "audio thread join interrupted");
+            };
+            audioThread = null;
+        }
+
         if (emulator.isOpen()) {
             emulator.close();
         }
@@ -193,6 +209,9 @@ public class EmulatorActivity extends AppCompatActivity implements View.OnClickL
         runnable = new EmulationRunnable(this.emulator, this);
         emulationThread = new Thread(runnable);
         emulationThread.start();
+
+        audioThread = new AudioThread(audioTrack, emulator);
+        audioThread.start();
     }
 
     public void loadRomButton(View v) {
@@ -216,6 +235,31 @@ public class EmulatorActivity extends AppCompatActivity implements View.OnClickL
         this.bios = getIntent().getByteArrayExtra("bios");
         this.screen = findViewById(R.id.gbaMockImageView);
         this.emulator = new Emulator();
+
+        if (Build.VERSION.SDK_INT >= 23) {
+            AudioTrack.Builder audioTrackBuilder = new AudioTrack.Builder()
+                    .setAudioFormat(new AudioFormat.Builder()
+                            .setEncoding(AudioFormat.ENCODING_PCM_16BIT)
+                            .setSampleRate(SAMPLE_RATE_HZ)
+                            .setChannelMask(AudioFormat.CHANNEL_IN_STEREO | AudioFormat.CHANNEL_OUT_STEREO)
+                            .build()
+                    )
+                    .setBufferSizeInBytes(4096)
+                    .setTransferMode(AudioTrack.MODE_STREAM);
+            if (Build.VERSION.SDK_INT >= 26) {
+                audioTrackBuilder.setPerformanceMode(AudioTrack.PERFORMANCE_MODE_LOW_LATENCY);
+            }
+            this.audioTrack = audioTrackBuilder.build();
+        } else {
+            this.audioTrack = new AudioTrack(
+                    AudioManager.STREAM_MUSIC,
+                    SAMPLE_RATE_HZ,
+                    AudioFormat.CHANNEL_IN_STEREO | AudioFormat.CHANNEL_OUT_STEREO,
+                    AudioFormat.ENCODING_PCM_16BIT,
+                    4096,
+                    AudioTrack.MODE_STREAM);
+        }
+        this.audioTrack.play();
     }
 
     @Override
@@ -233,6 +277,7 @@ public class EmulatorActivity extends AppCompatActivity implements View.OnClickL
     @Override
     protected void onPause() {
         super.onPause();
+        audioTrack.stop();
         if (emulator.isOpen()) {
             if (runnable != null) {
                 runnable.pauseEmulation();
@@ -261,6 +306,7 @@ public class EmulatorActivity extends AppCompatActivity implements View.OnClickL
                 runnable.resumeEmulation();
             }
         }
+        audioTrack.play();
     }
 
     public void onSaveSnapshot(View v) {

AndroidApp/app/src/main/java/com/mrmichel/rustdroid_emu/ui/snapshots/SnapshotActivity.java

@@ -1,22 +1,13 @@
 package com.mrmichel.rustdroid_emu.ui.snapshots;
 
-import android.app.Activity;
-import android.content.DialogInterface;
 import android.content.Intent;
-import android.net.Uri;
 import android.os.Bundle;
 
-import com.google.android.material.floatingactionbutton.FloatingActionButton;
-import com.google.android.material.snackbar.Snackbar;
-
-import androidx.appcompat.app.AlertDialog;
 import androidx.appcompat.app.AppCompatActivity;
-import androidx.appcompat.widget.Toolbar;
 
 import android.view.View;
 import android.widget.AdapterView;
 import android.widget.GridView;
-import android.widget.ListView;
 import android.widget.Toast;
 
 import com.mrmichel.rustdroid_emu.R;

AndroidApp/app/src/main/java/com/mrmichel/rustdroid_emu/ui/snapshots/SnapshotItemAdapter.java

@@ -5,7 +5,6 @@ import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.ArrayAdapter;
-import android.widget.ImageButton;
 import android.widget.ImageView;
 import android.widget.TextView;
 
@@ -15,8 +14,6 @@ import androidx.annotation.Nullable;
 import com.mrmichel.rustdroid_emu.R;
 import com.mrmichel.rustdroid_emu.core.Snapshot;
 
-import org.w3c.dom.Text;
-
 import java.sql.Timestamp;
 import java.util.ArrayList;