build: reorg jni files

app/src/main/cpp/jni_lockstep.cpp

@@ -0,0 +1,43 @@
+#include "PlaybackEngine.h"
+#include <jni.h>
+#include <oboe/Oboe.h>
+
+extern "C" {
+
+/**
+ * Creates the audio engine
+ *
+ * @return a pointer to the audio engine. This should be passed to other methods
+ */
+JNIEXPORT jlong JNICALL
+Java_at_lockstep_pb_PlaybackEngine_native_1createEngine(
+        JNIEnv *env,
+        jclass /*unused*/, jstring filesDir, jint resid) {
+    const char* filesDirTemp = env->GetStringUTFChars(filesDir, NULL);
+    std::string filesDirString(filesDirTemp);
+    env->ReleaseStringUTFChars(filesDir, filesDirTemp);
+
+    // We use std::nothrow so `new` returns a nullptr if the engine creation fails
+    auto *engine = new(std::nothrow) PlaybackEngine(filesDirString, resid);
+    return reinterpret_cast<jlong>(engine);
+}
+
+JNIEXPORT void JNICALL
+Java_at_lockstep_pb_PlaybackEngine_native_1deleteEngine(
+        JNIEnv *env,
+jclass,
+jlong engineHandle) {
+
+delete reinterpret_cast<PlaybackEngine *>(engineHandle);
+}
+
+JNIEXPORT void JNICALL
+Java_at_lockstep_pb_PlaybackEngine_native_1setDefaultStreamValues(JNIEnv *env,
+                                                                  jclass type,
+                                                                  jint sampleRate,
+                                                                  jint framesPerBurst) {
+    oboe::DefaultStreamValues::SampleRate = (int32_t) sampleRate;
+    oboe::DefaultStreamValues::FramesPerBurst = (int32_t) framesPerBurst;
+}
+
+} // extern "C"