- OpenMP parallel processing disabled by default; can be enabled in compile-time

- Android: Workaround for threading issue to enable OpenMP parallel processing in Android

configure.ac

@@ -85,8 +85,8 @@ AC_ARG_ENABLE(integer-samples,
 
 AC_ARG_ENABLE(openmp,
               [AC_HELP_STRING([--enable-openmp],
-                              [use parallel multicore calculation through OpenMP [default=yes]])],,
+                              [use parallel multicore calculation through OpenMP [default=no]])],,
-              [enable_openmp=yes])
+              [enable_openmp=no])
 
 # Let the user enable/disable the x86 optimizations.
 # Useful when compiling on non-x86 architectures.

source/Android-lib/.classpath

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <classpath>
-	<classpathentry kind="src" path="src"/>
-	<classpathentry kind="src" path="gen"/>
 	<classpathentry kind="con" path="com.android.ide.eclipse.adt.ANDROID_FRAMEWORK"/>
 	<classpathentry exported="true" kind="con" path="com.android.ide.eclipse.adt.LIBRARIES"/>
 	<classpathentry exported="true" kind="con" path="com.android.ide.eclipse.adt.DEPENDENCIES"/>
+	<classpathentry kind="src" path="src"/>
+	<classpathentry kind="src" path="gen"/>
 	<classpathentry kind="output" path="bin/classes"/>
 </classpath>

source/Android-lib/jni/Android.mk

@@ -36,10 +36,16 @@ LOCAL_SHARED_LIBRARIES += -lgcc
 LOCAL_LDLIBS    += -llog
 # for native asset manager
 #LOCAL_LDLIBS    += -landroid
-# don't export all symbols
+
-#
+# Custom Flags: 
-# in ARM-only environment could add "-marm" switch to force arm instruction set instead 
+# -fvisibility=hidden : don't export all symbols
-# of thumb for improved calculation performance.
+# -fopenmp : enable these flags to allow using OpenMP for parallel computation 
-LOCAL_CFLAGS += -fvisibility=hidden -I ../../../include -fdata-sections -ffunction-sections
+LOCAL_CFLAGS += -fvisibility=hidden -I ../../../include -fdata-sections -ffunction-sections #-fopenmp
+
+#LOCAL_LDFLAGS += -fopenmp
+
+
+# Use ARM instruction set instead of Thumb for improved calculation performance in ARM CPUs	
+LOCAL_ARM_MODE := arm
 
 include $(BUILD_SHARED_LIBRARY)

source/Android-lib/jni/Application.mk

@@ -6,4 +6,5 @@
 APP_ABI := all #armeabi-v7a armeabi
 APP_OPTIM := release
 APP_STL := stlport_static
-APP_CPPFLAGS := -fexceptions
+APP_CPPFLAGS := -fexceptions # -D SOUNDTOUCH_DISABLE_X86_OPTIMIZATIONS
+

source/Android-lib/jni/soundtouch-jni.cpp

@@ -46,6 +46,54 @@ static void _setErrmsg(const char *msg)
 }
 
 
+#ifdef _OPENMP
+
+#include <pthread.h>
+extern pthread_key_t gomp_tls_key;
+static void * _p_gomp_tls = NULL;
+
+/// Function to initialize threading for OpenMP.
+///
+/// This is a workaround for bug in Android NDK v10 regarding OpenMP: OpenMP works only if
+/// called from the Android App main thread because in the main thread the gomp_tls storage is
+/// properly set, however, Android does not properly initialize gomp_tls storage for other threads.
+/// Thus if OpenMP routines are invoked from some other thread than the main thread,
+/// the OpenMP routine will crash the application due to NULL pointer access on uninitialized storage.
+///
+/// This workaround stores the gomp_tls storage from main thread, and copies to other threads.
+/// In order this to work, the Application main thread needws to call at least "getVersionString"
+/// routine.
+static int _init_threading(bool warn)
+{
+	void *ptr = pthread_getspecific(gomp_tls_key);
+	LOGV("JNI thread-specific TLS storage %ld", (long)ptr);
+	if (ptr == NULL)
+	{
+		LOGV("JNI set missing TLS storage to %ld", (long)_p_gomp_tls);
+		pthread_setspecific(gomp_tls_key, _p_gomp_tls);
+	}
+	else
+	{
+		LOGV("JNI store this TLS storage");
+		_p_gomp_tls = ptr;
+	}
+	// Where critical, show warning if storage still not properly initialized
+	if ((warn) && (_p_gomp_tls == NULL))
+	{
+		_setErrmsg("Error - OpenMP threading not properly initialized: Call SoundTouch.getVersionString() from the App main thread!");
+		return -1;
+	}
+	return 0;
+}
+
+#else
+static int _init_threading(bool warn)
+{
+	// do nothing if not OpenMP build
+	return 0;
+}
+#endif
+
 
 // Processes the sound file
 static void _processFile(SoundTouch *pSoundTouch, const char *inFileName, const char *outFileName)
@@ -118,6 +166,17 @@ extern "C" DLL_PUBLIC jstring Java_net_surina_soundtouch_SoundTouch_getVersionSt
     // Call example SoundTouch routine
     verStr = SoundTouch::getVersionString();
 
+    /// gomp_tls storage bug workaround - see comments in _init_threading() function!
+    _init_threading(false);
+
+    int threads = 0;
+	#pragma omp parallel
+    {
+		#pragma omp atomic
+    	threads ++;
+    }
+    LOGV("JNI thread count %d", threads);
+
     // return version as string
     return env->NewStringUTF(verStr);
 }
@@ -176,6 +235,9 @@ extern "C" DLL_PUBLIC int Java_net_surina_soundtouch_SoundTouch_processFile(JNIE
 
 	LOGV("JNI process file %s", inputFile);
 
+    /// gomp_tls storage bug workaround - see comments in _init_threading() function!
+    if (_init_threading(true)) return -1;
+
 	try
 	{
 		_processFile(ptr, inputFile, outputFile);

source/Android-lib/res/layout/activity_example.xml

@@ -25,7 +25,7 @@
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:ems="5"
-                android:inputType="numberDecimal"
+                android:inputType="text"
                 android:text="100" >
             </EditText>
         </TableRow>
@@ -46,8 +46,8 @@
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:ems="5"
-                android:inputType="numberSigned"
+                android:inputType="text"
-                android:text="0" >
+                android:text="-0.318" >
             </EditText>
         </TableRow>
     </TableLayout>

source/Android-lib/src/net/surina/ExampleActivity.java

@@ -146,11 +146,10 @@ public class ExampleActivity extends Activity implements OnClickListener
 		}
 
 		
-		/// Processing routine
+		
-		@Override	
+		/// Function that does the SoundTouch processing
-		protected Long doInBackground(Parameters... aparams) 
+		public final long doSoundTouchProcessing(Parameters params) 
 		{
-			Parameters params = aparams[0];
 			
 			SoundTouch st = new SoundTouch();
 			st.setTempo(params.tempo);
@@ -178,6 +177,15 @@ public class ExampleActivity extends Activity implements OnClickListener
 			return 0L;
 		}
 
+
+		
+		/// Overloaded function that get called by the system to perform the background processing
+		@Override	
+		protected Long doInBackground(Parameters... aparams) 
+		{
+			return doSoundTouchProcessing(aparams[0]);
+		}
+		
 	}
 
 
@@ -202,8 +210,9 @@ public class ExampleActivity extends Activity implements OnClickListener
 			
 			Toast.makeText(this, "Starting to process file " + params.inFileName + "...", Toast.LENGTH_SHORT).show();
 
-			// start processing task in background
+			// start SoundTouch processing in a background thread
 			task.execute(params);
+//			task.doSoundTouchProcessing(params);	// this would run processing in main thread
 			
 		}
 		catch (Exception exp)