Very useful function to calculate sizes of a data chunks (#10)

Author: tiermak

include/cuq.h

@@ -21,12 +21,28 @@ class LambdaGPUTask : public GPUTask {
     void doWork() {
       gpuCalculations(params);
     }
+ 
+  int calculationsCount(int localI, int groupSize, int wholeSize) {
+    int startingIndex = localI * groupSize;
+
+    if (startingIndex < wholeSize - groupSize) //we are not close to an end of our data
+      return groupSize;
+
+    int rest = wholeSize - startingIndex;
+
+    if (rest >= 0) //the last chunk of the data
+      return rest;
+
+    return 0; //the data ended, nothing more to process
+  }
 
   private:
     T params;
     std::function<void(T)> gpuCalculations;
 };
 
+int calculationsCount(int localI, int groupSize, int wholeSize);
+
 class GPUTasksQueue {
   public:
     bool resetDeviceAfterFinish;

src/cuq.cpp

@@ -8,6 +8,20 @@
 
 using namespace std;
 
+int calculationsCount(int localI, int groupSize, int wholeSize) {
+  int startingIndex = localI * groupSize;
+
+  if (startingIndex < wholeSize - groupSize) //we are not close to an end of our data
+    return groupSize;
+
+  int rest = wholeSize - startingIndex;
+
+  if (rest >= 0) //the last chunk of the data
+    return rest;
+
+  return 0; //the data ended, nothing more to process
+}
+
 GPUTask::~GPUTask() {
 }