Commit c6f6d59e authored by Xuan Thang Nguyen's avatar Xuan Thang Nguyen
Browse files

function for choosing pivot

parent aaf607d6

quicksort/helper.cuh

+33 −0
Original line number Diff line number Diff line
@@ -54,3 +54,36 @@ __device__ void calcBlocksNeeded(int elemLeft, int elemRight, int &blocksLeft, i 
    blocksRight = elemRight / minElemPerBlock + (elemRight% minElemPerBlock != 0);

    

}



template <typename Value, typename Device, typename Function>

__device__ Value pickPivot(TNL::Containers::ArrayView<Value, Device> src, const Function & Cmp)

{

    return src[0];

    //return src[src.getSize()-1];



    /*

    if(src.getSize() ==1)

        return src[0];

    

    Value a = src[0], b = src[src.getSize()/2], c = src[src.getSize() - 1];



    if(Cmp(a, b)) // ..a..b..

    {

        if(Cmp(b, c))// ..a..b..c

            return b;

        else if(Cmp(c, a))//..c..a..b..

            return a;

        else //..a..c..b..

            return c;

    }

    else //..b..a..

    {

        if(Cmp(a, c))//..b..a..c

            return a;

        else if(Cmp(c, b))//..c..b..a..

            return b;

        else //..b..c..a..

            return c;

    }

    */

}
 
 No newline at end of file

quicksort/quicksort.cu

+6 −2
Original line number Diff line number Diff line
@@ -54,7 +54,7 @@ __device__ void multiBlockQuickSort(CudaArrayView arr, CudaArrayView aux, TASK * 
    static __shared__ int pivot;



    if(threadIdx.x == 0)

        pivot = depth %2 == 0? arr[arr.getSize() - 1] : aux[aux.getSize() - 1];

        pivot = pickPivot(depth %2 == 0? arr: aux, Cmp);

    __syncthreads();

    

    bool isLast;
@@ -213,7 +213,11 @@ __device__ void singleBlockQuickSort(CudaArrayView arr, CudaArrayView aux, const 
            end = stackArrEnd[stackTop-1];

            depth = stackDepth[stackTop-1];

            stackTop--;

            pivot = depth%2 == 0? arr[end - 1] : aux[end-1];

            pivot = pickPivot(depth%2 == 0? 

                                    arr.getView(begin, end) :

                                    aux.getView(begin, end),

                                Cmp

                            );

        }

        __syncthreads();