static MergeObj TopDownSplitMerge(uint[] B, int iBegin, int iEnd, uint[] A)
{
MergeObj mergeBox = new MergeObj();
if (iEnd - iBegin <= 1)
{
mergeBox = CopyToMergeObjA(mergeBox, A);
mergeBox = CopyToMergeObjB(mergeBox, B);
return(mergeBox);
} // if run size == 1
// consider it sorted
// split the run longer than 1 item into halves
int iMiddle = (iEnd + iBegin) / 2; // iMiddle = mid point
// recursively sort both runs from array A[] into B[]
mergeBox = TopDownSplitMerge(A, iBegin, iMiddle, B); // sort the left run
A = mergeBox.A;
B = mergeBox.B;
mergeBox = TopDownSplitMerge(A, iMiddle, iEnd, B); // sort the right run
// merge the resulting runs from array B[] into A[]
A = mergeBox.A;
B = mergeBox.B;
mergeBox = TopDownMerge(B, iBegin, iMiddle, iEnd, A);
return(mergeBox);
}
static MergeObj CopyToMergeObjB(MergeObj mergeBox, uint[] B)
{
for (int i = 0; i < 256; i++)
{
mergeBox.B[i] = B[i];
}
return(mergeBox);
}
static MergeObj CopyToMergeObjA(MergeObj mergeBox, uint[] A)
{
for (int i = 0; i < 256; i++)
{
mergeBox.A[i] = A[i];
}
return(mergeBox);
}
public uint[] MergeSort(uint[] A, uint[] B, int n)
{
MergeObj mergeBox = new MergeObj();
mergeBox = CopyToMergeObjA(mergeBox, A);
mergeBox = TopDownMergeSort(A, B, n);
B = mergeBox.B;
return(B);
}
static MergeObj CopyArray(uint[] A, int iBegin, int iEnd, uint[] B)
{
MergeObj mergeBox = new MergeObj();
for (int k = iBegin; k < iEnd; k++)
{
B[k] = A[k];
}
mergeBox = CopyToMergeObjA(mergeBox, A);
mergeBox = CopyToMergeObjB(mergeBox, B);
return(mergeBox);
}
static MergeObj TopDownMergeSort(uint[] A, uint[] B, int n)
{
n = 0;
MergeObj mergeBox = new MergeObj();
for (int i = 0; i < 256; i++)
{
if (A[i] != 0)
{
n++;
}
}
mergeBox = CopyArray(A, 0, n, B); // one time copy of A[] to B[]
A = mergeBox.A;
B = mergeBox.B;
mergeBox = TopDownSplitMerge(B, 0, n, A); // sort data from B[] into A[]
return(mergeBox);
}
static MergeObj TopDownMerge(uint[] A, int iBegin, int iMiddle, int iEnd, uint[] B)
{
int i = iBegin, j = iMiddle;
MergeObj mergeBox = new MergeObj();
// While there are elements in the left or right runs...
for (int k = iBegin; k < iEnd; k++)
{
// If left run head exists and is <= existing right run head.
if (i < iMiddle && (j >= iEnd || A[i] <= A[j]))
{
B[k] = A[i];
i = i + 1;
}
else
{
B[k] = A[j];
j = j + 1;
}
}
mergeBox = CopyToMergeObjA(mergeBox, A);
mergeBox = CopyToMergeObjB(mergeBox, B);
return(mergeBox);
}
