Sorting Algorithms In C#

using System;
using System.Collections;

namespace NSort
{
	public class DoubleStorageMergeSort : SwapSorter
	{
		public DoubleStorageMergeSort() : base() {}

		public DoubleStorageMergeSort(IComparer comparer, ISwap swapper)
			: base(comparer,swapper)
		{}

		public override void Sort(IList list) 
		{
			object[] scratch = new IComparable[list.Count];
			Sort(list, 0, list.Count-1, scratch);
		}

		private void Sort(IList list, int fromPos, int toPos, object[] scratch) 
		{
			int mid=0;
			int i;
			int t_low;
			int t_high;
		
			if (fromPos < toPos) 
			{
				mid = (fromPos + toPos) / 2;
				Sort(list, fromPos, mid, scratch);
				Sort(list, mid + 1, toPos,scratch);
				
				t_low = fromPos;
				t_high = mid + 1;
				for (i = fromPos;i<=toPos;i++) 
				{
					if (t_low <= mid) 
					{
						if (t_high > toPos) 
						{
							scratch[i] = list[t_low];
							t_low++;
						} 
						else 
						{
							if (Comparer.Compare(list[t_low], list[t_high])<0) 
							{
								scratch[i] = list[t_low];
								t_low++;
							} 
							else 
							{
								scratch[i] = list[t_high];
								t_high++;
							}
						}
					} 
					else 
					{
						scratch[i] = list[t_high];
						t_high++;
					}
				}
				for (i = fromPos;i<=toPos;i++) 
				{				
					Swapper.Set(list, i, scratch[i]);
				}
			}
		}
	}
}