using System;

namespace Performance
{

	public class Signal
	{
		/**
		 * This is a dumb substitute for the real class for the purposes of benchmarking
		 */
		public Signal (int numRow, int numCol)
		{
			Random rand = new Random();
			this.numRows = numRow;
			this.numCols = numCol;
			this.data = new double[numRow*numCol];
			
			for (int i = 0 ; i < data.Length ; i++)
				data[i] = rand.NextDouble();
		}
		
		public double[] 	data;
		public int			numRows;
		public int			numCols;
	}

	
	public class TestConvolution
	{
		public unsafe static void convolve (Signal Sa, Signal Sb, Signal So)
		{		
			int La = Sa.numRows;
			int Lb = Sb.numRows;
			int nvar = Sa.numCols;
	
			double[] Va = Sa.data;
			double[] Vb = Sb.data;
			double[] Vo = So.data;
			
			// loop over variables
			for (int iv = 0 ; iv < nvar ; iv++)
			{
				// main convolution
				for (int i = 0 ; i < (La-Lb) ; i++)
				{
					double sig = 0;
					for (int j = 0 ; j < Lb ; j++)
						sig += Va[(i+j) * nvar + iv] * Vb[(Lb-j-1) * nvar + iv];
					
					Vo [i*nvar + iv] = sig;
				}
				
				const double pad = 0;
				
				// boundary condition
				for (int i = Math.Max ((La-Lb), 0) ; i < La ; i++)
				{
					double sig = 0;
					for (int j = 0 ; j < Lb ; j++)
					{
						double v = ((i+j) < La) ? Va[(i+j) * nvar + iv] : pad; 
						sig += v * Vb[(Lb-j-1) * nvar + iv];
					}
					
					Vo [i * nvar + iv] = sig;
				}
			}
		}

	
		public static void Main (string[] argv)
		{
			const int signallen = 100000;
			const int nvar = 1;
			const int iterations = 2;
			
			Signal Sa = new Signal (signallen, nvar);
			Signal Sb = new Signal (signallen, nvar);
			Signal So = new Signal (signallen, nvar);
			
			Console.WriteLine ("starting evaluation"); 
			DateTime Tstart = DateTime.Now; 
			
			for (int i = 0 ; i < iterations ; i++)
			{
				convolve (Sa, Sb, So);
			}
			
			DateTime Tend = DateTime.Now;
			TimeSpan span = Tend - Tstart;
			Console.WriteLine (" timing: " + span); 
			
			double sum = 0.0;
			for (int i = 0 ; i < So.data.Length ; i++)
				sum += So.data[i];
			
			Console.WriteLine ("force evaluation: " + sum);
		}
	}
}