C++amp矩阵相乘

参考自：https://msdn.microsoft.com/en-us/library/hh873134.aspx

#include <iostream>
#include <amp.h>
using namespace concurrency;

// 常规矩阵相乘计算
void MultiplyWithOutAMP()
{
	int aMatrix[3][2] = { { 1, 4 }, { 2, 5 }, { 3, 6 } };
	int bMatrix[2][3] = { { 7, 8, 9 }, { 10, 11, 12 } };
	int product[3][3] = { { 0, 0, 0 }, { 0, 0, 0 }, { 0, 0, 0 } };

	for (int row = 0; row < 3; row++)
	{
		for (int col = 0; col < 3; col++)
		{
			// Multiply the row of A by the column of B to get the row, column of product.
			for (int inner = 0; inner < 2; inner++)
			{
				product[row][col] += aMatrix[row][inner] * bMatrix[inner][col];
			}
			std::cout << product[row][col] << " ";
		}
		std::cout << "\n";
	}
}


// 使用C++amp矩阵相乘计算
void MultiplyWithAmp()
{
	int aMatrix[] = { 1, 2, 3, 4, 5, 6 };
	int bMatrix[] = { 7, 8, 9, 10, 11, 12 };
	int productMatrix[] = { 0, 0, 0, 0, 0, 0, 0, 0, 0 };

	array_view<int, 2> a(3, 2, aMatrix);
	array_view<int, 2> b(2, 3, bMatrix);
	array_view<int, 2> product(3, 3, productMatrix);

	parallel_for_each(
		product.extent,
		[=](index<2> idx) restrict(amp)
		{
			int row = idx[0];
			int col = idx[1];
			for (int inner = 0; inner < 2; inner++)
			{
				product[idx] += a(row, inner) * b(inner, col);
			}
		}
	);

	// copy the values of the product variable vakc to the productMatrix variable
	product.synchronize();

	for (int row = 0; row < 3; row++)
	{
		for (int col = 0; col < 3; col++)
		{
			std::cout << productMatrix[row * 3 + col] << " ";
			//std::cout << product(row, col) << " ";
		}
		std::cout << "\n";
	}
}

// 使用C++amp,分块矩阵相乘计算
void MultiplyWithtiling()
{
	// The tile size is 2.
	static const int TS = 2;

	// The raw data.
	int aMatrix[] = { 1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8 };
	int bMatrix[] = { 1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8 };
	int productMatrix[] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };

	// Create the array_view objects.
	array_view<int, 2> a(4, 4, aMatrix);
	array_view<int, 2> b(4, 4, bMatrix);
	array_view<int, 2> product(4, 4, productMatrix);

	// Call parallel_for_each by using 2 x 2 this.
	parallel_for_each(product.extent.tile< TS, TS>(),
		[=](tiled_index<TS, TS> t_idx) restrict(amp)
		{
			// Get the location of the thread relative to the tile (row, col) and the 
			// entire array_view(rowGlobal, colGlobal).
			int row = t_idx.local[0];
			int col = t_idx.local[1];
			int rowGlobal = t_idx.global[0];
			int colGlobal = t_idx.global[1];
			int sum = 0;

			// Given a 4 x 4 matrix and a 2 x 2 tile size, this loop executes teice for each thread.
			// For the first tile and the first loop, it copies a into locA and e into locB.
			// For the first tile and eht second loop, it copies b into locA and g into locB.
			for (int i = 0; i < 4; i += TS)
			{
				tile_static int locA[TS][TS];
				tile_static int locB[TS][TS];
				locA[row][col] = a(rowGlobal, col + i);
				locB[row][col] = b(row + i, colGlobal);
				// The threads in the tile all wait here until locA and locB are filled.
				t_idx.barrier.wait();

				// Return the product for the thread. The sum is retained across 
				// both iterations of the loop, in effect adding the two products
				// together, for example, a * e
				for (int k = 0; k < TS; k++)
				{
					sum += locA[row][k] * locB[k][col];
				}

				// All threads must wait until the sums are calculated. If any threads
				// moved ahead, the values in locA and locB would change.
				t_idx.barrier.wait();
			}

			// After both iterations of the loop, copy the sum to the product variable bty using
			product[t_idx.global] = sum;
			// the global location.
		}
	);

	// Copy the contents of product back to the productMatrix variable.
	product.synchronize();
	
	for (int row = 0; row < 4; row++)
	{
		for (int col = 0; col < 4; col++)
		{
			// The results are available from both the product and productMatrix variables.
			//std::cout << productMatrix[row * 3 + col] << " ";
			std::cout << product(row, col) << " ";
		}
		std::cout << "\n";
	}
}


void main()
{
	/*MultiplyWithOutAMP();
	MultiplyWithAmp();*/
	MultiplyWithtiling();

	getchar();
}