my_first_kernel.cu

cuda简单例子

/*
 * Copyright 1993-2008 NVIDIA Corporation.  All rights reserved.
 *
 * NOTICE TO USER:
 *
 * This source code is subject to NVIDIA ownership rights under U.S. and
 * international Copyright laws.  Users and possessors of this source code
 * are hereby granted a nonexclusive, royalty-free license to use this code
 * in individual and commercial software.
 *
 * NVIDIA MAKES NO REPRESENTATION ABOUT THE SUITABILITY OF THIS SOURCE
 * CODE FOR ANY PURPOSE.  IT IS PROVIDED "AS IS" WITHOUT EXPRESS OR
 * IMPLIED WARRANTY OF ANY KIND.  NVIDIA DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOURCE CODE, INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE.
 * IN NO EVENT SHALL NVIDIA BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL,
 * OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
 * OF USE, DATA OR PROFITS,  WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION,  ARISING OUT OF OR IN CONNECTION WITH THE USE
 * OR PERFORMANCE OF THIS SOURCE CODE.
 *
 * U.S. Government End Users.   This source code is a "commercial item" as
 * that term is defined at  48 C.F.R. 2.101 (OCT 1995), consisting  of
 * "commercial computer  software"  and "commercial computer software
 * documentation" as such terms are  used in 48 C.F.R. 12.212 (SEPT 1995)
 * and is provided to the U.S. Government only as a commercial end item.
 * Consistent with 48 C.F.R.12.212 and 48 C.F.R. 227.7202-1 through
 * 227.7202-4 (JUNE 1995), all U.S. Government End Users acquire the
 * source code with only those rights set forth herein.
 *
 * Any use of this source code in individual and commercial software must
 * include, in the user documentation and internal comments to the code,
 * the above Disclaimer and U.S. Government End Users Notice.
 */


// includes, system
#include <stdio.h>
#include <assert.h>

// Simple utility function to check for CUDA runtime errors
void checkCUDAError(const char *msg);

// Part 3 of 5: implement the kernel
__global__ void myFirstKernel(int* md  )
{
	int bx=blockIdx.x;
	int by=blockIdx.y;
	int tx=threadIdx.x;
	int ty=threadIdx.y;
	md[ty+2*tx+4*bx+8*by]=ty+2*tx+4*bx+8*by;



}

////////////////////////////////////////////////////////////////////////////////
// Program main
////////////////////////////////////////////////////////////////////////////////
int main( int argc, char** argv) 
{
    // pointer for host memory
    int *h_a;

    // pointer for device memory
    int *d_a;

    // define grid and block size
    int numBlocks =4;
    int numThreadsPerBlock = 4;

    // Part 1 of 5: allocate host and device memory
    size_t memSize = numBlocks * numThreadsPerBlock * sizeof(int);
    h_a = (int *) malloc(memSize);
    cudaMalloc( (void**)&d_a , memSize);

    // Part 2 of 5: configure and launch kernel
    dim3 dimGrid( 2 , 2 );
    dim3 dimBlock( 2 ,2  );
    myFirstKernel<<<dimGrid ,dimBlock >>>( d_a );

    // block until the device has completed
    cudaThreadSynchronize();

    // check if kernel execution generated an error
    checkCUDAError("kernel execution");

    // Part 4 of 5: device to host copy
    cudaMemcpy(h_a,d_a,memSize,cudaMemcpyDeviceToHost);

    // Check for any CUDA errors
    checkCUDAError("cudaMemcpy");

    // Part 5 of 5: verify the data returned to the host is correct
    for (int i = 0; i <    4      ; i++)
    {
        for (int j = 0; j <     4              ; j++)
        {
            assert(h_a[i * numThreadsPerBlock + j] == 4 * i + j);
        }
    }

    // free device memory
    cudaFree(d_a);

    // free host memory
    free(h_a);

    // If the program makes it this far, then the results are correct and
    // there are no run-time errors.  Good work!
    printf("Correct!\n");

    return 0;
}

void checkCUDAError(const char *msg)
{
    cudaError_t err = cudaGetLastError();
    if( cudaSuccess != err) 
    {
        fprintf(stderr, "Cuda error: %s: %s.\n", msg, cudaGetErrorString( err) );
        exit(-1);
    }                         
}