cuda-samples/Samples/0_Introduction/template/template.cu

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/* Template project which demonstrates the basics on how to setup a project
 * example application.
 * Host code.
 */

// includes, system
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

// includes CUDA
#include <cuda_runtime.h>

// includes, project
#include <helper_cuda.h>
#include <helper_functions.h> // helper functions for SDK examples

////////////////////////////////////////////////////////////////////////////////
// declaration, forward
void runTest(int argc, char **argv);

extern "C" void computeGold(float *reference, float *idata, const unsigned int len);

////////////////////////////////////////////////////////////////////////////////
//! Simple test kernel for device functionality
//! @param g_idata  input data in global memory
//! @param g_odata  output data in global memory
////////////////////////////////////////////////////////////////////////////////
__global__ void testKernel(float *g_idata, float *g_odata)
{
    // shared memory
    // the size is determined by the host application
    extern __shared__ float sdata[];

    // access thread id
    const unsigned int tid = threadIdx.x;
    // access number of threads in this block
    const unsigned int num_threads = blockDim.x;

    // read in input data from global memory
    sdata[tid] = g_idata[tid];
    __syncthreads();

    // perform some computations
    sdata[tid] = (float)num_threads * sdata[tid];
    __syncthreads();

    // write data to global memory
    g_odata[tid] = sdata[tid];
}

////////////////////////////////////////////////////////////////////////////////
// Program main
////////////////////////////////////////////////////////////////////////////////
int main(int argc, char **argv) { runTest(argc, argv); }

////////////////////////////////////////////////////////////////////////////////
//! Run a simple test for CUDA
////////////////////////////////////////////////////////////////////////////////
void runTest(int argc, char **argv)
{
    bool bTestResult = true;

    printf("%s Starting...\n\n", argv[0]);

    // use command-line specified CUDA device, otherwise use device with highest
    // Gflops/s
    int devID = findCudaDevice(argc, (const char **)argv);

    StopWatchInterface *timer = 0;
    sdkCreateTimer(&timer);
    sdkStartTimer(&timer);

    unsigned int num_threads = 32;
    unsigned int mem_size    = sizeof(float) * num_threads;

    // allocate host memory
    float *h_idata = (float *)malloc(mem_size);

    // initalize the memory
    for (unsigned int i = 0; i < num_threads; ++i) {
        h_idata[i] = (float)i;
    }

    // allocate device memory
    float *d_idata;
    checkCudaErrors(cudaMalloc((void **)&d_idata, mem_size));
    // copy host memory to device
    checkCudaErrors(cudaMemcpy(d_idata, h_idata, mem_size, cudaMemcpyHostToDevice));

    // allocate device memory for result
    float *d_odata;
    checkCudaErrors(cudaMalloc((void **)&d_odata, mem_size));

    // setup execution parameters
    dim3 grid(1, 1, 1);
    dim3 threads(num_threads, 1, 1);

    // execute the kernel
    testKernel<<<grid, threads, mem_size>>>(d_idata, d_odata);

    // check if kernel execution generated and error
    getLastCudaError("Kernel execution failed");

    // allocate mem for the result on host side
    float *h_odata = (float *)malloc(mem_size);
    // copy result from device to host
    checkCudaErrors(cudaMemcpy(h_odata, d_odata, sizeof(float) * num_threads, cudaMemcpyDeviceToHost));

    sdkStopTimer(&timer);
    printf("Processing time: %f (ms)\n", sdkGetTimerValue(&timer));
    sdkDeleteTimer(&timer);

    // compute reference solution
    float *reference = (float *)malloc(mem_size);
    computeGold(reference, h_idata, num_threads);

    // check result
    if (checkCmdLineFlag(argc, (const char **)argv, "regression")) {
        // write file for regression test
        sdkWriteFile("./data/regression.dat", h_odata, num_threads, 0.0f, false);
    }
    else {
        // custom output handling when no regression test running
        // in this case check if the result is equivalent to the expected solution
        bTestResult = compareData(reference, h_odata, num_threads, 0.0f, 0.0f);
    }

    // cleanup memory
    free(h_idata);
    free(h_odata);
    free(reference);
    checkCudaErrors(cudaFree(d_idata));
    checkCudaErrors(cudaFree(d_odata));

    exit(bTestResult ? EXIT_SUCCESS : EXIT_FAILURE);
}