库达访问 3D 阵列

Question

我正在尝试弄清楚如何在设备上分配一个 3d 数组，填充它，然后将其返回给主机代码。

我尝试使用"Cuda C 编程指南"第 3.2.2 节 pg、21 和 22 中的代码。当我尝试编译此代码时，出现此错误：

错误：无法使用类型为"void *"的值初始化实体 类型为"字符 *"

/* host code */
#include <stdio.h>
#include <math.h>
#include "mex.h"
/* Kernel function */
#include "simulate3DArrays.cpp"
/* Define some constants. */
#define width  5
#define height 9
#define depth  5
void mexFunction(int        nlhs,
             mxArray    *plhs[],
             int        nrhs,
             mxArray    *prhs[])
{
double *output;
mwSize ndim3 = 3;
mwSize dims3[] = {height, width, depth};
plhs[0] = mxCreateNumericArray(ndim3, dims3, mxDOUBLE_CLASS, mxREAL);
output = mxGetPr(plhs[0]);
cudaExtent extent = make_cudaExtent(width * sizeof(double), height, depth);
cudaPitchedPtr devicePointer;
cudaMalloc3D(&devicePointer, extent);
cudaMemcpy3DParms deviceOuput = { 0 };
deviceOuput.srcPtr.ptr = devicePointer.ptr;
deviceOuput.srcPtr.pitch = devicePointer.pitch;
deviceOuput.srcPtr.xsize = width;
deviceOuput.srcPtr.ysize = height;
deviceOuput.dstPtr.ptr = output;
deviceOuput.dstPtr.pitch = devicePointer.pitch;
deviceOuput.dstPtr.xsize = width;
deviceOuput.dstPtr.ysize = height;
deviceOuput.kind = cudaMemcpyDeviceToHost;
simulate3DArrays<<<1,depth>>>(devicePointer, width, height, depth);
/* copy 3d array back to 'ouput' */
cudaMemcpy3D(&deviceOuput);
return;
} /* End Mexfunction */
/* device code from pg 22. */
__global__ void simulate3DArrays(cudaPitchedPtr devPitchedPtr, 
                             int width, 
                             int height, 
                             int depth) 
{
char* devPtr = devPitchedPtr.ptr;  /* << error occurs here */
size_t pitch = devPitchedPtr.pitch; 
size_t slicePitch = pitch * height;
for (int z = 0; z < depth; ++z) 
{ 
    char* slice = devPtr + z * slicePitch; 
    for (int y = 0; y < height; ++y)
    {
        float* row = (float*)(slice + y * pitch);
        for (int x = 0; x < width; ++x) 
        {
            float element = row[x]; 
        }
    } 
}
}

不确定它是否真的与这个问题相关，但我的环境是：

• 视窗 7 x64
• 矩阵实验室 2012a
• 库达开发工具包 4.2
• 特斯拉 C2050 显卡

Answer 1

如@talonmies所示，您需要将 void* 指针转换为正确的类型。 在本例中，字符*：

char* devPtr = (char *)devPitchedPtr.ptr;