[菜鳥每天來段CUDA_C]CppIntegration在C++程序中引用CUDA程序

本文主要實現在C++程序中引用CUDA程序，主要意義是使順序定義的數據能在CUDA程序中並行執行，然後返回結果。

程序主要包括main.cpp                                 定義main函數，需要處理的數據

                        Integration.cu                         CUDA初始化，顯存分配，核函數調用，顯存釋放

                        Integration_kernel.cuh          核函數

程序輸入爲：Rovvy*ay|vn8

運行結果爲：Hello World.

1. main.cpp

#include <stdlib.h>
#include <cutil_inline.h>


extern "C" bool RunTest(char* data, int2* data_int2, unsigned int len);

int main()
{
	int len = 16;
	char str[] = { 82, 111, 118, 118, 121, 42, 97, 121, 124, 118, 110, 56, 10, 10, 10, 10, '\0'};

	int2 i2[16];
	for (int i=0; i<len; i++)
	{
		i2[i].x = str[i];
		i2[i].y = 10;
	}

	bool bTestResult;

	bTestResult = RunTest(str, i2, len);

	printf("%s\n", str);

	for (int i=0; i<len; i++)
	{
		printf("%c", i2[i].x);
	}
	printf("\n");

	return 0;
}

2. Integration.cu

#include <cutil_inline.h>
#include "Integration_kernel.cuh"

bool InitCUDA(void)
{
	int count = 0;
	int i = 0;

	cudaGetDeviceCount(&count);
	if(count == 0) {
		fprintf(stderr, "There is no device.\n");
		return false;
	}

	for(i = 0; i < count; i++) {
		cudaDeviceProp prop;
		if(cudaGetDeviceProperties(&prop, i) == cudaSuccess) {
			if(prop.major >= 1) {
				break;
			}
		}
	}
	if(i == count) {
		fprintf(stderr, "There is no device supporting CUDA.\n");
		return false;
	}
	cudaSetDevice(i);

	printf("CUDA initialized.\n");
	return true;
}

extern "C" bool RunTest(char* data, int2* data_int2, unsigned int len)
{
	if (!InitCUDA())
	{
		return 0;
	}

	const unsigned int num_threads = len / 4;
	//cutilCondition(0 ==(len%4));
	const unsigned int memsize = sizeof(char) * len;
	const unsigned int memsize_int2 = sizeof(int2) * len;

	char* d_data;
	cutilSafeCall(cudaMalloc((void**)&d_data, memsize));
	cutilSafeCall(cudaMemcpy(d_data, data, memsize, cudaMemcpyHostToDevice));

	int2* d_data_int2;
	cutilSafeCall(cudaMalloc((void**)&d_data_int2, memsize_int2));
	cutilSafeCall(cudaMemcpy(d_data_int2, data_int2, memsize_int2, cudaMemcpyHostToDevice));

	dim3 grid(1, 1, 1);
	dim3 threads(num_threads, 1, 1);
	dim3 threads2(len, 1, 1);

	mykernel<<<grid, threads>>>((int*)d_data);
	mykernel2<<<grid, threads2>>>(d_data_int2);

	cutilSafeCall(cudaMemcpy(data, d_data, memsize, cudaMemcpyDeviceToHost));
	cutilSafeCall(cudaMemcpy(data_int2, d_data_int2, memsize_int2, cudaMemcpyDeviceToHost));

	cutilCheckMsg("Kernel execition failed!");

	cutilSafeCall(cudaFree(d_data));
	cutilSafeCall(cudaFree(d_data_int2));

	return true;
}

3. Integeration_kernel.cuh

__global__ void mykernel(int* g_data)
{
	const unsigned int tid = threadIdx.x;
	int data = g_data[tid];

	g_data[tid] = ((((data <<  0) >> 24) - 10) << 24)
				| ((((data <<  8) >> 24) - 10) << 16)
				| ((((data << 16) >> 24) - 10) <<  8)
				| ((((data << 24) >> 24) - 10) <<  0);
}

__global__ void mykernel2(int2* g_data)
{
	const unsigned int tid = threadIdx.x;
	int2 data = g_data[tid];

	g_data[tid].x = data.x - data.y;
}