我有一个问题,需要将一些嵌套的for循环从C/C++转换成CUDA。基本上,我有4个嵌套的for循环,它们共享同一个数组并进行位移操作。
#define N 65536
// ----------------------------------------------------------------------------------
int a1,a2,a3,a4, i1,i2,i3,i4;
int Bit4CBitmapLookUp[16] = {0, 1, 3, 3, 7, 7, 7, 7, 15, 15, 15, 15, 15, 15, 15, 15};
int _cBitmapLookupTable[N];
int s = 0; // index into the cBitmapLookupTable
for (i1 = 0; i1 < 16; i1++)
{
// first customer
a1 = Bit4CBitmapLookUp[i1] << 12;
for (i2 = 0; i2 < 16; i2++)
{
// second customer
a2 = Bit4CBitmapLookUp[i2] << 8;
for (i3 = 0; i3 < 16; i3++)
{
// third customer
a3 = Bit4CBitmapLookUp[i3] << 4;
for (i4 = 0;i4 < 16;i4++)
{
// fourth customer
a4 = Bit4CBitmapLookUp[i4];
// now actually set the sBitmapLookupTable value
_cBitmapLookupTable[s] = a1 | a2 | a3 | a4;
s++;
} // for i4
} // for i3
} // for i2
} // for i1
这是我应该转换成CUDA的代码。我尝试了不同的方法,但每次都会有错误的输出。这里我发布了我的CUDA转换版本(内核部分的代码)。
#define N 16
//----------------------------------------------------------------------------------
// index for the GPU
int i1 = blockDim.x * blockIdx.x + threadIdx.x;
int i2 = blockDim.y * blockIdx.y + threadIdx.y;
int i3 = i1;
int i4 = i2;
__syncthreads();
for(i1 = i2 = 0; i1 < N, i2 < N; i1++, i2++)
{
// first customer
a1 = Bit4CBitmapLookUp_device[i1] << 12;
// second customer
a2 = Bit4CBitmapLookUp_device[i2] << 8;
for(i3 = i4 = 0; i3 < N, i4 < N; i3++, i4++){
// third customer
a3 = Bit4CBitmapLookUp_device[i3] << 4;
// fourth customer
a4 = Bit4CBitmapLookUp_device[i4];
// now actually set the sBitmapLookupTable value
_cBitmapLookupTable[s] = a1 | a2 | a3 | a4;
s++;
}
}
我在CUDA方面是个新手,仍在学习中,但是对于嵌套循环问题,我真的找不到解决方案。谢谢您提前的帮助。
i1
...i4
初始化为从未被使用的值。 - leftaroundabout