CUDA Thrust: Summary: host_vector, device_vector, device_ptr, raw pointer conversions

 

http://stackoverflow.com/questions/7678995/from-thrustdevice-vector-to-raw-pointer-and-back 

   1:  // our host vector 

   2:   

   3:  thrust::host_vector<dbl2> hVec; 

   4:   

   5:   

   6:   

   7:   

   8:  // pretend we put data in it here 

   9:   

  10:  ….

  11:   

  12:   

  13:   

  14:  // get a device_vector 

  15:   

  16:  thrust::device_vector<dbl2> dVec = hVec; 

  17:   

  18:   

  19:   

  20:  // get the device ptr 

  21:   

  22:  thrust::device_ptr devPtr = &d_vec[0];

  23:   

  24:   

  25:   

  26:  // if you want to pass it to the kernel, need to convert to a raw pointer

  27:   

  28:  dbl2* ptrDVec = thrust::raw_pointer_cast(&d_vec[0]); 

  29:   

  30:    

  31:   

  32:  // To get back from the raw pointer to device_ptr so that host code can access it  

  33:   

  34:  thrust::device_ptr<int> dev_ptr = thrust::device_pointer_cast(raw_ptr); 

  35:   

  36:  // Now we can, for example: 

  37:   

  38:  // use device_ptr in Thrust algorithms 

  39:   

  40:  thrust::fill(dev_ptr, dev_ptr + N, (int) 0); 

  41:   

  42:  // access device memory transparently through device_ptr 

  43:   

  44:  dev_ptr[0] = 1;

  45:   

  46:    

  47:   

  48:  // On a side note, if you have a device_vector, you can get its device_ptr 

  49:   

  50:  thrust::device_vector<double> v1(10); // create a vector of size 10 

  51:   

  52:  thrust::device_ptr<double> dp = v1.data(); // or &v1[0] 

  53:   

  54:    

  55:   

  56:  // Now: From thrust::device_ptr<T> we can construct thrust:device_vector<T> 

  57:   

  58:  thrust::device_vector<double> v2(v1); // from copy 

  59:   

  60:  thrust::device_vector<double> v3(dp, dp + 10); // from iterator range 

  61:   

  62:  thrust::device_vector<double> v4(v1.begin(), v1.end()); // from iterator range