__kernel void
twice(__global int *data_count,
      __global int *input_data,
//       __constant int *n,
      __global int *output_data)
{
    long count = (long)data_count[0];
    for (int i = 0; i<count; i++) {
        output_data[i] = input_data[i] * 2; // n[0];
    }

}