How to pass pointers over interface calls

• version

  1.1.1

• scope

  Example.

  This code is provided as example code for a user to base their code on.

• description

  How to pass pointers over interface calls

• boards

  Unless otherwise specified, this example runs on the SliceKIT Core Board, but can easily be run on any XMOS device by using a different XN file.

Interface functions can take pointer arguments:

interface my_interface {
  void msg(int *p);
};

The client end can then pass a pointer into the function:

void task1(client interface my_interface c)
{
  int a[5] = {0,1,2,3,4};
  int *p = &a[0];
  c.msg(p);
}

On the server end the select case can access memory via the pointer.

void task2(server interface my_interface c)
{
  select {
  case c.msg(int *p):
    printintln(*p);
    printintln(*(p+2));
    break;
  }
}

Since passing the pointer implies that both tasks need access to the same memory space, if an interface includes a function that passes pointers, you cannot use it between tasks on different tiles.