How to call a Library Functions void XXX (void) generated by Simulink/ert_shrlib.tlc using M script

I convert a simulink model to a shared library function by Simulink/ert_shrlib.tlc.

The model hava four input, Add1,Add2,Sub1,Sub2, and two output, AddOut, SubOut.

The functions definition in the generated header file is

void dllTest_initialize(void), void dllTest_step(void), void dllTest_terminate(void).

All the ports are defined as structure:

/* External inputs
typedef struct {
XXX
} ExtU_dllTest_T;
/* External outputs
typedef struct {
XX
} ExtY_dllTest_T

The .c file defines the external ports

ExtU_dllTest_T dllTest_U;
ExtY_dllTest_T dllTest_Y;

The dllTest_initialize is

void dllTest_initialize(void)
{
  /* Registration code */
  /* initialize error status */
  rtmSetErrorStatus(dllTest_M, (NULL));
  /* external inputs */
  (void)memset((void *)&dllTest_U, 0, sizeof(ExtU_dllTest_T));
  /* external outputs */
  (void) memset((void *)&dllTest_Y, 0,
                sizeof(ExtY_dllTest_T));
}

I want know to how to pass a value before calling the dllTest_initialize and dllTest_step.

I can creat a C structure and Pointer using

InputStruc=libstruct('ExtU_dllTest_T',Input);
InputPtr=libpointer('ExtU_dllTest_TPtr',InputStruc);

BUT don't know how to pass it to input ExtU_dllTest_T dllTest_U.