c# - convert struct object into byte[] and vice versa in windows phone 7 application -

i want convert struct object byte[] , vice versa in windows phone 7 application have used code works in windows form application perfect not working in windows phone application , error

'system.runtime.interopservices.marshal' not contain definition 'allochglobal'     'system.runtime.interopservices.marshal' not contain definition 'freehglobal' 

my code

public static byte[] getbytes(object o)         {             int size = marshal.sizeof(o);             byte[] arr = new byte[size];             intptr ptr = marshal.allochglobal(size);             marshal.structuretoptr(o, ptr, true);             marshal.copy(ptr, arr, 0, size);             marshal.freehglobal(ptr);             return arr;         }          public static object getstruct(byte[] arr, object o)         {                         int size = marshal.sizeof(o);             intptr ptr = marshal.allochglobal(size);             marshal.copy(arr, 0, ptr, size);             o = (object)marshal.ptrtostructure(ptr, o.gettype());             marshal.freehglobal(ptr);             return o;         }