netripper

// Only used to determine Code
    [StructLayout(LayoutKind.Sequential)]
    internal struct TagFM_NOTIFICATION_INTERNAL
    {
        public FMN_ACTIONS Code;
        public uint Timestamp;
        public IntPtr DataPtr;
    }

// Based on code, Ptr is marshalled to FREQ
    [StructLayout(LayoutKind.Sequential)]
    internal struct TagFM_NOTIFICATION_FREQ_INTERNAL
    {
        public FMN_ACTIONS Code;
        public uint Timestamp;
        public FMN_FREQUENT_CHANGED FreqData;
    }

// Or to RDS
    [StructLayout(LayoutKind.Sequential)]
    internal struct TagFM_NOTIFICATION_RDS_INTERNAL
    {
        public FMN_ACTIONS Code;
        public uint Timestamp;
        public FMN_RDS_RECEIVED_INTERNAL RdsData;
    }

// RDSData is another IntPtr as it points to an array
    [StructLayout(LayoutKind.Sequential)]
    internal struct FMN_RDS_RECEIVED_INTERNAL
    {
        public ushort RDSCount;
        public IntPtr RDSData;
    }

// Marshalling each group and adding it to a list
                    List<FM_RDS_GROUP> groups = new List<FM_RDS_GROUP>();
                    for (int i = 0; i < iRdsNotify.RdsData.RDSCount; i++)
                    {
                        IntPtr ptr = iRdsNotify.RdsData.RDSData;
                        int intptr = (int)ptr;
                        intptr += i * Marshal.SizeOf(typeof(FM_RDS_GROUP));
                        ptr = (IntPtr)intptr;

                        FM_RDS_GROUP group = (FM_RDS_GROUP)Marshal.PtrToStructure(ptr, typeof(FM_RDS_GROUP));
                        groups.Add(group);
                    }