How to implement DDIO logic in I/O block.

Hi,

I want to implement Double Data Rate logic in I/O block.I have written a verilog code for that.After compilation I checked that logic written for DDIO is not implemented in I/O block.When I use altera's DDIO component it generates DDIO logic in I/O block.For my project I can't use altera's DDIO component. So is there any method to implement DDIO logic in I/O block.

Thanks in advacne.

Regards,

Krupesh