Many simulators support multi-language simulations, allowing you to simulate VHDL controller designs with Verilog models. However, in many cases, both a Verilog and VHDL license must be purchased. If this is not possible, the VHDL memory model must be obtained from the third-party vendor. If the vendor does not currently supply VHDL models, there are third-party companies that can provide VHDL Memory Models.
While every device might not have a corresponding VHDL model, a similar device's memory model can be used as a starting point. The site accessed from the following link might be useful for locating VHDL memory models. Xilinx has not performed any testing with these third-party models and cannot guarantee their accuracy or functionality. Xilinx provides no support for models acquired from this site: