USB 'Serial Interface Engine' where can download the sources

[xiongdh]

vhdl “serial interface engine”

anybody could tell me about the VHDL 'Serial Interface Engine' ?, is it
possible to get the VHDL sources? where?
Thank you

 

[xiongdh]

serial interface engine vhdl

I find the paper "Designing a robust USB serial interface engine(SIE)",but i can't find the SIE source module introduce in the paper.
where can i find the souce module