Where can I get the yaffs-for-vxworks related source code?

By reading from http://www.yaffs.net/documents/yaffs-vxworks#What_is_Yaffs_-for-VxWorks, 

I got that yaffs has add supports for the vxworks, but I can find the source code about it in the yaffs source code,

for example: yaffx_vx_glue.c.