X-HDL - Verilog VHDL bi-directional translator

X-HDL is an excellent Verilog <=> VHDL bi-directional translator developed by X-Tek, although it seems X-Tek had difficult time before 2005. X-HDL performs translation of even the most complex RTL/gate-level code efficiently and requiring few, if any, "hand tweaks" of the translated code. X-HDL also contains specialized algorithms which are very effective in translating behavioral-level code to functionally equivalent target-language code.

Key Features

• Provides both GUI and command-line modes
• Performs automatic hierarchical translations as well as file-at-time translations.
• Translates structural, RTL and behavioral code
• Preserves comments with placement nearly identical to the source
• Consistent code formatting with user customizations
  • VHDL'87 or VHDL'93 syntax generation
  • Verilog-2001 syntax generation
  • Code alignment controls
  • Indentation controls
  • Line wrap controls
• Supports component libraries
• Smart overloaded subprogram handling
• Intelligently determines if translated Verilog tasks/functions are local or global within the VHDL.
• VHDL conversion function filtering
• Conversion definitions to support user-defined translation
• Support for pre- and post-processing scripts to enable user-specific translation needs.

The current version is X-HDL 4.1.4.For more detail information, please see

http://www.x-tekcorp.com/docs/xhdl4/X-HDL.pdf

Other this kind of tools include v2v.