gEDA: Open-source VHDL compiler takes fresh approach

[Paul Hartke <phartke@stanford.edu>]

Open-source VHDL compiler takes fresh approach
By Richard Goering, EE Times
May 2, 2003 (7:52 AM)
URL: http://www.eedesign.com/story/OEG20030502S0026 

SANTA CRUZ, Calif. — An open-source VHDL simulator, called GHDL, takes 
a different approach from other free VHDL offerings by serving as a 
front end to the Gnu Compiler Collection (GCC) suite. GHDL compiles 
directly into an executable file, avoiding the intermediate steps 
required by most open-source compilers. 

GHDL is the creation of Tristan Gingold, who describes himself as 
a "developer" and user of Unix and Linux tools. He wrote GHDL in order 
to learn more about VHDL. 

"GHDL is different from other open-source VHDL in two points: it is 
written in Ada95, and it is a direct compiler, using the GCC 
technology," Gingold said. "You analyze your VHDL sources and then you 
build an executable. To start a simulation, you run your executable." 

GHDL caught the attention of Phil Tomson, the engineer who created the 
Ruby-based RHDL open-source simulator. Tomson was involved with the 
Free HDL project, which is working to build an open-source VHDL 
simulator for Linux. 

"VHDL designs can be compiled directly to executables using GHDL," he 
said. "There is no intermediate conversion to C or C++, which then has 
to be compiled using a C/C++ compiler. We considered using this 
approach when we started the FreeHDL project, but none of us knew 
enough about GCC internals." 

"I recently tried out GHDL and under Linux, at least, it seems to work 
pretty well," Tomson said. 

GHDL does, however, have some limitations. The GHDL Web site notes that 
the current version is "very beta" and does not support all VHDL 
features. It implements "nearly all" VHDL87 features and "some 
features" of the more recent VHDL93. 

GHDL is available under the open-source GNU Public License (GPL).