Follow the steps below to create a simple “Hello, World” program in VHDL using GHDL.
VHDL, or “VHSIC Hardware Description Language”, is a programming language used to simulate the operation of computer hardware in software. It provides a standardized method of designing and testing electronic hardware, which reduces the difficulty of the design’s eventual translation into real, physical components.
GHDL is an open-source simulator that can compile and run VHDL code.
1. Download and extract GHDL. As of this writing, the latest Windows version is available at the URL “https://github.com/tgingold/ghdl/releases/tag/v0.33”.
2. Locate “GHDL.exe” within the “bin” directory of the newly extracted GHDL archive. Make a note of the path of GHDL.exe. If desired, this path can be added to the system’s PATH environment variable.
3. In any convenient location, create a new directory named “VHDLTest”.
4. In the newly created VHDLTest directory, create a new text file named “hello.vhdl”, containing the following text. This code is taken from the file “ghdl.htm” within the GHDL archive.
-- Hello world program. use std.textio.all; -- Imports the standard textio package. -- Defines a design entity, without any ports. entity hello_world is end hello_world; architecture behaviour of hello_world is begin process variable l : line; begin write (l, String'("Hello world!")); writeline (output, l); wait; end process; end behaviour;
5. Open a command prompt window and run the following commands, substituting the full path of the file ghdl.exe where necessary:
ghdl.exe -a hello.vhdl ghdl.exe -e hello_world ghdl.exe -r hello_world
6. Verify that the message “Hello world!” appears in the command prompt window.