VHDL pre-processing Method

In this approach the test specific code is written in VHDL. It is stored in a file separate from the transactor code. To set up the transactor for a specific test, a pre-processor will insert that file into the transactor code and then the transactor is recompiled. The place where the file is inserted is marked with a special comment e.g. "--insert_file inp.cmd" where inp.cmd is the file name.

In Unix the pre-processor would be run like this:

        awk -f insert.awk < transactor.vhd > precompiled_transactor.vhd
        vcom precompiled_transactor.vhd

The file test_code.vhd is assumed to be in the current directory. (The compilation command would be appropriate for the MTI simulator, it needs to be replaced by an equivalent command for other simulators.)

Some problems of this approach are:

• Reliance on OS specific tools (not strictly pure VHDL)
• Recompilation adds to simulation time

Some of the benefits are:

• Tests can be compiled before simulation, so syntax errors are detected before the simulation runs
• Tests can be readily understood by designers who are familiar with VHDL
• All structural elements of VHDL are available
• Tests can react flexibly on the response of the DUT, full access to all signals known to the transactor is possible

Below are the files which have been executed in this section:

insert.awk	test_code.vhd	transactor.vhd