VHDL'87: avoiding FATAL ERROR when "Failed to open VHDL file" occurs

[sigwalt]

Hi all,

i think a simulation environment should be able to cope with new input
files without collapsing, just because there is an optional input file
missing.
EVEN IF VHDL'87 is indeed VERY POOR as far as file handling is
concerned
(the line
file stimulus: TEXT is in "optionalstuff.dat";
always leads to a FATAL error in case the file is missing)

does anyone know a way to avoid the "file not found" bug?

maybe some Modelsim setting?

thanx
sean

 

[Jonathan Bromley]

i think a simulation environment should be able to cope with new input
files without collapsing, just because there is an optional input file
missing.
EVEN IF VHDL'87 is indeed VERY POOR as far as file handling is
concerned

Stop futzing around with VHDL-87's ghastly file arrangements and
use VHDL-93 style instead. It's only slightly better, but at
least it offers you the chance to recover gracefully from a
file-open failure.

Not that you can do much about it. VHDL conspicuously lacks
any way to investigate or explore the host file system, so
if you can't open the file you wanted, there's little chance
of getting VHDL to find the file somewhere else.

The right solution is to hard-code the filenames in your
VHDL sim, then wrap the simulation in a Tcl script that
carefully puts the right files in the right places for the
simulation (and moves any output files from their hard-coded
places to somewhere more useful once the sim is done).
Tcl is very good indeed at messing with the host file system
to find files, create directories, invent unique filenames
based on the system date and time, and so forth. VHDL
(any flavour) is useless for such things.
--
Jonathan Bromley, Consultant

DOULOS - Developing Design Know-how
VHDL * Verilog * SystemC * e * Perl * Tcl/Tk * Project Services

Doulos Ltd., 22 Market Place, Ringwood, BH24 1AW, UK
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are not the views of Doulos Ltd., unless specifically stated.

 

[kenm]

Hi all,

i think a simulation environment should be able to cope with new input
files without collapsing, just because there is an optional input file
missing.
EVEN IF VHDL'87 is indeed VERY POOR as far as file handling is
concerned
(the line
file stimulus: TEXT is in "optionalstuff.dat";
always leads to a FATAL error in case the file is missing)

does anyone know a way to avoid the "file not found" bug?

maybe some Modelsim setting?

thanx
sean

Hi Sean,

The "-absentisempty" option on the "vsim" command in ModelSim will do
what you need.

e.g. vsim -absentisempty top_level_of_your_design

It will actually behave as if the file is present, but empty, which is
probably the best way to handle this.

Cheers,

Ken Morrow,
Morrow Electronics Limited, UK
www.morro.co.uk
(website still under construction after change of ISP)

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