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Copyright 2003 Stephen Williams <>
Icarus Verilog source can be compiled with the mingw C/C++ compilers
to get a Windows binary that does not require the POSIX compatibility
cruft of the Cygwin.dll library. The resulting program can be run with
or without Cygwin, so this is the preferred Windows distribution form.
The configure scripts automatically detect that the compilers in use
are the mingw compilers and will configure the Makefiles appropriately.
However, the mingw tools do not include all the other tools around the
compiler, including the shell interpreter for the configure script,
bison, flex, gperf, etc. Therefore, you still need Cygwin to compile
Icarus Verilog, even if you don't need the Cygwin compilers. There are
also a few precompiled library prerequisites that you need.
* Some Preliminary Comments
The Windows port of Icarus Verilog is the most difficult of all the
ports. The Windows system off the shelf is completely stripped, devoid
of any support for software development. Everything needed to compile
Icarus Verilog must be collected from various sources and stitched
together by hand. Normal human beings with a basic understanding of
software development can do this, but some patience (and access to the
Internet) is required. You may choose to print these instructions.
I have no plans to intentionally support MSVC++ compilation. Don't ask.
* Summary of Prerequisites
This is a brief list of prerequisite packages, along with the URL
where each can be found. In most cases, the specific version is not
critical, but these are the versions I use.
Cygwin <>
Mingw32-2.0.0 <> <> <> <> <> <>
The above table lists the packages required. It is convenient to
install them in the above order. Many of these packages are also
collected into the directory:
Incidentally, besides Mingw32, none of these packages are needed after
installation of Icarus Verilog is complete. These are only needed to
build the compiler. The Mingw32 package can be used to compile VPI
modules if you choose.
* Install Cygwin
So, step 1 is "Download and Install Cygwin." See the web page for instructions and the files to do
this. Cygwin *is* a kool package, and is worth having anyhow. There is
a convenient setup program that you download first. You execute the
setup program, and that prompts you to select the package you want.
You need in particular the Cygwin base, bison (see notes) flex, make
and gperf. If you are compiling from CVS, you also need cvs, rcs and
automake packages. You will also need tar and gunzip, but these are
hard to not install. I recommend installing the "which" package as
well. Beyond the basics, be sure to install these Cygwin packages:
bison (*not* 1.875. See Notes.)
ghostscript (makes the documentation)
tar (tar and gunzip for unpacking the source)
unzip (For unpacking zip compressed packages.)
bison-1.875 is broken, it generates invalid C/C++ code. You
don't want that version for anything you do. If you have that
version (use "bison -V" to check the version) then use the
Cygwin setup program to get a different version. I've downgraded
to 1.75 and couldn't be happier. In fact, a whole host of insane
bison bugs can be avoided that way.
There is a mingw32 runtime package included in the Cygwin
distribution. You do *not* need that, as you will be getting
everything from the mingw32 distribution itself.
Other then the install of mingw32, most of the remaining steps are
best done in a Cygwin window. When you installed Cygwin, a start menu
entry was created to allow you to start up the Cygwin window. I'll use
the string "$ " to represent a command prompt in this window, because
that is the usual bash prompt.
* Install Mingw32
The obvious step 2, then, is install the mingw compilers. These can be
found at the web page <>. The Mingw-2.x.x version
comes prepackaged in a convenient, Windows style, installer. I
recommend you download this package instead of picking and choosing
When I install Mingw32 (using the installer) I typically set a
destination directory of d:\mingw-2.0.0 or the like. You will be using
that path later.
If you intend to compile VPI modules for Icarus Verilog, you
need Mingw32, even if you are using a precompiled binary. VPI
modules only require Mingw32, and none of the other libraries.
* Install Mingw32 Packages
There is a collection of precompiled libraries and add-on packages
that are intended for use with the Mingw32 compiler. These do not come
with simplified Windows installers, but they are pretty easy to
install by hand. Icarus Verilog uses the readline-4.2 package from
that collection.
Since I installed Mingw32 in d:\mingw-2.0.0, I also created a
Mingw-packages directory called d:\mingw-packages. The install, then,
is as easy as this:
<cygwin shell>
$ cd d:/mingw-packages
$ unzip
[lots of inflating...]
Done. On to the next packages.
* Install GnuWin32 Packages
The GnuWin32 project is a collections of open source programs and
libraries ported to Windows. These also work well with the Mingw
compiler, and in fact Icarus Verilog uses a few libraries from this
You will need these gnuwin32 packages to compile Icarus Verilog:
I suggest creating a common directory for holding all your gnuwin32
packages. I use D:\gnuwin32.
After downloading these packages, put the .zip files in your gnuwin32
directory and install them like so:
<cygwin shell>
$ cd d:/gnuwin32
$ unzip
[lots of inflating...]
$ unzip
[lots of inflating...]
$ unzip
[lots of inflating...]
$ unzip
[lots of inflating...]
* Unpack Icarus Verilog source
Unpack the compressed tar file (.tar.gz) of the source with a command
like this:
$ gunzip -d verilog-20030303.tar.gz | tar xvf -
This will create a directory "verilog-20030303" that contains all the
source for Icarus Verilog. Descend into that directory, as that is
where we will work from now on.
$ cd verilog-20030303
The exact name of the file will vary according to the
snapshot. The 20030303 name is only an example.
* Select the mingw compilers
In your cygwin window, if you type "which c++" you might get the
response path "/usr/bin/c++" which is the cygwin compiler. This is not
the one we want to use, however. Tell the shell where the mingw
compilers are by setting the search path like so:
$ PATH=/cygdrive/d/mingw-2.0.0/bin:$PATH
This assumes that you installed mingw in D:\mingw-2.0.0. The actual
programs are in the bin directory under the root. After this command,
check that you are now getting the right compilers with this "which"
$ which c++
* Configure Icarus Verilog
Now we are all set to configure and compile Icarus Verilog. Choose a
destination path where you will want to install the binaries. I chose
on my system the directory "D:\iverilog". This choice is not
permanent, so don't get too much angst over it. Just choose a name
without white space.
Now, configure the source to make the makefiles and configuration
details. Run these commands:
$ CPPFLAGS="-Id:/gnuwin32/include -Id:/mingw-packages/include"
$ LDFLAGS="-Ld:/gnuwin32/lib -Ld:/mingw-packages/include"
$ ./configure --prefix=d:/iverilog
The CPPFLAGS and LDFLAGS variables tell configure where
the gnuwin32 packages are. The configure program will
write these values into the Makefiles, so you only need to
keep these variables long enough for the configure program
to work.
Your PATH variable was set in the previous step.
Use forward slashes as directory characters. All the various
tools prefer the forward slash.
Substitute your chosen directory for the prefix. This will cause the
makefiles to build and the source code to configure. The configure
program will detect that this is a mingw environment and set things up
to build properly.
(For a prefix, use the drive letter notation; the mingw compiled parts
require it, and the Cygwin tools should be able to handle it. You may
need to check or upgrade your Cygwin installation if this causes
problems for you.)
* Compile Icarus Verilog
This, believe it or not, should be the easy part:
$ make
It could take a while. Now is a good time to go get some coffee or
take a tea break.
* Install Icarus Verilog
If the compile ran OK, then next you install Icarus Verilog in the
directory you have chosen. When you are ready, install like this:
$ make install
This is part of what the configure program did for you. The Makefiles
now know to put the files under the D:\iverilog directory (or whatever
directory you chose) and away you go.
You may find that you need to put some of the prerequisite DLLs into
the d:\iverilog\bin directory. These include:
If you already have these in your Windows path (i.e. your system32
directory) then you do not need to copy them into the iverilog
directory. However, prepackaged Icarus Verilog binaries include these
* Running Icarus Verilog
Finally, put the D:\iverilog\bin directory in your Windows path, and
you should be able to run the iverilog and vvp commands to your
heart's content.
Currently, the iverilog.exe uses the path to itself to locate the
libraries and modules associated with itself. In other words, if you
execute the D:\iverilog\bin\iverilog.exe program, it will locate its
subparts in the D:\iverilog directory and subdirectories below
that. This means you can move the Icarus Verilog installation by
simply moving the root directory and all its contents.
The vvp.pdf and iverilog.pdf files document the main commands. View
these with Acrobat reader, or any other viewer capable of displaying
PDF format files.
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