Monday, December 24, 2007

[FORTRAN] Making a DLL for VB6

As a break from trying to figure out how to get a pattern matching library DLLified (and UTF-32 sensitive), my boss gave me something else to do, something on the one hand similar (wrap something in a DLL) and on the other quite different (wrap two knapsack algorithms done in Fortran 90).

The knapsack code is derived from
Algorithm 4.9, Donald Kreher and Douglas Stinson, Combinatorial Algorithms, CRC Press, 1999, page 125.
and was downloaded from FORTRAN Source Codes, specifically, the COMBO library. Many thanks to John Burkardt for making this resources available.

The files used from the COMBO library were knapsack_01.f90, knapsack_rational.f90, knapsack_reorder.f90, rvec_backtrack.f90 and r_swap.f90, and were compiled using Compaq Visual Fortran.

Seeing as CVF is no longer available (except perhaps on eBay) you might get away with the
Intel® Fortran Compiler for Windows, SilverFrost's FTN95 or g95.

Don't try it with
Watcom Fortran, however, because that only does Fortran 77. Mind you, if the algorithms you're wrapping are F77 ones from NIST's 'Dictionary of Algorithms and Data Structures' or Steven Skiena's The Stony Brook Algorithm Repository you may do okay with the Watcom offering or even GNU's g77.

I really like Fortran. I remember writing some VAX-11 FORTRAN back in 1983 (along with a bit more VAX-11 COBOL) and found it quite powerful and expressive. I know that there's been a fairly widespread pooh-pooh-ing of Fortran in recent years, but I try not to be influenced by peer-group pressure, preferring to actually see for myself whether a language is any good or not.

Okay, off the soap box and down to the code. I'm not going to bother posting all the COMBO code, just what I wrote to wrap it.

These are the three exposed routines and have essentially the same framework: a subroutine header, two declarations controlling symbol names and method of access, the call to the COMBO routine, the return and the end of subroutine. Really, really, simple. Gobsmackingly simple, compared to some other languages I could mention. Rather embarrasing really ... so little to show.

If you're wondering why I explicitly state that the parameters are being passed by reference (!dec$ attributes reference ...), it's because a side effect of specifying "stdcall" is that it forces the passing mechanism into pass-by-value, and in this case, quite a few of the parameters are being modified by the subroutine.

The other routines are linked in during the compile and I end up with a nice little .DLL.

Okay, so maybe there's something more to show on the VB6 side.

First off, the declares. VB6 defaults to pass-by-reference, thus the missing "ByRef" ahead of each parameter.

Next the test code which is derived from TEST094 and TEST095 found inside COMBO's combo_prb.f90.

Do note that the floating point variables are defined here as Single. This seems to be the best match to an undecorated Fortran REAL. Maybe if I'd tweaked the COMBO code to REAL*8, I could have used Double on the VB6 side.

Hmm ... nothing much amazing there either. But that's how it was with wrapping the Fortran. Simple and powerful at the same time. So far as I'm concerned, if we ever have to rewrite Protium, Fortran's going to be very near the top of the list.

© Copyright Bruce M. Axtens., 2007

Thursday, December 20, 2007

[Visual BASIC 6] BOOST (v2)

I revisited BOOST this week. A friend had pointed out to me some time back that /P: and /L: were a bit of a pain when one wanted to speed something up quickly, or kill it quickly. So this version changes the command line handling.

This version also demonstrates how to kill a process. In fact it kills every process of the same name. I wish I'd had this a couple of years ago when I was doing stuff with Excel -- I'd end up with multiple Excel sessions which I would then have to kill off one-by-one through the Task Manager. (I eventually ended up installing Cygwin so that I could script the process.)

If you remember the original VBScript of BOOST and the first VB6 version, you'll see some similarities.

I've given up on using
setsubsys in favour of using VBAdvance (which is now freeware) to handle the compile-to-console-app process. I'm still compressing the app using UPX.

First a few constants and the declarations, found on, for doing console I/O.

Next, a few supporting functions. First off the rank, is an invocation syntax display. Notice that priority can now be specified either by a number (0 to kill, 1-6 for low to realtime) or by name (kill, low, belownormal, normal, abovenormal, high, realtime).

Second, the command line parser. This splits on space and tab and is based on code found at

Third, the two routines which wrap the WMI functions to set priority and to kill process. The latter was found at
tek-tips. If I remember correctly, the places in each routine where it says
sComputer = "."
could, in fact, have some other computer's name. If you had sufficient privilege you could be tweaking or killing a process on someone else's machine.

Finally, the Main subroutine. Notice the additions to the priorities collection. Note also the change in the way the command line is handled.

Because there's no .Exists method on Collections, the .Item call is wrapped in an 'On Error' so that a non-existent item situation is caught appropriately.

What's next with this thing? I suppose one could explore the possibility of influencing the lives of applications on other computers:
BOOST Skype.exe kill /C:GUEST_01
There's also the fact that the commandline parser doesn't properly handle double-quoted names. If an .exe had a space it its name, you wouldn't be able use BOOST on it.

Finally, here's a short batch file (killall.bat) I use for killing applications en masse. It was originally designed to get around the 'typing the /P and /L' issue, but I'm so used to using it now ...

An example invocation:
killall excel.exe outlook.exe

© Copyright Bruce M. Axtens, 2007

Monday, December 17, 2007

[Programming] Okay, Ignorance is Bliss ...

If by Ignorance you mean an implementation of the Bliss programming language, then yes, Ignorance is Bliss.

After two and half weeks of Ada, I had to have a break. I wandered over to the
Retrocomputing Museum and downloaded the Ignorance source code. While I was at it I also downloaded the source for CUPL, the Cornell University Programming Language. Interestingly, the same interpreter also works for CORC, the CORnell Compiler. The man behind the website, Eric Raymond, has the following, less than flattering, words to describe CUPL:
"Another hideous old design, CUPL — Cornell University Programming Language. It looks something like a really archaic BASIC with linear-algebra builtins."
And what's wrong with BASIC and linear algebra? (That was a rhetorical question.)

I've been able to get CUPL to work, but haven't had any success with Ignorance. Or, for that matter, with

To find out more about these languages, HOPL is your friend:
Bliss, CUPL and JOSS.

as is Wikipedia:
Bliss, CORC (CUPL precursor) and JOSS.

© Copyright Bruce M. Axtens., 2007

Thursday, December 13, 2007

[Ada (GNAT)] Who said, "Ignorance is bliss"?

Ignorance isn't bliss. For the past two days I've been trying to do what I expect an Ada freak could do in 2 minutes. It's been a very frustrating, sleep-depriving process.

After trying to do amazing things with GNAT.Spitbol, I'm now trying to do the same to Dr. Dmitry A. Kazakov's
match library. And, as usual, it has not been an easy journey.

UTF-32 aside for now, I've been trying this week simply to make the Matching and Pattern packages available to the Windows programmer via the DLL mechanism.

At this point, all I have is a wrapper for the match() function.

I really hope there is an easier way of doing this. As I've said a few times before, I'm a newbie when it comes to Ada but have been forced to jump into the deep end of the pool. Please, if you know a better way, tell me!!

Oh, and I should point out that, though it seems I'm passing the right stuff to match(), in its current form the VB6 code keeps receiving an error code from the Matching package. It may be because I'm not declaring the pattern properly.

Okay, to the code. First up, the BOS.ADS spec file:

Next, the body (BOS.ADB). There are lots of Put calls in here for debugging. These are what appear if you run the VB6 code as a console app.

For the sake of completeness, BOS.DEF, BUILD.GPR and BUILD.BAT. Note that in BUILD.BAT, I specify match\match.o as an object file for gnatlink.

Finally, the VB6 code being used to test it all. Please note that I'm using
SetSubSys to turn the resulting EXE into a Console application. If you don't do that, the output from Ada's Put() statements will not be made visible.

It's not pretty code, but it does the job. By the way, if you don't do the StrConv, you'll be passing UTF-16 strings.

© Copyright Bruce M. Axtens., 2007

Tuesday, December 11, 2007

[Google] AdSense and Analytics

On the suggestion of my eldest, I've added Google Analytics. In the next couple of days I should hear back from Google AdSense and will trial having Google Ads on the page. If it earns, fine. If not, I think I'll give it a miss. "Suck it and see," as my late father would have said.

Monday, December 10, 2007

[Ada (GNAT)] A 32bit GNAT.Spitbol.*

It is said that, "a wise man knows his own turnips." In my case, I've run into some difficulty converting GNAT.Spitbol to UTF-32. The compiler error messages are marvellously helpful, but I'm a newbie to Ada and ... yeah, well, you get the idea.

The source code is up on, if you feel so inclined as to download it and tell me where I'm going wrong.

Monday, December 03, 2007

[Ada (GNAT/GCC)] VARPTR, GNAT and data "transput"

Okay, have got it figured (soli Deo gloria!)

The following listings demonstrate the passing of a two part Type containing two Singles from VB6 into a GNAT/GCC DLL. Once inside, the elements of the Type are swapped and control returns to VB6. VB6 then displays the results.

As before, the code has been worked out in the context of the afore-posted api project. If you want to play with this, just take the earlier work and tweak it appropriately.

First up, the additions to

Next, the additions to api.adb:

API.DEF must also be modified, adding swapsingles to the list of EXPORTS.

Next, some VB code to demonstrate ...

... and part of a sample output.

The project that all this was part of was done in both GNAT/GCC and ObjectAda 7.2.2. Interestingly, ObjectAda's Float is equivalent to VB6's Double, whereas GNAT/GCC's Float is equivalent to VB6's Single. Does anyone know why?

By the way, regarding "transput", Wikipedia's article on
Algol states:
ALGOL 60 as officially defined had no I/O facilities; implementations defined their own in ways that were rarely compatible with each other. In contrast, ALGOL 68 offered an extensive library of transput (ALGOL 68 parlance for Input/Output) facilities.
A extensive library of transput facilities is something you'll find in Protium, too.

© Copyright Bruce M. Axtens, 2007