Announcement

**Tom Hanlin** · 10 May 2001, 10:15 AM

Almost all versions of BASIC, from Apple II and TRS-80 on up through the
latest Windows versions of BASIC, have supported dynamic memory management
for strings and, often, arrays as well. This dynamic memory management has
always meant moving variables around in memory while the program is operating.
There's nothing unstable about it. If you need a block of memory that won't
move, however, there's no reason you can't allocate one directly from the
operating system.

The maximum number of parameters for a PB routine, 16, is rarely an issue
because it's most unusual that anyone would need more. When you see that
many parameters, it's time to consider the virtues of UDTs.

The CALL syntax is quite dated and may be overriding the safety checks that
VB normally provides to DECLAREd routines. You might want to pull the CALL
out and see if this gets you a more meaningful error message:

MonsterActions MapInfo(0), MCmd, ViewPort, FollowMode(0), Players(0), Attacker, Defender, CurrentPlayer, CurrentObject

...etc...

------------------
Tom Hanlin
PowerBASIC Staff

**Tyrone W. Lee** · 10 May 2001, 02:38 PM

Surely your not serious?

How can a programming statement be "dated"? I don't know if I should
take that as an insult or not... but surely you have a better
solution than that.

I remove the call and recieved the same error.. (not that it mattered).

The real wierd part is that the first line accepts the call
while the second produces a bogus error. -Ahh.. I think this 32bit
conversion is a waste, and I may just re-write the whole thing.

------------------
Explorations v3.0 RPG Development System
http://www.explore-rpg.com

**Tom Hanlin** · 10 May 2001, 04:01 PM

I'm always serious. And don't call me Shirley!

Line numbers became "dated" when alphanumeric labels were introduced. DEF FN
became "dated" when FUNCTIONs became available. And so on...

CALL became "dated" when DECLARE came around. It's not just unnecessary,
like LET. Using CALL may turn off the error-checking that is normally
afforded you by using DECLARE. I'm not sure about how VB6 in particular
handles that, so it may not be an issue in this particular case.

The problem is apparently in your VB code, so perhaps you would do better
to try a VB forum. However, I do have one further suggestion. The error
message you're getting sounds like you may have too much on the stack. You
might try making a chunk of your local variables into global variables and
see if that makes a difference. (If VB thinks you have local variables and
you disagree, be advised that VB wins: you might investigate what VB
considers "local").

I understand that moving to a new programming environment can be frustrating.
But, what you're trying to do is far from impossible. Stick with it and,
ahh... try to maintain your sense of humor!

------------------
Tom Hanlin
PowerBASIC Staff

**Michael Mattias** · 11 May 2001, 03:08 AM

Well VB5/32bit doesn't allow this because it moves variables around
in memory while the program is operating.. <<to me this is very unstable

Win/32 may "physically" move memory, but it does not move the logical address (unless you tell Windows its OK to do so. Even then Windows provides the tools to tell you if it did).

The data isolation across processes works in Win/32 is in my view a massive enhancement over Win/16.

The way your program chose to share data across the address space in the 16-bit software was an unfortunate design decision.

This is just one more case in support of my general opposition to trying verb-for-verb 'ports' of software. If you just go in to code and change integers to longs and so on, you really haven't ported. If you have a new environment, you have to do some things a new way.

MCM

[This message has been edited by Michael Mattias (edited May 11, 2001).]

**Michael Mattias** · 11 May 2001, 05:58 AM

Using CALL may turn off the error-checking that is normally
afforded you by using DECLARE.

Really?

On all my PB compilers, parameter checking is done unless you override with a BYVAL directive.

It does not matter if there is a DECLARE or simple procedure precedence in the file. (OK, i "beat" the compiler by passing CINT(x) to a function which wanted a LONG).

Here's some code you can use to check..

[code]

FUNCTION DOGGY (X AS LONG) As LONG

FUNCTION = 2
END FUNCTION

FUNCTION PBMAIN AS LONG

DIM STAT AS LONG

LET STAT = DOGGY(1,2,3) ' <<< compile error
LET STAT = DOGGY(CINT(1)) ' << compiles, works

END FUNCTION
[code]

MCM

**Lance Edmonds** · 11 May 2001, 06:07 AM

Michael, you are quoting out of context - Tom was discussing the VB end, not PowerBASIC.

------------------
Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

**Bern Ertl** · 11 May 2001, 07:43 AM

Tyrone,

Does VB have a limit on the number of parameters allowed? Your
two sub/function calls use 9 & 10 params respectively...

You might also consider storing all your params into a string
variable and passing that. Something like...

Code:

'Code following in VB - use VB equivalents for the following PB code
MonsterActionsParams$ = MKL$( VARPTR( MapInfo(0))) + _
                        MKL$( MCmd) + _
                        MKL$( ViewPort) + _
                        ... etc.

Call MonsterActions( MonsterActionsParams$)

....

'In PB DLL
MapInfoArrayPtr = CVL( MonsterActionsParams$)
Mcmd            = CVL( MonsterActionsParams$, 5)
ViewPort        = CVL( MonsterActionsParams$, 9)
... etc.

------------------
Bernard Ertl

**Tyrone W. Lee** · 12 May 2001, 07:48 PM

Nahh.. The problem is Microsoft.. And here is the lovely article to
prove it..
http://support.microsoft.com/support.../q179/1/40.asp

If this doesn't load go to the MS Knowledge base and search for
"Too many local nonstatic" and see what u get.. Apprently, this is
a bug left in VB5. It occurs when the compiler tries to alot
space for passing UDT's to .DLL's -The part about this article
that I find most amuzing is that they claim this error will occur when
your variable size approaches 64K - Well my UDT is only 2K.

Furthermore, it appears that VB Compiler is trying to sum up all the
variables calls within a given application. And if the sum is > 64K it
causes an error. Because the sample code provided within this
Knowledge base page has a subroutine with 10 or so calls
to a DLL passing a UDT of aprox 4K.

The 11th call is commented out. When the ' is removed the
compiler will yield the error on the 11th line. Why? To me, the
compiler should look at each call independantly. So if the 11th call
causes an error it means the presence of the previous 10 has
some bearing on the condition of the 11th.. *LAME*

The solution is to store your UDT is a string? And pass the first
byte to the DLL. (This is ridiculous!)

I heard there was a secret VB VARPTR command that will return the
pointer to a variable.. but its undocumented. If I can
find out how to use it, I'll take that approach.

* This is a NOTE for 32bit moving variables..

I wrote a PB application that would output to a file the pointer
of a UDT passed from VB.

When I application ran the output file had several different memory
addresses for the same GLOBAL variable. So either VB, or the fact
that the OS is 32bit means that the variables address is being
moved.

I guess I didn't understand what u meant by "logical address" and
"physical address". When a VARPTR command is executed in PB does it give
the Windows/VB logical or physical address? - This sound like a
very unstable way to maintain an OS.. which explains why Windows crashes
soo much.

Maybe I'm being a little tough on Microsoft, but this article really
insulted my intelligence. Why create a VB/DLL link to pass UDT's if its
going to fail the 11th time its called? Thats NOT a development
platform. Thats russian roullette development..

------------------
Explorations v3.0 RPG Development System
http://www.explore-rpg.com

**Tyrone W. Lee** · 12 May 2001, 07:58 PM

And furthermore,

Microsoft offers this little piece of code as a fix for this problem.
You use the CopyMemory command from KERNEL to create this little
piece of code.

CopyMemory ab(0), aLargeUDT, UDT_SIZE
MySub ab(0)
CopyMemory aLargeUDT, ab(0), UDT_SIZE

CopyMemory is a KERNEL DLL routine.
Mysub is your DLL procedure.

But what I'm trippin on is this... If you can pass the UDT *unlimitted*
times to the CopyMemory routine and the compiler doesn't crash
why is Mysub treated any differently?

------------------
Explorations v3.0 RPG Development System
http://www.explore-rpg.com

**Lance Edmonds** · 12 May 2001, 09:55 PM

'Physical' addresses are not of any concern to the programmer - the Windows memory manager maps memory into and out of process address space transparently. All you need to deal with is the address passed to or from the VB code. Assuming you can get the VB code to compile that is!

Internally, VB stores strings in Unicode. When passing a dynamic string to a DLL (BYVAL), VB converts the string to ANSI and passes the address of the ANSI copy to the DLL. Therefore, for each successive call to a DLL, the target strings memory location is almost guaranteed to change because of this "hidden" Unicode<->ANSI conversion process.

While I'm not a VB programmer, it does seem quite likely that VB has to do a similar thing to UDT's, since VB supports dynamic strings within a UDT (although it actually stores pointers to the string data in the UDT and the actual string data is stored elsewhere). Therefore, it seems likely that each time you pass a UDT, you actually get the address of a "translated" copy of the UDT, so it's address will move around too.

It also seems to me that you may want to make the job easier on yourself and move the complete application into PowerBASIC where you control memory allocation and addressing in a consistent manner.

------------------
Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

**Michael Mattias** · 13 May 2001, 04:57 AM

If this doesn't load go to the MS Knowledge base and search for
"Too many local nonstatic" and see what u get.. Apprently, this is
a bug left in VB5. It occurs when the compiler tries to alot
space

While PB will use the "l" word (limitation), the same "b" word is in the PB compilers.

The PB compilers will not report an error when you define too many local nonstatic variables; instead, you wait for run-time and get a GPF. Of course, with PB, you get 1 1Mb stack space, so it doesn't show up. (64K? Is that for real? What a poor design decision by the Lords of Redmond!)

I posted in some thread here not too long ago the same fix: instead of doing a LOCAL (bigvar), you create a LOCAL array(0) AS BigVar. This moves the allocation except for the array descriptor off the stack and onto the heap.

MCM
(yes, I've already filed a formal "b-word" report to the correct department)

**Tyrone W. Lee** · 13 May 2001, 06:59 AM

When passing strings to PB I use something like this:

DECLARE ReadObject Lib "DATABASE.DLL" (ByVal Rec%, ByVal file$, vbObject AS ObjDataType)

On the PB side I use

Sub ReadObject(ByVal Rec%, File As ASCIIZ, vbObject as ObjDataType)

blah blah..
End Sub

So I have a PB DLL of hundreds of re usable & veryu handy DOS, MATH,
2D/3D point equations, gaming FUNCTION, and MAPPING.

The routines are very fast, isolated to the .DLL, and in theory totally
dependent of a UDT pass. Just as many of the Win API calls are dependent
on a UDT pass.

When operating on VB3, I could pass a UDT to the DLL, alter or update
values to the UDT and the VB side would be able to view it. This
function call doesn't require alot of stack space if the UDT is
small. And to tell you the truth, passing UDT's is the entire
strength of using DLL's without a UDT pass DLL's are useless.

Think about it, without being able to pass and recieve a UDT from a
DLL the only method of information transfer between these two
program states is BYTE, LONG, INTEGER, and STRING. Returning a sting
implies a possible UDT, but its still not quite as good.

Moving variables around in memory..
It is understood, that using a ByVal parameter will make a copy of
the item passed. Thus giving a new VARPTR location for the
parameter passed. But when using a UDT, I do NOT use a ByVal
declaration so I *EXPECT* the location to be identical to the
original UDT so The DLL can return/adjust any values within the
UDT.

A great Example. I have a great 3D polygon filling routine. The routine
allows me to take a simple POINTAPI Type foundation. And
use it to create a very powerful UDT for Line calculation.

Without a solid UDT pass, I would have to pass these small UDTs
as individual variables and *QUICKLY* reach the 16variable limit
of PB/VB- Thus, making this type of DLL impossible to create on a 32bit
platform.

Except for making more DLL subroutines.. I'll make a routine to
recieve/calculate the first 16 variables called Calc1 and the
other routine will calculate the second 16values. -Thats ridiculous.

I have a Pentium 1.5Ghz machine but can only make a program to pass
16 variables at a time.. haha - who writes this stuff?

*This alone is VERY VERY lame, and is clearly showing an unexcusable
limit to 32bit Windows development..

------------------
Explorations v3.0 RPG Development System
http://www.explore-rpg.com

**Lance Edmonds** · 13 May 2001, 07:19 AM

Maybe I'm overlooking something here, but if since you are passing the UDT structure BYREF, you are actually passing a pointer to the UDT storage. PB can access the UDT memory, regardless of where it happens to be stored with each instance of the DLL call.

So, I have to ask: Why are you concerned with the location changing each time? (Remember, it is VB doing this to you, not PowerBASIC!).

I'm sure R&D could make PB handle more than 16-parameters, but they chose that particular limit for a reason (probably a performance issue). Actually, passing large numbers of parameters adds overhead to the application (stack frame set up time, etc), so if you are after performance (which your comments on a "moving" UDT suggest), then using large numbers of sub/function parameters is slightly counter-productive.

In summary, the issue here is primarily VB. VB has to jump through a few hoops to pass some types of data to a DLL (it is 'documented' VB behavior). I'm afraid I just don't understand why you are so concerned.

------------------
Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

**Tyrone W. Lee** · 13 May 2001, 08:25 AM

Lance,

This thread has two conversation going on at the same time, and you just
managed to blend them.. hehe

Originally, VB3/PB2.0 - Could pass a UDT ByRef to PowerBasic and the
DLL could edit it throughout the programs entire execution.
I only had to pass the parameter once and the two programs. (VB/PB DLL)
were actually using the same variable.

I need to convert to 32bit because Win2000 is not accepting 16bit
code very well.

So It requires me to pass the parameters for every .DLL call. This
caused my list of parameter to pass to grow considerably. So I
have to make sure I am under 16 parameters PLUS/on the VB side if I
call a DLL routine and pass a UDT it gives a bogus error. The Microsoft
article above documents this error.

BUT CHECK THIS!

I think its a *count* within VB to determine how many times you
call a DLL within your code. If the count is >10 : bogus error and
crash.

My original though was brought about by Microsofts suggested solution
to bypass this error. They suggest you pass the UDT to a KERNEL.DLL
function.. Well if the system is going to crash on a DLL pass, it should
crash on *ANY* DLL crash unless its something intentional..!??!

And to test this little idea, I made a redirection routine..

I call this function 62 times in my code and I recieve that bogus
error.

Call GetPlayer(idx%, PlayerType)

So I wrote a simple VB routine called..

Sub vbGetPlayer(idx, PT as PlayerType)
GetPlayer idx%, PT
End Sub

And I global search and replaced the original calls with a call to
my new vbGetPlayer to redirect the number of calls to the .DLL ....And GUESS WHAT?!?! It works.. Not one error..

Seems like MS is counting the number of times you call a DLL
routine..and specifically the number of times you call *non-system*
DLL's..

Something smells a little fishy in here.. Anyone wann shed light on
why a compiler would want to monitor the # of calls to a function
in a DLL.. From my experience with compiler design- who cares
how many times u call a function in a DLL?

------------------
Explorations v3.0 RPG Development System
http://www.explore-rpg.com

**Bern Ertl** · 14 May 2001, 08:51 AM

Tyrone,

It sounds like what you are really after is making your UDTs GLOBAL
to the VB app & PB DLL. Perhaps you can use an API call to
allocate a memory block, store all your UDT(s?) info in the memory block
in a predefined order and just pass the address of the memory block
to the DLL subs/Fns.

------------------
Bernard Ertl

**Tyrone W. Lee** · 15 May 2001, 05:59 AM

All of my UDT's are GLOBAL.. Which is why the VB error was bogus.
The fix that I came posted works and my application is running..

Though its not faster than my 16bit version.. A guess I have a new
question..

------------------
Explorations v3.0 RPG Development System
http://www.explore-rpg.com

**Knuth Konrad** · 16 May 2001, 01:09 AM

Originally posted by Tom Hanlin:
CALL became "dated" when DECLARE came around. It's not just unnecessary,
like LET. Using CALL may turn off the error-checking that is normally
afforded you by using DECLARE. I'm not sure about how VB6 in particular
handles that, so it may not be an issue in this particular case.

Are you really sure that CALL became dated? I guess you need to revise your opinion after looking at
http://msdn.microsoft.com/vbasic/tec...de/calling.asp

CALL will be *required* in the upcoming VB.NET when calling a procedure (SUB) that you pass at least one parameter...

Knuth

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http://www.softAware.de

**Tom Hanlin** · 16 May 2001, 09:22 AM

Knuth, I think you misread that. To the best of my knowledge, it's parentheses that
the vb.net beta requires, not CALL:

Code:

   CALL MySub (Parameter)  ' oldest calling method (still available)
   MySub Parameter         ' current BASIC practice
   MySub (Parameter)       ' vb.net beta required calling method

I consider CALL obsolete because it has been superfluous for, oh, let's see... maybe
15 years? But the main consideration here is that using CALL tells some BASICs
to turn off the parameter checking that they'd otherwise supply. There is no good
reason to use CALL (unless you're using CALL DWORD), and adequate reason to avoid it.

------------------
Tom Hanlin
PowerBASIC Staff

Announcement

Passing Parameters..

Passing Parameters..

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