PowerBasic vs C++

[Tyrone W. Lee]

This website has various benchmark tests and articles that claim or express that
PowerBasic compilers faster code than C.. Or- something to that
effect..

Well I created this simple routine that will randomly fill an array with colors
When the array is filled the program will send the array to a PictureBox
in VB. The dissapointing part about this routine is that it is incredibly
slow. If i wrote this routine in C, I think I would get better results..

Can someone explain to me, why? Or maybe give me some incite on what
commands optimize during execution... I can't understand why the
performance is so slow? This is a 16bit DLL compiler, would 32bit improve this?

$HUGE
$COMPILE DLL
$INCLUDE "C:\DEVEL\EV3\DLL\WINAPI.INC"

Sub RandomizeBMP (ByVal hDC%, ByVal bWidth%, ByVal bHeight%) EXPORT
Dim x%, y%, color As WORD, acnt As DWORD, ok As DWORD
Dim TOTALBYTES As DWORD

TOTALBYTES = bWidth% * bHeight%
ReDim bmpdata(TOTALBYTES) as WORD

acnt = 0
For y% = 0 to bHeight%-1
color = int(65000 * rnd(1))+1
For x%= 0 to bWidth%-1
bmpdata(acnt) = color
incr acnt
Next x%
Next y%

ok = SetBitmapBits(hDC%, TOTALBYTES*2, bmpdata(0))
End Sub


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

[Tom Hanlin]

The only parts of that code liable to be slow in any respect are the RND
function and the call to SetBitmapBits. At that, the RND function uses a
well-optimized proprietary design that is faster than most.

It may be that you need to adjust your expectations. The code shown
should be reasonably efficient. "Slow", well... that depends on what
you want out of it. It is almost always possible to speed things up.
In order to find out which parts would benefit most from optimization,
you'll need to do more detailed investigation.

Sure, C can do some things faster than PowerBASIC and, of course, vice
versa. I doubt the choice of language would make any real difference for
code of this nature. At any rate, this is a PowerBASIC forum, and not a
place to start a language flame war.

Would a 32-bit compiler improve the speed? I'd guess it wouldn't make
much difference in this case. Maybe, as a 32-bit environment is better
designed for handling large amounts of data: no segmentation to fiddle
with. Of course, much better graphics APIs are available under 32-bit
Windows, and there are other advantages.

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

[Borje Hagsten]

PowerBasic is BASIC, with additional power. C++ stands for extended
Chinese, for most of us, thus the need for PB. For best possible
speed, use assembler and 32-bit environment. I doubt C++ would be
much faster here.

In this case, VB's PictureBox may be slowing down things quite a bit.
Have you set AutoRedraw to False? Maybe using a STATIC control (Label),
or BitBlt to a Form directly will give better results? What happens if
you remove the SetBitmapBits -part and just run the code by itself?

(forget it - just read the other thread..)
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[This message has been edited by Borje Hagsten (edited March 05, 2001).]

[Peter Manders]

Tyrone,

I don't see why this would have to be slower than C++.

Some ideas:

RND(a, b) may be faster (haven't tested).

Try using a pointer to the first array element and increment it, instead of accessing the array every time.

You don't have to redim if TOTALBYTES didn't change.

Use LONGs where possible.

Use an inline random function.


Peter.


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[email protected]

[Tyrone W. Lee]

No flame war here...

I don't like C/C++ (I used to love it.) But since I found PB, I've turned
my back on C all together. he he .. So don't worry guys, I'm 100%
loyal to PB.

My intent with this project is to improve my gaming project. Right now
its written in VB and WinAPI with PowerBASIC optimized routines. I wanted
to pull away from WinAPI and write a PowerBasic HIGH SPEED Graphic routine..

*I didn't want the baggage of DirectX*

I'm very good at modular code, but optimization sometimes depends on
the compiler. So, thats why I posted. I just expected more speed starting
out. (All the code is run on a AMD380Mhz) -

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

[Barry Erick]

A few months ago, vbpj had a article on use c++ to make your VB
programs fly. It had the original vb code and the c++ code for
the check. I stuck the vb code in PBDLL and ran the test with
c++ and pbDll libs in the vb program. The c++ matched the article
speed, the vb matched the article speed, and PBDLL ran faster than
the c++ code by a few points. Then I optimized the code with
PB built in stuff, and it ran almost twice as fast as the c++ code
.
--Barry


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[Tyrone W. Lee]

I understand what you are saying.. but I can't find what documentation
explains what these optimize PB features are and how to implement
them.

Saying that PB has certain features that run better than C++
does explain what they are.. Could you give a blind developer a
little direction?


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

[Tom Hanlin]

I think it's more a matter of being familiar with the tools you use. However, one
of the conveniences of PowerBASIC is all of the built-in functionality. While
some similar functions may be available in C or C++ runtime libraries, the C
versions are likely to be coded in C, whereas the PowerBASIC runtimes are crafted
directly in assembly language by a master programmer. To the extent you can use
built-in PowerBASIC statements, you'll not only be able to code faster, you will
often have faster code.


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

[Tony Altwies]

An important thing to remember is that the C++ compiler is
highly optimized. It has removed the boundary calculations
"bHeight%-1" and "bWidth%-1" from inside the For Loop.
Furthermore, the y% and x% variables are more than
likely assigned to Assembly registers.

For y% = 0 to bHeight%-1
color = int(65000 * rnd(1))+1
For x%= 0 to bWidth%-1
bmpdata(acnt) = color
incr acnt
Next x%
Next y%

I remember once (long ago) when an unnamed programmer created
a For loop using an un-optimized C compiler that looked like:

For (i=0; i < strlen(MyString); i++)
{
.
<code>
<code>
.
}

He wanted to know why the processing loop got exponentially slower
and slower as MyString grew in size. Once the proper correction
was made, loop performance shot up by over a factor of 10.

Even with optimized compilers, I still do common sense manual
optimizations when I code.

I'm sure there are other reasons but these are just a couple
of examples.

-Tony




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[Tom Hanlin]

PowerBASIC does these things too, of course...

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Tom Hanlin
PowerBASIC Staff

[Steve Hutchesson]

Its been by experience that optimising compilers may fix some of
the problems with bad code but they will never make really fast
good code.

Hand optimised assembler has the performance edge over machine
optimised code and when a compiler is built in this manner, its
speed averages are generally better.

Runtime library comparisons fail in benchmark testing because of
the enormous variation between routines but loop optimisation is
another matter, hand optimised loops run with the minimum overhead
and the maximum performance.

Regards,

[email protected]

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[Michael Mattias]

It's not the (surprise!) source language, it's the compiler.

MCM