Saturday, September 28, 2013

Windows DLLs with Harbour code

There are a lot of infomation that can be gleaned if one chose to go through the \doc folder of any official harbour installation. In this post, I have chosen to re-publish the following:-

Windows DLLs with Harbour code

Programs created with Clipper or Harbour are traditionally a
monolithic EXE containing all executable code.  This includes
the Virtual Machine (VM) and the RunTime Library (RTL) as well as
your own code.  Running under Windows with Harbour, you
can now also create and use Windows DLLs that contain PRG code.

Harbour supports Windows DLLs in 3 ways.

  1) Self-contained DLLs containing functions from any platform.
     (These are not what we call a "harbour.dll", although they may
     be named that. The DLL entry points are different.)
     These have the VM/RTL inside them and can be used by any other
     Windows program. You can create a .lib for static linking,
     or use GetProcAddress as in any standard Windows DLL.
     Calling Harbour/Prg functions directly is limited to
     those that take no parameters unless you include C functions
     in the DLL that take parameters and then call the PRG-level

     To do static linking, do this to create the .lib:
        implib harbour.lib harbour.dll
     For the Borland C platform, use that library and import32.lib
     and cw32.lib from Borland, and you are ready to go.

  2) PCode EXEs using a Harbour.dll

     A Harbour.dll is designed to be called from a Harbour app.
     A pcode EXE is a small Harbour executable that does not contain the
     VM/RTL. To execute its functions, it must load and access a
     If you want dynamic linking, then use this to execute a Harbour
     dynamically loaded pcode DLL function or procedure:
        HB_DllDo( [,] ) --> []

     This lets you have all your common code in a DLL, and have lots
     of small EXEs that use it.  Realize however that, even though this
     may be a nice way to manage your code, each EXE may
     load its own image of the Harbour.dll into memory at runtime.
     In terms of Windows memory, there may not be a benefit to using pcode
     EXEs over monolithic EXEs. But it may be a worthwhile maintenance
     benefit to have lots of replaceable small exes.

  3) PCode DLLs used from traditional EXEs
     A pcode DLL does not contain the VM/RTL.
     It is a library of Harbour-compiled PRG code that uses the VM/RTL
     of the EXE that calls it.  This has the benefit of having
     replaceable modules in DLLs that don't necessarily require updating
     your EXE.

The following is clipped from a msg by Antonio Linares to the Harbour
developer list explaining some of the details:

Please notice that there are three different Windows DLL entry points:
   + src/vm/
   * maindll.c     Windows self-contained DLL entry point
   * maindllh.c    Windows Harbour DLL entry point  (harbour.dll)
   * maindllp.c    Windows pcode DLL entry point and VM/RTL routing functions

   >    * maindll.c     Windows self-contained DLL entry point
   To produce Harbour code, as DLLs, that may be used
   from other programming languages applications (as VB,
   Delphi, C++, etc...)

   >    * maindllh.c    Windows Harbour DLL entry point  (harbour.dll)
   To produce Harbour.dll, to be just used from small pcode Harbour EXEs

   >    * maindllp.c    Windows pcode DLL entry point and VM/RTL routing
   To produce small pcode DLLs, to be used just from Harbour EXE apps.
   maindllp.c is the entry point for the Harbour pcode DLLs. pcode DLLs
   are quite small DLLs, that just contain pcode and/or C (using extend
   api) functions.

   mainwin.c is the entry point for Windows EXEs, not for DLLs.

   You may use maindll.c, maindllh.c or maindllp.c based on
   your needs.

   If you are looking to build a Harbour.dll, then you must use

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Welcome to Clipper... Clipper... Clipper

In 1997, then using Delphi 3, I had already created 32-bits Windows applications for HRIS, ERP and CRM. In 2007, using Ruby on Rails, an AJAX powered CRM site running on Apache & MySQL was created and I am now using Visual Studio .Net 2008 to create web-based projects and Delphi 7 for Win32 applications using SQL2005 & DBFCDX.

So, why then am I reviving the Original Clipper... Clipper... Clipper via a Blog as CA-Clipper is a programming language for the DOS world ? Believe it or not, there are still some clients using my mission-critical CA-Clipper applications for DOS installed in the late 80's and up to the mid 90's. This is testimony to CA-Clipper's robustness as a language :-)

With the widespread introduction of Windows 7 64-bits as the standard O/S for new Windows based PCs & Notebooks, CA-Clipper EXE simply will not work and it has become imperative for Clipper programmers to migrate immediately to Harbour to build 32/64 bits EXEs

Since 28th January 2009, this blog has been read by 134,389 (10/3/11 - 39,277) unique visitors (of which 45,151 (10/3/11 - 13,929) are returning visitors) from 103 countries and 1,574 cities & towns in Europe (37; 764 cities), North America (3; 373 cities) , Central America & Caribeans (6; 13 cities), South America(10; 226 cities), Africa & Middle-East (12; 44 cities) , Asia-Pacific (21; 175 cities). So, obviously Clipper is Alive & Well : -)

TIA & Enjoy ! (10th October 2012, 11:05; 13th November 2015)

Original Welcome Page for Clipper... Clipper... Clipper

This is the original Welcome Page for Clipper... Clipper... Clipper, which I am republishing for historical and sentimental reasons. The only changes that I have made was to fix all the broken links. BTW, the counter from is still working :-)

Welcome to Chee Chong Hwa's Malaysian WWW web site which is dedicated to Clipperheads throughout the world.

This site started out as a teeny-weeny section of Who the heck is Chee Chong Hwa ? and has graduated into a full blown web site of more than 140 pages (actually hundreds of A4 size pages) ! This is due to its growing popularity and tremendous encouragements from visiting Clipperheads from 100 countries worldwide, from North America, Central America, Caribbean, South America, Europe, Middle-East, Africa and Asia-Pacific. Thanx Clipperheads, you all made this happen !

What is Clipper ?

You may ask, what is this Clipper stuff ? Could Clipper be something to do with sailing as it is the name of a very fast sailing American ship in the 19th century ?

Well, Clipper or to be precise, CA-Clipper is the premier PC-Software development tool for DOS. It was first developed by Nantucket Corporation initially as a compiler for dBase3+ programs. Since then, CA-Clipper has evolved away from its x-base roots with the introduction of lexical scoping & pre-defined objects like TBrowse. As at today, the most stable version ofClipper is 5.2e while the latest version, 5.3a was introduced on 21 May 1996.

As at 11th November, 1996, an unofficial 5.3a fixes file was made available by Jo French. See the About CA-Clipper 5.3a section for more details. BTW, Jo French uploaded the revised 5.3a fixes file on 20th November, 1996.

Latest News

The latest news is that CA has finally released the long-awaited 5.3b patch on 21 May, 1997.

For 5.3b users, you must a take a look at Jo French's comments on unfixed bugs in 5.3b.

BTW, have you used Click ? If you're a serious Clipperprogrammer and need an excellent code formatter, Click is a natural choice. How to get it ? Simple, access Phil Barnett's site via my Cool Clipper Sites.

32-bits Clipper for Windows ?

Have you tried Xbase ++ ? Well, I have and compared to Delphi (my current Windows programming tool of choice), I'm still sticking to Delphi.

Anyway, you should visit the Alaska Home Page. Give it a chance and then draw your own conclusions !.

The Harbour Project

Is this the future of Xbase ? Take a look at at the Harbour Project

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