Re: RE: RE: [Help-glpk] VBA/dll for Excel

[glpk xypron]

Hello Marc,

there are indeed compiler settings controlling byte alignment. This is 
described for Visual C++ in the following article:
http://msdn2.microsoft.com/en-us/library/83ythb65(VS.80).aspx

Best regards

Xypron

-------- Original-Nachricht --------
> Datum: Sun, 6 Apr 2008 12:36:20 -0400
> Von: "Meketon, Marc" <address@hidden>
> An: "glpk xypron" <address@hidden>, address@hidden
> Betreff: RE: RE: [Help-glpk] VBA/dll for Excel

> Xypron:
> 
> Thank you for the work that you did on this.  I ran out of time to test
> it a few weeks ago, but was able to do so this weekend (it's amazing how
> much time your have when flying from Melbourne, Australia to Newark, New
> Jersey via Kuala Lumpur and Stockholm!)
> 
> So far, I've managed to get it working.  But there are two tricky
> points, one of them might just be a compilation setting.  I thought
> sharing these points might help others trying to use GLPK from VBA.
> 
> (1) To control the simplex there is a control parameter structure called
> smcp.  Similarly for controlling the integer programming routine there
> is a control parameter called iocp.  Focusing on iocp, you can almost
> duplicate this structure in VBA by using a "type" statement (I left off
> the last few lines):
> 
> Type GLPK_INTOPT_PARM
>     msg_lev     As Long    'message level
>     br_tech     As Long    'branching technique
>     bt_tech     As Long    'backtracking technique
>     filler1     As Long    '==>for data alignment
>     tol_int     As Double  'tol_int
>     tol_obj     As Double  '
>     tm_lim      As Long
>     out_frq     As Long
>     out_dly     As Long
>     cb_func     As Long    'really the address of a callback function
>     cp_info     As Long    'really the address of an information
> structure
>     cb_size     As Long
>     pp_tech     As Long
>     filler2     As Long    '==>for data alignment
>     mip_gap     As Double  'data alignment problems
>     mir_cuts    As Long
>     gmi_cuts    As Long
>     foo_bar00   As Double
>     ...
> End Type
> 
> Notice that there are two fields called "filler1" and "filler2".  I
> needed to force tol_int and mip_gap to be on an 8-byte boundary.  I
> wonder if there is a compiler setting to have the elements in a "struct"
> be aligned on 4-byte boundaries instead of forcing doubles to be aligned
> on 8-byte boundaries?
> 
> Or perhaps in a later release these structures could be reorganized to
> have the doubles come first to ease the interoperability with other
> languages.
> 
> (2) The other thing to note is that for some reason, VBA does not allow
> the second statement below:
> 
>     Dim iocp as GLPK_INTOPT_PARM
>     iocp.cb_func = AddressOf MyCallBackFunction  '==>Fails in
> compilation
> 
> And the workaround is to set it via a subroutine:
> 
>     Public sub setCBFunc(iocp as GLPK_INTOPT_PARM, addressOfCBFunc as
> long)
>         iocp.cb_func = addressOfCBFunc
>     End sub
> 
> And then use
>     setCBFunc iocp, AddressOf MyCallBackFunction
> 
> instead of the assignment statement.
> 
> -Marc
> 
> -----Original Message-----
> From: glpk xypron [mailto:address@hidden 
> Sent: Tuesday, March 18, 2008 11:03 PM
> To: Meketon, Marc; address@hidden
> Subject: Re: RE: [Help-glpk] VBA/dll for Excel
> 
> Hello Marc,
> 
> The following module correctly shows a collected message until GLPK
> aborts the program due to the nonexistent column, using the library in
> ftp://glpk.dyndns.org/glpk/glpk_4_27.dll.stdcall.zip
> (see my prior mail).
> 
> Attribute VB_Name = "TestGLPK"
> Option Explicit
> 
> Public Declare Function glp_create_prob Lib "c:\temp\glpk\glpk_4_27.dll"
> () As Long
> Public Declare Sub glp_set_prob_name Lib "c:\temp\glpk\glpk_4_27.dll"
> (ByVal lp As Long, ByVal name As String)
> Public Declare Sub glp_delete_prob Lib "c:\temp\glpk\glpk_4_27.dll"
> (ByVal lp As Long)
> Public Declare Function glp_get_prob_name Lib
> "c:\temp\glpk\glpk_4_27.dll" (ByVal lp As Long) As Long
> Public Declare Sub glp_term_hook Lib "c:\temp\glpk\glpk_4_27.dll" (ByVal
> func As Long, info As Long)
> Public Declare Sub glp_set_col_name Lib "c:\temp\glpk\glpk_4_27.dll"
> (ByVal lp As Long, ByVal j As Long, ByVal name As String)
> Private Declare Function SysAllocStringByteLen Lib "oleaut32" (ByVal
> pwsz As Long, ByVal length As Long) As String
> 
> Public Function MessageHandler(ByVal info As Long, ByVal msg As Long) As
> Long
>   Static collect
>   Dim mess As String
>   mess = SysAllocStringByteLen(msg, 1024)
>   mess = Left$(mess, InStr(mess, Chr$(0)) - 1)
>   collect = collect & mess
>   MsgBox collect
>   MessageHandler = 0
> End Function
> 
> 
> Sub test()
>   Dim i    As Long
>   Dim l    As Long
>   Dim lp   As Long
>   Dim info As Long
>   Dim name As String
>   
>   lp = glp_create_prob()
>   Call glp_term_hook(AddressOf MessageHandler, info)
>   name = "MyProblem"
>   Call glp_set_prob_name(lp, name)
>   name = "nonsense"
>   Call glp_set_col_name(lp, 100, name)
>   name = ""
>   l = glp_get_prob_name(lp)
>   name = SysAllocStringByteLen(l, 512)
>   Call glp_delete_prob(lp)
> End Sub
> 
> 
> -------- Original-Nachricht --------
> > Datum: Tue, 18 Mar 2008 12:49:35 -0400
> > CC: "Xypron" <address@hidden>
> > Betreff: RE: [Help-glpk] VBA/dll for Excel
> 
> > Thanks.
> > 
> > I produced a DLL as well by adding __stdcall __export to the right
> > function calls.  [BTW, I'm using the free Turbo C++ compiler from
> > Borland.]
> > 
> > BUT, I cannot seem to get the callback function for "glp_term_hook" to
> > properly work.  Before I begin to setup the problem, I use very
> similar
> > VBA code to what the Version 10 of the Informatiks software uses:
> > 
> >   Const MAXMSG as long = 500
> >   Private ActMsg as long
> > 
> >   Private Messages(MAXMSG) as string
> > 
> >   Public sub INIT_GLPK()
> >     Dim info as long
> > 
> >     info = 0
> >     glp_term_hook AddressOf MessageHandler, info
> >     ActMsg = 0
> >   end sub
> > 
> > and
> > 
> >   public function MessageHandler(ByVal info As Long, ByVal msg As
> Long)
> > As Long
> >     Dim l As Long
> >     Dim Err_Message As String
> > 
> >     On Error Resume Next
> > 
> >     If ActMsg < MAXMSG Then
> >         ActMsg = ActMsg + 1
> >     End If
> >     l = lstrlen(msg)
> >     Err_Message = Space$(l + 1)
> >     lstrcpy Err_Message, msg
> >     Err_Message = Left(Err_Message, l)
> >     Messages(ActMsg) = Err_Message
> > 
> >     MessageHandler = 1
> >   End Function
> > 
> > However, when the "xputs" function in GLPK tries to return, the code
> > bombs.  The "xputs" does call the "MessageHandler", and it seems to
> pass
> > in the correct string, and xputs does see the correct return.  I
> believe
> > that somehow the stack gets messed up a bit, but I haven't figured out
> > any workaround.
> > 
> > Any ideas on how to successfully invoke the call-back function for the
> > terminal hook?
> > 
> > -Marc
> > -----Original Message-----
> > From: Xypron [mailto:address@hidden 
> > Sent: Tuesday, March 18, 2008 10:53 AM
> > To: Meketon, Marc
> > Cc: address@hidden
> > Subject: Re: [Help-glpk] VBA/dll for Excel
> > 
> > Hello Marc,
> > 
> > couldn't You use the DLL produced by
> > w32/Build_GLPK_with_VC6_MT_DLL.bat
> > with Visual C++ 7.0 or 6.0?
> > (see ftp://glpk.dyndns.org/glpk/glpk_4_27.dll.tar.gz)
> > 
> > Best regards
> > 
> > Xypron
> > 
> > Meketon, Marc wrote:
> > >
> > > A while back there was a version of GLPK for VBA applications (such
> as
> > 
> > > in Excel). That was based on version 10 of GLPK. Does anyone work
> with
> > 
> > > GLPK in VBA with a recent version of the software? If so, can you 
> > > please provide links? It appears that the original folks (Informatik
> 
> > > Fuchs) do have a version 23, but it's on a CD for 50 euros, and
> there 
> > > is no English page for it, so I'm not sure how possible it will be
> for
> > 
> > > me to get the CD.
> > >
> > > FYI, the German web page for the version 10 VBA implementation is: 
> > > http://www.informatikfuchs.de/Software/GLPK/glpkVBDownload.htm (and 
> > > there is a link for the English version of this web page on this
> > page).
> > >
> > > -Marc Meketon
> > >
> > >
> >
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> > >
> >
> ------------------------------------------------------------------------
> > >
> > > _______________________________________________
> > > Help-glpk mailing list
> > > address@hidden
> > > http://lists.gnu.org/mailman/listinfo/help-glpk
> > >   
> > 
> >
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