Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17


Converting C header file statements to Delphi

Posted on 2004-04-27
Medium Priority
Last Modified: 2012-11-10
I need help converting two statements from a C header file to their Delphi equivalents.  The first one is the extern const statement below.  I'm not sure if this should be defined as a pointer or what.

The second statement is the typedef that I've attempted to convert...I just wanted someone to check it and let me know if it is correct.


/* Memory function tables */
extern const BioAPI_MEMORY_FUNCS BioAPIMemoryFuncs;

2. Original C statement...

 typedef void * (BioAPI *BioAPI_MALLOC) ( uint32 Size,
                                                              void * Allocref,
                                                              const char * File,
                                                              uint32 Line);

My converted Delphi equivalent.....

    BioApi_Malloc = procedure( Size: Cardinal;
                                             Allocref: Pointer;
                                             Const _File: Char;
                                             Line: Cardinal);

Question by:rwcochran
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 3
  • 2
  • 2
  • +1
LVL 26

Accepted Solution

Russell Libby earned 200 total points
ID: 10930845

The typedef for  _File should be PChar. It would also help to see what BioAPIMemoryFuncs is actually declared as, before making a judgement on the data type definition

LVL 26

Expert Comment

by:Russell Libby
ID: 10930869

This also returns a void (generic) pointer, so it is not a procedure

    BioApi_Malloc = function(Size: Cardinal;
                                        Allocref: Pointer;
                                        Const _File: PChar;
                                        Line: Cardinal): Pointer;

LVL 11

Expert Comment

ID: 10930950
    BioApi_Malloc = function(Size: Cardinal;
                                        Allocref: Pointer;
                                        Const _File: PChar;
                                        Line: Cardinal): Pointer; stdcall;

To guess at the calling convention.

The other declaration is a global variable which is not easily accessible in Delphi.
What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.


Author Comment

ID: 10932816
Thanks for the help guys.  I found the BioAPIMemoryFuncs definition in another source file (see below) would this be converted to Delphi?

Thanks again....

/* Memory function tables */
const BioAPI_MEMORY_FUNCS BioAPIMemoryFuncs =
LVL 26

Expert Comment

by:Russell Libby
ID: 10933028

Here is the delphi translation based on C source I found on the Net. Appears uou might have a newer definition, as the malloc function takes more parameters than the version I looked at. Also, are YOU are supposed to implement the memory functions on your side of this?? Hard to tell without seeing the full source, so I declared _BioPAPI_XXXX calls as variable types.

  TBioAPI_MALLOC       =  function(Size: Cardinal; Allocref: Pointer): Pointer; stdcall;
  TBioAPI_FREE         =  procedure(MemBlock: Pointer; Allocref: Pointer); stdcall;
  TBioAPI_REALLOC      =  function(Memblock: Pointer; Size: Cardinal; Allocref: Pointer): Pointer; stdcall;
  TBioAPI_CALLOC       =  function(Num: Cardinal; Size: Cardinal; AllocRef: Pointer): Pointer; stdcall;

  TBioAPI_MEMORY_FUNCS =  packed record
     Malloc_func:      TBioAPI_MALLOC;
     Free_func:        TBioAPI_FREE;
     Realloc_func:     TBioAPI_REALLOC;
     Calloc_func:      TBioAPI_CALLOC;
     AllocRef:         Pointer;

  _BioAPI_malloc:      TBioAPI_MALLOC; // These obviously need to be set
  _BioAPI_free:        TBioAPI_FREE;
  _BioAPI_realloc:     TBioAPI_REALLOC;
  _BioAPI_calloc:      TBioAPI_CALLOC;





Author Comment

ID: 10933397
Very helpful....thanks.  As far as whether I have to implement the memory functions on my side or not, at this point I'm not sure.  

I'm just slowing working through the basic BioApi functions.... I'm trying to get to the point where I can talk to the fingerprint reader.  I ran into the BioAPIMemoryFuncs reference when working on the following function:

      bioReturn := BioAPI_ModuleAttach(uuid, bioVersion, BioAPIMemoryFuncs, 0,
                                  0, 0, 0, NULL, 0, NULL, &hModule);

I've already implemented the following BioApi functions and they seem to work fine.
  bioReturn := BioAPI_Init( bioVersion, 0, nil, 0, nil );
  bioReturn := BioAPI_ModuleLoad( uuid, 0, nil, nil);

The next BioApi function I'll be woking on is:
    bioReturn = BioAPI_SetGUICallbacks(hModule,
                                       NULL, NULL,
                                       state_callback, &callbac_ctx);

I really appreciate all the help.

Expert Comment

ID: 38473456
hi rllibby,
"Here is the delphi translation based on C source I found on the Net"
i need translations of other files.. if you see them i wil be Thankfull.

Expert Comment

ID: 38587869
hi rllibby and  rwcochran ,

rllibby :"Here is the delphi translation based on C source I found on the Net"
i need translations of other files.. if you see them i wil be Thankfull.

rwcochran , can you help to me  same problem as you already solved?

Featured Post

Concerto Cloud for Software Providers & ISVs

Can Concerto Cloud Services help you focus on evolving your application offerings, while delivering the best cloud experience to your customers? From DevOps to revenue models and customer support, the answer is yes!

Learn how Concerto can help you.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This article explains how to create forms/units independent of other forms/units object names in a delphi project. Have you ever created a form for user input in a Delphi project and then had the need to have that same form in a other Delphi proj…
Creating an auto free TStringList The TStringList is a basic and frequently used object in Delphi. On many occasions, you may want to create a temporary list, process some items in the list and be done with the list. In such cases, you have to…
Sometimes it takes a new vantage point, apart from our everyday security practices, to truly see our Active Directory (AD) vulnerabilities. We get used to implementing the same techniques and checking the same areas for a breach. This pattern can re…
In this video, Percona Solution Engineer Dimitri Vanoverbeke discusses why you want to use at least three nodes in a database cluster. To discuss how Percona Consulting can help with your design and architecture needs for your database and infras…
Suggested Courses

722 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question