[fpc-pascal] I am offering a $100 reward for linking static libraries

Tony Whyman tony.whyman at mccallumwhyman.com
Tue Aug 23 10:34:00 CEST 2022

Once upon a time (late-1990s) I had some reasonable success (shareware) 
marketing a JPEG library for Delphi. This was a wrapper around the 
Independent JPEG Group's JPEG software which was written in 'C'. My JPEG 
library had thus to link to a 'C' library and both dynamic and static 
linking was offered. I too had the problem of too many C DLLs to link in.

The way it was solved for static libraries was to first link in the JPEG 
object files e.g.

{IDG JPEG objects modules to both compression and decompression}

{$L jdapimin.obj}
{$L jmemmgr.obj}
{$L jmemnobs.obj}
{$L jerror.obj}

{IDG JPEG modules for decompression}

{$L jdinput.obj}
{$L jdtrans.obj}

and then to identify the missing 'C' library functions (via linker 
errors). I then wrote Pascal equivalents (placed just before the $L 
statements. e.g.

{ Stubs for external C RTL functions referenced by JPEG OBJ files.}

function _malloc(size: Integer): Pointer; cdecl;
   GetMem(Result, size);

procedure _free(P: Pointer); cdecl;

procedure _memset(P: Pointer; B: Byte; count: Integer);cdecl;
   FillChar(P^, count, B);

procedure _memcpy(dest, source: Pointer; count: Integer);cdecl;
   Move(source^, dest^, count);

function __ftol: Integer;
   f: double;
     lea    eax, f             //  BC++ passes floats on the FPU stack
     fstp  qword ptr [eax]     //  Delphi passes floats on the CPU stack
   Result := Trunc(f);

As long as you can reduce the missing dependencies to a relatively small 
number, it should all work.


Tony Whyman


On 21/08/2022 18:34, Anthony Walter via fpc-pascal wrote:
> I will pay $100 to the first person that can solve my problem of 
> linking a compiled C static library to a Free Pascal program on Windows.
> Recently I have been building many C libraries with GCC on Linux and 
> linking them to Free Pascal. These include building C libraries such 
> as "libxmp" for decoding mod/tracker music into PCM audio samples, 
> "libchuimpmunk2d" for simulating 2D solid body physics, or "libsdl2" 
> for cross platform controller input and haptic feedback among other 
> things.
> So far on Linux I am happily able to use a cmake/make/gcc toolchain to 
> build these C libraries from source and easily statically link them to 
> my Free Pascal programs.
> Here is an example and abbreviated Pascal unit that links to a static 
> build of Chimpmunk 2D:
> unit Chimpmunk2D;
> interface
> type
>   cpSpace = Pointer;
> function cpSpaceNew: cpSpace; cdecl; external;
> procedure cpSpaceDestroy(space: cpSpace); cdecl; external;
> implementation
> {$ifdef linux}
>   {$linklib c}
>   {$linklib m}
>   {$linklib chipmunk-linux}
> {$endif}
> end.
> Where libchipmunk-linux.a is my static library build on Linux from the 
> Chipmunk2D C source code and is in the same folder as the source code 
> as "Chimpmunk2D.pas". This works fine on Linux.
> I am also able to use mingw32 gcc to compile this same C source into a 
> static library for Windows using these two commands while inside the 
> folder containing the Chipmunk2D sources:
> x86_64-w64-mingw32-gcc-win32 -static -static-libgcc -std=gnu99 
> -ffast-math src/*.c -Iinclude -c
> x86_64-w64-mingw32-ar rcs libchipmunk-win.a *.o
> rm *.o
> The problem then arises when I try to use {$linklib chipmunk-win}. No 
> matter how I try to arrange the static dependencies I cannot resolve 
> missing functions.
> Many attempts were made compiling against other mingw32 static 
> libraries for Windows.
> {$ifdef windows}
>   {$linklib mingw32}
>   {$linklib mingwex}
>   {$linklib kernel32}
>   {$linklib msvcrt}
>   {$linklib chipmunk-win}
> {$endif}
> I get many errors similar to these below:
> Verbose: Compiling resource 
> C:\Development\Projects\physics\lib\x86_64-win64\Physics.obj
> Verbose: Linking C:\Development\Pascal\Projects\physics\Physics.exe
> Physics.lpr(30,1) Error: Undefined symbol: ___chkstk_ms
> Physics.lpr(30,1) Error: Undefined symbol: __mingw_raise_matherr
> Physics.lpr(30,1) Error: Undefined symbol: __imp_WideCharToMultiByte
> Physics.lpr(30,1) Error: Undefined symbol: __imp_IsDBCSLeadByteEx
> Physics.lpr(30,1) Error: Undefined symbol: __imp_MultiByteToWideChar
> Physics.lpr(30,1) Verbose: There were 5 errors compiling module, stopping
> Verbose: Compilation aborted
> If I use mingw32-w64 on Linux to create a DLL instead, then m 
> problems on Windows go away.
> x86_64-w64-mingw32-gcc-win32 -static -shared -static-libgcc -std=gnu99 
> -ffast-math src/*.c -Iinclude -o libchipmunk-win.dll
> However, I am not satisfied with an ever growing list of DLLs (I am at 
> 6 currently) that must be deployed on Windows to build / run any 
> project using my Pascal toolkit. I thought I could resolve this static 
> linking problem on Windows at a later date, thus eliminating all the 
> DLLs required to run projects using my toolkit on Windows, but every 
> time I return to try another attempt I cannot resolve the external 
> dependencies of something like "libchipmunk-win.a".
> Therefore, if anyone has expertise in the area of linking static C 
> libraries and can provide an example of how to link just one 
> ("libchipmunk-win.a") on Windows either providing a different Windows 
> C compiling method (MSVC as opposed to x86_64-w64-mingw32-gcc-win32) 
> and the proper directives to correctly link a static library, I would 
> gladly pay that person $100.
> Additionally, I would write up a guide for other people if they have 
> trouble while attempting to do the same thing.
> If you have any tips or suggestions you can respond to this thread. If 
> you have a solution and want to collect the reward, reply to my email 
> address associated with this thread.
> For reference, here are links to Windows static and dynamic libraries 
> I;ve already built. Feel free to build new static libraries yourself, 
> but just be sure to provide the list of tools and arguments you used 
> if sending a solution.
> https://files.codebot.org/sysrpl/applications/libchipmunk-win.a
> https://files.codebot.org/sysrpl/applications/libchipmunk-win.dll
> _______________________________________________
> fpc-pascal maillist  -fpc-pascal at lists.freepascal.org
> https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
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