Re: [Tiny-cobol-users] options for subprogram linkages.

[John R. C. <jo...@we...>]

On Friday 29 December 2006 02:40, David Essex wrote:
> John R. Culleton wrote:
>  > I am converting a batch of programs from a Microfocus
>  > for Unix system to TinyCobol (Linux) and am having
>  > trouble with subprogram linkages.
>  > Here is the situation:
>  >
>  > In main program "general" I have calls to subprogram
>  > maps03 in the form:
>  > CALL "maps03" USING MAPS03-WS.
>  > ...
>  > The subprogram contains the line:
>  > ...
>  > PROCEDURE DIVISION USING MAPA03-WS.
>  > ...
>  > Let's assume static linkage (simpler?) and Legacy
>  > layout
>  >
>  > 1. What options should I have on the compile of maps03.cbl?
>  >
>  > 2. What options should I have on the compile of general.cbl?
>
> It really not difficult, once you understand some basics.
>
> First of all COBOL, unlike other languages such as C, does not have a
> default entry point. Meaning the first program (function) to be executed
> withing the binary.
>
> TC will try to determine which is a main-program, and which are
> sub-programs. It does so by using the 'STOP RUN', for main, and 'EXIT
> PROGRAM', for sub-programs.
> Once TC detects a main-program, it will automatically generate a entry
> point 'main', and the code to call the COBOL main-program.
>
> Since this method does not work 100% of the time, you can override this
> behaviour using the command line, or resourse file options. Then it will
> up to the programmer to define the entry point.
>
> Note that TC version 0.63, does not allow the use of '-' (dash) in a
> program name (PROGRAM-ID). This is due to a x86 assembler limitation.
>
> Finally, the type of COBOL CALL will determine which type of linkage used.
> If you use CALL 'literal', then compile time linkage is used.
> If you use CALL identifier, then run-time linkage is used. Meaning that
> the TC run-time library will try to find and load the library containing
> the sub-program.
>
> Note that run-time linkage works well on UN*X (ELF), but not so well on
> Win32 (PE-COFF).
>
>  > Currently when compiled general.cbl can't find subprogram
>  > maps03 which was compiled with the -a option.
>  > I also compiled it with the -c option.
>  > All are in the same directory.
>  > The assembler pass says:
>  >
>  > general.o(.text+0x3dc): In function `general':
>  > : undefined reference to `maps03'
>
> Actually that is a linker error.
>
> As per you example above, you could use the following:
>
> htcobol -c general.cbl
> htcobol -c maps03.cbl
> gcc -o what-ever general.o maps03.o -L ...
>
> Or if you have a library of routines, you could use the following:
>
> htcobol -c sub01.cbl
> ...
> htcobol -c subNN.cbl
> ar cr libsubs.a sub01.o ... subNN.o
> ranlib libsubs.a
>
> gcc -o what-ever general.o -L... -lsubs ...
>
>
> There are some examples in the 'test.code/t07' and 'test.code/t15'
> directories.
> Or if you would like some advanced examples see the 'test.code/t33' and
> 'cobrun/test.code' directories.
>
>
> Hope this helps.
>
>
>

Thanks much. My next question was going to be: "Which examples in test.code 
show linkages to subprograms?" But you answered it ahead of time.

The Tiny-Cobol manual remains unfinished, which is a pity. I'll substitute 
your message above for the missing piece. 
-- 
John Culleton
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