How can I call CERNLIB routines from C?

General

Furthermore, a tool exists (cfortran) to use headerfiles in the C code with the definition of the FORTRAN routines. Then the call of the FORTRAN routine is very easy and all parameters can be handled without special tricks. Especially the calling sequence is independent from the compiler and operating system! Additionally, a tool exists to create such header files (f2h), which is available in the standard CERN program directory. The complete documentation is in cfortran.doc.

Interface to CERN Library routines

/cern/pro/include/cfortran

asisftp.cern.ch:/cernlib/share/pro/include

To call a (FORTRAN) CERN library routine from C, you have to do the following steps:

1. Include in you C files the following header files:

   #include "cfortran.h"
   #include "hbook.h"   /* if you use hbook routines e.g. */
   

2. Call the fortran routine with "FORTRAN" style parameters (call by value), routine name in capitals:

   main(){
          real xmin,xmax;
          integer ncha;
          HLIMIT(1000);
          .
          .
          HBOOK1(100,"test spectrum",ncha,xmin,xmax,0);
          .
          .
   }  
   

3. Compile using the following flags:
   1. HP:

      cc -c -Dextname -Ae -I/cern/pro/include/cfortran cfilename.c
      fort77 +ppu -c ffilename.f
      fort77 +ppu cfilename.o ffilename.o `cernlib packlib ...` ... -o outfilename
      

   2. LINUX:

      gcc -c -Df2cFortran -I/cern/pro/include/cfortran cfilename.c
      g77 -c ffilename.f
      g77 cfilename.o ffilename.o `cernlib packlib ...` ... -o outfilename
      

   3. AIX:

      xlc -c -Dextname -I/cern/pro/include/cfortran cfilename.c
      xlf -qextname -c ffilename.f
      xlf -qextname cfilename.o ffilename.o `cernlib packlib ...` ... -o outfilename
      

   4. DIGITAL UNIX/ OSF

      cc -c -Dextname -I/cern/pro/include/cfortran cfilename.c
      f77  -c ffilename.f
      f77 -nofor_main cfilename.o ffilename.o `cernlib packlib ...` ... -o outfilename
      

   5. SUN/ Solaris

      cc -c -I/cern/pro/include/cfortran cfilename.c
      f77  -c ffilename.f
      f77 cfilename.o ffilename.o `cernlib packlib ...` ... -o outfilename
      

   6. VMS:

      cc /INCLUDE=CERN_ROOT:[INCLUDE] cfilename.c
      fortran ffilename.FOR
      link/exe=outfilename cfilename,ffilename, ...
      

Example

• chbook-example.c , using basic HBOOK routines
• hbook-ntuple.c using (row-wise) Ntuples in HBOOK
• minuit-main.c and minuit-fcn.c show the usage of minuit from C.

They have been compiled, linked and run with the following commands (using the first code example)

1. HP:

   cc -c -Dextname -Ae -I/cern/pro/include/cfortran chbook-example.c
   fort77 +ppu chbook-example.o `cernlib packlib,mathlib` -o chbook-example
   ./chbook-example
   
   

2. LINUX:

   gcc -c -Df2cFortran -I/cern/pro/include/cfortran chbook-example.c
   g77 chbook-example.o `cernlib packlib,mathlib` -o chbook-example
   ./chbook-example
   
   

3. AIX:

   xlc -c -Dextname -I/cern/pro/include/cfortran chbook-example.c
   xlf -qextname chbook-example.o `cernlib packlib,mathlib` -o chbook-example
   ./chbook-example
   
   

4. DIGITAL UNIX /(former) OSF:

   cc -c -Dextname -I/cern/pro/include/cfortran chbook-example.c
   f77 -nofor_main chbook-example.o `cernlib packlib,mathlib` -o chbook-example
   ./chbook-example
   
   

5. VMS:

   cc /INCLUDE=CERN_ROOT:[INC] chbook-example.c
   link/exe=CHBOOK-EXAMPLE CHBOOK-EXAMPLE.obj,cern_root:[lib]packlib/lib,mathlib/lib,kernlib/lib
   RUN CHBOOK-EXAMPLE
   
   

If you prefer to use the gnu C compiler gcc, you could link using gcc and adding the FORTRAN specific libraries after the CERN libraries. The names of these libraries are different on all systems:

1. HP:

   -lcl -lisamstub
   Example: gcc chbook-example.o `cernlib packlib,mathlib` -lcl -lisamstub -o chbook-example