= Fortran Support in ZOO Kernel =

This page will contain full information about the Fortran support in the ZOO Kernel.

== Fortran code snipest ==

Let us create a small example of a Fortran function which simply multiply by two the value passed as argument.

{{{
C     ex4.for 
C     ARRAYS X, Y and Z are respectively :
C     main_conf, inputs and outputs
      FUNCTION HELLOWORLD(X, Y, Z, X0) RESULT (R)
      INTEGER(4) :: R
      CHARACTER*1024 X(10,10)
      CHARACTER*1024 Y(10,10)
      CHARACTER*1024 Z(10,10)
      CHARACTER*100 X0
      CHARACTER*1024 TMP
C      CHARACTER*(*) X(1:10,1:10), Y(1:10,1:10), Z(1:10,1:10)
      PRINT *,'FROM FORTRAN : '//X0//'\n'
C      PRINT *,'FROM FORTRAN Y(1,1) : ('//Y(1,1)//')\n'
C      DO i = 2,10 
C       DO j = 2, 10
C  PRINT *,'FROM FORTRAN Y(',j,',',i,') = ['//Y(j,i)//']\n'
C END DO
C      END DO
      PRINT *,'FROM FORTRAN Y(1,1) = ('//Y(1,1)//')\n'
      PRINT *,'FROM FORTRAN Y(2,1) = ('//Y(2,1)//')\n'
      PRINT *,'FROM FORTRAN Y(3,1) = ('//Y(3,1)//')\n'
      PRINT *,'FROM FORTRAN Y(4,1) = ('//Y(4,1)//')\n'

      Z(2,1) = TRIM('name')//CHAR(0)
      Z(5,1) = 'result'//CHAR(0)
      Z(8,1) = 'value'//CHAR(0)
      Z(1,2) = 'Hello from the Fortran world !'//CHAR(0)
      Z(4,2) = 'datattype'//CHAR(0)
      Z(7,2) = 'string'//CHAR(0)

      Z(3,1) = 'name'//CHAR(0)
      Z(6,1) = 'result'//CHAR(0)
      Z(9,1) = 'value'//CHAR(0)
      Z(2,2) = 'Hello from the Fortran world !'//CHAR(0)
      Z(5,2) = 'datatype'//CHAR(0)
      Z(8,2) = 'string'//CHAR(0)

C      DO i = 1,10 
C       DO j = 1, 10
C  PRINT *,'FROM FORTRAN Z(',j,',',i,') = ['//Z(j,i)//']\n'
C END DO
C      END DO
C      PRINT *,Z(1,2)
C      PRINT *,TMP
      R = 3
      END
}}}

To create a shared library of this code snipest, use the following command :

{{{
#!sh
gfortran -fno-f2c -shared -s -o ex4.so ex4.for
}}}

Then the loading process isthe same as before, using the dlload, dlsym then use the funcion.

The snipest C++ code bellow will load, extract the function from the fortran shared library then run the function and finally close the shared library.

{{{
#!C
// ex4fortranloader.c
#include <iostream>
#include <dlfcn.h>

void inplace_trim(char* s)
{
    int start, end = strlen(s);
    for (start = 0; s[start] && isspace(s[start]); ++start) {}
    if (s[start]) {
          while (end > 0 && isspace(s[end-1]))
          --end;
    }
    memmove(s, &s[start], end - start);
    s[end - start] = '\0';
}

int main()
{
    void *hDll = dlopen("./ex3.so", RTLD_NOW);
    typedef int (* LPFNDLLFUNC) (char***,char***,char***,char*);
    LPFNDLLFUNC lpFunc = NULL;
    lpFunc = (LPFNDLLFUNC)dlsym(hDll, "helloworld_");
    int i, numPts = 10;

    /**
     * Creating the string matrix contigous
     */
    char main_conf[10][10][1024];
    char inputs[10][10][1024];
    char outputs[10][10][1024];
    printf("first allocation has been made\n");
    for(int i=0;i<10;i++){
        for(int j=0;j<10;j++){
                memset(main_conf[i][j],0,1024);
                memset(inputs[i][j],0,1024);
                memset(outputs[i][j],0,1024);
        }
    }

    sprintf(inputs[0][0],"name");
    inputs[0][0][4]=0;
    printf("inputs[0][0] = %s\n",inputs[0][0]);
    sprintf(inputs[0][1],"S");
    inputs[0][1][1]=0;
    printf("inputs[0][1] = %s\n",inputs[0][1]);
    sprintf(inputs[0][2],"value");
    inputs[0][2][5]=0;
    printf("inputs[0][2] = %s\n",inputs[0][2]);
    sprintf(inputs[0][3]," Your Name Here ");
    inputs[0][3][16]=0;
    printf("inputs[0][3] = %s\n",inputs[0][3]);
    printf("Allocation made of inputs values\n");
    char *tmp=(char*)malloc(100*sizeof(char));
    sprintf(tmp,"My Test String");
    int res=lpFunc(main_conf,inputs,outputs,tmp);
    printf("function ran successfully and retruned : %d\n",res);

    fflush(stderr);
    fflush(stdout);

    i=0;
     for(int j=0;j<10;j++){
        inplace_trim(inputs[i][j]);
     printf("Y(%d,%d)='%s' ",j+1,i+1,inputs[i][j]);
     }
     printf("\n****************\n");
     for(int j=0;j<10;j++){
        inplace_trim(outputs[i][j]);
      printf("Z(%d,%d)='%s' ",j+1,i+1,outputs[i][j]);
     }
     printf("\n****************\n");

    dlclose(hDll);
    return 0;
}
}}}

Compile this code using the following command : 
{{{
#!sh
g++ -o ex1fortranloader ex1fortranloader.cpp -ldl
}}}

Now, to process the function you'll only have to run the following command :
{{{
#!sh
./ex1fortranloader 
}}}

Which should output :
{{{
#!sh
first allocation has been made
inputs[0][0] = name
inputs[0][1] = S
inputs[0][2] = value
inputs[0][3] = Your Name Here
Allocation made of inputs values
 FROM FORTRAN : Your Name Here

 FROM FORTRAN Y(2,1) = ( name)

 FROM FORTRAN Y(5,1) = ( S)

 FROM FORTRAN Y(8,1) = ( value)

 FROM FORTRAN Y(1,2) = ( Your Name Here)

function ran successfully and retruned : 3
Y(1,1)='name' Y(2,1)='result' Y(3,1)='value' Y(4,1)='Hello from the Fortran world !' Y(5,1)='datatype' Y(6,1)='string' Y(7,1)='' Y(8,1)='' Y(9,1)='' Y(10,1)='' 
****************
Z(1,1)='' Z(2,1)='' Z(3,1)='' Z(4,1)='' Z(5,1)='' Z(6,1)='' Z(7,1)='' Z(8,1)='' Z(9,1)='' Z(10,1)='' 
****************
}}}

== Conclusion ==

So we can say that loading a C SSO (Service Shared Object) or a Fortran one work in the same way.

The goal is now to be able to pass maps* datastructure to the fortran function then let user easily get/set its data using this datastructure. Maybe a simple multidimentional array of CHARACTER* can be used. This way maps will be translated into CHARACTERS*1024 A(10,10) before being passed to the Fortran function. So this way we would get a 10*10 matrix of 1024 bytes length string.

Hopefully the code provided here display well the result value in the right array (matrix!? :) ).

== Documentation list ==

 * [http://www.math.utah.edu/software/c-with-fortran.html Using C and C++ with Fortran]
 * [http://www.idris.fr/data/cours/lang/fortran/f90/F77.html#p2.1 Fortran 77 for beginners]
 * [http://folk.uio.no/steikr/doc/f77/tutorial/index.html Fortran Tutorial]
 * [http://www.obliquity.com/computer/fortran/ FORTRAN 77 Reference]
 * [http://arnholm.org/software/cppf77/cppf77.htm Mixed language programming using C++ and FORTRAN 77]
 * [http://perso.enstimac.fr/~gaborit/lang/CoursDeFortran/ INITIATION AU FORTRAN] (in french only)