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Scilab help >> API Scilab > Scilab Gateway API > How to > Calling a scilab function (macros) from a C gateway

Calling a scilab function (macros) from a C gateway

Calling a scilab function (macros) from a C interface

WARNING: This API is deprecated from Scilab 5.2.0 and is going to be removed with Scilab 6.0. Please use API Scilab (the new Scilab API).

When you write a interface with scilab, you can need to call another function directly from your function. You can pass a pointer on scilab function to your function.

The source files of this example are stored in the directory examples/call_scifunction.

How to use this example:

exec call_scifunction.sce; // launch scilab 
v = call_scifunc(30,12,scilabfoo);

you pass a pointer on a scilab function (scilabfoo macro) to your function 'call_scifunc'.

C2F(scifunction) calls another scilab function (here scilabfoo).

You need to indicate :

position of the first element (Rhs) in the Scilab memory
pointer on scilab function
number of Lhs (output of scilab function called)
number of Rhs (input of scilab function called)

The script call_scifunction.sce used to build and load the C interface into Scilab is the following:

files=['sci_call_scifunc.c']; // Defines the list of file
ilib_build('callscifunc',['call_scifunc','sci_call_scifunc'],files,[]); // Build the files and creates the loader

exec loader.sce;

function r=scilabfoo(x, y)
  r = x + y;
endfunction

v = call_scifunc(30,12,scilabfoo);
disp('result : ' + string(v));

v = call_scifunc(300,120,scilabfoo);
disp('result : ' + string(v));

ulink(); // unload the dynamic library

The file sci_call_scifunc.c is the following:

#include "stack-c.h"
#include "Scierror.h"
#include "localization.h"

int sci_call_scifunc(char *fname) 
{
  int m1    = 0, n1    = 0, l1    = 0;
  int m2    = 0, n2    = 0, l2    = 0;
  int m3    = 0, n3    = 0, l3    = 0;
  int rm1   = 0, rn1   = 0, rl1   = 0;
  int m_out = 1, n_out = 1, l_out = 0;
  double v1 = 0, v2 = 0, r = 0;
  int positionFirstElementOnStackForScilabFunction = 0;
  int numberOfRhsOnScilabFunction = 0;
  int numberOfLhsOnScilabFunction = 0;
  int pointerOnScilabFunction     = 0;
        
  CheckRhs(3,3);
  CheckLhs(1,1);
        
  if (GetType(1) != sci_matrix)
  {
    Scierror(999,_("%s: Wrong type for input argument #%d: A real expected.\n"),fname,1);
    return 0;
  }
        
  GetRhsVar(1, MATRIX_OF_DOUBLE_DATATYPE, &m1, &n1, &l1);
  if ( (m1 == n1) && (n1 == 1) )
  {
    v1 = *stk(l1);
  }
  else
  {
    Scierror(999,_("%s: Wrong size for input argument #%d: A scalar expected.\n"),fname,1);
    return 0;
  }
  
  if (GetType(2) != sci_matrix)
  {
    Scierror(999,_("%s: Wrong type for input argument #%d: A real expected.\n"),fname,2);
    return 0;
  }
  
  GetRhsVar(2, MATRIX_OF_DOUBLE_DATATYPE, &m2, &n2, &l2);
  if ( (m2 == n2) && (n2 == 1) )
  {
    v2 = *stk(l2);
  }
  else
  {
    Scierror(999,_("%s: Wrong size for input argument #%d: A scalar expected.\n"),fname,2);
    return 0;
  }
  
  if (GetType(3) != sci_c_function)
  {
    Scierror(999,_("%s: Wrong type for input argument #%d: A scilab function expected.\n"),fname,3);
    return 0;
  }
  
  // get pointer on external function (here scilabfoo)
  GetRhsVar(3, EXTERNAL_DATATYPE, &m3, &n3, &l3);
        
  // r = scilabfoo(x, y)  
  // rhs eq. 2
  // lhs eq. 1
        
  // Position first element in the Scilab memory to use by Scilab Function 
  // v = call_scifunc(300,120,scilabfoo);
  // On stack : 300 is on Top position (1)
  // 120 second position
  // scilabfoo third position
  // we want to pass 300 & 120 to scilab Function
  // First position is here : 1
        
  positionFirstElementOnStackForScilabFunction = 1;
  numberOfRhsOnScilabFunction = 2;
  numberOfLhsOnScilabFunction = 1;
  pointerOnScilabFunction     = l3;

  // r = scilabfoo(x, y)  
  // Scifunction call a scilab function
  Scifunction(&positionFirstElementOnStackForScilabFunction,
              &pointerOnScilabFunction,
              &numberOfLhsOnScilabFunction,
              &numberOfRhsOnScilabFunction);  

  // result r is now on position positionFirstElementOnStackForScilabFunction on stack
  GetRhsVar(1, MATRIX_OF_DOUBLE_DATATYPE, &rm1, &rn1, &rl1);
  r = *stk(rl1);
        
  CreateVar(Rhs+1, MATRIX_OF_DOUBLE_DATATYPE, &m_out, &n_out, &l_out);
  *stk(l_out) = r;
  
  LhsVar(1) = Rhs + 1;
  
  return 0;
}

The main function in this C file is Scifunction. It allows to call a Scilab function inside a C interface.

Calling a scilab function (macros) from a C gateway

Calling a scilab function (macros) from a C interface

See Also