Calling a scilab function (macros) from a C gateway

Calling a scilab function (macros) from a C interface

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"

#error This code is deprecated

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.

See Also

• Scierror C gateway function which displays an error message to the user (same profil as the printf function) and returns an integer value specifying an error level
• sci_types a C enumeration which defines the types available for a variable