CALLC

The CALLC statement is used to invoke user supplied C functions compiled and built into standard libraries.

COMMAND SYNTAX

CALLC Cfunction{(argument{,...})}

or

CALLC @Variable{(argument {, argument ... })}

SYNTAX ELEMENTS

Cfunction must correspond to a valid C function name in an associated C source.

argument must correspond to a valid variable name

Variable must correspond to a valid variable name which contains the name of the C function to invoke.

NOTES

The indirect, '@', form of the statement expects the specified variable to contain the name of the 'C' function to be invoked. All arguments to be passed to and from the calling program to the 'C' function must be of type VAR and the 'C' function coded accordingly, the 'C' function should also be coded to return a result of type VAR. Refer to the jsystem.h header file and jBASE 'C' programming for more information on the jBASE VAR type. The 'C' functions should be coded in a separate source, then compiled and built into a shared library and made available to the calling program similar to subroutines

EXAMPLE

MYB - Base source program in file BP

A = 10; B = 1000
MyFunction = "MYC1"
CALLC @MyFunction
Result = CALLC MYC2(A, B)
CRT "Result is ":Result

MYC.c - 'C' source program

#include <jsystem.h>
VAR *MYC1(VAR *Result);
VAR *MYC2(VAR *Result, VAR *VarA, VAR *VarB);
/*
** Function MYC1
*/
VAR *MYC1(VAR *Result)
{
INT32 Value;
printf("Here in C function MYC1\n");
return(Result);
}
/*
** Function MYC2
*/
VAR *MYC2(VAR *Result, VAR *VarA, VAR *VarB)
{
INT32 Value;
Value = CONV_IB(VarA) * CONV_IB(VarB); /* Multiply variables after conversion to integer */
STORE_VBI(Result, Value); /* Place value in return variable */
return(Result);
}

jBC