User Guide

Include Files and System_Calls

Axcess Programming Language

! Place each definition section in its own include file

! Group sections of the main program into include files

! Place all subroutines into an include file

! Place routines that you want to share between multiple programs into an include file

! Place code you wish to re-use in other systems into include files

Include files are loaded and edited using the Axcess editor much like normal program files. Like

program files, the Axcess name (not the DOS name) of the include file is stored on the first line of

the file as a PROGRAM_NAME declaration.

System_Calls and Library files

Using include files makes it convenient to share pre-written code between multiple programs. For

example, if you had created a subroutine to handle an audio/video switcher, and the subroutine was

saved into an include file. If you need to use the subroutine in another program, you could insert the

include file into the new program as a pre-written piece of code.

Library files are special types of include files which have the DOS extension .LIB. The difference

between library files and include files is that library files must contain a DEFINE_CALL

subroutine with the same name as the PROGRAM_NAME on the first line of the library file. This

DEFINE_CALL can then be called from within a program using the SYSTEM_CALL keyword.

Here is an example of a small library file listing:

PROGRAM_NAME = 'SQUARE'

DEFINE_CALL 'SQUARE' (NUMBER)

{

NUMBER = NUMBER * NUMBER

}

This is the entire contents of a library file. Now, if you have a variable X which you want to square

within a program, use the following line:

SYSTEM_CALL 'SQUARE' (X)

This line generates a call to the subroutine SQUARE. This is because a SYSTEM_CALL statement

is identical to a CALL statement, except that the actual DEFINE_CALL is in a library file instead

of the main program.

In this example, after Axcess compiles the main program, it searches through all available library

files for the one that has the following statement on the first line:

PROGRAM_NAME = 'SQUARE'

When Axcess finds this file, it is compiled. Since the library file contains a DEFINE_CALL with

the same name as the PROGRAM_NAME in the file, the SYSTEM_CALL to SQUARE actually

calls the DEFINE_CALL SQUARE in this library file, as shown in FIG. 27.