Using Graphical Data Display Manager (GDDM)

The Graphical Data Display Manager (GDDM) provides programmers with a comprehensive set of functions for displaying or printing information in the most effective manner. The major functions provided are:

• A windowing system that the user can tailor to display selected information
• Support for presentation and interaction through the keyboard
• Comprehensive graphics support
• Fonts, including support for double-byte character sets (DBCS)
• Business image support
• Saving and restoring graphics pictures
• Support for many types of display terminals, printers, and plotters.

Because GDDM uses OS-style linkage, calls from C to GDDM require the #pragma linkage pragma, as in the following example:

#pragma linkage(identifier, OS)

In C++ code, calls to and from GDDM require that any GDDM functions you use be prototyped as extern "OS", as shown in the following example:

extern "OS" {
  ASREAD( int *type, int *num, int *count );
  CHAATT( int num, int *attrib );
  CHHATT( int num, int *attrib );
}