Use of Services by Applications

Application code should contain calls to the services as if they were ordinary function calls. Each source file containing service calls should also include the header file INTERFAC.H which contains macro definitions for each service. The macro expands the source line to a call to a common service requestor and forces pointers to far pointers, as in the code example below.

#include "interfac.h" 

Fun1() 
{ 
int x,y,attr; 
char *str; 
...  
m_disp(x,y,str,attr); 
...  
} 
effectively expands to 

#define FUN_M_DISP ((SC_SCREEN << 8)|SCR_M_DISP) 

c_service(FUN_M_DISP ,x,y,(char far *)str,attr);