C251 User's Guide

XVAR

The XVAR macro accesses variables of any type at fixed absolute memory locations in the code memory class.

The XVAR macro is defined as:

#define XVAR(object, addr) (*((object volatile xdata *)(addr))) /* XDATA */

You may use this macro in your programs as follows:

#include <absacc.h>             /* include absolute memory access macros */
   :
   :
int i;
long l;

l = XVAR (long, 0xFFE0);        /* read long value at XDATA 0FFE0H      */
XVAR (int, 0x1000) = i;         /* write the value of i to XDATA 1000H  */

#define IO  XVAR (char, 0x1000) /* IO port at XDATA 1000H               */
if (IO == 0) IO = 1;            /* test port and write 1 to IO address  */