XCROM Compiler Directive

XC

None.

All xdata variables are initialized during the execution of the startup code.

Options — C51 — Misc controls.

The XCROM directive causes the compiler to store initialization for const xdata variables directly in ROM memory rather than using a table entry in ?C?INITSEG. This allows you to use xdata memory for constants and frees up code memory for your application program.

Note

• Some new 8051 devices provide memory management units that can map ROM space into the xdata memory area.
• For classic 8051 devices, you may use a ROM device instead of a RAM for the xdata space.

STRING

// "Hello World\n" is stored in a ROM that
// is addressed in the xdata memory space.

#pragma XCROM   // Enable const xdata ROM
const char xdata text [] = "Hello World\n";

void main (void)  {
  printf (text);
}