5.11 __indirect_jump_to Intrinsic Function

The IAR __indirect_jump_to intrinsic function jumps to the specified address via a ijmp or eijmp instruction.

Suggested Replacement

There is no MPLAB XC equivalent built-in function; however, these instructions can be inserted explicitly using in-line assembly code.

Use in-line assembly to directly write an ijmp or eijmp instruction.

Caveats

Where an eijmp instruction has been inserted, make sure to restore the state of the EIND register afterward.

Examples

Consider migrating IAR code such as:

void leap(unsigned long addr) {
    __indirect_jump_to(addr);
}

to MPLAB XC8 code similar to:

#include <xc.h>

unsigned char indirect_jump(unsigned long addr) {
#ifdef __AVR_HAVE_EIJMP_EICALL__
  /* Extract 3rd byte of address to h */
  unsigned char h = addr >> 16;
  /* Record existing EIND reg val in res */
  unsigned char res;
    __asm__("in %[EIND_SAVED], %[EIND_REG] \n\t"
            "out %[EIND_REG], %[HH] \n\t"
            "movw r30, %[ADDR] \n\t"
            "eijmp \n\t"
            : [EIND_SAVED] "=&r" (res)
            : [HH] "r" (h),
              [ADDR] "r" ((unsigned int)addr),
              [EIND_REG] "I" (_SFR_IO_ADDR(EIND))
            : "r30","r31");
  return res;
#else
    __asm__("movw r30, %0 \n\t"
            "ijmp \n\t"
            : : "r" ((unsigned int)addr) : "r30","r31");
   return 0;
#endif
}

void leap(unsigned long addr) {
    indirect_jump(addr);
}

Further Information

See the In-line Assembly section in the MPLAB XC8 C Compiler User's Guide for AVR MCUs for more information on this qualifier.