void __asm add64 (register __a0 struct EClockVal *dst,
                  register __a1 struct EClockVal *src);

void __asm sub64 (register __a0 struct EClockVal *dst,
                  register __a1 struct EClockVal *src);

int __asm cmp64 (register __a0 struct EClockVal *dst,
                 register __a1 struct EClockVal *src);