Forum Post: RE: RL78 problem with hardware multiplier/divider accumulator in G13 CPUs with GCC compiler V15.01

A third possibility would be to disable interrupts while doing the multiplication. To do this you could pack the call for multiplication in a macro like this: #define MULTIPLY(IN1, IN2, OUT) \ __builtin_rl78_di ();  \ OUT = IN1 * IN2;  \ __builtin_rl78_ei ();