1typedef unsigned int USItype __attribute__ ((mode (SI))); 2 3USItype 4__mulsi3 (USItype a, USItype b) 5{ 6 USItype c = 0; 7 8 while (a != 0) 9 { 10 if (a & 1) 11 c += b; 12 a >>= 1; 13 b <<= 1; 14 } 15 16 return c; 17} 18