libgcc/config/msp430/mpy.c

   1 /* Public domain.  */
   2 extern int __mulhi3 (int, int);
   3
   4 int
   5 __mulhi3 (int x, int y)
   6 {
   7   char bit;
   8   int neg = 0;
   9   int rv = 0;
  10
  11   if (y < 0)
  12     {
  13       y = - y;
  14       neg = 1;
  15     }
  16
  17   for (bit = 0; y && bit < sizeof (y) * 8; bit ++)
  18     {
  19       if (y & 1)
  20         rv += x;
  21       x <<= 1;
  22       y >>= 1;
  23     }
  24
  25   return neg ? - rv : rv;
  26 }